The Truth About Your RV's Heated & Enclosed Underbelly // Air Sealing for Comfort and No Critters

1-Year Update Here:
• Sealing My RV's Underb...
Almost every modern RV is offered with this common selling point--a "heated and enclosed underbelly." And, really you'll find this same selling point on just about every RV regardless of the price point. You'll hear sales people bring it up frequently along with it being mentioned in RV tours time and time again. Everything from entry-level travel trailers to high-end fifth wheels come with it. But, while manufacturers all boast that they have a "heated and enclosed underbelly" have you ever actually looked at your RV's underbelly? I'm on my 5th RV and every RV that I've owned (3x Forest River, 1x Grand Design, and 1x Jayco) have all suffered from the term I'm going to coin as a "leaky underbelly." What this means is, not only is potentially conditioned air leaking in and out of your underbelly, there are also gaps and cracks for critters and bugs to easily crawl into. In today's video I'll show you how I've refined my air sealing process over the years to my current iteration on my Jayco Pinnacle. I'll use a combination of primarily zip flashing tape and expanding black foam. This video is all part of my in-depth series on the Jayco Pinnacle line-up featuring my 2021 Pinnacle 37MDQS. If you haven't seen the full video tour that kicked off the series, be sure to check it out and subscribe!
What do you think? Is it a good idea to air seal your RV's underbelly, or do you think it is better to let your underbelly "breathe" like most RV manufacturers ship their finished products to dealers? Let me know what you think in the comments below.
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#sealedunderbelly #leakyunderbelly #jaycopinnacle

[@AdventureRocks]

One year follow-up for those interested... kzbin.info/www/bejne/bpTRpaaknsaao8U

[@godrulesme8619]

Great video!!! Thank you!!! Really helpful

[@AdventureRocks]

@@godrulesme8619 thank you, appreciate that!

[@leewhizhulbert9276]

One of the interesting things, is that all RV's, depending on costs and quality, are sealed differently. An interesting way to test your RV if you have a good fan system is to turn on your fan so that it draws air from the roof into the RV and in doing so it "pressurizes" the inside of the RV. Then you can go on the outside with a bolt type sprayer filled with water and a liquid soap and spray around windows, doors and then underneath around areas that may have air leaks and you'll see bubbles if it's a smaller leak. I do have and more upscale brand motorhome and my manufacture actually uses a power blower attached to a ceiling vent to pressurize the RV to then check for air leaks. And for the bottom of the coach they use almost a truck bed liner spray to cover everything.

[@johnuppole]

My wife and I are moving to Montana, and out of convenience, we're going in our 5th wheel. My plan before we leave is to drop the underbelly, foam seal the penetrations between the floor and underbelly, add tank heating pads, insulate water lines, and then seal all penetrations in the underbelly to the outside (or as well as I can). I worked for a while doing energy audits and weatherization work, sealing up existing construction homes and installing ERV's for homes that we made tight enough to require mechanical ventilation. It's MUCH better to control the air exchanges vs letting them happen haphazardly in accordance with the surrounding atmosphere. I'm with you on the thoughts that the slides and roof vents not being 100% airtight being able to provide the passive ventilation needed to keep the air from getting too stagnant. I also intend to use a dehumidifier during the winter, to keep the moisture under control from the temperature differential. Glad to see someone applying modern building science

[@AdventureRocks]

Wow, you've got a really interesting background and experience! I've always thought it would be interesting to run a smoke blower/incense test on an RV and visually see all the air leaks. You'll have to let us know how everything turns out once your mods are finished. Great to hear about the plans and ideas.

[@jeffkemp1904]

Skirting it might make it bearable in Montana

[@rongray4118]

My wife and I are staying in our 40' Jayco Jayflight LOFT while we build a small modified Earthship Biotecture style home in Northern Nevada. Thank you for posting your video. Once we are parked on permanent concrete pad... this will be the first thing to be done!

[@johncole3010]

I would leave weep holes throughout the underbelly shell just as a way for the air to equalize letting moisture escape.

[@91CavGT5]

We just went through a winter blast here in Texas while full timing in our 2022 Columbus 379MBC. Temps dropped down to 13 degrees one night. I filled the fresh water tank prior to this and disconnected the fresh water hose. With turning the heating pads on for the holding tanks and setting the furnace to 65 degrees, we slept soundly and had zero problems. Prior to all of this I had checked the underbelly and found it to be sealed pretty nicely. I saw no gaps, no bulges, and no dips in the coroplast.

[@utsandstone]

My 20 year old Arctic Fox trailer curled down at the edges eventually. Last year I saw some cactus spines sticking in the fiberglass matting. I unscrewed the whole panel and dropped it down to find a pack rat nest in it complete with sticks, bones and other bits. I pulled off all the other panels. Also, the installers had smashed the panels with the self drilling screws causing the brittle plastic to separate. One of the screws had been driven nearly into a sewer drain pipe and last year had worn through finally causing a leak. That was the first panel I removed. I didn't need to heat the tanks anyway being in the Southwest.

[@danielhopkins3090]

The accessabelly product or underbelly panels on my Wildwood were garbage. They have cracked and I've lost two while traveling. I am in the planning process of replacing them with corrugated plastic sheet or rigid foam insulation panels. Accessabelly is thin, cheap, and poorly installed, but that is the problem with RVs today, built fast and cheap.

[@AdventureRocks]

Very helpful feedback. Thank you for sharing your experience.

[@sigfridorodriguez8511]

Thank you! for such a good Video! I myself being a little bit of a handy man got a taste of clumsy manufacturing myself after 3 travel Trailers and 3 fifth wheels of how bad these things are put together. Last owned a Jayco Seismic 5th wheel it actually spent more time getting fixed than I was able to ever use it. Needless to say, the leak from the underbelly was outrageous and critters did get in and out all the time.

[@user-cs4bz2lz2f]

If you were selling these for a living the dealership would fire 😔 you for. Telling the truth 😮 thanks 🙏👍 I live in my r.v.

[@DebbieNobodyneedstoknow1]

I totally agree. I had to seal up so many gaps in my 5th wheel. It had so many drafts

[@JeffSwal]

Love this! I'm going to do our 2022 Northpoint this week! Thanks for producing this and sharing the info.

[@AdventureRocks]

Glad to help! And congrats! You're going to love the North Point. They have so much to offer in the end, so even with the normal RV issues we all encounter, I think Jayco did such a great job on both North Point and Pinnacle. I love the new changes they've added on 2022s such as the vessel sink in bathroom and hutch/buffet on dinnette wall.

[@kaetischmalenberg222]

I had to do that to all of our campers. I used the black gorilla tape on the loose seams. I will look for that zip tape. Have to do our Pinnacle also. And used foam to keep critters out. If your brick and mortar house is completely sealed, it’s required in our state to put in an air exchanger to keep the humidity down.

[@user-ke7dk5qp6p]

I really appreciate this video. This is my 1st year owing an RV and I am looking to use it during the winter. Thanks for going over the details and sharing your expertise.

[@AdventureRocks]

Glad to hear it. Hope your experience goes well!

[@mikebailey2504]

Im considering installing angle iron around edges. Or even going over the bottom with a light corrugated metals

[@ceimo856]

Thank you for posting this video. I will be sealing up the underbelly of my 2022 Jayco 310 NP. I haven’t had any issues, but sealing makes a great preventive maintanence and makes good common sense.

[@MYAFCCA]

I do agree. I just bought a 2023 Transcend 247 BH. I just crawled underneath the underbelly and was shocked to find what I thought was cardboard and the foam. I thought that it was made of metal like underneath cars. Now I am understanding more about the corrugated plastic. I am going to take your advice to seal the air leaks. I don't see how this will protect your RV from rodents.

[@caravanstuff2827]

Thanks for posting this... it's the one thing most RV manufacture's can't seem to get right , it's pretty obvious that just attaching the skin at the edges isn't going to cut it , it needs to be secured onto the cross members as well , it would be relatively easy to do this with the frame up side down using tec screws and big washers then tape the outer edges like you have.. given the sort of money there asking these days there's really no excuse for this!!.😡💕🇺🇸🇺🇦

[@MYCHANNELWITHMYSTUFF]

A bit of information about accessibelly panels from Forrest River Forums: "After owning the camper for about 3 months, going down the highway the front AccessiBelly panel came lose and ripped out from under the camper. I had it replaced under warranty. I've now owned the camper for 15 months so it's out of warranty. The 2nd AccessiBelly panel has now done the same thing. This time I saw it hanging down at a gas station during a trip so I was able to duck tape it up before it ripped out. I just got back from my trip and went to go remove the 2nd panel only to notice that the 1st panel that was replaced under warranty is also cracked and getting ready to come apart. Looking down the underside of the camper I can see the 3rd panel is barely starting to crack too!"

[@Msrverpilot]

I totally agree with you, This a project that is on. my list and NOW that I've seen what you did, I am looking forward to doing it, I have the 42 FSKG Riverstone Legacy,and its got some AIR leaks around lots of places, BUT it still is better than My GD momentum.. Thanks again for your videos ,I have found them VERY HELPFUL , especially with the many functionality of the RAM 3500

[@AdventureRocks]

Thank you! I hope it goes smoothly. I love the Riverstone units...VERY nice!

[@Tito1984]

Just read about @Tim K Tim listed below falling off his nose trying to seal a leak in a light. I am impressed you were able to land on your feet! Could have been a lot more serious had it been a hip or arm or leg. Standing on the edge of my nose scares me and I am a rock climber. I have a Jayco Eagle and the temps surprised us by going into down to 17 degrees on our March 4th trip near Price UT. We were boondocking and I ran out of generator fuel. Furnace was set to 55 so the battery would last longer. Battery quit at 4AM then ran the generator until the fuel dried up. Yes the water froze until later, but no damage as best as I can tell. Seems there is a factory cutout for access that had started to peal. I was able reach up and feel the underside of a tank. No extra insulation. Nothing. I have been shopping for better quality 5th wheel and Northpoint and Pinnacle are on the list. Nice looking rigs, but seems to be similar attention to the underbelly as my Eagle. For the price I would have expected better quality. What about the Montana? They have a huge following of cold weather users. Anyone out there have experience working under a winter rated 5th wheel the can add some more information?

[@AdventureRocks]

The underbelly is definitely a weak spot in my opinion on both the Pinnacle and North Point, but in general in the RV industry there's a lot of marketing hype over enclosed underbellies that are very leaky and don't do a lot of favors in cold temperatures. temperatures. It's really the furnace pumping hot air constantly into the space that keeps them from freezing. I'd say until you get north of 150K MSRP such as Luxe, DRV, etc. there's probably a lot to be desired in terms of insulation. But at the same time that's not to say that models such as the Solitude or Montana don't have their selling points as well. I'd say you can't go wrong with any of them, so get what you like in terms of the design and appearance combined with the features and availability.

[@EscobarReuben]

What an AMAZING video! I've also been learning over the years from Matt Risinger. I planned to drop my underbelly and just inspect things before reinstalling it and sealing it. I'll probably add better insulation as well. Thanks again for this video. By the way, you actually sound like Matt. 😄

[@FatHeadCycles]

Matt would lose his mind over the way rvs are built. I would love to see a blower door test on an rv

[@1960tec]

I just this last month sealed up sections of the underbelly of my 2019 Jayco Eagle, but mainly did the obvious areas where’d the plastic wasn’t even tucked up ⬆️ not the frame. After watching your video I think I’ll do what you have done. I used a gorilla tape but look at the tape you mentioned. Iv also foamed areas but need to do more I think. Thanks for the video.

[@raydavis3471]

Super job with the video ! I spent 43 years in the residential construction business and attended many seminars on energy efficiency and air sealing, mostly back in the 1980's when a great many methods were tried. Some failed others were successfull. It was a trial and error time in the industry, after the "energy crisis." The common theory that was mostly settled with good testing methods and data was to seal as effectively possible, and then control fresh air and airchanges rather than be subject to stagnant outdoor air and at other times, wind blowing. No controls and allowing a house to "breathe," leaves you subject to conditions at the moment. Positive and negative pressures can also influence the moisture that can move into insulated wall cavities which is not good. So, Rv's??? Are they to be treated the same? Probably not altogether. I think that your sealing techniques are quite good, but I only question the possible occurance of a water leak that may not be noticable as soon, thence allowing for the pooling of water above the underbelly, possible interacting with some insulation and electrical components. You make very good points. One additional item for those that love the marketplace.....ZIP Stretch is an exceptional product in difficult situations. A quick search will turn up the product description. Thanks for putting this educational video. OH, here is what to ask those staunch old fashioned guys, "why does it have to breathe?"

[@thecracken9855]

Glad I came across this. Just got a 23’ Keystone Sprinter. To the underbelly I go!!

[@patrickmorrissey8429]

Nice video. Other options for tape include Eternabond and scrim tape. Both work very well when cleaned with denatured alcohol.

[@AdventureRocks]

Great tip, thank you!

[@davemoench8789]

Thanks for this! I just bought a used Pinnacle. It has several tears in the underbelly material. I searched for a fix and your video is the first I saw. I don’t need to search further. Thank you. I will be applying your suggestions to my purchase. 😊

[@AdventureRocks]

Thank you, and congrats on purchase! I really enjoyed my Pinnacle...they have so much to offer.

[@davemoench8789]

@@AdventureRocks Thank you! We’re planning on living in it full time, for some time. I did spot this video on how to deal with the slide holes, if you’re interested. Very cleaver. kzbin.info/www/bejne/a6nIXqZtit56jbssi=oymJIiO1pjO53TrE

[@oldrudedog]

I see a lot of exposed wood in storage area's, especially travel trailers. First thing I would is spray urethane on the wood to seal it and then put foam panels on it. If there's exposed wood under your bed it will get moist air on the plywood and the warm air from your mattress coming together and you will get mold!

[@dougmcnattin386]

Good subject. I have a 2019 hybrid Outback that has an underpinned underbelly. One time I noticed during a rain storm when we pulled over because of heavy rain ;that there was a river running across the floor. After investigating I found holes not sealed and even the edges of the paneling underbelly not even sealed. So I got some expanding foam Insect repellant foam. I sealed all the edges and plumbing penetrations and no more river. Also better heating in the cool months. By the way the color didtmatch so I got a good can of black spray paint and painted the foam. It worked. I may have to paint it one more timeout you can't see much under the camper anyway. I liked your follow up as well.

[@AdventureRocks]

Great feedback and ideas. Thank you for sharing!

[@NormRidg]

Thanks for the info. Looks like I have a spring project. Mine has panels using cross boards to screw them together. Need to tape those as well. Also found the cap/closet area had insulation gaps around the corners with noticeable air draft during cold weather.

[@AdventureRocks]

Thank you. Hope it goes well!

[@hiddenspringshappenings3945]

Great video. Thanks for sharing. Great ideas that I plan to implement.

[@AdventureRocks]

Thank you, appreciate the feedback

[@OutdoorsEngineer]

Great Vids! I used some Gorilla Tape and sealed the bigger gaps in my underbelly, mainly for critter passage (not the duct tape variety - they make a waterproofing tape as well similar to the flashing used in this video). Now it's time to go back and do everything for air movement. It pays to watch the entire video as I thought about the penetrations for the slides in the frame and wondered how you addressed them. No easy way. Nice work producing your content. Keep at it and your sub count will increase. Just takes time.

[@AdventureRocks]

Thank you!

[@bobmanemann3033]

Just found this video. Great summary. There are some many gaps on the Pinnacle underbelly. I covered my Pinnacle underbelly with aluminium diamond plate. Took several weeks of time. But feel much better about rain and critter intrusion.

[@AdventureRocks]

Wow, diamondplate! Impenetrable! Great idea. I bet that does an excellent job.

[@roneilparling7179]

I agree with you. Iam no engineer but my experiences have ended up with positive results

[@johnfcomeau5011]

Great video, I need to do mine. Also I like the barn you have there.

[@AdventureRocks]

Thank you!

[@garylewis327]

I think sealing it up is a good idea. Regarding the manufacturing process and the leaks that make their way to the consumer, it's no surprise. Somewhere here on KZbin there is a video of a Jayco crew putting a new trailer together. They are operating at full speed all the time. My understanding is that these workers are paid by piecework, not by the hour. So it's in their best interest to slap these things together as fast as possible and maybe to overlook imperfections that occur along the way. It's pretty well known that the first owner of an RV is the one who has to go back and forth with the dealer to get all the bugs out. I had a friend who went through this. They had driven screws through wiring harnesses that resulted in lights that didn't work, etc. There were other issues as well, but I don't remember now what they were. Apparently the quality control process is as bad as the manufacturing process.

[@scott5747]

You would think that people who actually work on RV's would comment on these sites. They would have great insight.

[@DavidLinn]

i also learned the science of sealing a building from matt, and i agree with sealing a building. it's better to use a dehumidifier or humidifier for humidity control and open a window or have a few potted plants for fresh air and be in complete control of your internal atmosphere than to let the building breathe and only be mostly in control of the temperature. same with an rv.

[@AdventureRocks]

Matt Risinger is a great resource, have learned a lot from his content. Super helpful.

[@WildnUnruly]

Potted plants? Any specific varieties? I have some mini countertop aerogardens I intend to us. Grow food: strawberries, herbs, tomatoes and use as humidity control.

[@jimmyFX]

Yes i own a house with a crawl space,2 choices,,open air to let it breath ,or condition the crawl space ,like that photo you showed,seal up and insulate it,and have furnace heat like the rtest of the house, now my Rv trailer im thinking the same,1 inch rigid insulation,front to back,full width ,posible put 2 small adjustable vents,

[@tracegentis4989]

I've lived in RV's for 30+ years. The only reason any enclosed area in any home needs to "breathe" is to carry any moisture laden air which might cause condensation on a cooler surface away. Prevention of moisture-soaking fiberglass insulation, or moisture-soaking wood which causes rotting being the primary reason for this. Otherwise, breathing or ventilating enclosed spaces in a home is completely unnecessary and unacceptable in colder climates. Enough said.

[@larryjanson4011]

back in the 1950 every building no matter how big, had windows that opened. to allow colling air in. but by the 1970's or so building were sealed closed. only ac air moved around in them. and created what is termed a "sick building". so if you do seal up your rv (this approach is the best for heating and cooling. and goes a long way to keep critters out). but you should allow some kind of controlled venting. to keep the "sick" part away. if not for the cost i would heat, and seal up my under belly.

[@raystanton238]

For many years since buildings had sealed windows, those buildings use an outside air supply fan system that distributes fresh air to all floors through the buildings main air distribution supply ducts. That outside air supply can go to a minimium allowable setting during extreme cold weather.

[@rcheas4894]

Definitely something I will be doing

[@DoctorSmartyPants]

I love your barn!!!

[@AdventureRocks]

Thank you!

[@td5997]

Great video- now I got work to do 😊

[@AdventureRocks]

Thank you. You got this!

[@vap0rtranz]

Reisinger is great. Air sealing is what RV makers never talk about. They only talk insulation. Controlled breathing needs to happen. Leaks are uncontrolled breathing. So I'm going to seal the underbelly with a one way vent to allow the vented heated air to escape and keep outside air (and bugs) out.

[@PeterGiard]

Great video. Thanks

[@AdventureRocks]

Thank you

[@JoseMartinez-pq4hl]

Mr,thank you very much ,awesomeeeeeeeee video.god bless.

[@LordFalconsword]

Having already lived in mine for 3 years, I wouldn't want to seal like that without taking EVERYTHING off underneath first. And that is a project. I'm planning on it anyway, because I really want to install Seelevel tank systems, as I have 5 tanks, and the factory system no longer works on either of the black water tanks.

[@jeanwonnacott2718]

Thank you. Just looking and dreaming. I am aware some of those dreams could become nightmares....crap. This is going to be way too much money....huh? I will have to sell my manufactured home....😢....taxes and insurance are very high now, over 2,000.00 a year, crazy....do I dare ??? ❤❤ great advice, thanks for showing me❤Jeannie in Lakeport California

[@chadmorris664]

Sealing my 2023 TT soon.

[@jakobh6257]

Great info

[@talaxee1]

Using the zip tape was an excellent idea. Looks 99.8 % better, great job. The bottom should be air tight.

[@bluestarhealingangels9162]

We skirted around the 5th wheel & around our slides we don’t get cold cold but we can get 3-4 days where it’s cold we get more wind we have heated under belly we’re in southern part in NM if we were in a colder area we would do what you all did

[@TheRealBiggerAl]

Nice job, I’ve done a little sealing on my underbelly, but now thinking I want to remove the coroplast and really see what’s going on from the factory. I’d like to shore up tanks if needed and be sure the heated part of the underbelly is efficient. I’ve run a scope in the underbelly and from what I can see the heating duct is a tangled mess and my bedroom register has about half the airflow compared to the rest of the registers.

[@AdventureRocks]

Thank you! Yeah, it seems manufacturers in general overlook the air sealing and energy efficiency details. It's been that way in the residential housing market for a long time until more recently, so not surprising to find similar issues in the RV market. You'll have to keep us posted on what you find if you dig deeper and all the improvements you make along the way + results in the end.

[@TheRealBiggerAl]

@@AdventureRocks absolutely! Nice barn BTW, I’ve learned a lot from Matt Risinger too.

[@AdventureRocks]

@@TheRealBiggerAl thank you!

[@craigwilliams1073]

Good stuff and thank you!!!

[@AdventureRocks]

Thanks for watching!

[@mishkie07]

I used industrial rubber roofing tape which is very sticky and stretches' very well. I did add some screened vents on the opposite end of the underbelly to to create a warm air flow from the the front heater connection to the underbelly. A better solution for the vents would be to have sufficient opening back into the opposite end of the living space

[@AdventureRocks]

Great idea. Thank you for sharing!

[@td5997]

What is it called if I wanted to purchase???

[@2hotscottpro]

I had 1 foot wide rubber tape on my underbelly plastic .It held on like liquid nails.Had to cut if to get a section removed.

[@JasonEmanuel]

Great idea!

[@AdventureRocks]

Thank you!

[@shawn4101]

Thanks for the video. I'm looking at Heartland Pioneer with an enclosed underbelly; however, it is not sealed to the frame. This could be an option using the zip tape.

[@AdventureRocks]

Great point, thank you!

[@spankymagee]

Fantastic points. Basically what I was thinking but wanted another opinion about it before I started fixing mine. Everything froze on my camper last weekend even with my propane heater set almost at 80 which is way too hot. But I was trying to keep it from freezing and still didn't work. Seems like this whole 'heated underbelly' thing is a way for them to just cut holes and do huge amounts of sloppy, unsealed work because they know its all going to be hidden. If my plastic sheating wasn't under there, it'd look like a nightmare because of all the huge holes and pipes going everywhere that they did haphazardly. Probably better to get one without underbelly so they do a better job initially...then do your own underbelly. Had you thought of plasti-dip spray over your Spray Foam to make it last 5x longer?

[@AdventureRocks]

Great thoughts! I'm testing a similar product from Gorilla, "Patch & Seal Waterproof" spray over the foam to see how it performs. Only did a couple test areas to make sure it performs as expected. I like the plasti dip idea too though.

[@spankymagee]

@@AdventureRocks nice, yeah Gorilla makes amazing stuff, let us know how it turns out.

[@philcathybiddy1326]

@@AdventureRocks how did plasti dip go?

[@AdventureRocks]

@@philcathybiddy1326 Seems to be holding up just fine. The areas that I sprayed it on have held up great over last year. So maybe for smaller holes or to protect expanding phone with outer layer it's a nice "finishing" touch.

[@jerryjohnson2276]

@@AdventureRocks love this video. What are your thoughts on using the plastidip as a “primer” for the Z tape? It appears the corrugations leave a small/ big enough space for ants and other tiny insects. Please don’t hesitate to tell me if I missed something.

[@valentinabadaloni6511]

Hi, incredible amount of information here!! thank you for sharing all your experience. Here comes my question, is there any type of insulation inside the under belly? asking because I want to do it on my trailer.

[@AdventureRocks]

Thank you. Some brands use no insulation. Typically as price goes up they'll at least use some kind of insulation. Most common is fiberglass bats, just like in a house, or the other common one as used (and it's in Jayco) is reflectix (shiny silver bubble wrap essentially). If I was doing it from scratch, I think I might even try the rigid 2" foamular panels (R10).

[@artsisland1683]

I have a premium 5th wheel, with the "Extreme Weather Package". I have had the "opportunity" to do repairs in both the underbelly and the roof. I was very disappointed with the lack of care and shortages of the insulation. They used both the reflective bubble and fiberglass mat products. The insulation was not at all "fitted" to the walls, with large gaps, averaging 6" along the perimeter edges. On the roof, they apparently ran out of the product from the insulation spool and it was no Insulation at all in the forward two and a half feet of the RVs ceiling. It is my belief that this is not indicative of just my RVs manufacturer, but of the entire industry. The customer can't see the quality of work, or the lack thereof, when they make their purchase. It is also my belief, the RV industry has a whole, appreciates the life expectancy of about 10 years before an RV is pretty much spent, thus driving new sales. For just a little bit more money, and especially considering the efficiencies during the construction process, they could do a much better job with sealing your RV. As an example, It is a joke that they still use butyl caulk on the roof joints when there is a far superior permanent solution by the name of Externa Bond. Same goes for ceiling the underbelly. I have been rving for 20 years and have had a lot of experience with different rigs and manufacturers. The term, lipstick and rouge apply to most of the RV industry. The RV may look nice, but they are literally thrown together by individuals that perhaps do not care about the quality that goes into their product. There are also under pressure to just get the product out and start on the next item.

[@mustangkline]

I have the scrim tape and just finished putting insulation back in areas that for some reason was removed. I’ll look for the zip tape as it appears to be a bit more flexible and less expensive than scrim tape.

[@AdventureRocks]

Thank you. I'm always amazed at how neglected the underbelly is during manufacturing. The zip tape seems to really stick and hold up though.

[@mustangkline]

@@AdventureRocks did you get a chance to look at the frame work for the tank’s? Ours are very stout compared to our old camper. We have the same model as yours built in 2019 for model year 20

[@AdventureRocks]

@@mustangklineI did not get a chance, but that is good to know for sure!

[@Joe-yn7pk]

Steel rust New England😊 if you will live in a trailer any trailer you run all your water pipes on the inside of the walls not underneath a trailer you may buy it new that way but after a few frozen pipes or remodel you will end up plumbing everything inside except a septic drain when you put a underbelly and it does not breathe the condensation for rusted frame

[@td5997]

I just looked at mine today - it’s a mess - Montana 5th wheel - what should I use to repair???

[@Docmuretta]

Hey thanks for some great videos. I'm definitely learning a lot from them. I have one question regarding this one that I can't seem to see anybody asking yet, when you said you used the either black foam insulation or the pond insulation to fill in some gaps when you said how many you can you used did you actually insulate along the frame before you put the zip tape on or did you just use that in really big gaps? I just purchased a new travel trailer and I think this definitely would help in the winter since I'll be living in it full time so I want to do this but I want to do it correctly.

[@AdventureRocks]

Thank you, appreciate the kind words. I think I ended up using 3 cans of the expanding foam in total. I did just the larger gaps (over 1/4") with foam, and then came back with the tape across all the seams to fine-tune. Some of the larger plumbing penetrations were the worst offenders as far as the foam goes.

[@BGlimme]

Accessbelly is maybe ok if installed properly by the manufacturer. However my Salem TT had these and the front one was installed with over tightened screws which cracked the plastic at the joint. They also did this on the second panel. This becomes visible as the first panel blew out from vibration and cracking from travel. So as I waited from March to June for the first unit on back order at my dealership, and now September 2022 for the install, the second panel has cracked and popped out from air turbulence. I think a half inch corrugated panel would work much better than either solution to prevent sagging. Something better suited for cold weather plastics would be recommend.

[@AdventureRocks]

Very helpful feedback. Thanks for sharing. Sorry to hear about the damage. Hopefully you can get it fixed right once and for all.

[@charlesmurphy4075]

Very in formative.

[@wango556]

I had the underbelly come off completely on the entire side from front to back while driving. One big thing I learned is that rv manufacturers just let all the wires hang and they ready on the underbelly plastic sheets. They aren’t zip tied up or anything.

[@rciii2201]

I had to pull my underbelly off to search for a leak and couldn’t believe all the wiring just laying on top of it. Pretty poor installation IMO.

[@TheMoneyBed]

I love the conceptual process you took to talk this out with everyone who are none the wiser. You're spot on with everything with air sealing the underbelly except 1 detail. Rv heating is forced air which will always take the path of least resistance. So if the underbelly is sealed, no air will flow through the 1-1/2 auxiliary duct into the underbelly. Now theist efficient way to combat this is to leave the penetrations open from the underbelly into the living space acting like a positive return register. I'm an RV tech that deals with poor hvac flow constantly...well former. Well spoken video sir! And the Pinnacle was a great choice 👌

[@AdventureRocks]

Thank you. I would not recommend sealing the penetrations in floor between underbelly and living space in an RV. Definitely not. Sealing the underbelly should only be done from the outside. Any inside penetrations should be left open, as is. That might seem counterintuitive, but sealing the penetrations would create an isolated envelope for the underbelly with no ability for moisture or variances in air to dissipate. Plus, some of those penetrations particularly in basement storage areas are enormous and not practical to seal up. Since the underbelly has vitals in it such as water lines and tanks, it is important to keep those penetrations as is, especially in cooler months for air flow. In most RVs the furnace and its built-in intake for return air is intentionally located in an area with penetrations to the underbelly and basement area for this reason to facillitate air flow. So we definitely do want to seal up the outside of the underbelly leaking to the outside world, but we do not want to seal up the underbelly's penetrations to the inside of envelope.

[@jeffwoolyhand9759]

Logically it seems like common sense especially when you're dealing with moist air all year round❗

[@dougchurch9626]

I have never used expanding foam underside of my rv's that i have had. best is i cut the spray foam flush and i use rubber waterproofing tape and all seam and pipes just like i do for a house. Never had anything freeze or issues, and i live in Northern ohio and usually camp in freezing temp , lowest 0. No problems. That wouldn't occur.

[@td5997]

Found zip tape significantly cheaper on Amazon as well as the roller .. 😊

[@fatherfoxstrongpaw8968]

yay! fellow risinger fan. :)

[@livewire2474]

Great video.. just bought a new grand design imagine and we definitely paid a hefty price and really pray for good luck with it. I went thru it with a fine tooth comb and fuck sakes the build quality is very sloppy in areas where attention to detail is completed by a blind person.. I will spend hours upon hours of upgrading this thing sealing, firming things up, adding Ridgid insulation etc etc .... Things that should not have to be done by the buyer. But it is what it is just the way they are ALL build now adays. Quantity over quality

[@AdventureRocks]

Unfortunately it is what it is. Definitely could be better.

[@joshuarobbins9264]

Make an updated video and let us know how the underbelly does after a few trips. How much work needs to be redone?

[@AdventureRocks]

Great idea. So far I've had it sealed for about 6 months. The biggest difference I've noticed is that the heat stays in the underbelly longer when temperatures are under freezing. So that's nice. The other big benefit I've noticed is that when I turn on the exhaust fan, I can choose where I want the fresh air to come from, such as a window nearby rather than it pulling air from the underbelly essentially (no strange stale smells, etc.). It'll be interesting to see how it performs over summer this year.

[@kreutztimothy]

Excellent video... I'm going through exactly the same issue with our Pinnacle. I was talking with customer service at the manufacturer and the associate promptly stated "we do have our units rated as 4 season, but we do not recommend using the RV in temperatures below 32°F as there is a chance of it freezing" 😲... Wait what!!?.. that's literally a direct contradictory to the contrary .... Furthermore, after furthering the conversation; I was informed that a "fully heated underbelly" is not stranded, and is an option. Really??!!.. that's news to me. So, now I'm trying to figure out a good way to seal up the underbelly, so our galley grey tank doesn't freeze up anymore... I really appreciate the video that you've produced..I will be looking into the tape and foam you've shown, after, I'm done adding tank heaters to the entire system.

[@AdventureRocks]

That's crazy! Clearly misinformation they gave you on phone. It's definitely standard. That's frustrating anyway. You'll be in good shape once you seal up with the tape and foam. I've tested mine down to low 20s so far and with furnace set to 54 it keeps underbelly around 39 degrees (at galley tank). If set to 67 degrees, underbelly goes up to about 45 degrees.

[@kreutztimothy]

I'll definitely be looking at getting my tank heaters on today (hopefully). We've already been at 0° with -25 wind-chill, but the skirting I have does help with that dramatically. Regardless, the tank heaters need to be on the tanks, and I definitely need to get the bottom sealed up asap. By this coming Saturday, we'll be back down in the single digits. Thanks again fire letting me know I'm not alone on this..

[@AdventureRocks]

Would love to hear the end results when you're all done!

[@kreutztimothy]

@@AdventureRocks Here's a brief update: I took the underbelly down yesterday and found absolutely no insulation nor heating duct or pipe going to the galley area. Furthermore, there is absolutely no insulation between the tanks and the corrugated underbelly; the only thing that's there is the reflecitx barrier. Additionally, when you look closer, the holes in the frame for the hydraulic lines are right next to the galley tank, and therefore, completely open to allow the cold air to go to the galley tank. Well, $80 later, there is now R36 insulation in entire living room/galley underbelly area. Once I'm done, I'll edit the video and link it here if that's ok with you.. Thanks again for starting this conversation.

[@AdventureRocks]

@@kreutztimothy Thank you. That is correct on my unit too...no fiberglass insulation in underbelly. I've seen other brands use it. I think the challenge is by the time the batts are inserted, they compress and lose performance, but still better to have the batt insulation than just the reflectrix for sure. I'd imagine that's why Jayco opted against it due to the clearance. The biggest weakness in my opinion is the leakiness of the underbelly overall. It's like having doors and windows open in your house, so no matter how good the insulation is it'll let conditioned air escape. I did a ton expanding black foam at the hydraulic lines and then used the zip tape to seal it all up. I do have a small 3" duct on my furnace plenum leading to underbelly and then blead-off from the trunk line running full length of main frame to rear. Plus there are some openings where air exchanges with underbelly at kitchen plumbing and converter box area. I think that's where Jayco is counting on the heat to get down there. Certainly could be better though. Another recommendation would be to check your front nose by the fifth wheel hitch. I had a TON of air leaking in there that led to the washer/dryer supply/sewage lines in that carpet bump out/step in bedroom creating a draft. So air sealing with foam at the outside hitch and the inside penetration on closet wall helped me too. They just have rubber flaps around hitch on mine at least. And, one other tip I did was to use duct sealing mastic on the air box/plenum off the furnace and trunk line as it was bleeding a LOT of heated air instead of going into ducts...not necessarily a bad thing since that location is within the RV envelope, but there's already a louvered register in passthrough storage for that purpose, so I'd rather have control over how much air is bleeding out. Plus that's more conditioned air to go further down the trunk line to rear of RV. I went through a hole tub of mastic between furnace plenum and AC returns/registers, etc. Please do share link. Would love to hear the difference after all your insulation and improvements. At 0-25 you're really putting it to the test for us! Thank you much for sharing!

[@mikechance3138]

I think what you've done is a definite plus, if even just keeping pests out. I also think that the rv industry as a whole, has a very long way to go when it comes to use of quality material and components. Especially considering what they currently charge for new rv's. Their QC is sorely lacking too. I mean, seriously, OSB for floor and roof decking??? Come on. Stupid. I've been rv-ing since I was a kid. It wasn't that long ago when rv's used marine grade decking for floors and roofs. Wood rot was not an issue. Not today. You're lucky if it outlasts you loan.

[@AdventureRocks]

Thank you, appreciate the feedback!

[@chrispybanana]

A practical question: how do you make sure you aren't trapping critters in the underbelly when you seal it? When they die in there, it's going to be BAD. Other than that, I agree with you completely.

[@AdventureRocks]

Great point. I'd say definitely solve the rodent problem first if you have an active infestation. However, sealing the underbelly should only be done from outside and not the inner penetrations leading to your living space. So if you did happen to seal the underbelly while you had a rodent inside, they would have a path of escape to your living space essentially.

[@trishaturnr-iw8hm]

Didn’t work for mine in Wyoming , 1st freeze , my black tank froze, had to cut open on a 2 month 5th wheel and installed a tank heater, and finally it thawed in two weeks when it warmed up , there is no insulation under my under belly . Dutchman really should put insulation in the underbelly

[@AdventureRocks]

Sorry to hear about that! One important detail is to have a heat source powerful enough to maintain above freezing in the enclosed space once sealed. Sometimes RV brands don't duct heat or at least they don't duct heat in the right places. The air sealing isn't necessarily adding R value, but rather keeping the conditioned air in the space longer as opposed to it leaking out.

[@penneyreed7316]

Thank you manufacturers for all the spray foam. It was so fun to pick it off of EVERYTHING to get at a leak where the gray tank meets it's pipe. Pry open your corporate wallet and spend a couple extra cents on doing it right

[@AdventureRocks]

Yes, I second that "thank you" for the extra foam :)

[@bradleywhite1533]

Thanks for this video! Did your underbelly come with insulation above it? If so, what kind? What are your thoughts on the necessity of that?

[@AdventureRocks]

On my Jayco they used something similar to reflectrix (foil bubblewrap-like) paper on the outermost underbelly, just inside the corrugated plastic. I've seen other brands like Grand Design fifth wheels actually put fiberglass batts though...could get messy if things ever got wet. If I was doing from scratch I like the idea of solid foamular panels...either the R-5 or R-10 panels...assuming there is enough room. But, I'd say if you're in a warmer climate then it may not be necessary. Some of the newer RVs use a single laminated piece of corrugated plastic with reflectrix-like coating on opposite side so it is all-in-one. I probably would first opt for air sealing though and then do the insulation aspect if needed.

[@bradleywhite1533]

@@AdventureRocks thanks so much for your detailed advice! Very helpful!

[@larryduvall5971]

What about expansion foam filling the entire cavities like we do in the 2x4 walls of homes?

[@AdventureRocks]

That could be interesting!

[@aaronflanagan6342]

Any worries about humidity/moisture trapped under the floor leading to mold as this may reduce ability of the space to dry out?

[@AdventureRocks]

Great point. That's the same controversial question that gets raised on houses that are sealed up, so lots of debate there. I will say on my corrugated plastic on the bottom it came with small little holes periodically throughout the field. I assume that's by design. Anyway, the holes look like small 1/8-inch holes and they're random across the middle front to back. I think of them almost like weep holes in a brick field that you'll find on a house. They're small enough that they're not going to reduce the performance of the underbelly, but large enough that if a tank or something else were to spring a leak that it'd drain through them. But that same space is connected to the living space through various plumbing and electrical penetrations or even the basement storage in the case of a fifth wheel.

[@jacquelinetatem175]

Would a stationary motor home ( no travel) need an underbelly wrap ? Homes on crawl spaces don’t have underbelly wrap. Could you not just insulate and seal ? Also t you can’t see leaks or fallen insulation when you have the underbelly wrap. I do have a vinyl skirt around the trailer . Awaiting an answer . Thanx

[@AdventureRocks]

Motorhomes are a little bit different in the way they're built compared to towables, so this video is strictly for towables like fifth wheels and travel trailers that use the corrugated plastic for underbelly. It's possible your motorhome could be sealed using zip tape, but again it's built quite a bit differently so just not certain without seeing it.

[@tomilee78]

Sealing the underbelly is a great idea. Did you also air seal the slide outs?

[@AdventureRocks]

Not yet, but 2.0!

[@BeeGee7719]

Any ideas on how to seal inside vents to generate more airflow into the other rooms? Currently, for some reason or another, our furnace control is in the bedroom instead of the main living room. There are also 2 floor vents in the bedroom. One in the restroom & one in the bedroom. Lots of airflow out of those and warms up quick but there is barely any flow to the other rooms. Any suggestions? Thanks

[@AdventureRocks]

Yes, actually I had the same exact problem in my unit with the bunkroom! Very common in RVs the way they are built. I used some sheet metal to create a "defectlor" that pinches off the hot air from furnace on that particular register. It's nearly invisible, super cheap/easy to implement, and solves the problem. Here's a link to timecode in the other video: kzbin.info/www/bejne/b16UiJhpbauCipo

[@jet0577]

@@AdventureRocks awesome idea. Thanks! Yes they put one in the small bathroom we have and it's really not needed since the bedroom is a bit small. We have a toy hauler and scarificed bedroom room for a bigger living space and back room(toy hauler area). But thanks again I will try this.

[@gregpatey6355]

the underbelly HAS to be SEALED.... any one who ever travels a gravel road in an rv with corroplast underbelly cover will wonder where all the dust comes from... it comes from the underbelly, as if its UNsealed, it will act like a vacuum and suck dust into the underbelly, and because of the slight vacuum effect that is in the living space of the rv as it moves down the road, it will suck the dust inside.... when i moved from an older toyhauler to a luxury 5thwheel, i was extremely disappointed in how there seemed to be no way to keep the dust out.... but after trying to seal the underbelly from where the dust was coming from, it has minimized it to almost zero dust intrusion when traveling down dusty roads.... if there is ANY controversy surrounding this, the ones who oppose the sealing of the underbelly dont have enough education in the matter to be an authority...so their advice and opinions are moot..... if it cant get wet, it doesnt need to dry out... if the air movement is so slow that it goes stale, its good insulation from heat and cold..... if its fully sealed, no rodents (or dust or road spray) can get in...... but if the corroplast is ventilated to the atmosphere in any purposeful manner, what is the point of it even being installed?..... all the ventilation it will ever need is supplied by the single 2" furnace duct that blows in when the furnace is working, which will keep the chill out, with the air being kept fresh and dry...

[@AdventureRocks]

Great points!

[@AdventureRocks]

I had not thought about dust coming in from the outside before, but that's a great point.

[@michelebeglau2821]

How easy it to remove the zip tape and how do you do it. Thank you

[@AdventureRocks]

It'll peel off mostly like any other tape or similar to a duct tape. It stays together typically as one piece as it has some stretch to it (no fiberglass or twine like duct tape). The zip tape is pretty tacky, but not permanent if you don't want it to be. So if you ever had to service it isn't a problem to remove.

[@NoleMercy]

I feel like air flow from a enclosed underbelly is not intentional from the manufacturer, therefore sealing it to improve your heating/cooling efficiency would be a good thing. I'm no expert by any means, but I am a builder of things and there's plenty of ways you get airflow in an RV than relying on stale, dirty, dank air from the underbelly. Just mho tho 🤷

[@leighsheppard8614]

My underbelly is packed with about 8-10 inches of Fiberglass Pink insulation. Because it is now over 15 years old, dirty and water damaged in several places, I am planning on replacing the whole thing with Coroplast lined with Reflectix and rigid foam insulation.. However, I notice you don't seem to have any insulation in your underbelly. Is it not a good idea to insulate the underbelly?

[@AdventureRocks]

The insulation package kind of varies for manufacturer to manufacturer, but with Jayco at least it seems it is more common to use the reflectrix and count that as r value, even though some might debate the legitimacy of reflectrix by itself. Anyway, all that to say, I think it is more common to see fiberglass bat insulation from RV manufacturers in the underbelly. I like your idea of the rigid foam insulation. I've often thought that'd be a great solution as you can get a R-5 per in so with a 2-in panel that's R-10...not bad. Plus it looks very neat and should be easy to install between the frame rails and stay in place well. I've often thought that then I would come back with some expanding foam and fill in the gaps between the foam panels and the frame to make a nice, tight seal. The main provision I would make is some weep holes in insulation panels, especially around the tanks and anywhere that water could leak potentially so that you would know about it rather than keep all that water trapped. And then perhaps some cutouts where valves are or any important motors so that you could get easy access in the future.

[@corywadedavis]

I wish that RV manufacturers would abandon the ridiculous styling inside and out and opt for clean lines and light, simple interiors. I HATE how our 2012 Montana looks-faux fancy. I also wish they'd spec dual pane windows as standard.

[@AdventureRocks]

Agree

[@twandarenovations4596]

I have a smaller camper and it is the first camper I have owned with an underbelly. It has some bad water damage on all four corners of the floor only. We took down the paneling in the corners and none of the insulation or studs are wet or appear to never have been wet. Leaving me to believe that water is getting trapped between the floor and underbelly and just sitting there causing some major damage. If you do not need the trailer to be four season is it wise to cut out the underbelly? I know I have to find the plumbing leak. But afraid that if I find it get everything cleaned up that it will happen again and you won’t notice until it has done damage again.

[@AdventureRocks]

A couple options there. You can add some access doors by cutting three sides of a rectangle in the underbelly and leaving the fourth side as a hinge and then just taping up the three sides when you're not needing access. Just make sure that the flap is cut such that the hinge faces forward, so that if it came undone while driving, the flap would naturally want to stay shut. And then another good idea is to add some weep holes, just small eighth inch or quarter inch holes in the underbelly I'm areas that you suspect may be problematic and that way if they did sprout leaks, you'd at least have some exit paths in the underbelly to see dripping indicating that you've got a problem again.

[@AdventureRocks]

@Mrs Overton That is crazy. I've seen some where the corrugated plastic sits on the outside of frame and then rain water gets trapped in the corrugated channels...super hard to get out then as it adds weight to middle and causes underbelly to bulge downward.

[@MsSherriSan]

What are your thoughts on if there is a leak somewhere? I’m thinking of doing this but wondering about a potential leak

[@AdventureRocks]

Yes, great question. So on my corrugated plastic on the bottom it came with small little holes periodically throughout the field. I assume that's by design, but curious if you notice the same on yours? Anyway, the holes look like small 1/8-inch holes and they're random across the middle front to back. I think of them almost like weep holes in a brick field that you'll find on a house. They're small enough that they're not going to reduce the performance of the underbelly, but large enough that if a tank or something else were to spring a leak that it'd drain through them. I suppose if you don't have them already on yours you could scatter some along the middle where the low points are located.

[@MsSherriSan]

Mine doesn’t have that but I considered adding it. Good to know. Thanks.

[@davidmontanez9066]

Professional

[@kevinburroughs6583]

2 Questions: Did you cut out the old spray foam before applying the new foam, or did you just put it around the existing foam? What do you do if you have to do a repair under the RV?

[@AdventureRocks]

In some cases I had to remove old spray foam, but othertimes it worked just to add on. It'll stick to itself and bond old to new, so no problem either way. Sometimes the old looked so sloppy, that I trimmed it too. On other question, access doors are the way to go for servicability. Here's a 1-year follow-up on the sealing where I discuss and show how to make one: kzbin.info/www/bejne/bpTRpaaknsaao8U

[@pierresarrazin4901]

Why do I have some vents on the bottom of my cover on my RV

[@AdventureRocks]

That's unusual. Could be something in there that needs to breathe, but hard to know for sure. What make and model do you have?

[@dondartt684]

We had mice so sealed up the underside and any whole the size of a dime.

[@AdventureRocks]

It's crazy how small of a hole that nice can sneak in.

[@michaelmazzucco]

Any reason you didn't just use the Typical mesh underbelly tape?

[@AdventureRocks]

The zip tape seems to be a lot tackier and stretchier. And if you do need to remove it, it doesn't seem to leave as much residue behind. I had used it when I built my barn for the zip panels and liked how it performed.

[@michaelmazzucco]

@AdventureRocks would you recommend this over the fabric underbelly tape for seaming repair cuts? In other words, do you think it performs better for keeping 2 panels tied together or do you recommend it just for sealing? I have some cuts underneath mine that rely on tape holding them together at this point.

[@AdventureRocks]

@@michaelmazzucco I like the zip tape better personally. It's kinda unconventional in the RV industry, but I have a lot of experience working with it after doing all the seams on barn. Key is to use alcohol or something similar to clean surfaces first and then roll it out right away to make good adhesion. I'm going on two years already and none has come undone on mine. Just my opinion though! :)

[@buzzhead817]

I have wondered about that should i seal all the air spaces

[@AdventureRocks]

It's worked great for me...about a year in now. The main thing is to leave the penetrations between your living space and basement/underbelly open, as is and only seal up the outer cracks/penetrations leading to the outside air. I still have some weep holes in the underbelly, but nothing like the giant gaps and cracks that mice and bugs could crawl into. I think of it kinda like the difference between having a door or window wide open versus cracked slightly.

[@buzzhead817]

Thank you for reading my email i am really into my rv and I want to make it solid i have a 2021 jayco eagle ht 24 re and me and my wife love it i pull it with my 2006 dodge 3500 4x4 5,9 the max weight is 9200 lbs my truck pulls it great i also have 242.000 miles on my truck I live in Texas we went all the way to South Carolina to pick it up I was averaging 13 to 10 miles to the gallon this was before gasoline price’s went up

[@AdventureRocks]

@@buzzhead817 Very nice combo!

[@AndrewMcSpadden]

Did you remove the underbelly first and then do the tape?

[@AdventureRocks]

On my unit the way the underbelly panel is mounted I simply cleaned both the underbelly and i-beam with alcohol first and then gently applied it to both substrates, running it out. But before doing that, I used the expanding foam to seal off the larger gaps.

[@AndrewMcSpadden]

@@AdventureRocks got it, ya that was my confusion. If the sealing foam was between the cab and the underbelly or on the ground side of the underbelly. Thanks! How is it holding up?

[@AdventureRocks]

@@AndrewMcSpadden It's been about 7 months since I sealed everything up, and I've noticed the biggest difference in the winter months as the heated furnace air stays much longer in the underbelly. And in the warmer months I've noticed that when I turn an exhaust fan on, I get to choose where the air comes from instead of it defaulting to the leaky underbelly. The zip tape itself has held up as expected, no peeling at all. It's so tacky that it'll stick firmly to just about anything.

[@alpinglow]

Breathable with drains at lowest points? Tyvek??? I have a project coming up where I have to redo an underbelly and there are SO many opinions on the best way but noone seems to agree. That's concerning!!!

[@AdventureRocks]

Do what makes sense to you. Basically YOU want to control where the air (or liquid) comes in/out. Each rig is different so gotta think through the variables and choose best option. Tyvek may be too thin...probably better in a vertical application.

[@raystanton238]

Does this 5th wheel manufacturer claim it's rated for 4 seasons or that it has some kind of arctic package? Look at 14:30 minutes in the video and you'll see the tanks drain piping and dump valves are "outside" of the heated underbelly. In below freezing temps that piping could easily freeze and break! I recently saw a new Keystone trailer that was claimed to be 4 seasons rated with the same exposed dump valves and piping. Having heated tanks is not going to prevent those pipes from freezing. A true 4 seasons camper will have the cable operated dump valves inside the underbelly. So be aware of manufacturers claims.

[@AdventureRocks]

Yes, the actual valves are typically right off the tanks inside the underbelly for best practices requiring a cable driven actuator. Hard to know which brand or model was featured in the AccessiBelly marketing photos...it could just be a dummy model for all we know.