Misconception: Crawl Space Dehumidifier with No Plastic or Loose Laid Vapor Barrier

[@JuddieJud]

I love your channel !! We put down a 20mm vapor barrier on the ground floor, we placed 4inches of 3/4 clear rock on top of the vapor barrier, It has brought humidity down from 65%/70% to 41% with no dehumidifier running. Thanks again for all your niche expertise man!

[@CrawlSpaceNinja]

Judson, we're glad you find our videos helpful!

[@iviaverick52]

essentially, the process is taken in steps to gradually make things better until you get to the point of full encapsulation. dehu is better than nothing, loose vapor barrier is better with a dehu than nothing, properly encapsulated crawl space with dehu is best.

[@CrawlSpaceNinja]

That is correct, thanks for watching!

[@jman4817]

Looks like it is time for me to install a vapor barrier to go with my dehumidifier! You guys are doing a great job! Thanks for all of the info!

[@CrawlSpaceNinja]

Thanks for the compliment, J Man.

[@chuckdavis4130]

I have a quandary in Central North Carolina which led me to this video. Unfortunately I'm not sure what the correct answer is in our particular situation. Soils in our area are generally unstable. We just had six helical piers installed to support part of the garage wall. Our particular location is also wet below ground. We had $20K of drainage work done several years ago on the outside of the foundation on two sides of the house and during that work there was a month's delay because the water table was above the footers. We also installed a berm on the upslope side of our lot to divert surface water to the woods. Two years ago, after a remodel, we had the crawl space encapsulated with spray foam and plastic. A 4-inch, 50 CFM inducer was installed in the HVAC system for the crawl space. After the encapsulation temperature held at 65-70 degrees year round. Humidity swung between 45% in winter to 70% in summer. Moisture was visible on the underside of the plastic membrane. Last fall parts of the kitchen started sinking, causing cracks between the crown molding and ceiling and between wall cabinets. In January we had a radon mitigation system installed under the membrane. The foundation contractor that we brought in to install piers and a beam under the kitchen said that the soil under the crawl space was too wet to support the piers. (Where they dug out for the piers was literally mud.) They installed a French drain around the entire perimeter of the crawl space with a sump pump. Some areas they dug out for the French drain had water 6-12 inches down. They had to cut away quite a bit of the membrane for the French drain, of course. Humidity in the crawl space jumped from 45% to 60%. I have an AprilAire E080 on order from your DIY store. The crawl space is 1500 sq. ft. and averages around 3 ft. in height. My quandary: Do I replace the membrane, trapping water underneath and probably making it impossible to re-level the kitchen or do I leave some (or all) of the membrane missing to allow the dehumidifier to (hopefully) pull sufficient moisture out of the top few feet of soil to stabilize that soil? As noted in your video, I understand that the dehu would probably end up running almost constantly. Any guidance or suggestions would be greatly appreciated. Is there any other way to skin this particular cat? Could the (new) radon system help in any way?

[@CrawlSpaceNinja]

70% humidity at any time is too high, the humidity level should never be above 59%, otherwise, mildew and/or mold will grow. You are doing everything that we would do and recommend, now it just needs time to drain and dry out. If you still have this issue in May, then you need to contact the company that installed the sump pump and french drain if the water isn't draining properly, also, it may take up to 3 months to dry out, each crawl space differs. What do you mean remove the membrane? Are you talking about on the ground or on the ceiling? Never ever install insulation or vapor barrier on the ceiling. If the ground, then yes, allow it to dry out for a while before installing the vapor barrier, but since it's already installed, it's fine to keep it on the ground and walls, just make sure the dehu is installed immediately to begin the drying out process, especially with humidity levels that high. There are no shortcuts to drying out and draining the crawl space, keep the radon system running and just be patient.

[@chuckdavis4130]

@@CrawlSpaceNinja Thanks for your prompt reply. The 10 mil encapsulation vapor barrier membrane is on the ground. About 20% of it has been cut away or pulled back around the unstable piers and for the French drain installation. I installed the AprilAire E080 dehumidifier (purchased from you) today. I understand that it will probably take at least several months to dry out the upper layer of soil and (hopefully) enable the piers to bear weight so that the kitchen can be jacked up and made plumb again. My quandary is what to do after the soil (hopefully) dries out.. Do I re-install/re-seal the vapor barrier membrane? This would trap the high level of soil moisture under the membrane and quite probably cause the soil under and around the piers to become soft again. Is there any chance that once the soil is dried out by the dehu, and the membrane reinstalled, that the radon system would be enough to keep the soil dry and piers stable? The dehu would keep the crawl space humidity level down, of course. Or, do I leave the soil exposed and use the dehu to continue to dry out the soil (and air), hopefully keeping the soil around the piers stable? As noted in your video, I would have to acknowledge and accept a shortened life for the dehu because of the extra run time. Other than possibly the radon system, is there any other way to actively draw moisture out of the soil with the restored membrane in place? Thanks again. This video and many of your other videos have been very helpful and informative as I've struggled with our "swamp." Also, Mary Beth was very helpful in my purchase of the AprilAire E080. (Side note - A neighbor had standing water in his crawl space and put his foot through his living room floor where it had rotted out. We really do live in a swamp.)

[@vinylrules4838]

So if you do not install a dehumidifier and have open vents, do you lay the vapor barrier loose or do you go ahead and attach the vapor barrier to the crawl space wall? In my case I will be installing a french drain. On a seperate note, an insurance company forced a local homeowner to treat the mold and encapsulate their crawl space in order to keep their homeowners insurance. Reluctantly the homeowner complied. The wood structure dry rotted and the floor collapsed. The house was deemed unsafe. The insurance company denied the claim even though they forced the homeowner to do this. Fortunately everything was in writing from the insurance company. A call to the state insurance commissioner did the trick. The Insurance company had to pay for tearing down the house and have it rebuilt. Why would the wood dry rot?

[@CrawlSpaceNinja]

Vinyl Rules, we would suggest attaching the vapor barrier to the crawl space because standing water could move a loose laid vapor barrier. Basically, the wood would dry rot if it wasn't originally dried out completely or treated for mold properly the first time. Dry Rot Mold comes from inside the wood, not on its surface.

[@kylekelley213]

Hello Michael, I am a licensed home inspector in southern Illinois. I have been seeing this one company that is doing " encapsulated crawlspaces " good plastic with spray foaming the block wall and sealing the vapor barrier, closing off all vents. I have been calling them out for sealing everything off without installing a dehumidifier or installing a return or supply duct work. When encapsulating a crawlspace it must have either a supply and return or a dehumidifier, Correct?

[@CrawlSpaceNinja]

Kyle, that is correct, but keep in mind we are saying that based on our local codes. Double check on the code requirements in Illinois as they may be different from Tennessee's. Thanks for watching!

[@tammyedinger6958]

We were told by one of your guys in Ohio to remove the existing barrier after soda blasting…. We still have some to do AND spray both coats… BUT running 6 fans & dehumidifier we are still at 75% what do we do to get it down to finish killing the mold to continue

[@dominiczuchowski6662]

If you reach out to our main office in knoxville I'd be happy to help yall out. Just ask for Dom.

[@CrawlSpaceNinja]

Were you able to get someone to assist you? If not, here is our contact form: crawlspaceninja.com/free-assessment/

[@MH-rw7gm]

We had a toilet leak in bathroom and have to replace subfloor. Looks like some mold in crawlspace, not a lot, but any isn't good. Quandry is our dryer vent duct that runs under house to outside has been missing for years so dryer has has been blowing into crawlspace plus Georgia summer heat. I would assume the mold is from toilet leak bc if caused by missing vent keeping humidity high when dryer's in use, wouldnt there be a ton of mold or fungus or an issue wayyyy before now? As I stated, duct has been long gone. Afraid adjuster will say oh i dont know if mold is from toilet leak (covered) or missing duct (not covered). The leak who knows how long it was going on before noticed. Months I know. House is 26 yrs old never had a mold or crawlspace issue before the leak...🤷‍♀️🤦‍♀️. The company coming to get rid of mold quoted for a 12 mil barrier over bare soil (can't afford encapsul), seal vents, new crawlspace door and dehumidifier. Do I need a dehum? Seal vents? I really need an expert opinion! Ty!

[@CrawlSpaceNinja]

So sorry, yes I would seal vents and use a dehumidifier. The dryer vent may have been contributing to high humidity and small amounts of mold until that leak supercharged it, but hard to say of course. In my experience some insurance adjusters look for reasons not to pay, while I have had some that went above and beyond to fix the issue.

[@worldlyamNOT]

I'm in Southern California where moisture in only a winter seasonal issue for us. We temporarily put in a vent fan blowing out, covered the other vents and put a small dehumidifier in the crawl space which has helped with the 'old house' smell and allergies. We would like to make this permanent after cleaning up the space and treating some of the wood. We were thinking of using the x70, vent fan, aprilaire dehu and outside vent covers. The crawl space is not very tall making an encapsulation almost impossible. Would this be a good solution for us and still protect the structure of the house?

[@CrawlSpaceNinja]

Yes that sounds great. if you can cover the soil with plastic, that could help keep the dehumidifier from running as much too. Hope that helps.

[@ShemBoothSpain]

question for the ninja, japanese kominka in japan have a ton of humidity, can vapor barrior be installed but no de humidifer?

[@CrawlSpaceNinja]

If the outside humidity is high where you live, typically above 60%, like it is here. You will likely need both. Hope that helps, and thanks for watching.

[@larissafranklin6944]

Renting a home that has no vents or vapor or dehumidifier. House stays so humid and smells musty. Wondering codes in east tn

[@CrawlSpaceNinja]

Always check local codes with your city. However mold is harmful if not fixed. A lot of homes may not have vents but encapsulation will help remove musty odor and mold.

[@rawendurancetricampny]

Hello. My crawlspace is 40x35. Half is a cement slab, half is loose rock and dirt. Can I cement over the rock and dirt and forego a plastic vapor barrier ? Then add the dehumidifier..?

[@CrawlSpaceNinja]

Hello Raw Endurance Tri Camp, Please check out this video "Crawl Space Concrete vs Crawl Space Vapor Barrier" kzbin.info/www/bejne/rnm8gZuunKmoe5o Thanks for watching and Have an amazing day!

[@Bonezz024]

Mine is a mess. A majority of my crawlspace is inaccessible and pretty much impossible to encapsulate without major engineer work/involvement because of the uneven dirt and tight spaces. It is not feasible for me to spend several 10s of thousands of dollars to rectify that. In that case is it still not worth it to try and put a dehumidifier down there while sealing up the vents?

[@CrawlSpaceNinja]

I think installing a dehumidifier is vital. Even if it must be mounted in the living space or attic and ducted to the crawl space.

[@marksarcevich9824]

My house is on a flood plain…. Every other year it FLOODS my crawl space… NOTHING you can do until water gos down …. Had vapor barrier but it’s a MESS every time it floods… had to remove it …. Vapor barrier is NOT a option

[@marksarcevich9824]

What can I do … I have new sump with back up with whole house Generator too …. What can. I do …?!? Thanks

[@CrawlSpaceNinja]

So sorry. Thanks for sharing.

[@stason99]

Is it Ok to have vapor barrier on the ground, but NO plastic liners on the walls, while running dehumidifiers with closed vents? So is it enough to get closed vents, proper dehumidifiers, and ground vapor barrier?

[@CrawlSpaceNinja]

Hey stason99, Check out these blogs we've done. crawlspaceninja.com/faq/are-wet-foundation-walls-bad/ crawlspaceninja.com/crawl-space-repair/misconception/loose-laid-vapor-barrier-control-moisture/ Thanks for watching and have a blessed day

[@stason99]

@@CrawlSpaceNinja Thanks! It says that generally wet walls are bad, but there's no specific mention about having dehumidifiers without plastic lining on the walls. Can this be more or less effective?

[@CrawlSpaceNinja]

This setup will work, but we would also recommend leaving one of the vents open and installing an AVS fan.

[@stason99]

@@CrawlSpaceNinja Thanks. AVS fan on exhaust, not intake, correct?

[@CrawlSpaceNinja]

@@stason99 Yes that is correct

[@stangssoftwash]

If you go below the sill about 3-4 inches whatever it may be, then what do you do about the holes in the cinderblock leading all the way down to the footer?

[@CrawlSpaceNinja]

Please tell me more. Holes in the top of the block or holes drilled for pest control in side of block?

[@brianpulley8652]

So surprisingly i live in central NC and I have no vapor barrier down and believe it or not the ground in my crawlspace is surprisingly dry and only when its extremely hot i get some condensation on my air handler....my question is for the remainder of this summer i want to put my dehumidifier down there and seal the vents to try and mitigate some of the condensation on the air handler until late winter or early spring when its definitely more comfortable to be crawling around under the house lol to put down a vapor barrier....so would the dehumidifier do any good until i did that and its abestorm SN 55 sentinel which appears to be the same as the April aire just rebranded and whats your thoughts on using block seal on concrete piers vs running plastic up them?

[@CrawlSpaceNinja]

Dehumidifiers can have a hard time drying a crawl space if the dirt is exposed without plastic covering it even if the dirt is dry but it would be recommended to go ahead and put the dehumidifier down there to try and get the wood dry if that's your only option. If you could put the plastic down even if it's just thrown to cover the dirt and put the deumidifier that would make it more energy effective.

[@happyhappyjoyjoy9795]

I'm highly sensitive to the chemicals found in vapor barriers, would you know of any materials to use in this case that don't off gas harmful chemicals?

[@CrawlSpaceNinja]

It seams just about everything today has some chemicals so I am not familiar with anything but if I do come across something, I will let you know. So sorry.

[@happyhappyjoyjoy9795]

@@CrawlSpaceNinja Thank you lots, I appreciate your response 🌟

[@CrawlSpaceNinja]

@@happyhappyjoyjoy9795 You are welcome

[@mteske1]

If crawlspace has a concrete floor should I still install vapor barrier?

[@CrawlSpaceNinja]

You can, keep in mind it is a moisture barrier

[@amv_pure]

What kind of ground though?

[@CrawlSpaceNinja]

The Art of Mixing Vinyl, basically any ground that allows moisture to evaporate through it. Thanks for watching!

[@christianjohnson6519]

1st!