High Performance Air Tight Build - How Do You Install Rigid Foam For Roof Insulation?

[@brolisimo]

There is not many videos where people build timber exposed roof and insulation on top. I think that looks amazing and this is exactly what my plan is- high ceilings with all that timber work exposed.

[@POCONOPOWERCORD]

Thanks for checking out my video and the kind words. I'd love to see your space when its done. Good luck!

[@clivewilliams3661]

I am bemused by this construction, the guy clearly hasn't got a clue what he is doing and there is no idea what he wants to achieve, he seems to be making it up as he goes along.

[@MegsCarpentry-lovedogs]

Revolutionary! Thank you so much for talking about some of the details and for visually showing what it looks like as well as in your sketch. So, one inch into the 2x10 is enough.....got it! Thank you! 🙏🇨🇦🍁☺

[@POCONOPOWERCORD]

Thanks Meg! I'd say 1-inch is enough but consult an engineer to be certain. I haven't had a problem after a few years. I've had 60 mph winds... snow loads.... no problems. Stay warm up there! And I love your dog videos! Our dogs say hi

[@jonathansage2147]

Rockwool's spec for long screw installation of comfortboard is 1.5" embedment into studs. I'd probably stick with that over 1" for peace of mind, but 1" is probably fine. Plus 1.5" wouldn't have worked for this application anyway.

[@JonnyJetPilot]

Man, that’s a crazy build! I went with a couple inches of iso board under my new metal roof, and i was shocked to see the differences in my attic temperatures. Next step is sealing off my soffit vents.

[@POCONOPOWERCORD]

Hey Jonny thanks for checking out my video. I can never go back either after air sealing and using foam insulation. What a difference right??!!

[@timquirk7551]

Love this man. I'm getting ready to do a big reno on an old cabin and planning to expose the structure and put a bunch of foam on the roof so this is great to see.

[@POCONOPOWERCORD]

Thanks Tim. Id love to see your project. That cabin will be nice looking with the timber frame exposed. Good luck with your reno.

[@aaronreynolds5206]

Thanks for posting this man, I have been searching for a way to do this exact thing.

[@POCONOPOWERCORD]

You made my day! So stoked that I could maybe help you out. Let me know if I could provide information about something.

[@Atiigo]

Thanks for this - I am doing something similar... and was not 100% confident is the design. This sets my mind at ease a bit.

[@POCONOPOWERCORD]

Thanks for checking out my video. Glad if I ended up helping.

[@twonulator]

Your attitude in the video is hilarious. I was laughing a lot. Thanks for sharing

[@POCONOPOWERCORD]

Thanks man. Wasnt sure if it would be worth editing and putting on youtube.

[@1truthseeking8]

​@@POCONOPOWERCORDperhaps the only thing initially that would have been an improvement would be "fender washers" or some sort of 4" wide plate with a hole in center to prevent the screws from just pulling through the foam... Other than that I can't wait to see how it does ..what are your thoughts about moisture? Did you consider putting some sort of tyvek or other in case moisture from inside comes up and gets trapped?

[@1truthseeking8]

​​@@POCONOPOWERCORDI am very interested in your experience, I am looking to create a log cabin "mobile" home (for R-rating, & strength) [using Shou sugi ban is a particularly striking method of preserving wood by charring it with fire.] on a flat semi trailer then tyvek, (then possible 1/4" space then one layer of rigid foam, then marine(cortan?) shipping container exterior. I plan on taking this to Alaska and wanted a very durable, and fairly resistant to entry by big creatures AND the severe cold... and possibly south into heat and high moisture... The advantage of semi trailer base is many: HIGH weight capacity, so the "Milled Beams/flat side Log walls and ceilings shouldn't be a weight issue.. but moisture is definitely a concern and the more extreme the weather or season or amount of moisture inside increases the concern... Part of the decision to use the milled beam as the interior finish to allow some breathability while also preventing areas where condensation could build up. Windows would be the MOST obvious first issue/point of condensation, then door latches, hinges, etc ... All electric and plumbing is planned to be exposed on the INTERIOR SURFACE of the milled log wall to prevent thermal bridging/condensation and obvious freeze thaw issues ... The same to be applied to all battery bays, and storage, water tanks compartments, etc -- which will be a particular challenge as anything that is NOT inside the "above" trailer deck "home" runs into additional points of contact with metal of trailer and additional possible areas of hidden moisture both from within and from outside traveling along metal and certainly openings that pass through from subfloor compartments to "home box" would have to be made additionally larger to cover the edges of the opening with the full amount of R-value insulation and moisture barrier... Obviously electric floor heating in the bottom of ALL subfloor compartments would help reduce condensation during cold - but certainly some sort of venting or air flow should be considered carefully...both to prevent fumes entering "home" air, but also for other issues. One issue that I intend to address is the battery and electric compartment being both insulated for R-value equivalent but ALSO to isolate via NON FLAMMABLE materials...and steel basin that is situated and plumbed to be "flooded" in the event of a thermal/fire event especially IF lithium batteries end up being used ... But to have the entire bank or multiple banks on a sliding draw so that if there is and issue that it can be slide OUT and drop OFF up to six feet or so away from trailer... (I am sure you have seen/ heard of the spontaneous issues that can arise with lithium batteries...

[@scottwilson2344]

So glad I found this..not many videos of this installation type. I’m just now peeling back shingles to replace a metal valley that had a huge leak because they put a crinkle in the peak which ended up cracking but worse it made a hump on the edge that nails to the plywood about a half inch gap and water ran down under the shingles into that. The people didn’t live here for seven years.. but the leak rotted the plywood and then the soffit below and then down through the Styrofoam. After all the critters got in from the soffit. So there really was no Styrofoam the water just poured down an angled 8 inch tongue and groove ceiling in a closet which, the critters are suspect, slid down and chewed up the bottom of the tongue and groove and had free reign of the house.. I found six snake skins inside 3’ to 5 1/2’…& lots of dead mice so believe it was rat snake. And there was pound upon pound of feces in the same closet where the hole in the ceiling was from the leak with a shelf right down from the hole with a pile about the size almost of a basketball of feces. All the same kind I’m thinking.snake..wow sorry for rambling but it’s crazy. The Styrofoam was gone in a big area where all the leaks and animals were and I didn’t the plywood yet which I’m going to do right after this comment. But they just used nail long spike and I don’t know what they nailed to yet but not a three-quarter inch thick tongue and groove ceiling .. and I only found four spikes in about a 5 ft.² section.. but the wildest thing to finish is the inside of this house is absolutely incredible. It’s 5000 something square-foot and it’s all exposed. Structural framing with big being and everything is Mortis and tendon with a spike through it. No glue no nails no screws just a lot of notches and half lap joinery & mortise and tenons & spikes..but outside falling apart I’m replacing a lot of cedar laps siding that’s just curl or fell off or cracked and showing OSB and I’m like you can’t let this house rot as too beautiful.. anyway I live here now because it was too far of a drive and I had to move anyway so I can stay here and work in the nicest home I’ve ever worked in. I am an interior finish carpenter for 23 yrs & framing & exterior trim & have trimmed 3 story houses with elevators on the ocean in Flagler beach & all around the beach & I’d take this house any day..can’t see or hear a neighbor…ahhh enjoy it while I can..soon as it’s fixed up I move on 😂😂☹️

[@POCONOPOWERCORD]

HI Scott thanks for checking out my video. Too bad about the leak. Sounds like a lot of critters, snakes, mice, etc found an entrance into some place warm. Its going to be a nice place when you are done and you will never forget what it was. I'd love to see what you've done there. I'm with you about not having neighbors nearby. I rather have less house and more land than more house and less land.

[@thaiiexpat10]

Funny, I am doing 5 inch on a roof now in italy. Same questions. We have CIP concrete structure so we poured 6" concrete edge around perimeters. We did similar to you. Wd had concrete dck so we anchored to concrete deck, easier. Our italian sub wanted to add 6" wood rippers vertically up the roof, anchoring down to deck, then they run Metal battens across top of insulation, screwing into yhe vertical wood nailers. Then, installed clay tile over the top.

[@POCONOPOWERCORD]

Hello from America. Thanks for checking out my video. That sounds like a fun project. Sounds like you could hit that building with a missile and it would be fine. You are lucky to find people in your area to do this type of work with extra steps. I'm now hungry for an italian sub.

[@dscott9613]

Well done, this is awesome! Before you added the insulation on top of the roof deck (the 2x10s) did you add a membrane or anything first before adding your first layer of rigid insulation or what is that black stuff? Did you have to be careful walking on top of the insulation before you had the top layer of sheathing on?

[@POCONOPOWERCORD]

Thanks for checking out my video. The black stuff on top of the 2x10s was roofing felt. 15# is pretty inexpensive and quick. I didn't know if the 2x10s would shrink more being in a conditioned space. They ended up shrinking a tiny bit and you can't see the felt. You dont have to be careful walking on the rigid insulation. The only damage I did was when I was carrying them. Really glad I added rigid foam under the slab too. I use electric for heat and a/c. The electric bill is always under $100/m.

[@ChrisMaveric]

Goddam bomb shelter!!!... super cool build dude.

[@POCONOPOWERCORD]

Thanks Chris appreciate it.

[@AnthonyRizzo-u1h]

Should be. Able to keep the place warm with a candle 😊

[@POCONOPOWERCORD]

Thanks for checking out my video. Yes the extra money and time insulating and air sealing instantly starting paying me back. We get 4 seasons here and even in the winter with the minisplit using electric to heat the building, it is less than $100/m.

[@AnthonyRizzo-u1h]

Looks great man ... 😊 good job

[@josquintibbits2871]

I saw some European videos where they add really thick insulation I think it is called Gutex. They also use really long screws but the engineers made them use a pattern of skewed and straight screws. Apparently the pattern massively changed the ductility of the structure.

[@POCONOPOWERCORD]

OH wow thanks for sharing. I haven't heard that. It makes sense though doesn't it? If the screws are mixed with angles you would have strength from different places you might have uplift. Wind can come from the north, east, south, west.... We never stop learning and innovating!

[@jonathansage2147]

Love the angled screw idea. You'd end up with crazy long screws in this application though. Would be hard to find. Way stronger, but probably overkill AF.

[@betterbuildings]

Nice job! Doing a similar project soon. Without seeing your video, am going to be doing almost the same thing with a roof. Found I could order eps to the thickness I want. Similarly, got a quote for 9" foam. May break it into two 4.5". Zone 6 Wisconsin.

[@POCONOPOWERCORD]

Thanks! I'd love to see the progress of your build. Foam shrinks a little over time so its good to do 2 layers with staggered seams vs 1 layer.

[@sinnombre5466]

beautiful

[@barbaraamoroso7020]

Love it!

[@betterbuildings]

Wondering also if you did anything to seal up the 2x10 ceiling or is that what the tape did on the eps? And, did the 2x10s stay straight and without much gap between them. I'm looking at tongue and groove 2x6's but the cost of them is a lot higher than using regular 2x10's same yellow pine.

[@POCONOPOWERCORD]

Thanks for checking out my video. I didnt seal the 2x10s. The rigid foam layers over them are all taped and each layer a staggered seam. I had found a great deal on the 2x10s and thats why I went that route. IF I found a great deal on 1x6 or 1x8 t&g maybe I would of went that way. I like that the 2x10s add strength to the roof though. Also If it was 1x boards I probably wouldnt of been able to walk on it to add the foam and would of had tighter spacing of the lvl joists.

[@DICEGEORGE]

I worry about water vapour from indoors getting into the 4 vertical sides, thinking of putting a plastic membrane under it and around it, and worrying about piercing it with screws which is both a vapour leak and a cold bridging leak ... maybe i worry too much

[@POCONOPOWERCORD]

YEah this stuff will drive you nuts because you dont want to have to re-do it later. I think its smart to obsess about getting it right. You will severely decrease the life of the home if it can't dry. From what I remember reading from professionals, is to only use plastic vapor barriers under concrete slabs. You don't want to stop water vapour from moving through your wall. It's not going to be your air barrier or insulation that stops cold from coming in. For walls, plastic is almost always unnecessary or even detrimental. What is super interesting is that when you use a vapor barrier, it doesn't need to be installed airtight. IF you use it in a crawl space, read articles about. I think I'm remembering that correctly, that it needs to cover a majority of the space to be affective. IF there are some holes poked in it, its still affective. The way my building was designed, my walls dry to the inside. They are inside the thermal break and rigid insulation. IF I added plastic inside the studs, it would turn into a mushroom farm. Good luck with your project. I'd love to hear how it goes.

[@jonathansage2147]

​@POCONOPOWERCORD I suspect that because you're leaving the rafters exposed, you should be fine with respect to drying. I did 4" of polyiso on my roof, but I'll be drywalling the ceilings, so I put a vapor diffusion port at the apex of my shed style roofs. I covered just the port slit with 4" of rockwool comfortboard, so it's vapor open and then used Dorken Delta-Trela over that. Vapor diffusion ports are only code for climate zones 1-3. I'm in 4. I'm pretty confident it will work though. Are you going to do a rain screen over the zip decking?

[@luciarael7134]

Have you looked into Hempwool or rockwool for roof insulation?

[@POCONOPOWERCORD]

Thanks for checking out my video. I'm aware of those but it works for cavity insulation. You wouldn't be able to do a 900sq ft continuous layer like I did. You would have rafters running in between each cavity. More heat loss.

[@buzzbustillos3016]

You have answered many questions 🤔🥃🇺🇲👍

[@mikegjohnston]

Genius! I love your rafters and ceiling. Where did you get the information to determine your rafter size and spacing? I can't find any calculators that work with spacing greater than 24".

[@POCONOPOWERCORD]

HI Mike There is also a website where you can add calculations. Forte Web by Weyerhauser. It was free at the time. Maybe still. It will help you design it and see if the space works and then avoid going back and forth with the engineer. Have an engineer check your work.

[@jl9678]

wow. this is like mindblowing priceless information. THANKS!!! I wish I could buy you a beer or coffee or something as Im about to do this. the 2x10 roof decks, were they tongue and groove, or butted? thanks

[@POCONOPOWERCORD]

Thanks for checking out my video! Your comment made my week! I edited the videos like I would want someone else to. I'm always looking for details about what the person is using in a video and sometimes they don't tell you. I got a great deal on the 2x10s and they are just butted up against each other. I'm happy with how it came out.

[@PatronSaintSpyridon]

should there be venting beneath the ISO or between ISO and the roofing material? I have been researching a lot for building a structurally supported cathedral roof. Most sources I find these days are doing the monopoly build where the attic and roofing becomes livable space but they all seem to still include a venting system of some sort on top of the roof while bypassing the need for a breathable soffit.

[@POCONOPOWERCORD]

Thanks for checking out my video. This is probably the part of the build that I spent the most time researching. Warm roof ? Cold roof? I'm an amateur and this was the first time building something from the ground up. So i'd get professional advice. It also depends with climate zone you are in. I found a lot of reliable info from greenbuildingadvisor and FHB and JLC. There were articles and forum topics about cathedral roofs and how to insulated them correctly.

[@Maynardd]

No, there is no reason to create a space to vent. You only need venting if there’s a space created that needs to be vented. There is no attic space here, therefore no venting.

[@markstipulkoski1389]

Nice job. I hope to build an ICF house similar to yours in a few years. I love your exposed lvl rafters and 2-by roof planks. I might consider it for myself. As for hitting the rafters with those 11" screws, one way to do it is to put screws in the facia marking the center of each rafter. Once the foam is glued down, run string lines from the rafter center marking screws up over the top of the foam. To get your screws perpendicular, you could make a jig out of stacked pieces of 2-by. Bore a perpendicular hole through the jig with a diameter about the same diameter as the screwhead. The process would be to press the point of the screw into the chalk line and then slide the jig over the screw, making sure the point of the screw stays embedded on the chalk line. The bore hole in the jig would guide the head of the screw. The important thing is to get that screw head into the bore hole from the start. I'm going into such great detail in this comment to document to my future self how to do it. Maybe someone cleverer than me will respond with a better way. Obviously not cost effective for a contractor, but that is why a DIY'er can sometimes build something bettter than contractors.

[@POCONOPOWERCORD]

Mark thanks for checking out my video. Thats a great idea on getting the long screws straight.

[@jonathansage2147]

I was worried about my contractor driving 8 inch screws through my wall assembly straight. I also suggested a jig. They scoffed at me. I'll admit, they didn't miss a single stud. Really impressed. If I had to do it, I'd drill press two holes in a 4x4, then use a mitre saw to cut down the halfway point of each hole. Slap a hinge holding the two pieces together as a single hole and put a hasp on the other side. That way you can get the screw going perfectly perpendicular every time and you can easily remove the jig once it's started.

[@jonathansage2147]

Gluing two layers of EPS together to make 4" thick 4'x8' sheets was probably a small mistake. It would have been better to lap them so the joints don't form a continuous break through that layer. That said, it looks like you lapped it with respect to the polyiso, so it's probably fine. Plus zip taping the joints was smart. Really nice roof assembly, well done.

[@Maynardd]

I think that’s more for sound. The two layers of 2.6 should be plenty of R value And he probably staggered those.

[@luishumbertochavezrodas3619]

why wouldnt you put the layer of zip system first and then the insulation?

[@POCONOPOWERCORD]

I'm under the same thinking; you want the sheathing on the inside of the insulation rigid foam (like I did with my exterior walls. Check out the Start To Finish video on this channel). I wouldn't be able to nail roofing to rigid foam though.

[@likeatr332]

@@POCONOPOWERCORD i agree, and I always like to do a single slant roof like that and have always wanted to put foam on the roof but i worry about condensation around the edges and rotting the boards... is there anywhere that made you feel safe from condensation? i'd like to figure it out myself.

[@jonathansage2147]

Specifically, the rot will happen at the roof apex if it happens at all. Since this has open rafters, I don't think he'll have a problem, though that might be wrong. I went with a vapor diffusion port covered with comfortboard 110. I'm in climate zone 4, so it's not code, but the guy who invented it and wrote the code thinks it should work. The rest of my roof has polyiso, but only 4 inches, though it wouldn't be that different from this.

[@antwain7942]

👏🏼👏🏼

[@paintersteve1970]

Turn the boards on there sides and use hurricane ties

[@herbrotter]

Depending on the jurisdiction, mostly likely they will require the imbedded depth of 1 ½ inches for a better pull-out resistance. The other possibility would be a roofing washing/cap plate underneath the screw head. In your case, since you are using 2x material, the 1 ½ depth would cause tip penetration. Most inspectors accept a sheet of CDX above the 2x material as long as the screw threads hit both. As for the Fastermaster, they should not have a problem with a grade 5 screw. Interesting on your roof insulation sandwich. Not sure exactly the R-value of the polyiso you have. With the aging factor they work in for foam, I believe you have about R-42 to R-45. Your actual performance value compared to other products the BTU retention is about twice your numbers. Thus, you have made an extremely nice sandwich.

[@POCONOPOWERCORD]

HI Herb thanks for checking out my video and complimenting my sandwich. I've also heard that. That you want 1-1/2 inch purchase. With an inch penetration that is holding the roof sheathing down, we are worrying about uplift or sideways force. Won't it be shocking if the roof blows away? And the perimeter of sheathing is screwed directly into the crazy-of-me 2x10 box I made. You might be right about the R value being less than R50. Still, compared to just fluffy insulation, in the summer and winter, I have electric heat and my bill is always less than $100 a month. I'm getting excellent performance in return of the time and money invested insulating and air sealing.

[@jamesgill5511]

"𝘋𝘦𝘱𝘦𝘯𝘥𝘪𝘯𝘨 𝘰𝘯 𝘵𝘩𝘦 𝘫𝘶𝘳𝘪𝘴𝘥𝘪𝘤𝘵𝘪𝘰𝘯, 𝘮𝘰𝘴𝘵𝘭𝘺 𝘭𝘪𝘬𝘦𝘭𝘺 𝘵𝘩𝘦𝘺 𝘸𝘪𝘭𝘭 𝘳𝘦𝘲𝘶𝘪𝘳𝘦 𝘵𝘩𝘦 𝘪𝘮𝘣𝘦𝘥𝘥𝘦𝘥 𝘥𝘦𝘱𝘵𝘩 𝘰𝘧 1 ½ 𝘪𝘯𝘤𝘩𝘦𝘴" As he mentioned, there is no inspection for the building. That doesn't mean he did anything illegal either. The UCC as adopted by PA exempts fully detached accessory buildings up to 1000sf from building permits and structural inspection as long as you follow setback and permeable area requirements. Some municipalities lower the exemption threshold to 250 or so square feet, and many urban/suburban areas of PA may even require a permit for a tiny prebuilt garden shed. The more rural an area of PA is, like where I live(and I'm assuming the same for the OP's location), the more likely the municipality is to follow the state limit. To be clear, that particular exemption to the UCC only applies to fully detached accessory buildings that aren't used as habitable space. There are also some other exemptions for 'recreational cabins' and private agricultural buildings though. Things like ADU's or mother-in-law suites are all subject to permits, inspection and require CO's regardless of their size. From his other videos the OP appears to be using this as a personal music studio/man cave rather than living space, which falls under the accessory building exemption.

[@JoshWeaverRC]

I just keep seeing the possibility to use braided cables to strap things down and around items. Possibly even from foundation over the roof and to the other foundation.

[@POCONOPOWERCORD]

I'd love to see that. Please post a video of you trying it.

[@ForTheAges]

Check out "Mr. Chickadee's" channel. He built his timber frame house and roofed it with Larsen trusses packed with mineral wool batt - on TOP of the structural roofing. I think he got R60 from it. I also like what you've done here. Just sharing another method in case you're curious.

[@POCONOPOWERCORD]

Thanks for sharing. I'm going to check it out.

[@garymitchell7551]

Could have done 2-2x10 on 4 foot centers

[@POCONOPOWERCORD]

Thanks for checking out my video. I like the way 1 lvl looks over doubled 2x10s or 2x12s.

[@GRIZYBAER]

Do you have a contact for the insulation from Albany?

[@POCONOPOWERCORD]

Send me an email

[@GRIZYBAER]

@@POCONOPOWERCORD hi, I couldn’t find your email address, is it in any of your videos?

[@herbrice8933]

How did you build this without any inspections? Didn’t you need plans an permits?

[@POCONOPOWERCORD]

Hi Herb thanks for checking out my video. I had to file a permit with my town but there is no building inspections if it’s under 1000 sqft. An electrical inspector had to inspect. Those are the rules in my area. Have a nice day.