High Performance Air Tight Build - How Do You Install Rigid Foam For Roof Insulation?
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- Опубликовано: 1 янв 2023
- What do you do if you plan 9-inches of rigid foam roof insulation? I couldn't find any exact advice online or in magazines on how to frame this. This video details how I build an open cathedral type ceiling with taped rigid foam above it. How do you build a box around 9-inches of rigid foam? I wish I saw the recent Matt Risinger video where they air seal AROUND the overhang. I probably would of framed it different. This video goes over solution I figured out. It ends up fine in the end. Do you have a better way? Please leave a comment.
I use PolyIso (Polyisocyanurate) and EPS (Expanded Polystyrene) over the roof rafters and 2x10s you see on the inside ceiling. I encapsulate the building in Huber Zip System 1/2-inch sheathing. I use a lot of Huber Zip Tape too. A lot. I use 11-inch screws to fasten everything together. I go over this design and why I think it was smarter this vs screwing into the rafters. I detail the tools and fasteners I used. I mention tools I wouldn't use again.
This building using almost no electricity to heat and cool with a mini split. It is quieter inside and the air quality is better too. The next building I build will be different. Sponsor me for that build. Come on.
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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.
Thanks for checking out my video and the kind words. I'd love to see your space when its done. Good luck!
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! 🙏🇨🇦🍁☺
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
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.
Thanks for posting this man, I have been searching for a way to do this exact thing.
You made my day! So stoked that I could maybe help you out. Let me know if I could provide information about something.
Looks great man ... 😊 good job
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.
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??!!
Bullet proof! Great job! We’re tired of cardboard built, cookie cutter houses.
Lived overseas for a decade with super insulated houses, a well insulated house will need a basement window left open once in a while, even in winter for airflow. Does little to energy loss.
Yeah why did it take so long for euro building techniques to come over to North America? I'm loving my mini split. It did fine when we had negative winter temps. Open up the basement window. Never thought of that. Makes sense though if heats rising through the house. Thanks for sharing.
You have answered many questions 🤔🥃🇺🇲👍
beautiful
Your attitude in the video is hilarious. I was laughing a lot. Thanks for sharing
Thanks man. Wasnt sure if it would be worth editing and putting on youtube.
@@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?
@@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...
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.
Thanks for this - I am doing something similar... and was not 100% confident is the design. This sets my mind at ease a bit.
Thanks for checking out my video. Glad if I ended up helping.
Should be. Able to keep the place warm with a candle 😊
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.
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.
Goddam bomb shelter!!!... super cool build dude.
Thanks Chris appreciate it.
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.
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.
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.
Mark thanks for checking out my video. Thats a great idea on getting the long screws straight.
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.
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.
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!
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.
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.
Thanks for sharing. I'm going to check it out.
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".
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.
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.
I'd love to see that. Please post a video of you trying it.
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
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.
@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?
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.
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.
Could have done 2-2x10 on 4 foot centers
Thanks for checking out my video. I like the way 1 lvl looks over doubled 2x10s or 2x12s.
why wouldnt you put the layer of zip system first and then the insulation?
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.
@@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.
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.
Do you have a contact for the insulation from Albany?
Send me an email
@@POCONOPOWERCORD hi, I couldn’t find your email address, is it in any of your videos?
How did you build this without any inspections? Didn’t you need plans an permits?
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.