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- เผยแพร่เมื่อ 13 พ.ย. 2018
- UPDATE!!--- How's the foam doing 3 years later: • Will rigid foam cause ...
Better than spray foam (thermal break and relatively consistent R-30+). Here's how to use 3 layers of 2 inch polyiso foam board to meet code and keep your new upstairs cozy.
**UPDATE WATCH THIS BEFORE YOU CUT FOAM • What is the best tool ...
I used a 2 inch rigid polyiso foam (GAF Energyguard) I got from a local roofing supply company (ABC Roofing). It is really the type of foam they use on commercial roofs beneath a membrane. I believe mine was made by GAF, and ran me about $18 per 4x8' sheet. I cut two layers to fit in the rafter bays (so that's 4 inches), spaced 1&1/2" away from the roof-deck with scraps of 2x4s (which maxed out my 5 1/2" inch rafters). Then I put another layer across the rafters, which made a total of 6 inches of polyiso. Each inch was R-5.4, so the total R value of all 3 layers was 32.4. Wherever there were gaps, I squirted some Great Stuff in, then shaved the overflow back with a flush cut hand-saw.-- Yes, it passed insulation inspection.
My other channel: / @scratchingthesurface2555
Disclaimer:
If you choose to imitate, duplicate or copy anything you may have observed in these videos, you do so at your own risk. The creator of this content does not take any responsibility for any action taken as a result of the information or advice on this TH-cam channel (or other platforms) and shall not have any liability in respect of any injury or damage that may result. - แนวปฏิบัติและการใช้ชีวิต
I did a project similar to this. A problem that occurred with it was that our vapor barrier got punctured allowing bathroom moisture into the insulation cavity. One wiring penetration wasn’t tightened up. 5 years later there was moisture in that insulation space and some rot in the roof deck. Roofer found it. We went back and fixed it. You can’t be too careful when you insulate in a space like that, especially if there is a shower in a bathroom or a kitchen. Venting moisture sources is so important.
This is a good book. Does provide a step by step introduction to how to build things th-cam.com/users/postUgkxhgbP-6hUnXu_QRaoHgLztgsI0YF3HqR0 , also does offer some steps. Includes pictures to give you ideas for layouts and such. If you are looking for a guide, this is not exactly what you want. But if you are trying to familiarize yourself with the way that pole barn building and other out buildings, are made, then this will work just as you need it to. A few things in this book are a barn (of course), detached garage, storage building, and coops.
Pretty ingenious. And I like how you left the all important gap between the roof decking and foam. And the third layer of foam stops the thermal bridging.
By "thermal bridging" you mean where the lumber, in this case joists, leave gaps that are not insulated? (I'm a lay person). I am curious, How think can you go on that third sheet? And how do you hang and join the drywall? It seems like it would be really hard to do it well.
@@bigtimepimpin666I want to see how that goes as well. Just longer screw I imagine would suffice for hanging the drywall.
Cant thank you enough for posting this. I'm considering a diy for my attic and the visual of your thought process is enormously helpful. Thanks dude!
Glad it was helpful!
TIP for working with insulation and fiberglass or polycarbonate translucent/transparent panels: Reverse your saw blade. It still cuts like butter through the materials but it does not kick out so much stuff all over the place.
Berkey Family this stuff cuts with a knife...
@@jeffborders5526
Whatever tickles your fancy!
Also reverse blade works to cut any thin aluminum siding - good thinking
Tried that out in a new video th-cam.com/video/Z292iuV91hA/w-d-xo.html
Are you saying that three layers of that expensive stuff is cheaper than spray foam
Your video is great, it is drawing out a plethora of comments from which we can overthink everything. We think you did a great job and credit you for pioneering this system. A friend did well with a cold roof design 20 years ago. (Your 1 1/2" spacing kept his shingles strong). Our plan was one layer of foam board followed by spray but you showed this to be more economical.
Thank you for your kind comments!
One could slightly improve this concept by have one side of foam board have the radiant reflector foil facing the under roof gap side.
What’s the r-factor if doing one slice of the foam board and then spray foam on top?
That’s exactly the idea I’ve been batting around in my head for years. Thanks for the vid.
😆 batting
I know Im asking randomly but does any of you know a way to log back into an Instagram account..?
I was stupid forgot my password. I would appreciate any assistance you can give me.
@Duke Gatlin Instablaster =)
@Chandler Pablo thanks so much for your reply. I got to the site thru google and I'm trying it out now.
Takes a while so I will get back to you later with my results.
@Chandler Pablo It did the trick and I now got access to my account again. Im so happy:D
Thanks so much, you saved my ass :D
Nice Work. Thank you for reaching out to help others !
I use a big shop vac hooked to the table saw for all my long rips. It cuts down on the foam board dust. Lots of dust like you show.
I had the same issue. We need only 1" of air gap above the insulation here in CA. Sister 1x2's to the rafters to give yourself 8" of space. Then take two layers of r-15, which will be 7" thick. Install normally. Prego.
Hi Dave, thanks for this vid. Last Nov 2019 I applied your technique in the porch ceiling of my home and made it into a cathedral ceiling! I want to thank you for caring to prepare and edit and share your video. Throughout the layering of insulation I incorporated two different layers of bubble foil for radiant heat effect. :) You rock! Imitation is the best form of flattery. This proverb imitation is the sincerest form of flattery means that one imitates someone else because one admires that person or values what that person is doing. Cheers from Atlantic Canada during Covid pandemic :)
I am thoroughly flattered! I'd like to know how the bubble foil goes. Sounds like a toasty upgrade. Thanks so much for the kind comment!
@@FamilyFriendlyDIY You are most welcome and most deserving of supportive comments. Bubble foil is a thicker version of reflective foil. Here were the layers that were placed and I am so thrilled from the results mostly due to your dedication to helping others in projects like this. Hi. No spray foam in my cathedral ceiling project. Here is the layering starting from under the roof sheathing; 2 inch air space, reflective foil facing up towards roof sheathing, 6 inches of XPS styrofoam)R5/1inch=30R rating! yupeee!!! Then a vapour barrier, another layer of reflective foil but this time facing down towards living space area, 3/4 inch strapping which also helps in creating the air space the reflective foil application needs for radiant effect to take place, ceiling planks are also attached to the strapping and voila! It was quite a project with lots of caulking for air gaps and sealing joints and a sprinkle of can spray foam here and there for the gaps as well. Stay safe Dave during covid! Scary times!
Thanks for all the detail! Many vids will tell you some and show nothing. Awesome job!
I like how the 3rd layer covers the roof rafters, makes it a little harder on the drywall hanger but it does save a lot of energy. It's amazing just how much energy you lose from wooden studs.
Thermal bridging can be eliminated by strapping.
What's strapping?
Thank you!! I’m a bit of a DIYer - redoing a master bedroom in a bungalow up in MA - 4x6 rafters. I was going to go closed cell spray foam because I didn’t want to lose headspace, but it’s so $$$! This video has completely changed my direction. Found R13 2” polyiso board - 3 layers will get me up to a compliant R 39 in my area and it will save me THOUSANDS. You are the man!
Awesome. Glad to have helped. Thanks for your comment!
Plus on site cell foam is always a crap shoot in terms of mixing and applying chemicals correctly...if not right you cna only correct with a new roof !!
In our area, home dep. sell a 2” thick iso board rated @ about R-13+, that has a heavy foil face on both sides. I’d advise sealing the edges using a good foil tape if edge is exposed.
Our attics are Code @ R-40. Unfortunately, most common roof framing is the cheap trusses, which have too-narrow an eave angle to fit even R-20 nearer the wall edge.
It’s tricky retrofitting that for better insulation.
Here, we plan to push-out walls under the eaves, to gain interior space, and install exterior insulation..which will also help those narrow angles in the attic periphery be better insulated. Strategic deco ceiling-to-wall Coving at those edges can also camouflage more insulation there.
Thanks. This gives me a good starting point.
Thank you for your effort and very helpful video.
hint for working with fibreglass.
stay as cool as possible, and don't sweat. if this means planning your work for cool days, do so!!!
Take a full, cool shower immediately after working, THEN heat yourself back up after you're fully scrubbed with the cold water.
This helps BIG TIME for the itchiness.
Have done similar - but with Festool TS55 hooked up to shop vac - absolutely minimum dust and super accurate cuts leaving only the awkward fitment requiring ‘filling’ the fit was so good that I could only press the insulation boards home slowly as had to allow the air pressure to dissipate.😀👍
Nice.
Liked your technic, thanks for sharing !!
Looks good; depending on how how hot your summer gets; a 10" auto shutter fan on one or both ends of the ridge would be a good addition; I had ridge vents across the entire length; and the heat still hangs without any prime mover.
Peace
I had the idea of doing this. You’re the first video i’ve Found on it!
did you try it yet?
LOVE the rain on the roof. Great place to sleep.
I used this exact material for my house addition. Fortunately, a manufacturer is only about 10 miles from me and sold "seconds" for a fraction of the cost of new. I saved myself thousands, but it was a lot of work and a itchy mess. I filled 2x10 rafters, so my R value was over 50. FWIW, a table saw works well to cut the material.
That's awesome, Bob. ... I did another video on cutting it, didn't try a table-saw though th-cam.com/video/Z292iuV91hA/w-d-xo.html
Bosch T313AW3 jig saw blade is designed to cut foam and will do so with little or no dust. 3 blades for $15 on Amazon.
Also you can create a box fan with filters in the back.
That's very cool. I had taken an old PC power supply and hooked it up to three strands of SS wire twisted to make a heating element and cut my 2" foam board that way but will try these blades. Doing the same thing this guy is but was looking for a better method before I move forward. My board is 100% foamular no fiber. I had used that do-it-your self foam but that stuff is a pain in the but and $$$. They want $125 for the hose $ gun then you have to keep going no stopping or you will probably have to buy another hose and gun since it get stopped up and changes the mixture colossal mess and waste of money. I would only use it on a boat hull not a house space. Thanks again for that tip brother.
Is Amazon the only online source ...? ! Bezos has enough wealth...wait a little longer and buy elsewhere. America doesn't need monopolies and trillionaires !
Earnie g
Cool. Thanks. I wonder if a sharp utility knife would work. No dust there.
You can use a Stinger cap nailer with 2” cap nail coils to make quick work of attaching the last layer of iso insulation to rafters.
How ya gonna do that when the foam board is 2"? Hmmm? :)
Looks like a toasty warm attic now, and for less money than spray foam! TY carpenter.
Thank you so much for this!! Your right you are the only video I have found that has the exact way my house is. So thank you!!
Glad it was helpful!
Forget the worm drive or hand saw. Us an electric Turkey carving knife. Works awesome!! Thanks for the video.
Or a hot knife works even better, no dust and leaves a cleaner edge. Super cheap as well.
My battery powered sawzall works really well although it takes a bit of skill to make nice cuts.
@@ShuasiBjorlen Hot Knife gives off alot of nasties when cutting chemical foam be careful man.
Yeah, it's like pick your poison. Good respirator for sure
Yes carving knife, also Bosch scalloped jig saw blade for more custom cuts
Polyiso foam cuts easily using a snap-off knife extended. Usually 2 passes with the knife will cut the foam cleanly. Plus this is quiet and no foam flying everywhere.
Exactly. I have cut hundreds of sheets that way. Probably thousands.
But you can't cut out notches like he was doing. A Jig saw with a foam blade is what he needed.
Spot on. I always use an extending, snap-off, Stanley type craft knife to cut foam (and polystyrene) and I get no dust, no mess and accurate cuts.
I can't believe how people use saw to cut it!
Home in the Earth Yes you can, it is very easy to do. I do it all the time.
opkcts especially circular saws. I don’t get that at all. Creates a huge mess.
Holy crap what a savings. Well worth the effort I'd say. I had no idea spray foam was so expensive. Whomever occupies that room will appreciate it because without that insulation it would be a sauna up there. I have a similar attic room and I actually tacked up on the ceiling this foil radiant barrier they sell at Home Depot. It's quilted with an air pocket built in and made a huge difference. Then I screwed down a grid of those 1x2 wood battens on top of the foil blanket and tacked on cedar planks for a cedar ceiling, so there's an air gap between the foil and the cedar ceiling. Must have dropped the room temperature down by 10 degrees or more.
Thanks for the comment. I'm sure some others might want to try that with the foil too. I saw it at HD too and was wondering how it would work. That's useful info.
Wow! I scanned the comments and found I already saw this..... I have officially watched every video on TH-cam and am starting again!
This video is a great place to start! tHanks for the video!
Ha ha! Thanks for the comment :-)
Because the portion of the wall is sloped, in Canada, it's considered a wall, as far as R-Value requirements. However, an air space of 2 1/2 inch is required. This is required to prevent choking air circulation between other compartments.
inaccurate
@@frostycools1315 Because..
@@p0llenp0ny r -50 is the min not r-30 , studs screwed not nailed, vapor seal boxes in interior partitions, no poly on top plates, and i only looked for less then 3 min of the video
Genius! I just purchased an old home with 2x6 rafters, and someone back in the 70s or 80s hung fiberglass insulation right against the boards that the shingles are attached to (on the underside obviously). I’ll have to rip that stuff down, but I’ll give this method a try. THANKS!
May you endeavor be a successful one. Thanks for the comment!
I have the same issue.
I just bought a home from the 20s and the only tring under the roof decking is a layer of air then on the underside of the rafters are stapled cardboard boxes 🤦♂️
Well done!!!! Where we live it is R22 on the diagonal & Vertical & R60 in top horizontal (Attic). Never thought of using your method and it is indeed a sound solution. Just as effective as sprayfoam but without the cost and possible off-gasing (if the two chemicals are not mixed just right). If I ever have to do this again I will copy your solution! Bravo
Polyiso off gasses for years, what’s the difference? At least spray foam won’t shrink and have gaps like this does.
@@brucea550 sprayfoam can offgas if the two chems are not mixed perfectly. Rigid foam does not. Gaps can be filled. If mixed right, spray foam is good but limited to the building structure. It is a death nail to older homes if used on double or triple brick construction. Eventually creates blowout in bricks.
@@JB-ct3cr how does it create blowout of bricks?
@@matthewmatheny A double brick wall has an air gap between the two walls that cross over every 5th or 6th course where the bricks are perpendicular to the course. This interlocks the two walls. That air gap was intended to let some heat from inside the house to penetrate through the inner course and thaw out any moisture that accumulated on the inside of the outter wall. Keep in mind that when these houses were built insulation was not what it is today. You were lucky if you got horse hair. Our home was built in 1886 and had none. Double brick walls use the suns radiant heat to warm up the walls creating an R13 effect while working with internal escaping heat to thaw out walls. All that being said, if you starve out oxygen and internal heat from hitting the inner wall then the outter wall becomes more impacted to thaw/freeze. As that water accumulates in the brick over time the freezing expansion breaks down the brick. It takes time but it is a guarantee. Batt insulation against a double brick wall is fine so long as it does not exceed R30. In a stick frame home this is fine but sprayfoam and yesterdays building tech are proving to fail over time.
If you live in an old stone home where the floor joists rest on the first course of bricks instead of internal framing, sprayfoam will suffocate the ends of the wood excellerating rot. Hope this helps. Builders Science of Ontario also has info on Do's and Don'ts of renovating homes built prior to 1900
@@JB-ct3cr great info
Countersunk screws work nicely with fender/repair/penny washers and sit flush.
An insulation saw with teeth like a bread knife makes less powder.
Foil faced PIR insulation gives a built in vapour barrier. Foam fill any gaps and cover all joints with aluminium tape.
We use inch and a half polyiso on our rim joists with 2X4 compression blocking under stud centers to nail the belly board to. I use a wallboarder's Buddy drywall cutter for the polyiso. Score both sides and snap. No dust floating around in the air. It is really accurate and straight
I'm in commercial roofing and very familiar with this material. Only thing I would have changed would have been to Isolate the air cavity with poly film. The facer of this insulation is organic and depending on location could result in unanticipated condensation and mold growth potential.
Thanks for that info, Chris.
poly before the insulation? or on top of the insulation?
Having a house from 1900 it's not recommended to spray insulation.
When buying the property two years ago knew I’d add an attic room, but needed to learn how. It's not as easy as I thought.
With the Derecho storm hitting the property at 140 mph insurance with USAA is covering the roof, fascia, and new gutters.
The contractor is sealing it so can add insulation and make it a room. So, that problem was solved with as little as my insurance deductible 😁
Older houses have great high-quality beams, but as you note not wide enough.
Thankfully, the property has a pyramid-style roof, but don't wanna sacrifice height since I'm tall, and for future generations wanna ensure it'll suffice.
This method is gold. I theorized and plotted with research, but nothing came close to this tutorial.
Thank you for the wisdom and ideas.
For here the energy inspection recommended a 36R value. I didn't call to ask for city rules. Thanks for the info.
Thank you for the kind comment, Miss Patience. I wish you the best on your undertaking!
Great video and very informative, thanks
I love GRK screws! Expensive, but well worth the cost!
you could find an off brand and use off brand washers. those screws are about 3* the cost of the regular stuff
Yes! They don't strip out when going in old dense wood!
Just read over a lot of the comments, and here's some more info ...
I cut the foamboard outside and wore a dust-mask too.
I'm in zone 3
R-30 is code for ceilings where I live.
This is permitted and inspected construction. I told the inspector my insulation plan before-hand and he approved. It passed inspection and is now covered in finished and painted drywall.
The insulation is GAF Energyguard.
I could not find the board for sale online, but purchased a pallet of them from a local roofing supply company (ABC Supply, Greenville, SC) for less than $20 per sheet. www.gaf.com/en-us/roofing-products/commercial-roofing-products/insulation-cover-boards/cover-board/hd-polyiso/energyguard-hd-cover-board
These particular boards are usually used in exterior roofing applications, but I confirmed with the dealer that I could use them how I did.
The boards are polyisocyanurate covered with a vapor permeable fiber-reinforced paper.
The inspector required 1.5 inches ventilation space between the insulation and the roof regardless of what type of insulation was used (including spray-foam) [*edit: unless my shingle manufacturer okayed no ventilation. They did not.] That is why my last layer is across the rafters. I would have rather it all been inside the bays and had the headroom instead of having a thermal break, but had to do what I had to do.
Thanks for the comments. A lot of good suggestions out there.
**WATCH THIS BEFORE YOU CUT FOAM th-cam.com/video/Z292iuV91hA/w-d-xo.html
I can't believe your inspector required 1 1/2" space between insulation and roof sheathing. He must not have ever heard of a "hot roof". A lot of builders are doing it the way now and for good reason, just have to use "better" roof materials. I didn't agree with a non-vented roof at first till I did some extensive research.
The inspector said I could eliminate the ventilation space if I contacted the shingle manufacturer and they okayed it. I contacted the manufacturer and they did not okay it. Their warranty documentation required the installation to have at least the 1.5 inch space between the sheathing and decking.-- I think it's good that the inspector's default requirement is the spacing (at least until the rules officially change) because a lot of folks would be unknowingly voiding their roof warranties. Though I was wary at first I like the inspector(s) I've had. They've been very fair and open-minded (in my opinion).
Dave Voskos makes sense, I know there are builders in Texas that use this method without any problems, usually doing metal roofs or premium fiberglass shingles.
--Thanks for the comment. It was a good question. It spurred me to go back and edit my original comment to clarify.
@@woohunter1 everybody who is a internet ninja knows spray foam is the only thing that works lol but like he mentioned his shingle mfg would not sign off on spray foam because they are smart enough to know that without airspace the shingles would not last and would be a warranty issue....any real builder would either leave space usually if they know sprayfoam will be used and it's much easier to vent the roofing if new construction
I usually fir the rafters 2” down for this exact reason. Good solution either way.
Very nice!! Thanks for the video.
Thanks for watching!
Just foam it. Leaving an air space invites moisture-laden air to condense inside of the cavity. University of Dayton had this problem, removed all the insulation, foamed 4" of closed-cell foam on the underside of the cathedral roof deck. Everybody happy, and all good. Montgomery County building department (who had originally insisted on an air space) admitted they were wrong.
He just did a 3 year update with a borescope and the roof decking looked fine.
Dude totally showed how he provided code ventilation at each rafter.... I'm putting a double throwdown impeachment fact check on to you for false information propaganda, hate speech, insurrection, racism, terrorism and racist terrorism wich is a hate crime. The racism made me sad and i wound up crying and peeing in my pants and that's assault which is a misdemeanor in most States. I don't even know where to begin about how you should be completely deplatformed and banned from the internet forever for openly speaking despairingly about Montgomery County. No! Not everybody is happy, i'm totally triggered and i must inform you by law that i am going to my safe spot, slamming the door behind me and calling my emotional support therapists to tell on you.
Spray foam is slowly being outed in northern Ontario, impossible to get consistent quality control. Rock-wool, which is replacing spay foam, does the same thing for most applications, and it’s fire and mold proof.
Totally unnecessary. Obvious wrong method of installation was used. Leaving air gaps between joints & seams should be addressed during intalation, joints get taped and gaps filled and sealed. Even BlueSkin as first barrier will stop any leaks. As far as a home attic diy; this will be a excellent start.
I wish I could have done that to my house. My 2x6 rafters are not accessible accept through a tiny crawl space. Your project looks great though.
Good info! I've built a lot of SIP structures. Try using a hot knife to cut the foam. No dust.
Thanks for the comment! new comparison video th-cam.com/video/Z292iuV91hA/w-d-xo.html ... I didn't use a hot knife because after some research I found it won't cut the fiberglass reinforced paper, and it cuts slower through thick foam.
To cut without a mess, box cutter score both sides and snap. Or box cutter for the facing and a hot wire cutter for the foam
Nice to see someone doing it right.
Shure? In Europa werden don't do this for 20 years. You Cannes make so much mistakes. Look at the airthickness in this projekt. Foam is Not thick.
I have never heard of a building inspector forcing r30 for a remodel on existing construction... New additions, yes but if it was legal when built, they can't force you to upgrade it.
There's bound to be some variation from local to local but, at least where I live in the Pacific Northwest, converting an area from an unfinished/non-occupancy space to a living space must include bringing it up to modern code standards. So, if a loft conversion area isn't properly insulated, you must install additional insulation. If there were windows at either end of the attic, but they don't meet egress or energy standards, you have to replace or even reframe and replace the windows. Electrical, plumbing, the pitch of the staircase all have to satisfy modern code requirements, too.
@@MrPeterJHarrison well remodeling unfinished space is a different thing, granted how are they going to know if it was finished or not previously. First inspections come after you already gut it so they wouldn't know.
In our jurisdiction, if an area was ever livable, then you can gut/remodel it. They can't force you to rebuild the building to achieve code compliance if it met code in the past.
I think the key is that it wasn’t living space before the remodel so it now has to come up to existing code if you want a permit.
@@johngermany2089 yeah if the home owner isn't claiming it was a livable space, then they might force him. But there are large windows already up there, that would be odd to have if it was completely unfinished. Also livable is not necessarily based on current code but the code under which it was originally built or remodeled.
Permit is mistake #1.
thank you. this is great. There was 0 insulation between Rafters in my place and I installed a Sika 1/2 inch Insulation below Roof Decking between rafters, with a 2 inch air gap below it, to at least have something. Used strapping above insulation as spacer - and below it to hold it in place. Attic has No ridge vent, and won't have one ( historical home / not dealing with the association) so I stopped the insulation 8-12 Inches from the roof ridge to avoid creating a heat bomb at the ridge. Will install Gable vents on either side of the attic to help move the heat out. While installing, when my face is right in front of the insulation and air gap, I can feel the heat. It's amazing. Also installing insulation between joists above all ceilings. Attic is not a living space, and not for storage, but it does have flexible A/C vents run through it, and Air Handler for AC is located in attic too. Hoping this moderate Sika 1/2 inch R 3.2 install with Gable Vents will reduce the "oven effect" in the attic.
Awesome. I hope it works well for you :-)
Could you have just spray foam in between layers of the 2 inch foam board? Looking to do the exact same thing. Was thinking of batts on the knee walls and ceiling, but I've seen others do the whole thing with foam board.
Radiant barrier on the top layer would have been a great idea.
What’s the best way to do that though. I haven’t found a baffle that wasn’t pure flimsy junk, much less a high reflectivity one.
@@TheChupacabra Aluminum Foil. Yes, plain old foil.
What would be the proper spacing for the radiant barrier? As in, touching the plywood? Touching the insulation? Somehow suspended between them? Also, the rafters are supposed to also be protected by barrier, not just the flats between the rafters. So, how would that work?
@@CaseAgainstFaith1 I’m planning on going with touching the baffle or the insulation. That radiation will be reflected back (in part) presumably to get reabsorbed by the underside of the roof deck. I’m hoping that as this radiant ping pong is going on that the inch or two of air channel is continually pulling cold air from the soffit up to the ridge and out, taking heat with it.
I cut 2" foilfaced foamboard with a razor just like drywall, it's quicker and if you razor it well it breaks very evenly.
Sure, but that makes too much sense and isn't macho enough. Why do it the non-messy way when there's a 10000rpm power tool handy?! LOL
you're right th-cam.com/video/Z292iuV91hA/w-d-xo.html wish I'd known that sooner
Excellent tutorial! Thanks so much!! We are tackling the same type project now in northern Wisconsin. Question: Why did you use batting insulation above the collar ties instead of the same rigid insulation you used on the slope?
Thanks! ... I used the 9 1/2" batts above the collar ties because I had a deeper space to work with, and it's cheaper and easier to install. My goal was to do it all as cheaply as possible, while conserving headroom and meeting code. Thanks for the comment, C Bayles!
Almost all major shingle makers allow for a unvetted roof using closed cell foam that is at least 1.5-2".
Also XPS foam you can score and snap with no mess
You can tape a vacuum hose to the back of the saw
Or you can try using utility knife and cut it like a drywalls...
I just went through this. Building code approved all insulation installed and within 3 months everything weaped and condensates so bad it would have rotted off the roof in less than a couple years. It had full R and air space and still failed. Spray foam, spray foam, spray foam. Worth every cent.
I own a 2600 sqft cape with a walk-out basement, I had all exterior walls including exposed basement walls, the ceiling of the 18' dormer, and rim joist spray foamed, cost me $7500 including labor. Well worth the cost here in NH. I recommend you get a quote from your local insulation company before you insulate anything because they beat the cost of insulating my garage by $300, labor included!!! I quoted out the cost of the insulation from Home Depot and they came in $300 cheaper including labor, so I didn't have to deal with getting itchy, sweating my ass off, or breathing in any of the glass. The insulation companies buy the product wholesale which allowed them to quote cheaper than the big box stores including labor. Dave did a great job here and I'm impressed by how nice the job came out, but time is money so you need to include your time as well in the cost of the job, not to mention your health.
@Volkan Builders installed products located in Auburn NH
Great job gonna do this to my pole barn cabin already have bubble foil on roof under metal I knew I needed air gap thanks
Good luck!
I also have a pole barn that we are turning into a shop. It also has the bubble wrap under metal. The reason for air gap is so warm moist air can vent out and that is the problem I'm having with the bubble wrap/moisture barrier.
@@rogerd0 Mine got insulated on the inside along with ship lap on ceiling, walls are 6” thick stuffed with insulation too we don’t have electric yet but it feels cool inside even in the 90’s
Good job.
UPDATE!! How's the foam doing 3 years later??? We send an endoscope up the air gap. Check it out here: th-cam.com/video/5oSQhPvCvz0/w-d-xo.html
they do make roxul 2x6 in r24 its super dense and hard to work with
Definitely nice job. Looks like commercial roof insulation for edpm or rubber roofs. Which i would have probably used roof plates instead of washers. Nice job no matter what I say.👍
Thanks, and you're right, William, that is the same insulation. I think I'll try those roof plates when I insulate the other half of the attic---some others mentioned those as well. Thanks for the comment.
The technique is interesting and it gives an air-break for the framing lumber which is good. The thing I don't understand is why do so much work to avoid a larger rafter. Just make it 2 x 10 rafters and avoid all of the finishing issues of the foamboard on the interior ceilings?
Have you priced a 2x10 lately?
Besides which, this isn't new construction, it's a remodeling if an old house. Here in Texas we have no snow loads and a lot of builders use 2x4 for rafters. Only a custom home where the architect required it would go for wider boards.
I understand you need a channel between the rafters from the soffits to the ridge vent. But do you have intake vents at the soffits themselves, or just need an air channel between insulation and shingles so they can breathe (in effect just allowing airflow from the ridge vent)?
channel/air gap is needed if there are soffit and ridge vents but if using aluminum foil faced the gap is needed to reflect heat back out. Obviously this here is not a shiny surface on the polyiso. In a case of no soffit and ridge vents probably no gap and make sure everything connecting to that roof space is absolutely air tight for an unvented roof assembly. I just re decked my rood after this particular assembly after 12 years or so and there was no deck rot aside from what was there from leaks 20-30 years ago but I sealed every penetration, every wire, top plate etc....I replaced the deck because I am getting solar and wanted thicker than the 75 year old 3/8" deck.
What was the cost did I miss it? Because I had my whole 2700 sq ft home foam sprayed at 7,500 walls ,ceilings, etc
Here we have to put in attic vents (insulation baffles) between the rafters to allow air flow from the soffits up to the inside of the attic. Personally I would have ripped down some strapping pieces and tacked them on the rafters to increase the depth then used regular batt insulation. Polyiso foam works worse in colder temperatures which is why it is useless in Canada.
I'm doing my attic any recommendations other than spray foam
I don’t agree with your statement of polyiso working worse in cold temps. It is among the best insulation for dealing with cold temps....what is your source of info?
Good information. Thanks for the comment.
This is the best job I’ve seen yet. Did you consider a sealant or coating (maybe aluminumized) on the underside of the roof. I was thinking that so much hot humid air is going to be moving through these conduits that protecting the wood would be wise. I was also thinking about using a foil faced foam to reflect more of that radiant heat back at the roof.
Just reading through some comments I missed. Thanks Mike. I thought about it, but I was trying to get by with the least expense and satisfy the inspector. We just scoped the roof though, check it out 3 years later th-cam.com/video/5oSQhPvCvz0/w-d-xo.html
I have a friend that does flat roofs, they use this exact insulation board on the roof before the rubber roof, he was talking about how high the r value was, I was building living quarters on a garage I already had, and I bought about 1500 sqft of these insulation boards from the company they used. I had it stacked on my trailer in my garage intel I was ready for it, I walk in there one warm day and the fumes coming of that insulation smelled terrible, it was so bad I thought no way em I using that in a air tight living space If it smells like that in this 50x50 with 16 ft ceiling garage, after doing some research and talking to the manufacture, this insulation is not certified for interior use, it’s sold for use on exterior of building, it is not Certified for indoor air quality requirements. I decided against using it, and sold it. It’s now on the exterior of another Friends roof he used it under a metal roof.
We've never noticed a smell, but you're right, this type of insulation is typically used under membrane roofs. According to GAF, the manufacturer, the only stipulation is it must be separated from the interior by 1/2" gypsum board per Section R316.5.2 of the IRC. ...You've definitely given folks something to consider. Thanks for the comment.
Nice job friends.
Hi, this is exactly the idea I was looking for. Thanks for sharing this. My rafters are spaced with the gap being 14-15 inches. What do you recommend for cutting the 8x4 iso panels? Go 12 inches wide and get 3 out of a sheet and fill the gap left and right with spray foam? Did you fasten the first two layers separately, or all three with the rafter screws at once? Thanks in advance! Herb
Good questions, Herb. If I were working with 16 OC rafters like it seems you have, I'd cut the boards about 14.5 inches wide, or a hair wider (enough for a friction fit), and use the leftover 4.5" for cracks and crevices or cut slivers to help wedge any boards in place that don't have enough friction to hold them (fasteners aren't used for the first 2 layers--just friction). I know it sounds a little wasteful, but otherwise there's no good way (that I can think of) to hold the boards in place. If you end up trying the 12" cuts and it works well, please comment back. There are always better ways to do things, and you might have found one. Thanks for the comment, and all the best on your project!
Polyioscyanurate is know to experience thermal value drift. Within a year of install, you are closer to R 28. If you choose to follow a path like this, shoot a bit higher than the code value so that you meet your performance target after the drift.
Polyiso dose not experience thermal drift.
@@chadstocking7174 this is not what the research has proven. While the drift is minimal compared to some other products, it does drift as gravity will compress it a bit over time. Thus my comment about shooting for a few points higher than the desired level long term. Please research before making comments about “does not” vs “does minimally.”
@@musicteacherbuilder I work for a polyiso manufacturer. The theory of drift was started by the rock wool industry. The only r-value drift you get is at -40 F when the gas’s in the polyiso starts to decrease the overall r value by .5. You recover the r value when the temperature increases. You will never have a compression drift unless it is installed as a roof system and foot traffic control s the reason for compression.
should have put some reflective foil on the top layer to reflect the radiant heat coming in from the sun....
A vapor barrier in a cold space like that is usually a bad idea. If any wet air gets under it there's no way for it to dry.
He didn't say vapour barrier he said silver foil insulation as a solar reflector. The most common pir board insulation that we use here in the uk has a silver effective coating on both sides,it adds to the insulation value. We use insulation like king span or celotex it's worth googling. You can actually get thin silver insulation on a roll that has good r value and it's only a quarter of an inch thick.
@@danielmilliken1684 yea i'm not talking about vapor barriers....
What if there’s no ridge vent, or soffit vent either? I’ve got a garage with similar plank roofing and only 2x4 rafters. Wondering if it makes sense to have that 1-1/2” air gap if there’s nowhere for the air to vent out
you can cut any foam insulation board with a long box cutting knife, no dust if done that way. just score it a few times.
You're right! th-cam.com/video/Z292iuV91hA/w-d-xo.html Thanks for the comment, Khan!
Forget the space, with foam just go direct contact with the roof. If your inspector doesn't understand, ask him to show the code. Spray foam is direct contact, and well fitted sealed foam panels is to. Ventilation is way overhyped. especially in the north east.
I was about to say the same thing. California does not even allow this ventilation. Code mandates insulation to be in direct contact with the roof.
He said go with what the shingle manufacturer says. GAF said it must be vented.
I’m so jealous of your R-value #boss
Great video and great way to save money!
Thanks!
I would've just cut some 1/2" ply gusset plates and furred out the rafters wjth 2x4. I hate foam board because I have done a lot of demo work. A lot of it was from tearing out dry rot where there were foam boads installed! But, I can see why you have an air space...
How are you planning on attaching drywall to that now?
Drywall screws. th-cam.com/video/dGeoA1ji_iM/w-d-xo.html
Timber framers that use 6"-8" thick roof panels don't have a air space?
Bebo May vented nail base is an assembly that includes insulation, sheathing, and an airspace in 1 assembly.
Hot roofs work....I have built many. Sealing joints is the most difficult and important step.
I'm in Canada, and those sheets come in 4'x8'x2" for $48.00! Also, building code may require the addition of a non-flammable surface in the room (dry wall), as the surface it comes with may not be accepted - definitely needed for 'bare' foam boards, of spray foam.
This insulation is made to go on top of metal roof decks. It's pretty much already fireproof.
It is not fireproof, when fireproofing is needed on a roof theres gyplap sheeting and/or densdeck which fireproof the product
Dens is a fire break, but mainly to prevent the polyiso from crushing into the flues of the pan decking. You can torch polyiso surface for awhile before it burns.
Are these the GAF EnergyGuard sheets? ...and you're right, this foam requires 1/2" drywall between it and the living space. Thanks for the comment.
Ouch! Here in California a 4x8x1.5 cost me $18 a sheet
Super nice Job. The only thing I would have improved on was to put something in from the eve to the peak and keep your air space at 1-1/2 all the way up under the complete span of the rafter. This then helps keep a dead air space in the other areas and you don't get any air washing going on. The industry works so hard to air seal the vertical walls, but ignore the ceiling area for some reason.
Thanks and thanks for the info @24revealer. You just made me look up "air washing." I didn't know it was that big of a deal, but you're right, I probably should install some sort of baffles.
Best way to cut this poly-iso board without making a mess... Just sharpen the side of a thin putty knife. It will zip right through it. Trust me, last thing you want to be doing is cutting this with a saw.... They make special blades for doing it that are dustless,... But the putty knife will work just fine.
I agree that the sharpened putty knife is the only way to go. Accurate and very clean cuts.
I'll try to remember that when I do the other half of the attic. Thanks.
@@FamilyFriendlyDIY you won't regret it.
Sharpen the edge and you'll do fine, use whatever works for a straight edge if you need it. But after you get the hang of it, you should be able to free hand it fairly easily. Just watch your fingers, good luck.
The covering on that particular poly-iso board is fiberglass reinforced felt.
But thinking about your price per board. If you find a manufacturer around you. A lot of the times you can buy "seconds/non confirming" board directly from them.
When I worked at Firestone building products, they would generally give it away if the person that came in asked if they had any to donate, if they asked to buy it, they would sell it for dirt cheap.
Most the times the boards are perfectly fine, in our case anyhow, they typically just was barely under or over min/max thickness spec by a 1/16 or same for length width of the board. Just barely under/over spec. But still a perfectly fine board.
tried your tip in a new video ... th-cam.com/video/Z292iuV91hA/w-d-xo.html it worked well!
Grk screws are super expensive
Really really apreciated.i will do mine
Good luck with yours. Thanks for the comment :-)
Thanks for the video. I didn't see how you attached the top layer. Did you use long screws and a washer like on the 3rd layer to attach so the layer was suspended?
The two layers between the joists are held with a friction fit. I tried to cut mine a hair too wide so they'd stay in on their own. But if cut too narrow, you can use foam trimmings/shims to wedge them in until you come back with a can of foam. The foam will glue them in place "permanently."
Get a couple 20 in box fans and a couple cheap 20x20 air filters and duct tape the air filters to the intake side of the box fan. Constantly filters the air... I'd still wear a mask bro!
Never thought of taping air filters before that's brilliant! Thanks.
@Tony Tiger No, to keep the fiberglass in the air from settling and to draw the suspended fiberglass to the air filter. This is pretty smart and would be a heck of a lot cheaper than getting a super expensive filter designed for this purpose. For your health you really should avoid inhaling fiberglass it is glass and very thin. It is obvious once pointed out... fiberglass should not be a inhaled! It will burrow into your lungs and cause damage even though you cannot feel it. Does this mean you are certain to get cancer? No, but it is pretty likely that some folks will. It totally sucks that no one tells the labor things like this in the name of saving a buck.
@Tony Tiger You are right if using manual tools. but if you are trying to speed things up with power tools you should take care as others have suggested. i e @Berkey Family suggestion of putting the saw blade on backward.
Silicosis,.. use the filters and a dust mask... The fine dust from using the saw on it float in the air longer and better than you would think.
Filters plus vent it outside if you can, still wear a mask too !
I ground all the teeth off a 10” blade so it has a knife edge. I cut lots of styrofoam installation with that blade in my table saw with little or no dust or styrofoam chips.
That sounds pretty smart. We built a hot wire cutting table for a bigger project of ours. It works pretty quick. But your solution is cheaper smaller an more portable. I imagine it would work well with slow rpm as well. Maybe with a lubricated disc. Reciprocating saw maybe?
@@kistuszek Would a hot wire cutter work with the fiber-reinforced backing?
@@misterlyle. I dont think so. But i have no experience with that stuff.
@@kistuszek Thanks for your reply! I think you are right.
I did something very similar. In place of the foam board you used, I used 2" Super Tuff R which I was easily able to cut with my leatherman knife. I also ran the insulation from the bottom of the floor joists joining the other side following the horizontal ceiling. I put 2 layers of the Super Tuff R in and over the walls at each end. It is now like one big refrigerator. This guy is losing out on air sealing by not doing the hole envelope. I also did not see the need to seal every layer. I only sealed to outer layer.
Thanks for the comment, Ryan. Good info.
@@FamilyFriendlyDIY was there a reason you didn’t do this?
I have a similar setup in my own home but wondered why you didn’t expose the whole thing. Any reason?
Great video btw.
@@ecthelion205 Thanks :-) .. Yes. I was trying to keep the cost down as much as possible, and only insulate what absolutely needed insulating. The space behind my kneewalls is pretty expansive, and would've taken a lot more insulation. As it is, it satisfied the inspector and keeps it nice and cozy up there. Thanks for the question!
@@FamilyFriendlyDIY that makes sense! Thank you for the explanation
PIR boards made by Kingspan have thick aluminium foil on both sides, therefore I've found that this type of PIR board is the best to work with. But anyway - I would create a ventilatiom gap underneath the roof using OSB3 tongue+groove 15mm boards and the 400mm gap for blown in thermoinsulating cellusose covered by 12,5mm Fermacell board. Estimated R40 ensured 😎😇
As a Nu-Wool installer i concur
Maybe cheap in 2018, but here in 2020 2" foam boar is pushing almost $30 a sheet. It will take me well over $1000 just in foam board for a little bonus room.
Dave,
What zone are you in? I like the idea but two things - where do you find this stuff? And second, is it safe to have that paper packing on the foam when you are layering it? It's a common no-no to have something like faced poly-iso stacked because you trap moisture in between two layers that can never evaporate once you seal the gaps. Same principal with laying paper faced fiberglass insulation on top of paper faced fiberglass insulation. Nice work, be sure to invest in a $30 respirator so your lungs don't kill you from those particals.
Roofers apply this "iso" in layers all the time. Not a problem.
Nicpedia It was stated that The poly-Iso is faced with a permeable paper layer.
I have a similar situation with 2x4. I was going to sister truss 2x10s and do this process but some of the roof bays don't have soffits. I think I'm going to do flash and batt, I can't think of any other way to do the roof without soffit vents.
was outsulation an option for your need?
Hey Dave, so when you added the drywall you simply used longer screws to overcome the foam? Thanks.
Hey Alex, yes that's right, but it took me some figuring out because I couldn't find long enough drywall screws near me and had to order them. Here's a follow-up video where I talk about the drywall and screws. th-cam.com/video/dGeoA1ji_iM/w-d-xo.html And thanks for the comment.
Forgot to add that the 3rd layer at 90 degrees is great for making a thermal break for the wood rafters. Wood is just a moderate insulator.
You can easily cut most foam insulation board with a 6" drywall taping knife and straight edge to almost eliminate the dust...
Given that a 2x8 is actually 7 1/4" deep and R15 insulation is 3.5", what are you thoughts on using 2 layers of R15 insulation in the 2x8 cathedral ceiling? Depth wide it adds up to 7" and also the R values add up to 30.