Insulation questions

[jsamhall]

Hi all,

I've done my best to research this subject and haven't found the exact answer, maybe I'm using the wrong terminology as this is all new to me. I'll apologize in advance for ostensibly silly questions, I'm new to all this and doing my best to learn as I go. This forum has been an outstanding resource!

This thread has been the most helpful and sounds pretty comparable to my situation but I'd still appreciate advice from those with more knowledge on this subject.

I am preparing to insulate my workshop in a couple months, so I want to establish a battle plan and budget for materials. There is a pretty good amount of above grade exposed cement wall with 2x6 wall built atop that. Here is a photo of its current state:

First some relevant details...

As-per profile, I'm in northern VT. It gets wicked cold. Last week was negative double digits before taking wind chill into consideration.

Building is 29' deep by 36' wide for about 27' 8" x 34' 6" inside dimensions. Everything is framed 24" OC.

There is 2" foamboard insulation below the slab (not yet poured) and on the inside of the below grade foundation walls. No insulation on the outside of the exposed cement walls.

We have a 75k BTU Modine heater that will be suspended from the ceiling.

I estimate about 600 sq/ft of 2x6 cavities

I estimate about 400 sq/ft of exposed cement wall

I intend to finish with drywall as I prefer the aesthetic to OSB or other alternatives.

I intend to use 2" foam board over the cement and either R19 or R21 fiberglass in the 2x6 cavities. I'll do a thorough round of spray foam and caulking to help mitigate air leaks.

My Questions!
I'll try to make these as straightforward as possible. If I'm not making sense or have not provided enough information, please let me know and I'll do my best to clarify. Thank you very much to anyone who can contribute!

1) For the foam board, I intend to use 2" XPS 4x8 sheets "FOAMULAR 250" from Owens Corning (pink board). Is this the right product to use, or would ISO foam board be a better choice?

2) I am conflicted about the best way to install the foam board. One method I've seen is to adhere it to the cement and install furring strips over that to hang drywall from. Another method which claims to be more energy efficient is to first attach the furring strips to the cement wall then cut and fit the foam board between them. Which method should I use?

3) The cement walls are 8" thick on two sides of the building and 10" thick on one side (the tall retaining wall). This leaves a couple inches on the top of the cement before the 2x6 framing. Should I just put foam board over this small area of concrete as well, or build out the 2x6 wall to make it "flush" with the cement wall + foam board?

4) For the ceiling, I plan on hanging drywall and blowing in loose fiberglass from above i.e. the attic. I get the impression this would be quicker and more cost effective than R30 batts. Is this a good idea? There is currently plywood flooring in the middle section of the attic trusses and nothing in the webbing area.

5) I've seen many installations that use a 6mil poly as opposed to kraft faced insulation. Is one superior to the other? I'm having a hard time finding a conclusive answer, and Kraft faced insulation seems to be vastly more popular at Lowes and Home Depot.

----

I think that does it. Sorry for so many questions and thanks in advance for any guidance!!

 

[tonyciambrone]

I would really consider doing 2" Foamular 150 in the stud bays, seal the edges with some great stuff or similar. Then do rockwool, preferably or fiberglass over that. Especially if your pole barn doesn't have continuous sheathing with a weather barrier (i.e osb with tyvek) on the exterior. The wind is just gonna blow drafts right through the fiberglass. At least that's what happens in my shop.

Each sheet would just take two runs through a table saw. Yeah it's more money but you have to live with whatever you choose here basically forever.

 

[jsamhall]

I would really consider doing 2" Foamular 150 in the stud bays, seal the edges with some great stuff or similar. Then do rockwool, preferably or fiberglass over that. Especially if your pole barn doesn't have continuous sheathing with a weather barrier (i.e osb with tyvek) on the exterior. The wind is just gonna blow drafts right through the fiberglass. At least that's what happens in my shop.

Each sheet would just take two runs through a table saw. Yeah it's more money but you have to live with whatever you choose here basically forever.

Thanks for the response! I should've provided more details!

It is a stick built structure, vinyl sided over black tyvek on OSB then 2x6 walls.

 

[jsamhall]

I edited the original post to fix the image and added another photo of the outside!

 

[jack stand]

I am also a fan of cut & fitting rigid foam & sealing edges in your stud bays. I used - used p-iso for the better R value. I have 2 layers of 1 1/2" with each layer sealed individually. There are several outlets for used or 2nds for foam that I've seen in VT on CL. Like tonyc said above, "you'll have to live with it forever" along with the energy costs. Sound's like you've done some homework and are on the right track, except for the f/g part. I hate that **** and it's "performance" or lack thereof. Put some of your future fuel costs into the best insulation pkg you can reasonably afford now. In year ?? 2-3-4? you be ahead of the game, from then on......

 

[stm317]

Yep. Rigid foam in the joist bays, and then fiberglass or rock wool. If you'll be adding furring strips or building the stud walls out to be flush with the concrete, then you should have plenty of depth.

Fiberglass ***** at stopping air movement, and that negatively impacts it's R value and gives you a drafty building. Foam is great at stopping air movement, so having foam closest to the exterior will stop the air movement and allow the batts on the interior to focus only on insulating.

If you have foam in the walls, and all of the seams/joints are sealed as well, then the foam will be your vapor barrier and you don't want any kind of additional vapor barrier. No Kraft paper and no plastic. For the ceiling though, I'd want a vapor barrier up before the Sheetrock.

 

[frankush]

If you're going to spray foam, air infiltration should not be an issue. Fiberglass will work fine, but there are better choices if you're willing to put out the extra dollars. Any insulation blown in the attic, will settle over time and require topping off down the road. If you plan on using the attic for storage, the joist cavity height will limit your R-value, wherever you have flooring. A vapor barrier is only as good as the guy installing it. I don't think either is better, but if you punch a hole in it, seal it with tape for that purpose. A 4X8 sheet of foam over the top of the wall studs will eliminate thermal bridging and add R-value. You'll just need longer screws for the drywall. You can purchase the foam board with a foil vapor barrier and then all you have to do is tape the seams with metal foil tape.

 

[tjpavlov]

For the concrete walls I'd recommend Insofast panels. Cover with plywood then sheetrock. You can run electrical behind it through built in chases.

Insofast.com

Check it out. I used in my basement so PM me with questions.

 

[matt_i]

Here's where I'm at. I have a similar setup with the attic storage trusses with openings at the ends of the attic space.

- bought a case of caulk tubes and caulked the joint between plywood and framing. Not 100% everywhere but every other bay.

- used Roxul in the walls -- do *all* of your electrical work first. I also spray foamed all of the holes I drilled in the framing with GreatStuff.

- used loose fill cellulose in the ceiling. I'm using NuWool but I don't think there's much variation in competitive products. I'm messing around with breaking the insulation by hand in a garbage can, mixing it with a drill paddle to break up the chunks and then placing it with a long handled wooden "hoe". This is more labor intensive but seems like I can get it in a state where its a little denser and less susceptible to settling. This part is in the experimental phase. I can always go rent the blower.

I cut 2" foamular to fit at the end of the truss bays, top of the wall, where insulation would pour out into the soffit. This so I can fill to the full 9-1/4" depth. This is also air-sealed.





I air sealed all electrical boxes wall and ceiling with 100% silicone, where the wire goes into the blue boxes for sure but also the unused "knockouts" also have leaks. Currently hanging drywall, planning to seal the drywall cutouts with something like Big Stretch caulk instead of drywall mud. I'm planning a knockdown random texture so I think this will work OK.

Adding: purchased a 2" thick foam filled garage door instead of standard 1-3/8".

 

[theoldwizard1]

The first rule of insulation is INSTALL AS MUCH INSULATION AS POSSIBLE !

Second rule, is deal with all cracks/gaps/external hole FIRST ! This is why they recommend a 1"-2" layer of spray foam on the metal walled buildings.

The foam board may be better against concrete as any moisture leaching from the concrete will not affect it. It you have a good snug fit in the stud bays I don't think foam is really necessary around the edges. If it is not a snug fit, yes, use spray foam.

Loose fiberglass or cellulose insulation is usually the cheapest and fastest way to do a ceiling. Cellulose used to be cheaper, but check today's prices. Critics say it "sinks" over time.

Mineral wool (Roxul) is EXPENSIVE, although it does provide better sound insulation. No improvement on actual R-value.

Another way of speeding up installation is to use loose fill in the walls especially if you have 2x6 studs. Install "skrim"/fine netting and then blow in from the top. On the areas where you have concrete, I would install 1" foam board first.

 

[MushCreek]

I had stabilized cellulose blown into my attic, and it hasn't settled. Stabilized cellulose has a very thin glue mixed in as it's blown.

For the ceiling in my shop, the loft floor is already in place, and the 2x10 joists are on 12" centers, so no fiberglass batts. I'm going to staple fabric (I've heard landscaping geotextile works well and is cheap) and they'll blow cellulose in at the end of each bay. Haven't decided on my 2x6 walls yet. They certainly leak a lot of air, so I need to address that first. Siding is a single layer of T1-11, so no vapor barrier. I'm not looking for livable comfort, though, rather just take the chill off, and I'm in relatively balmy SC.

I studied this a lot prior to building our house. Air infiltration can have as much impact as insulation, so make sure you take care of that. As pointed out, fiberglass is lousy at stopping air movement. Air comes in everywhere- electrical boxes, door locksets, any penetrations, such as pipes and wires. I bought a gun (about $40) and big cans of foam, rather than spending my life savings on Great Stuff at the big box store. The foam comes in regular, and low expansion so you don't distort window frames. Amazon carries all of this stuff.

https://www.amazon.com/dp/B01N44BB15/?tag=atomicindus08-20

https://www.amazon.com/dp/B00176L4UQ/?tag=atomicindus08-20

 

[NUTTSGT]

1. Which has the best R-value ? Look on CL for reclaimed or a seller that'll sell polyiso in bulk, cheaper than a big box store. While you may be able to save a few dollars now, the best insulation will continue to pay for itself every time you fire up the heater.

2. The back wall of my garage is block, I attached 2x2s with tapcons and slide the insulation in between. The exterior has firring strips with foam insulation in between, covered with OSB then vinyl siding.

3. I would "frame" up the concrete wall and cover with foam board. I would take that framing up to the stud wall. cover with some foam board them plywood. Create a small shelf area for future use.
The high side wall, near the hill, I would make it continuous across the entire wall. The back wall, only what it needs as the rest will probably be workbench area ?

4. Cellulose is cheap and fast, however a PITA if you need to get back into it. Make sure to get all your wiring done prior.
If doing a new build like yours, one I thing I might consider is to use a combination of blown cellulose and fiberglass batt. I use fiber glass batts under the attic floor with some foam board blocking at each end then fill the open areas with cellulose.

5. Probably going to get varying opinions on this one. I believe kraft paper is now considered a vapor retarder and not a vapor barrier.

 

[Dzlpete]

The pink foam you specify, directly over the concrete walls, and firring over top that and secured to the concrete is far and away the better of the two options, but it will be a little more work.
You can get or rent a hilti, or ramset type powder actuated nailer to speed it up.

It is the best way, because you create a perfect insulated wall with no insulation differential, between the foam panels, and the infilled strapping if you attach the strapping to the concrete. You would also have to use PT lumber for direct attachment- costs more.
Finishing with drywall will almost demand the first approach, because if you do not, you risk getting “ghosting” lines directly through the framing which has less R value, thus will be colder, thus will create the opportunity for condensation lines- the “ghosting”, which will in turn start your drywall screws to rusting and bleeding through the paint at some point.

Regarding stud infill, if at ALL possible, skip the fiberglass and use the ROXUL, along with the poly sheet vapor barrier instead of kraft paper. Better, denser, easier, and, well, BETTER!
Fiberglass is close to **** in comparison.

Blown in dense pack cellulose in ceiling would be ideal, Roxul would be the second choice.

These are my opinions, based on about 30 years now as a builder in MA, and what I would do.......

The difference of the number on the pink foam, refers to density- higher number= higher density

 

[matt_i]

Mineral wool (Roxul) is EXPENSIVE, although it does provide better sound insulation. No improvement on actual R-value.

I have to point out the falsehood you are propagating here. Roxul is rated at R-23 for 2x6 walls and fiberglass is R-19 for same 5-1/2" depth of insulation. Yes, more expensive. Having installed both, I also believe the "working" R-value for Roxul to be higher because its easier to maintain the proper dimension being considerably more dense. Fiberglass needs a lot of "fluffing" to get it positioned just right so its not overcompressed.

 

[Briguy_123]

I used Z-furring channel with tapcon screws and PL premiem to secure xps foam to the poured concrete sections of my interior walls. I already had 4" of xps installed from the top of my footings to about 4 inches above my finished floor. I could only find 2x2 Z-furring so I installed 2 layers the first vertically and the second horizontally. I faced the ends with true 4" steel stud track.

 

[69gp]

For the concrete walls you could use 2" Z channel. This is fast and allows for a better fit of the insulation since it has a score every 16". This will also give you a nailing edge to screw your finish over the installation when you are ready. Add a sheet metal L bracket along the bottom and you would have a nice clean install.

https://www.clarkdietrich.com/products/drywall-framing/z-furring-channel

https://www.riversidesheetmetal.net/flashing-metal/masonry/z-furring-channel/

 

[ddawg16]

Would metal studs be a better way to fur out the concrete side? Anchor using tapcons or just concrete nails...foam in between.....then you have something to anchor the drywall to. I don't see the metal being any worse overall for thermal bridging as compared to wood.

And....is it too late to insulate the outside concrete?

 

[nelstomlinson]

Consider putting heat tube in your slab. Use one foot of half inch tube per square foot, distributed evenly. Make all your loops the same length, and no loop longer than 300 feet. Staple it to the foam, or tie it to the steel. This is pretty cheap, and gives you options later.

If you plan to put in a lift, or bolt stuff to the floor, put in appropriate thick areas, and route heat tube around them.

You need a vapor barrier on the warm side of the wall.

On your questions:
1) Foamular is good stuff. I'm using it above ground and under slabs. I was able to find it used, at half the box store price or less. I have also used the white, expanded-bead, coffee cup-style insulation under slabs.
2) I would avoid thermal bridges like firring between foam sheets. Ideally, glue the foam on, then glue the sheet rock to it. As a reasonable compromise, firring inside the foam secured through the foam. The nails driven through the foam that secure the firring will be thermal bridges, though.
3) Firring out the frame walls above the concrete gives more room for insulation, so it's a no-brainer. You always want more insulation.
4) We've used blown in with good results. You can put it in a lot thicker than R30. You always want more insulation.
5) Kraft faced is ok, but you need the 6mil poly inside with or without it. It's not a vapor barrier, it just lets you staple the bats in place.

 

[Sparkynutz]

I'm in Wisconsin. cold here too. I have a 26x26x9ft stick 2x4 built. osb tyvek and vinyl siding exterior. Previous owner had walls half insulated with fiberglass batts so that's how I finished the rest. Id like to put 2" pink foam on outside walls down to 2' below grade if I ever tear off siding previous owner already had installed.
I put two layers opposite direction in center of ceiling where plywood is down for storage purposes. The rest of ceiling will have 12-16" of cellulose insulation in it depending how far the 40 bags goes once I actually have time and warmer weather to blow it in.
Plastic on walls and ceilings with every single staple hole taped, boxes, windows, and bottoms of plastic sealed with fire caulk.
The whole garage is drywall and painted with gloss exterior house paint.

Only thing I'd do different is 2" or maybe even 2 layers of 2" foam on outside under siding and not put vapor barrier on inside of walls. Looks like your garage is too late for that unless you want to take siding off too.

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[DC73]

I have to point out the falsehood you are propagating here. Roxul is rated at R-23 for 2x6 walls and fiberglass is R-19 for same 5-1/2" depth of insulation. Yes, more expensive. Having installed both, I also believe the "working" R-value for Roxul to be higher because its easier to maintain the proper dimension being considerably more dense. Fiberglass needs a lot of "fluffing" to get it positioned just right so its not overcompressed.

Have to agree. When I installed mineral wool in my workshop, standard Roxul batts were R15 while standard fiberglass batts were only R13. Yes, I could have special ordered R15 fiberglass batts but at a cost near that of Roxul. In addition to the sound proofing qualities, mineral wool is fireproof, and is much more dense so that it blocks the flow of air through the wall much better than fiberglass. I've installed both and I also agree it's easier to get mineral wool right.

DC

 

[DC73]

I've done my best to research this subject

If you get conflicting answers here or are just not comfortable with the answers you are getting, post your questions on the Q&A forum at GreenBuildingAdvisors.com. There are building science gurus who hang out there and this is right up their alley.

DC

 

[Sparkynutz]

I got r13 batts of fiberglass for $2 each after rebate so it was a no brainer in my case tho.

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[machsnell]

There is a lot of work involved and expense with the pink xps. Then the foaming of the seams.

I am cheap as hell and maybe this was mentioned but have you thought about spray foam?

I didnt want to pay the big money for it and I could have saved 2 or 3k but man the spray foam is so nice and sealed on all electrical outlets and around lights you dont have to go crazy sealing every nook and cranny.

Check it out it wasnt too awful and if was done in a day.

Its 72 in my garage right now as I right this with my pellet stove going.

Whatever you do know that your concrete is a huge heat (or cold) sink.

Foam under slab is amazing. Dry help hold temps when you condition.

The poster that advised on installing pex under slab is correct.

I was in a hurry and had a slot open for one of my crews and I got the slab done but I really wish I had done radiant. It is cheap to operate if you have gas (which it sounds like you do.

Also the heat doesnt dry out the place.

If you have someone do the batts I have heard from many that you can buy for what insulation guys will provide and install for. It doesnt pay to diy.



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[matt_i]

If you have someone do the batts I have heard from many that you can buy for what insulation guys will provide and install for. It doesnt pay to diy.

I would want to inspect the "guys" work before committing. Insulation is an easy place to cut corners in the fitting of it, its really easy to slap it up and leave a lot of uninsulated voids, especially around wiring, piping, or junction boxes. The uninsulated voids get paid for, forevermore, by YOU the owner. Granted there are more scrupulous contractors than others, and material discounts for big volume buyers, but I always back up a bit when I hear that the materials + labor is cheaper than the materials.

Roxul is more finnicky because its higher density requires precision cutting and I've often wondered how any "pro" installer could make money putting it up because the labor cost would be so high.

 

[machsnell]

I would want to inspect the "guys" work before committing. Insulation is an easy place to cut corners in the fitting of it, its really easy to slap it up and leave a lot of uninsulated voids, especially around wiring, piping, or junction boxes. The uninsulated voids get paid for, forevermore, by YOU the owner. Granted there are more scrupulous contractors than others, and material discounts for big volume buyers, but I always back up a bit when I hear that the materials + labor is cheaper than the materials.

Roxul is more finnicky because its higher density requires precision cutting and I've often wondered how any "pro" installer could make money putting it up because the labor cost would be so high.

It is pretty widely known that batt insulation as a trade doesnt pay to DIY. It has been discussed on here several times as well.

Also I watched the installers, periodically that spray foamed my garage, to keep them honest and watch what is a pretty cool process.

My buddy that is a home builder does everything he can (because he is cheap) with his group of employees, which range from labor to masons finish and frame carpenters. He said insulation and drywall not worth touching. He does buy the drywall/mud for the installer and they install tape and mud and mud again and sand. Level 2 I guess. His painters touch up. He gets that for $15 a sheet. Cant touch that.

That being said I did my own drywall because I am cheap also and I kinda like it.

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[jsamhall]

Wow, thanks everyone for the awesome replies! This has given me a lot more clarity on the subject. This is an awesome forum!

It is pretty widely known that batt insulation as a trade doesnt pay to DIY. It has been discussed on here several times as well.

You know, I keep reading this same thing but have yet to find an insulation contractor that comes anywhere close to just material costs I've up come up with, and I'm talking at least double. Maybe its just my area, who knows. It goes without saying, I'd love to pay someone to do it for less than I could myself... that just sounds too good to be true.

Anyhow, after reading all the praise for mineral wool / rockwool insulation for the 2x6 wall cavities I've decided I'll definitely go that route. I called a few local places and they were able to beat the big orange/blue stores at around $1.15 sq/ft.

For the exposed concrete walls, I got some advice from my father in law very similar to what a few posters here have said. My FIL suggested first adhering 2" XPS to the cement, foaming/taping gaps everything to ensure a continuous barrier, then framing a 2x4 wall in front of that and installing insulation batts into the bays. He suggested this would provide a greater R-value than foam alone and make life easy when it came to running electric and hanging drywall, albeit consuming a bit of floor space.

Basically I'd end up with something along these lines:

While that will be a bit more work for me, I'm happy to do whats best in the long run.

This leads me to a new question

I don't want to build the 2x4 wall from the floor all the way up to the ceiling joists. Could I get by with simply framing the wall and securing the bottom plate to the slab with masonry anchors? This will result in a "shelf" shape in the wall where the concrete ends.

Thanks everyone for the incredibly helpful responses!

 

[b-boy]

You know, I keep reading this same thing but have yet to find an insulation contractor that comes anywhere close to just material costs I've up come up with, and I'm talking at least double. Maybe its just my area, who knows. It goes without saying, I'd love to pay someone to do it for less than I could myself... that just sounds too good to be true.

This might be regional, because I can't find anyone either.

I hired a guy about 2 years ago. He was not cheap, and I wasn't thrilled with his work. That's I'm doing it myself now.

 

[jsamhall]

This might be regional, because I can't find anyone either.

I hired a guy about 2 years ago. He was not cheap, and I wasn't thrilled with his work. That's I'm doing it myself now.

Glad I'm not the only one!! Thanks for the input!!

As a side note, I value gaining knowledge and experience, so I'm not losing any sleep over the DIY route. No doubt its a lot of work and I'll surely encounter some frustrations, but at the end of the day I'll have a new experience under my belt and that is worth a lot to me!

 

[kj_mustang]

Did you get anyone to price wet blown cellulose for the stud wall cavities? I found that to be very cheap and the best R value per inch outside of spray foam.

 

[Whitworth]

I am cheap as hell and maybe this was mentioned but have you thought about spray foam?

I didnt want to pay the big money for it and I could have saved 2 or 3k but man the spray foam is so nice and sealed on all electrical outlets and around lights you dont have to go crazy sealing every nook and cranny.

Check it out it wasnt too awful and if was done in a day.

Several problems with spray foam have cropped up in the past couple years. One is it provides a pathway for termites to travel thru a structure, other is spray foam holds and conceals water leaks, leading to water damage, rot, mold. The other is off-gassing of the product, a subject of various lawsuits. I think for certain structures, like metal buildings it may be ideal, but wood frames buildings I'd think twice.

 

[jsamhall]

I thought of another question regarding the installation process of foam board insulation on concrete.

Our walls have a bunch of these things all over them, I think they're form ties?

It looks like they all got whacked with a mallet but not much more than that. Some of them pretty flat and some looked like they snapped off, but some protrude from the wall about a 3/8" or so like the one circled. These are on both the inside and outside.

Should I remove these before installing the foam board? Would I go at them with a hammer and chisel? I looked on YouTube for what to do but I'm finding videos with larger ties used, or ones that snap right off, so unsure how to proceed here.

 

[anythingyoucanimagine]

Don't really know where you are at with the project. A month ago you weren't poured and now you are talking attic (upstairs/rafter) insulation.

You want drywall not wood/osb walls. Do 5/8" firecode drywall just because it is heavier and a royal pain in the a$$ to hang full sheets. But seriously it is more durable than 1/2" and a lot quieter. Hopefully your outlet boxes are spaced properly.


You need to get rid of that pink foam stuff at your soffits. Others have mentioned green building advisor forums. The goal is to keep the bottom of your roof deck the same climate (temp and humidity) as outside ambient air. Google insulating cathedral ceiling on green building advisors. You want air flow coming up from soffit vents, passing along bottom of roof deck and then exiting out roof ridge and gable vents. Even with steep roof you still want (need) air flow. You want the underside of your roof deck to be same climate as outside (I know I said that twice). Air flow comes up from soffits, passes along bottom of roof deck and then out ridge and gable vents. There are ratios for soffit-to-ridge/gable vent square inches. (google it) Up north like you I would consider either a plenum under your ridge and tall stacks (snow depth) or I'd consider a smaller plenum with gable vents at the ends.

 

[DC73]

Several problems with spray foam have cropped up in the past couple years. One is it provides a pathway for termites to travel thru a structure, other is spray foam holds and conceals water leaks, leading to water damage, rot, mold. The other is off-gassing of the product, a subject of various lawsuits.

The issue with termites and foam came about when people started installing foam sheets on the exterior of buildings. Termites were found to bore through and possibly nest in the foam which then gave them easy access to wood structures. The solution is to install a termite shield (basically metal flashing) to prevent access to the foam.

Closed cell foam does not hold water, it sheds water. Open cell foam allows water to pass through. The problem is that any insulation, foam or conventional, installed under the roof or in the wall can re-direct the water to make it difficult to pinpoint the source of a leak. Closed cell foam just makes it easier for the water to be re-directed further away from the source of the leak making diagnosis more difficult. A slow leak can take so long to show up that it can lead to rot and mold but that's true regardless of the type of insulation used.

Off-gassing of spray foam is generally due to operator error. Either the A & B components were not mixed in the correct ratio or the foam was applied at improper temperature and/or humidity.

DC

 

[jsamhall]

Don't really know where you are at with the project. A month ago you weren't poured and now you are talking attic (upstairs/rafter) insulation.

You want drywall not wood/osb walls. Do 5/8" firecode drywall just because it is heavier and a royal pain in the a$$ to hang full sheets. But seriously it is more durable than 1/2" and a lot quieter. Hopefully your outlet boxes are spaced properly.


You need to get rid of that pink foam stuff at your soffits. Others have mentioned green building advisor forums. The goal is to keep the bottom of your roof deck the same climate (temp and humidity) as outside ambient air. Google insulating cathedral ceiling on green building advisors. You want air flow coming up from soffit vents, passing along bottom of roof deck and then exiting out roof ridge and gable vents. Even with steep roof you still want (need) air flow. You want the underside of your roof deck to be same climate as outside (I know I said that twice). Air flow comes up from soffits, passes along bottom of roof deck and then out ridge and gable vents. There are ratios for soffit-to-ridge/gable vent square inches. (google it) Up north like you I would consider either a plenum under your ridge and tall stacks (snow depth) or I'd consider a smaller plenum with gable vents at the ends.

Sorry if anything has been confusing but I started this thread by showing the state of the building. Thanks for the input re: drywall, definitely going with 5/8" and I ensured the electricians spaced the outlet boxes accordingly! There is currently zero insulation in the building, rim joists or otherwise. Thanks for the explanation re: roof temperature, that makes a lot of sense to mitigate ice damming. I think "stage one" for me will be to insulate and finish the first floor (shop area) and figure out what I want to do with the attic sometime down the road. I think I'm going to do blow-in insulation for the ceiling for the ease/cost effectiveness. I know that doing this I need to ensure the soffits don't get blocked so they can still allow cold air to reach the attic. Thanks for the tips!