Insulating a wood sided shop?

[Tractor Seabee]

Fiberglass batts are the cheapest way to go. R-19 fits in the cavity of 2 X 6 studs, available in 16" center and 24" center stud spacing. It has a vapor barrier face. On the walls w/o studs Just add non-load bearing studs on 16' centers. 2 x 4 ok just set out at 5.5" from the existing wall to their face. Then you have a way to add sheeting and/or shelves to the walls. R-19 is the energy code minimum any where where codes are enforced.

Ron

 

[Morning Wood]

No offense, but from the described build out of your shop; your biggest problem is going to be air leaks. You need to stop cold air from getting into the building. It will come in everywhere. From places you don't even think air would go through even. Spray foam may seal up leaks, but it needs to be covered for fire rating purposes. I prefer to use dense pack cellulose whenever possible. I'd invest a little time into tightening up your shell and making sure you have no water issues in the walls or T1-11 first and then insulate. Fiberglass does nothing for stopping air infiltration by the way.

 

[aczlan]

No offense, but from the described build out of your shop; your biggest problem is going to be air leaks. You need to stop cold air from getting into the building. It will come in everywhere. From places you don't even think air would go through even. Spray foam may seal up leaks, but it needs to be covered for fire rating purposes. I prefer to use dense pack cellulose whenever possible. I'd invest a little time into tightening up your shell and making sure you have no water issues in the walls or T1-11 first and then insulate. Fiberglass does nothing for stopping air infiltration by the way.

I have noticed the air infiltration. On the old (long) wall there are 30+ knotholes that I have found. No water leaks on any walls that I have found though.

How well would it work to wrap the inside of the studs and posts with Tyvec (or similar) after filling all the knotholes/cracks I can find with foam and/or calk?

Covering foam wont be an issue as I plan to put plywood over the walls at ~8' and put something else (sheetrock? metal roofing?) over that.

IMO when the ends went on, they should have covered the walls with Tyvec.

Aaron Z

 

[KennyG]

When I did my pole barn, after I filled between the posts with foam sheets (and spray foamed the gaps/holes) I covered the whole walls with sheet plastic to both stop air and provide a vapor barrier. Then I covered it with used T-11 and new OSB. I think to make the insulation worthwhile, you need the vapor barrier and then it's common sense to put something up as a fire barrier.

My polyiso was salvaged from a commercial building roof. At the roofing company, I could sort through the piles and take what I wanted (1.5" and 2" thick) for $5 a sheet. It had the attachment holes to be filled and minor edge damage. In the last few years it's been available at that price several times but I haven't seen any advertised lately.

 

[aczlan]

Fiberglass batts are the cheapest way to go. R-19 fits in the cavity of 2 X 6 studs, available in 16" center and 24" center stud spacing. It has a vapor barrier face. On the walls w/o studs Just add non-load bearing studs on 16' centers. 2 x 4 ok just set out at 5.5" from the existing wall to their face. Then you have a way to add sheeting and/or shelves to the walls. R-19 is the energy code minimum any where where codes are enforced.

As I see it, either way, I will need to wrap the existing wall in tyvec or plastic to keep the wind out of the cavities, that's $0.06/SF (plus tax).
If I then put in R19 fiberglass, a 9 pack of Kraft face is $0.52/SF (plus tax), but I would need to stud out the long wall every 16" or 24" ($$$$).
If I put in foam (R15), I can put it over the top of the posts or studs (faster install) and it would be $0.59/SF (plus tax and foam), HOWEVER, it should insulate better as air infiltration should be nil.
If I really wanted to superinsulate, I could backfill the foam with blown in cellulose for an extra $0.30/SF on the 2x6 stud walls and $0.20/SF on the 2x4 post walls.

Guessing here, but the end walls are probably about 520SF between the two (once you take out the window, the man door and the garage door) and the long wall is ~480SF.

So, if my SF measurements are correct, it would be $1270ish to put tyvec on the walls around the studs, insulate the walls with foam and backfill with cellulose (assuming 200SF of wasted foam and $200 in spray foam, calk, etc).
I need to look at the roof and see how the trusses go together, if they are single, I might put foam between them and glue it up, then add braces every 4 feet (1 at each end and 1 in the middle) or something.

Aaron Z

 

[KennyG]

What is the spacing on your trusses? If it's 4 feet, you can directly attach metal panels and then blow insulation above it. The ceiling is more important than the walls if you want to heat it. I covered it with plastic, added the metal liner panels and then blew in cellulose. Not too expensive and very effective.

For vapor barrier on the inside of the walls (between heated space and insulation) you should use plain old plastic sheeting, not tyvek. Tyvek breathes and should be used on the outer surface before siding if you are replacing it.

 

[aczlan]

What is the spacing on your trusses? If it's 4 feet, you can directly attach metal panels and then blow insulation above it. The ceiling is more important than the walls if you want to heat it. I covered it with plastic, added the metal liner panels and then blew in cellulose. Not too expensive and very effective.

I think its 4 feet. The complication with the roof is that there is a 8' wide loft on the end next to the barn and I still need to be able to get in from the side...

For vapor barrier on the inside of the walls (between heated space and insulation) you should use plain old plastic sheeting, not tyvek. Tyvek breathes and should be used on the outer surface before siding if you are replacing it.

Here is a picture of what I am thinking of doing now:

From the top down (outside in):
Green with a black border is the outside T1-11
Blue with a black border is studs/posts
Red is Tyvec
Yellow is blown in cellulose
Orange is plastic (needed with foam?).
Purple with a black border is foam insulation
Pink with a black border is the inside wall covering (plywood for the first 8 feet, then possibly sheetrock or metal).

Does that make sense? Any suggestions on changes? I suppose I could skip the foam and just fill with blown in Cellouse, but then I would need to stud out the long wall...

Thanks

Aaron Z

 

[forgeblast]

I keep going back and forth on insulating the barn, but I think no matter what I put in the mice will love it.

 

[sld]

You don't need to go overkill on the walls other than to stop any air leaks. The ceiling is where you will make the most difference.

If on a budget, I would simply go the cheapest way on the the walls and super insulate the ceiling.

 

[BukitCase]

As Kenny mentioned, Tyvek breathes, which makes it an AIR barrier but NOT a VAPOR barrier. Plastic is BOTH, because NOTHING passes it (unless you make LOTS of holes in it )

Here's the main thing to watch out for - when you heat a space, the moisture in it wants to leave - water vapor is so fine it will go thru pretty much ANYTHING that isn't non-permeable. So the moisture in the room tries to exit thru anywhere it can.

Rule of thumb for occupied spaces is that the vapor barrier goes toward the HEATED side, in order to prevent moisture in the wall or ceiling - so in Florida, a vapor barrier would go on the OUTSIDE of the wall but in your area, you want it on the INSIDE.

MOST IMPORTANT - you NEVER want more than ONE vapor barrier, because in the REAL world, moisture WILL get into the wall at times - so if you accidentally end up with something that works as a vapor barrier on BOTH sides of a wall, that pesky moisture that makes it into the wall (one way or another) will get TRAPPED inside and will cause rot, mold and mayhem.

By limiting actual VAPOR barriers to ONE side, the wall can eventually dry out inside, which is what you want.

For normal house materials, even a good coat of latex paint will act as a vapor barrier, as will "trailer trash" plasticized paneling. Paper or foil as used on fiberglass batts is also a vapor barrier, especially if it's installed according to directions (overlap the backing on studs for a continual surface) - Foil on the foam insulation is the vapor barrier, so if you use that and cover the SEAMS with foil tape, that's your vapor barrier.

On the "vintage" side, tar paper on the OUTSIDE, if overlapped like shingles but NOT sealed, works as an AIR barrier but allows breathing - so it would work similarly to Tyvek.

Point being, if you're aware of what DOES act as a VAPOR barrier, just make sure you only use those materials at the INSIDE of your walls and use BREATHABLE stuff elsewhere, such as Tyvek for an AIR barrier on the outside.

I purposely didn't try to tell you exact materials to use, only an idea of which ones work where and why. I've seen enough of your posts to know that's probably more than you need :thumbsup: ... Steve