Vapor barrier on out building

1135 Views 14 Replies 7 Participants Last post by Master Brian, May 3, 2020

Master Brian

Discussion Starter · Apr 30, 2020

My cousin is working on turning an old chicken coop into a functional space for working out/ playing music. Probably close to 100yr old building built with hollow clay block, concrete floor, wood framed roof with tin covering shake shingles. Not sure how he plans to heat/ cool the space, discussed mini split, but no solid decision made yet.

I plan on helping him frame the interior walls, so he can run electrical and then install some sort of wall covering soon. He's thinking shiplap or something, doesn't think any drywall. Out in the country and no inspections or permits, but trying to do mostly correctly.

The question is, what's the best way to vapor barrier this so he can hang bat insulation in the 2x4 wall cavities?

I suggested, 1/2" foam taped seems and spray foam the joints in hard to manage areas as I've seen that being method for basements. What about xx mil plastic sheets? Either stretched across back of 2x4 framing and stapled or attached to roof framing and draped to the floor, so the batting can't contact the block?

I'm not sure if the vapor barrier is essential as we're in South Central Kansas and heating/ cooling seasons are about equal here. Main goal is to protect the batting. But looking for input. We don't want to have to go back later.

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Bud9051

· #2 · Apr 30, 2020

Will this space be heated and cooled 365 or on and off as needed?

Intermittent conditioning can be a problem as any moisture left inside will look for cooler surfaces.

The thinking on vapor barriers has changed as they have learned vb were a mistake from the start. Citation available. There are places and climates where some are needed but for the most part they are not. The ability to dry is more important.

Let us know if this will be come fully conditioned or on/off?

Bud

Master Brian

Discussion Starter · #3 · Apr 30, 2020

I don't think they'll leave it fully conditioned, probably only as needed is my guess, but that may change once they start using it. Should he just forgo the barrier?

What about holding the insulation off the block? I suppose we could frame the walls so they are out a few inches, but loosing space isn't fun either. He said right now you can't feel the wind come though anywhere, so maybe he forgo's the bat insulation and just lets the air gap in those block do the job?!

Nealtw

· #4 · Apr 30, 2020

Master Brian said:
I don't think they'll leave it fully conditioned, probably only as needed is my guess, but that may change once they start using it. Should he just forgo the barrier?

What about holding the insulation off the block? I suppose we could frame the walls so they are out a few inches, but loosing space isn't fun either. He said right now you can't feel the wind come though anywhere, so maybe he forgo's the bat insulation and just lets the air gap in those block do the job?!

You could just add foam board to the walls and strap it with 2x4 on the flat.
Will you be doing a ceiling with a vented attic?

ClarenceBauer

· #5 · Apr 30, 2020

Clay tile / block you will do a lot of damage to these blocks when using nails & in most cases drilling will cause that old block to fail. I would look @ using the EPS board adhered to the Clay tile on the exterior for wall insulation with a Synthetic base & finish applied over the EPS.

SeniorSitizen

· #6 · Apr 30, 2020

Is there 2 different threads open on this topic?

SeniorSitizen

· #7 · May 1, 2020

SeniorSitizen said:
Is there 2 different threads open on this topic?

Records show i posted this earlier but i'll do it again here.
****************************************************
There is a reason chicken houses were built of clay tile block with shake shingles and there is a reason it still stands and will be standing when you'll see buildings much newer have fallen to the dirt. I'd leave -er alone and workout early A M in summer and late P M in winter. If other times are necessary consider it's like doing a marathon in inclement weather.

Master Brian

Discussion Starter · #8 · May 1, 2020

SeniorSitizen said:
Is there 2 different threads open on this topic?

Yes, there was a duplicate posted by my phone. Don't know how to delete it and said don't post here, but people did anyway!

Master Brian

Discussion Starter · #9 · May 1, 2020

ClarenceBauer said:
Clay tile / block you will do a lot of damage to these blocks when using nails & in most cases drilling will cause that old block to fail. I would look @ using the EPS board adhered to the Clay tile on the exterior for wall insulation with a Synthetic base & finish applied over the EPS.

The bottom plate will be nailed to the concrete floor and the top plate to the ceiling joists. Nothing will be nailed to the block!

He isn't covering the exterior wall, he wants that rustic block look! It's a really neat looking building with the old clay block and the weathered tin roof!! Obviously, this is an old farm stead of sorts.

Master Brian

Discussion Starter · #10 · May 1, 2020

Nealtw said:
You could just add foam board to the walls and strap it with 2x4 on the flat.
Will you be doing a ceiling with a vented attic?

I'm not really sure what his plans for the ceiling are at this stage. Just trying to get the walls up and see where it is. I would assume the minimal attic space will be vented to some degree, but it'll be partially vaulted ceiling.

I was trying to get him to buy foam board and glue it to the block...I think they are a flat enough to make that work. We'll see I guess.

Reactions: 1

Porsche986S

· #11 · May 2, 2020

Here is what I would do . I would spot glue 3/4 " foam or thicker to the interior side of the block and tape the seams . Then I would use 2x6's to stud the walls , run all electrical then fill stud cavities with standard fiberglass insulation . Now you have a fairly well insulated wall to secure the ship lap to .

SeniorSitizen

· #12 · May 2, 2020

After all that work, in a few years or sooner, Master Brian's cousin will be back asking what that strange smell is, why termites have eaten rafter tails and why is there so much mold between the tile and foam board insulation.

AllanJ

· #13 · May 3, 2020

... why is there so much mold between the tile and foam ...

When you commit to a vapor barrier on the (winter) warm side, just behind the shiplap or drywall, what is behind it needs to be hermetically sealed which in practically all projects does not happen. So every winter, moisture gets in and condenses on the cold side (against the tile wall or concrete basement foundation) and every summer not all of it comes back out, some having been trapped by the vapor barrier.

Reactions: 1

SeniorSitizen

· #14 · May 3, 2020

AllanJ said:
When you commit to a vapor barrier on the (winter) warm side, just behind the shiplap or drywall, what is behind it needs to be hermetically sealed which in practically all projects does not happen. So every winter, moisture gets in and condenses on the cold side (against the tile wall or concrete basement foundation) and every summer not all of it comes back out, some having been trapped by the vapor barrier.

That's what i've said for years, so now i'm waiting for someone to tell us how to hermetically seal this area.

Master Brian

Discussion Starter · #15 · May 3, 2020

So if insulating should be just hang non-craft face batting in the stud bays?

I've included a picture of the chicken coop. He inherited those 2x's years ago when he bought the place and has a trailer full of them, so that's what we used. They're totally non- structural, just something to install a wall covering to.

I also don't get the comment about termites eating the rafter tails in 10yrs. There's no wood in contact with dirt.

In my basement with concrete block wall and I read as much as I could on it when I was insulating. Everything seemed to say blue foam, dow, glued to block, then seams taped. I then framed the wall and installed batting. I couldn't locate the tape, so I used spray foam in every seam/gap I could find between foam and block. I've never seen any signs of mold/mildew down there. Are you guys saying that shouldn't have been done?

***105yr old house of that matters

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