Insulating a pine shed to be used as a studio
Hi there! We have a shed in our backyard that I’d like to convert into a studio space. Probably I’ll have a space heater in there in the winter – maybe one day a mini split. No plumbing and no one will be living in it, just working in it for a few hours at a time. We’re in Maine – cold winters and relatively warm/humid summers.
It’s pine siding without sheathing or WRB with 2×4 framing that’s exposed. The floor was actually insulated when it was built in case we wanted to insulate it down the road.
I’ve been researching Havelock wool insulation and my tentative plan is to use the wool batts with plywood for the walls without a vapor barrier (it looks like Havelock generally doesn’t recommend one.
My question is would you recommend something to the inside of the siding before I put in the batts? (Otherwise it’s siding, wool, plywood.)
And maybe it’s a moot point now, but would having tyvek attached to the framing (since there’s no sheathing) before the siding went on have been a good idea?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Replies
squirrel23,
There are several good articles on GBA about insulating walls with no sheathing. The most comprehensive is Martin's blog: https://www.greenbuildingadvisor.com/article/insulating-walls-in-an-old-house-with-no-sheathing.
Most important is establishing a continuous air-barrier. Otherwise all the new insulation will be ineffective.
Thank you so much, Malcolm! I read through that article earlier but I think it's all clicking more what you mean about the air-barrier now upon re-reading and having done more digging in the interim!
I also called a local green building supplier and asked if they had recommendations. They were really kind and had some suggestions (although they seem somewhat at odds with the article?).
They recommended
- In the 2x4 framing against the pine siding do the Havelock sheep wool insulation
- Then a membrane that they carry, with all seams well taped
- Then 2x2s horizontally to create a thermal block (where more insulation could be put as well they suggested) - they mentioned that the 2x4s of the framing would be a loss of heat
- And then the plywood walls
This is similar to what the article outlines but the air space is not next to the siding, the wool is. Is there something about it being air permeable that makes this okay? (Unless maybe the reverse order was what he was saying and I misunderstood.)
Having the air space next to the siding, and fully sealed off with the foam and tape, makes intuitive sense to me - with the wool batts inside of that. And it seems like that foam/tape layer would serve as the air barrier (and would be in place of the membrane option) if I understand correctly.
Thanks again for taking the time to share the link and your thoughts, Malcolm!
squirrel23,
The air-space next to the siding is there to stop water from moving through the siding into the rest of the wall assembly - sort of like an inverted rain-screen gap. In the absence of sheathing or a WRB it's fairly important that it be there. It can be as simple as house-wrap stretched tight and stapled in each stud bay, and as shallow as 1/2". If your primary air-barrier is going to be the interior membrane, you don't need to worry about sealing the exterior air-space from the rest of the wall.
The rest of the assembly they suggest is commonly called a Mooney wall. They work well. You can look it up and get some good illustrations of how it's done.