Insulating an Unconditioned Storage Shed
Sofiane
| Posted in Energy Efficiency and Durability on
Hi,
I’m planning on building a 14’x8’x9′ shed in the near future for general storage including our surplus wood floors and construction materials. It will have two doors facing NW with about an R5 value with no windows.
I live in zone 6 and was wondering whether it made sense to insulate the shed to keep it above freezing in the winter.
It’s unclear whether I can have a heating system installed. Assuming I cannot, what R values am I aiming for to keep the shed above freezing?
Thanks for your help!
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
I'm doing a similar project right now.
With no heat inside, it doesn't matter how much insulation you have. You will need at least one heat source. It doesn't need to be big though. With my design, I am aiming to be able to keep it above freezing by just using a few incandescent light bulbs. Can we assume that you will be able to run an extension cord and hang an incandescent bulb or two as a heat source?
A big question that I had in doing my design was whether or not I should try to use the ground as a heat source. There are two basic approaches:
1) Insulate the floor like you would insulate the walls and ceiling. Put a heat source inside the shed.
2) Keep the floor exposed to the earth (e.g. a cement slab with no insulation underneath.) Where I live, the ground is usually above zero and so it would act as a heat source in the winter. However, this approach can be difficult. If the ground ever freezes, then it will be very hard to get the shed back up above freezing.
I opted for approach 1. Too early to know how it will work.
Thansk for answering, I actually had a look at your posts.
We will have an electric installation inside, allowing for a few 100w bulbs shouldn't be a problem. The big question is how many wil be enough.
I was already planning to insulate the ground below the slab just to make the slab go through less freeze-thaw cycles. If I try to keep it above freezing, the R10 I was planing as the non-insulated shed most likely won't be enough though.
Any suggestions as to what would be necessary?
I must have skipped it, but how much insulation do you have in the walls?
I ended up doing 2x6 stud walls with Rockwool. Also 2x6 floor. So R22 Batts in the walls and floor. Managed to get more in the ceiling. No windows but I have a door and that is a weak spot. Thinking of installing a second door to address that.
> The big question is how many wil be enough.
You need to do a heat loss rate estimation for your shed at your worst case design temperature.
Your 2 100W bulbs will output 200J/s or 682BTU/h.
If your heat loss rate at the chosen design temperature is greater than that, you won't be able keep it above that temperature.
Why heat with 100W incandescent bulbs? They're just producing resistance heating, like any resistance heater. Plus, exposed hot bulbs in a shed can be a fire hazard. Just buy an inexpensive 1500W heater with a built-in thermostat. They're designed for this use, they will cost pretty much the same to run, and they'll be safer in the long run. Plus, the built-in fan will increase mixing and reduce stratification.