# Insulating and finishing an office shed?



## zuren (Feb 13, 2015)

This week I will be going to a shed dealer to discuss their offerings. They are prebuilt and bring them in on a trailer. I know a delivered shed kind of flies in the face of the DIY mentality here, but I'm picking and choosing where to fight my battles and spend my time. A prebuilt shed that is weathered-in will let me focus on other projects that I can realistically finish and buys me time to work on the interior myself.

The purpose of the shed is as my office, 9 to 5, Monday through Friday. I was working remotely before COVID, and had this idea of an office shed before working remotely became a widespread thing.

The size of the shed is 140 to 160 sq. ft. My biggest questions are insulation and HVAC:

Insulation
What would you do? I'm in southern Michigan so we see everything from 100 degrees and humid, to negative temps. I think standard fiberglass batting in a 2x4 wall gets a R-15 value at best. Spray foam gets around R-20 but is expensive. Panels of rigid foam with expanding foam around the perimeter of the bay is another option but haven't calculated what the R value or cost could be.

HVAC
I was hoping to do ductless mini-split to handle both heating and cooling, but I'm trying to sort out what I need. Some calculators suggest a 6000BTU system. Others say a 9000BTU system. You don't want to oversize a system, otherwise you deal with short cycling. I was also hoping to keep the electrical feeds to 120V but that seems to be a challenge as well, with more options available in the 9000BTU size. Is 9000BTU for under 200 sq. ft. too much?

I'll have more questions, but that is it for now.

Thanks!


----------



## farmgal (Nov 12, 2005)

All I can say is make sure your heat is vented. Forget spray foam it traps too much moisture.


----------



## zuren (Feb 13, 2015)

farmgal said:


> All I can say is make sure your heat is vented. Forget spray foam it traps too much moisture.


I'm not quite following the "heat vented" statement. Ductless mini-splits are electric, so there is no nat. gas or propane to worry about venting.


----------



## Jealous Gypsy Homestead (Apr 22, 2020)

zuren said:


> This week I will be going to a shed dealer to discuss their offerings. They are prebuilt and bring them in on a trailer. I know a delivered shed kind of flies in the face of the DIY mentality here, but I'm picking and choosing where to fight my battles and spend my time. A prebuilt shed that is weathered-in will let me focus on other projects that I can realistically finish and buys me time to work on the interior myself.
> 
> The purpose of the shed is as my office, 9 to 5, Monday through Friday. I was working remotely before COVID, and had this idea of an office shed before working remotely became a widespread thing.
> 
> ...


Rockwool insulation!! Its a lot better then the spray or that pink junk. We used it in our tiny home in northern Maine kinda alot like your weather. Its worth it to look at, plus it isnt itchy. My chickens have roosted in it and possibly eaten it lol. Its pretty safe and easy to work with heating. As far as your hvac i cant help ya, i installed a woodstove and thats all i use for the winter, works great if ya have wood &a splitter


----------



## GTX63 (Dec 13, 2016)

A pre built shed isn't sacrilegious to homesteading. I'm building a new chicken coop my self right now because I'm a cheap sob. If I didn't squeeze a dollar so tight I'd have the Mennonites backing flat beds up in my drive every week off loading their products for me to enjoy.

My opinion is a mini split is your best hvac solution. My neighbor's wife is a fraud claims agent who works out of a she shed about 75 yards from their house. Her husband cut a hole in the wall near the roof and put a window unit in.
Then he ran baseboard heaters. In hindsight he realized a minisplit would have been much more efficient when it comes to cooling/heating and with the utility bills. I would go 220v over 110.
You can get rigid foam insulation values of R19 on 2x4 construction. Your local lowes or HD should have current prices.
Don't forget to insulate below as well if you are on skids.


----------



## Fishindude (May 19, 2015)

For heat / cool, I would suggest a simple thru wall HVAC unit. Looks much like a window air conditioner but they have electric heat also.
So long as the shed is sealed up tight and insulated, it will take very little to condition the space.


----------



## weaselfire (Feb 7, 2018)

Bought two prebuilt sheds. Total price was just a hair over my material costs. Used fiberglass, finished interior with exterior sheathing. I can screw anything anywhere on any wall.

Mini splits work fine, go by the requirements of the specific manufacturer and model. Mine are combo window air/heat units, but I'm in Florida so the heat gets used about twenty minutes every decade or so. I do run dehumidifiers for most of the year, draining outside.

Jeff


----------



## random (Jul 23, 2020)

Mini-split or through-wall unit. I just installed a through-wall unit on a converted garage, does a great job keeping it cool. I'm heating another way, but they make units with heat as well. You may need to run 220 for that to work. HD has those and mini-splits: Search Results for through-wall air conditioner at The Home Depot

10,000 BTU should be sufficient for that space.

But insulate it like mad. Definitely consider the rockwool, fiberglass will give you about R-13 for a 2x4, or consider doubling up on that - you'd have to add to the studs though, I think.

Whatever you do, _do not forget_ under the floor! You've probably already considered it, but you'll get a ton of heat loss there. Roof/ceiling, too.


----------



## Jealous Gypsy Homestead (Apr 22, 2020)

random said:


> Mini-split or through-wall unit. I just installed a through-wall unit on a converted garage, does a great job keeping it cool. I'm heating another way, but they make units with heat as well. You may need to run 220 for that to work. HD has those and mini-splits: Search Results for through-wall air conditioner at The Home Depot
> 
> 10,000 BTU should be sufficient for that space.
> 
> ...


Yes, our tinyhouse is insulated under the floor. It has gotten to past -30 and weve kept warm


----------



## Rchickenlady (Sep 1, 2014)

We are close to the same spot you're at. Have a prefab shed, have wired it and put insulation in walls and ceilings. It won't be liveable this year, but we're doing the best we can for not knowing what we're doing. We're thinking some of that 2 inch foamboard on the floor, plus straw bales along the perimeter. I have a question, which you may have figured by now. The gable vents, on the ends....... is it ok to have R15 pieces of fiberglass around the vent, leaving it exposed, then a 2 inch foam sheet over that, with a cutout of the vent area that could be removed come warmer weather? Thanks, and good luck to you on your project. It's helpful to know that others are also trying.


----------

