Insulating new workshop barn

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Forum topic by Zvonko posted 10-30-2020 12:58 PM 574 views 0 times favorited 14 replies Add to Favorites Watch
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101 posts in 727 days

10-30-2020 12:58 PM

For those of you using a separate, standalone, building as your workshop in cold weather climates… How do you insulate it?

Although the winters are getting (a little) milder, they still get pretty cold here in Northeast Ohio. So I am thinking about how to insulate the barn not only for the winters but also for the summers when it gets really hot and humid here.

Should I be worried about the barn being “airtight” (I know it never will be 100%)? I want to avoid creating an environment where moisture is trapped in the barn. I also need to think about ventilation. Even once I get a good DC system, I probably still want to have some kind of ventilation system.

Since this is the first time I’m building a barn I want to try to learn from others’ experiences so I don’t do something I’ll regret later or over/under-engineer this.

Please tell me how you’ve dealt with this in your workshop.


-- You can't always control WHAT happens, but you can always control HOW you respond.

14 replies so far

View Fred Hargis's profile

Fred Hargis

6557 posts in 3406 days

#1 posted 10-30-2020 01:32 PM

Are you considering a pole barn, or post and beam construction? At our last place I had a nice pole barn and could not figure out a way to insulate it to the R value I would want (affordably). Fortunately we also had a detached 2 1/2 car garage so I used it. Pole barns have other problems as well. In humid weather (if they are enclosed tightly and insulated) it will rain inside as the humidity condenses on the underside of the roof panels. So a little more info on what exactly you are thinking might be useful.

-- Our village hasn't lost it's idiot, he was elected to congress.

View ibewjon's profile (online now)


2136 posts in 3706 days

#2 posted 10-30-2020 01:37 PM

A friend spray foamed his walls, put in a sheet metal ceiling, and had blown in, fiberglass or paper, blown in for the ceiling.

View Tennwood's profile


113 posts in 4094 days

#3 posted 10-30-2020 02:30 PM

Three resources I would look at that discuss this issue.

Fine Woodworking has had a couple of issues discussing workshop remodels and several stand alone shops tours with details. Unfortunately most are behind the paywall. One free article that may be of help is editor’s Mike Pekovich’s garage to shop makeover.

Fine Homebuilding also has several articles addressing this. Again, some may be behind their paywall. They have a forum that is often monitored by building pros.

Lastly – check out Green Building Advisor. They address insulation in many articles and their forum is very friendly with building pros often answering people’s questions.

Good luck with the build.

-- Jim, SE Tennessee, "Don't spare the kindling Dear, we have plenty"

View metolius's profile


260 posts in 1643 days

#4 posted 10-30-2020 04:42 PM

Spray foam is good advice to look into. Here is some foam FAQ marketing material I have bookmarked.

I have a dirt floor pole barn and have recently been considering if its feasible to convert it to a personal workshop. I haven’t yet decided how serious those thoughts are, or if the barn is truly worth it… Please, post progress if you move forward.

-- derek / oregon

View JohnMcClure's profile (online now)


1107 posts in 1553 days

#5 posted 10-30-2020 05:12 PM

I just had my metal shop building spray foamed with open-cell. 30×30x10 shop, cost was 2600.
A word of advice: cover the floor first. Also I sprayed closed cell foam from a can around the bottom 1st as a precaution against moisture.

-- I'd rather be a hammer than a nail

View EllenWoodHead's profile


117 posts in 289 days

#6 posted 10-30-2020 06:27 PM

I have a steel pole barn that I am remodeling to use as a shop. It was built to the cheapest possible specs, most notably 0 pound chords. I had no idea that was even possible. So that rules out hanging a ceiling, or anything at all, from the trusses, except perhaps lightweight insulation sheets made for hanging from trusses.

My area has hot summers and cold winters. It would be way expensive to retrofit the barn to the same standards as a house, and I want to keep costs as low as possible. I need heating and maybe a bit of cooling a for a few months of the year, and only when I am using the shop. This is my plan:

1. Insulate the walls and roof with fiberglass batts. Roof already has a 2” insulation blanket.
2. I have a propane torpedo heater connected to a 120 gallon tank. It is stinky and noisy, but it’s cheap and heats the space up fast. I’m not growing orchids, I just need it warm enough to work comfortably.
3. The insulation may be enough to keep it cool enough in the summer. If it isn’t, a swamp cooler provides cheap cooling.
4. Not worried about making it super tight, in fact I need it a bit leaky because of the torpedo heater, and to help with dust control.

This is a dry climate, though in winter it is more humid, which makes it less than ideal for lumber storage. Not sure what to do about this, for now I store the wood for current projects in my garage for a couple of weeks to acclimate it.

The floor is stable mats over sand and dirt. Next year I hope to have a concrete floor installed, meanwhile I have a temporary floor of plywood sheets over the stable mats. The plywood will become walls after the concrete floor is in.

My long-term plan is to go solar. We have plenty of room for our own little solar farm, and perfect exposure. I wish the money fairy worked a little faster so we could get this done sooner :)

-- "wood" and "good" rhyme, but not "food"

View ibewjon's profile (online now)


2136 posts in 3706 days

#7 posted 10-30-2020 07:00 PM

Your climate will also affect your choices. Hot, humid summer and cold winter, or hot dry summer and cool, wet winter.

View Mosquito's profile


10507 posts in 3205 days

#8 posted 10-30-2020 07:08 PM

I have a garage door in my standalone shop, so I wasn’t worried about being too airtight.

I installed vapor barrier per building code, and R13 Kraft faced fiberglass insulation. I used house wrap tape for all the seams, and places where the vapor barrier met the ceiling, and around all outlets or lightswitches. I had a company install blown in insulation in the attic, and they also spray foam sealed around all ceiling outlets and can lights before insulating.

I have heat in my shop for the winter (dual vented sealed combustion furnace), and I run a humidifier all winter to keep the humidity up around 45-50%. In the summer I run a dehumidifier to keep the humidity down to about the same, otherwise the really humid or rainy stretches it would creep up to 60%. Being more air sealed just helps decrease the costs of heating and conditioning (humidity) the space.

I did fiberglass batt insulation instead of spray foam because of cost and uncertainty around electrical and HVAC install at the time. I wasn’t sure what type of heat I was going to go with, and liked the idea of not having to mutilate sprayfoam insulation to run a gas line or new electrical circuits.

If everything was 100% planned out, and/or doing all surface mount electrical and cost wasn’t a factor, I would definitely have gone with sprayfoam, but that’s just not the world I live in :)

-- Mos - Twin Cities, MN - -

View Robert's profile


4137 posts in 2394 days

#9 posted 10-30-2020 07:39 PM

I think Fred is right, the construction is important to consider. Either way, you need to end up with an insulatable wall.

For the roof if you want metal, one option is sheathing with felts under metal. You don’t want bare metal exposed in he shop because it will condense water in the winter. That said, I’ve heard you can spray foam directly on metal, but what about leaks? Inevitably they will occur with anything other than a standing seam.

In my climate (NE FL) air conditioning would be a luxury, but insulating it and what to do with an exposed metal roof is too much for me to even think about.

-- Everything is a prototype thats why its one of a kind!!

View DrPuk2U's profile


81 posts in 3205 days

#10 posted 11-06-2020 08:27 PM

FWIW, here is how I insulated my pole barn.

Works great! Not through a whole winter yet, but some of it. Very snug. Biggest problem is the ratty old (or nonexistent) door sills. On the list.

-- Ric, Western Oregon, "Design thrice, measure twice, cut once... slap forehead, start over"

View mike02719's profile


266 posts in 4699 days

#11 posted 11-07-2020 03:15 AM

I took over my three car garage and use two for my shop. four inches of fibreglass insulation on the ceiling,m two inches on the walls and one inch of foam sheets on the floor. the walls and ceiling are half inch osb. the floor is three quarter ply over two by threes laid on the flat. Heat is from a direct vented natural gas heater with a blower Ceiling insulation is very important and the floor is always comfortable to walk on and allows wiring to be easily installed.

-- Mike, Massachusetts

View Zvonko's profile


101 posts in 727 days

#12 posted 11-10-2020 02:58 AM

Hey, thanks for all the replies. Good info.

I’m not sure what size qualifies as a barn. Mine is a gambrel style 16×24 shed/barn. I mention this because of Fred asking if I was building a pole barn, or post and beam construction. I’m not really sure of the difference. Here’s a picture I found online that I’m basing my design off.

Main difference is mine is on a concrete pad.

-- You can't always control WHAT happens, but you can always control HOW you respond.

View gerrym526's profile


290 posts in 4721 days

#13 posted 11-23-2020 06:46 PM

I used to live in the Midwest, so I’m very familiar with your climate in NE Ohio. Since you’ve shown a picture of the building, if it has wall studs on 16” or 20” centers, I ‘d recommend fiberglass batts in the walls (and perhaps in the roof as well-if you don’t plan to have a ceiling).
Don’t think about making the building “airtight”—you will trap moisture and get mold. Another reason why I recommened unfaced fiberglass-spray foam insulation is notorious for trapping moisture. You really want the building to “breathe” so it releases moisture, rather than trapping it.
Noticed you also have windows, so why not use them for ventilation?
Hope this helps.
I live in North ID which is a drier climate in the mountains vs. the Great Lakes, but have used unfaced fiberglass in my house and shop building, and they both stay very cozy in snowy winters, and cool in hot summers.

-- Gerry

View Woodmaster1's profile


1558 posts in 3500 days

#14 posted 11-24-2020 11:03 AM

I live in northeast Indiana and I have r19 fiberglass insulation in the walls and r30 in the ceiling. My shop is 33×30. I use a natural gas bigmaxx heater. By your design go with fiberglass with and a gas or electric heater gas being the cheaper alternative.

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