Insulating and heating my new workshop questions

[Jesse LoVerme]

Greetings everyone,

This is my first post and I am new to the forum, thank you for providing such a great resource. I need some advise on my new workshop. I just bought a home near Minneapolis, MN with a detached 30 x 40 foot stick building - it is built like a regular garage. I am moving from Southern CA in 2 weeks to my new home and the cold weather is completely new to me. I need to insulate and heat my workshop quickly before the winter sets in. I know how to build in CA, but I am completely confused on building in MN. I want to insulate the shop on a budget, so I want to put in bat or blow in, and not foam. I am completely confused on the vapor barrier/humidity/cold issue with insulation, not thinking about in in Southern CA as much, and I have read the MN residential code and remain confused. Does anyone have any advise on how to best insulate my workshop? Do I need vapor barrier on the walls and/or on the ceiling? I also don't have the ceiling figured out. It is 8 feet high and I prefer not to drywall it because I don't want to feel claustrophobic. Is there a way I can insulate the roof directly without causing moisture problems? I prefer open rafters in my shop, even it costs me more to heat it the space. I think I will definitely drywall the walls, but yes, would like to keep the top open.

That brings me to the other question, what is the best way to heat this thing using natural gas? I don't know the BTU size or best way to do this. As far as I have read the hanging furnaces will be a code violation because I don't have 8 feet of clearance. I was thinking also that I have an old force air furnace in the 4000' house (could be to big and I don't know the BTU on it?) that I want to replace because it's old. Can I just replace the home furnace and put the old force air one in the shop as a ducted forced air unit? I could move the old house A/C in with the old furnace. I think my wife would like this option, free home furnace and A/C upgrade without spending money on the shop heating.

Thanks, woodworking in the frigid north is a new one to me!

[Frank Pratt]

I'm in southern Alberta & it can get pretty cold here but I don't know how that compares to MN. Fiberglass batt is probably the most economical way to do the walls. It you want to keep the trusses open & insulate the roof then it gets more complicated. I suggest you go to the Fine Homebuilding website or www.greenbuildingadvisor.com (http://www.greenbuildingadvisor.com) & see what info they have. Insulating a roof really has to be done right.

Good luck.

[Cliff Polubinsky]

Jesse,

I just did the same thing - turned a garage-like outbuilding into a shop. For insulation look for Roxul. It's a rock wool material that has a higher R level than fiberglass and easy to install. It comes in 4' batts that you press between the studs. You can cut it to fit around junction boxes, etc. with a sharp knife, or I used a japanese saw. Vapor barrier goes on the inside, that is between your shop space and the insulation. The idea is to keep moisture from penetrating the insulation and freezing. Press the insulation between the studs and staple the vapor barrier over it, taping over the seams. Instead of drywall I used a composite siding that was pre-primed in tan. That way I didn't have to do any wall painting since the primer looked fine by itself and it takes nails and screws better than drywall and doesn't require mudding and sanding.

For one option for the roof, do a search on hot roof installations. With this type of setup you seal all openings in the roof and eaves so there is no air movement. Insulate between the studs and vapor barrier it off so it's completely sealed. You want no air movement in the space at all. Then you can dry wall that giving you a cathedral ceiling above your rafters, which is what I did. This also allows you to put your hanging furnace above your rafters so it will give you the 8' plus clearance. I had a HVAC dealer put mine in cause I didn't feel confident enough I could do the install with the gas line work, etc. and get it right enough that I wouldn't blow the place up, gas myself or put in the wrong size unit and have to do it again. With Minnesota winters you want the thing to work well from the start. Going from southern California to Minnesota is going to be a definite cultural and climate shift, if not shock.

If you want I can put up some photos of my shop.

Good luck and learn about thinsulate and down. You'll need them in a few months.

Cliff

[Ole Anderson]

Welcome to the Creek!!!:cool:

I would prefer painted 1/2" OSB on the walls, much tougher than drywall.

[Randy Rizzo]

2X4 or 2X6 studded walls? I'm in the U P, gets pretty frigid here in the winter months. I've got 2X6 walls, 9' ceilings. R38 in both floor and ceiling (shop is 2nd story over a garage) 75,000 Btu separated combustion Garage Guy LP heater. You need the separated combustion, keeps from sucking dust laden shop air into the furnace. My walls are R19 Fiberglas with pine panelling. Normally run it at 55 degrees, if I'm working, 70 or so. Luckily you em got access to NG, propane is expensive and last winter, thru the roof, literally. $6+ a gallon. This year as low as I've ever seen in my 20+ years here, $0.99. I'd stick with the 8' ceiling height, drywall it and insulate above. My shop is 24'X28'

[Larry Frank]

If you have not lived in cold weather areas, you are getting into an entirety new experience.

You need to insulate as much as you can afford....up there you can not have too much.

Does this building have garage car doors? If so, insulating them as much as the walls is not easy.

In addition to the garage insulation, you will need heavy winter coat, stocking cap, gloves, shovels and probably a snow blower. It will be interesting to hear your comments about your new home next January.

[Jim Dwight]

I would use fiberglass bats and plastic vapor barrier on the inside. The purpose of the vapor barrier is to block moisture from entering the insulation and condensing. That ruins the insulation value and can lead to mold problems. Outlets and light fixtures break the vapor barrier and should be sealed too. I bit the proverbial bullet and bought the $50 great stuff gun from Home Depot because I have an old house that needs a lot of sealing. It lets you use the foam more accurately and it seals up between uses so you can keep using the one large can as you have things to seal.

On the ceiling, if you can rig up the vapor barrier first you can use blow in and save some money. I would want a foot. You'll need to have it deeper because it will settle. Maybe 16-18 inches during application. Vaulted ceilings are nice but can be hard to seal up if there are collar ties.

Drywall is OK on the ceiling but I would use OSB on the walls. It's cheaper and works better. I skim coat it with drywall compound and paint it with ceiling paint. It brightens up the shop a lot and also lets me hang tools anywhere.

[Bill Adamsen]

The insulation will also help in the summer when you need to air-condition.

[Doug Swanson]

Welcome to the tundra...you are in for a treat :). Remember there is no bad weather just bad clothing choices. Being a native of MN here are my thoughts...
1.)Vapor barriers - Their purpose is to keep the warm moist air away from the cold..aka condensation in walls. There is some controversy if they really contribute more to keeping moister stuck in the wall cavity or help... but the code is the code...in short you should put in your elec/mechanicals in walls/ceiling...now put a vapor barrier on the ceiling and put your code compliant (must be fire rated...typically 5/8" sheetrock) ceiling in...I know you said open rafters but that's not a reality in MN...hot air rises and you want to keep all of it inside the envelope. Leave yourself an access panel in the ceiling so you can get up there and blow insulation...blown fiberglass is common but blown cellulose will hold it's r-value better when it gets really cold..don't be stingy on the ceiling insulation and make sure you put in the air chutes before you put up your ceiling...
The walls are next and you put in your insulation of choice in the wall cavities and then you put your vapor barrier up...followed by your wall covering of choice...At this point you will want to paint the walls a light color...it gets cold and dark in MN in the winter and a bright colored room is best.
2.)Heating - Your 8ft ceilings limit your options...You said you did have gas so that helps. An old furnace would work but the problem with that is it blows the air around and it sucks in that air...which means dust on your projects and in the fan...might not be that big of an issue. Running the ductwork will take up some of your space. You could use wall mounted heater(s) but they give off moisture and that could be a problem for you too. Electric is expensive to operate so baseboards are probably out. If money were no object I'd do radiant floor heat with a gas boiler. I have a radiant tube heater but my ceilings are 12' in my garage...

Best of luck...buy good winter boots...if your feet are warm in your shop it's more tolerable.

[Jim Laumann]

Jesse

Welcome to the Land of 10,000 Tax...errrr I mean Lakes. I live 90-100 miles S of the Cities. I must echo what Doug S. said - INSULATE - INSULATE and INSULATE.

I have a 40x30 pole frame shop, w/ 12' ceilings. I have 1.5" high density foam in the spaces formed by the purlins on the posts, followed by 6" of glass bats, a 6mil poly vapor barrier, and steel (same as the exterior) for the liner - walls are about R29. The steel is bright white - lots of reflected light, and I didn't have to paint it. The ceiling is also steel, w/ the vapor barrier, and blown glass - about 16-18" of it, or R44. Did I say INSULATE?

I have had the shop since 2010 and been heating it w/ a wood burner. This fall I intend to get my ceiling mount heater hooked up and operational. In my case, I burn LP. My intent is to let the gas burner keep the temp at 40-44 degrees, and use wood when I want more heat.

Check your buildings doors (overhead and passage) - make sure they are insulated and weather stripped - windows as well.

Since you have 8' ceilings, a ceiling fan or two could help w/ the heating and cooling. I put a one in my building, but w/ my high ceilings, its effect is limited to mostly the heating season.

Your floor (I assume concrete), is going to be cold - no way to avoid unless you can swing in-floor heat. I couldn't when I had my building put up, so I settled for having high density foam put under the concrete.

A word of caution - check with your municipalities building code department - check the electric code w/ regard to wiring run in stud cavities of a out building (non residence). I had to run all my wiring on the surface in EMT to be legal. Since I live in a rural area, that was a state electric code thing. It's perfectly legal to use the cavities of a un-insulated building, but as soon as you insulate - the rules change. Got this straight from the state electric inspector who covers my area.

Good luck, and keep us posted.

Jim

[roger wiegand]

Vapor barriers are not so much an issue in a shop without significant moisture sources, like cooking showers, etc. Plastic on the warm side will be fine. You can't have too much insulation, the roof is most critical, the walls less so. As important is air sealing. All the insulation in the world does little good if the wind is whistling through. You'll want to thoroughly caulk or foam seal the sills and top plates, as well as corners, and around windows.

You need to ventilate your roof, which is more complicated to do at the roofline. You need to have soffit and a ridge vent, and then use some sort of tray to maintain an open path from the soffit to the ridge so you don't stuff it with insulation while still keeping the roof cold. If you don't do this you can get awful ice dams and nasty flooding in your building. You might want to consider spray foam and a sealed roof for the roof insulation, as proper insulation is a PITA. If you want to keep the rafters open can you place a gas heater above them? The Modine Hot Dawg I have has that kind of installation in its instructions, so should be fine from a code point of view.

Packed cellulose is good bang for the buck for wall insulation. Fiberglass can be OK, but is very dependent on installation technique to achieve close to the rated R value. I'd strongly suggest you consider adding at least 1" of rigid foam on the inside over the studs in addition to filling the cavities to stop thermal bridging. This can also be your vapor barrier. Not so expensive and helps a lot with air sealing.

In your climate I think you will find the payback time for any of these insulation methods to be very reasonable unless you're able to heat with free wood in a stove.

[Jim Dwight]

A point about ceiling drywall. 5/8 fire rated is only required when there is living space above. I don't think that is the case in this situation so you can use 1/2 if you want. It's cheaper and lighter.

[Don Jarvie]

Try a cathedral ceiling. About 1/2 way up run the 2/4s across the ceiling. Add plastic vents from the soffit pas the 2/4s and the insulate over the vents and the ceiling. It will give you more room in the middle of the shop. Add a ceiling fan to blow the heat down. 3/8 drywall on the ceilings since it can be hung with one person using cleats to support one end.

[Phil Thien]

We are supposed to have a mild winter this year.

No, really. They said El Niño winter. Mild.

I swear.