Old Detached Garage - Insulating

[Rich_R]

I'm looking for some ideas, advise, suggestions on what to do with my 'new to me' garage. Please go easy as I'm new to this prospect of insulation but I'm handy enough with the tools to have a go at DIY and learn along the way!

I appreciate there is lots of information on this forum and i've read quite a lot of conflicting information as well, but hopefully some of you can point me in the right direction.

The garage is 20 years old, detached and a mixture of concrete walls and wood. The building itself is built into a slope, hence the use of concrete (and the support in the middle and back wall). To the right of the garage is a small workshop/storage room, which is separated by a stud wall and OSB, but is technically part of the overall building. Building is approx L28' x W36'

Climate: Canada, BC interior - temp range -30c to +25c (-22f to +77f). Tons of snow.

Heat source: At the moment a single baseboard electric heater, but will look at adding something better once I've got the place insulated.

Use: workshop, mechanics etc. I don't need it to be toasty warm in winter, but I'd like to make it more bearable in winter!

Ventilation: Soffit vents already installed in the roof over hangs and two good sized gable vents in the roof.

Vapour barrier: Install on the outer walls and roof/ceiling. Closest to the inside: Garage space (warm) - > OSB - > VB > Insulation > Outer wall -> Outside (cold) - Right?

Question 1: Do I need a vapour barrier on the internal wall between the workshop/storage and garage?

Question 2: Concrete walls. These surely let out a lot of heat, not sure what to do here? The back/rear wall just has OSB covering the concrete wall.

Question 3: Insulation type. The OSB is already in place. My plan is to paint it white eventually (Kilz->Latex paint). I'm thinking something like R12-14 in the walls and R30-R40 in the ceiling? But which type? Fiber or cellulose blow in? I still need to remove the OSB since I need a vapour barrier, so does blow in make sense?

Lastly, there is an open void in the ceiling at the moment, I will cover and enclose the roof space once insulated.

Pics:

(RED is the interior wall between the store room - GREEN pointing to the roof/attic space i need to close up after)

 

[Rich_R]

Any feedback? Did I post this in the wrong part of the forum?

 

[banjopete]

Nope you just have to use the patience! Welcome and welcome from another canuck. I'm one of many lower mainland kids that left for 'murica north in alberta.

You have a pretty awesome space there and a great starting point compared to many.

You have the inside to outside setup correct with your heated space to outside description.

If you are going to pull the osb off the ceiling you'll have easy access to all the joist spaces for whatever insulation you choose and as long as that joist spacing is standard batts will be friction fit so again adding to the ease of vapour barrier install.

I'm up in Edmonton and we dont get near the snow load you may in the interior but we get the cold without doubt.

From my own experience, we moved into our place 5 years ago and it was just bare framing 2x4 walls. I did a first phase of insulated walls and lived with that for 4 years until I could do some structural changes which I did this past summer. I then insulated and heated the ceiling to seal it all in.

Vapour barrier made a big difference, insulation made a huge difference for heat loss. The final touch was a quality natural gas heater. Buy once cry once. Tstat controls the heat, I keep it above freezing year round and can be very comfy when I'm working in there now.

If I were you, I'd finish the insulation whichever way you plan. Big r numbers are good but there are diminishing returns chasing bigger and bigger r values beyond a certain point. After seeing the chart below I worried less about "best" and quickly realized gas is cheap, and a tight well insulated space is more than enough for what I need, and efficient price wise.

I'd also recommend getting a natural gas heater, they generate lots of heat and when sized appropriately they'll keep you very comfortable as you need it. They dont cost a ton but are well worth the spend. I can't tell you how nice it's been change wise in my own shop. You can often find big old workhorse units for sale. I've got a 45k reznor and picked it up locally with the entire vent kit, tstat for just under $1100. We pay a lot more up here but that was still a fantastic deal to me.

No need for vapour barrier in internal walls withing heated spaces.

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[Chuckster in NJ]

Blown in insulation is what I would do. You can also "stud out" the concrete area with 2x3 or 2x4 metal studs and use "batts" or foam board in that area..... Or leave it alone.

That masonry is soaking up the freezing temps and is the "weak link" on insulating the building.

 

[nadogail]

IMHO, the open void and louvers might be the cause of a lot of heat loss. After your heat loss paths, including single pane windows are addressed you can begin to add insulation.
If you can reduce your heat losses the amount of makeup heat required will be reduced.

Good luck with your project.

 

[The Cobbler]

blown in the attic will be the most economical probably. usually the cost to have it blown in is less than you can buy the equivalent batts for.
there's ongoing discussions on whether or not you need vapour barrier in a garage.I wouldn't pull down the OSB just to install vapour barrier. forget the vapour barrier.
Your major heat loss right now is that open space int he ceiling . min r-12 on the concrete walls . frame & fiberglass batt .
as they say with insulation,you pay for it once, you pay for heat everytime you turn it on

 

[Rich_R]

Thanks for the replies! Good idea on the metal stud frame, I haven't thought about that.

Curious on the no vapour barrier concept for garages. Could anyone link me to a discussion about it?

After your heat loss paths, including single pane windows are addressed you

The window is double pane.

 

[u2slow]

IMHO, it would be foolish to pull the boarding down for insulation but not put in the 6mil poly VB.

I'm putting in roxul batt insulation because it will be some time before I have heat. Roxul won't grow mold/mildew in the meantime. (I'm on the BC coast.) OSB is out for me too, but I understand it holds up ok in dry interior regions.

Depending on your drainage, you may also get moisture transmission through the concrete. Usually shows up as that white powdery efflorescence. If that's present, you're probably best to leave the concrete exposed so it can breathe. There's several methods to attach things to concrete making only 3/16" and 1/4" holes, so don't think you need to board over everything over just for that.

Concrete likely wont be as cold as you think. Just like digging below your frost line... its not freezing there. You have a lot of thermal mass. Any heating or cooling change that deviates from the ground temp will take a lot of energy. I would try to maintain a low temp with natural gas, and try to use a woodstove as much as possible.

 

[banjopete]

https://www.greenbuildingadvisor.com/ these guys have some good information and our canadian gov has some good research articles all about building in northern climate zones.

I'm not offering my opinion on the appropriateness vapour barrier but would suggest you do your research before abandoning standard items of national and provincial building codes. Permit or not for the work I'd be very certain of why I was doing something or not.



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