Insulating my detached two car concrete block garage

[thomer]

I live in Chicago. I'm starting with a detached two-car concrete block garage with wooden trusses and a flat roof. There is a roof deck on top with a pergola where friends gather to hang out. The outside of the garage is stucco.

After long or heavy rain some parts of my concrete walls, usually nearer to the top, get damp. Sometimes the trusses, where they meet the concrete wall, are wet. Is a little wetness/moisture ok or do I need everything 100% dry before insulating?

I'm not yet sure if I will insulate the garage. But planning it out will help me make the decision.

For the perimeter walls, space is at a premium. What is the best thin insulation solution? I want to turn a 30 degree space into a 45 degree space with some heat.

The ceiling is already low, but I have more flexibility with the type of insulation up there.

I do not want to drywall/paint/make it pretty. Especially if the water issue gets more serious. Thanks for helping a noob.

 

[Jagmandave]

Sounds like 2" rigid foam will be your best alternative, but yes, you need to find out where the moisture is coming from and fix that first - water incursion is never a good thing.....

What are you going to use for your heat source?

 

[thomer]

There is a natural gas line already connected to the garage, so I was thinking a natural gas blower somewhere in the ceiling over the workbench area. I'd need to add a vent. I'm not keen on ventless solutions due to the carbon monoxide or condensation they can generate, but I may be ignorant on this topic.

I was hoping I could get away with a little bit of water. I already had some work done on the roof and they couldn't (yet) fix it 100%. I am not equipped to handle it and I'm getting tired of dealing with these guys.

Is there a likelihood of mold of the foam board gets wet?

Would I use 2" studs with the foam board? When hanging cabinets, shelves, etc, would I screw into those studs or can I use long enough screws/anchors and go right into the concrete?

 

[thomer]

Bump to get those last couple of questions answered and then this thread can fade away into the ether.

 

[socapots]

you should be able to mount the foam board directly to the concrete. And anything you want hang on the walls can be mounted through the foam board directly to the concrete.. At least that seems right. lol.
As far as the heater. look into radiant heaters. May be a good fit for what you want.
as far as mold. Whenever anyting gets wet its possible. Some products are mold resistant. But that does not mean that it will never happen.

Edit: and i am by far no expert. So someone please say something if you can correct me.

 

[curiousB]

Couple thoughts.

You really want to understand the leaking water issue before you cover it up with insulation. Water problems lead to wood rot and other structural issues over time so you may make a little problem bigger in the end.

As for insulation, rigid foam is good but you'll have to cover it with drywall (or some other fireretardent covering) to make it firesafe. Foam insulation is quite flammable and the vapors of combustion are toxic. So just factor in the need to fireguard the foam as part of your work plan.

If you have natural gas then I'd go with a Mr Heater style heater hanging from the ceiling and vented vertical or horizontal as best suited for the space. I agree with you vent free is not a way to go. I had one and pulled it out a couple years later due to the water vapor it generated and the noxious feeling I got in the garage (I am convinced CO is not controlled well in these vent free devices). I switched to Mr Heater 3 years ago and couldn't be happier with the change away from vent free.

 

[thomer]

Is it city code to cover the foam board to make it 'firesafe'? If the drywall only adds a marginal benefit for insulation purposes, takes up extra space, and requires studs.. I think I'll pass, if I can get away with it. I'm not planning on getting a permit for this work but I don't want to do anything I'll regret.

 

[BUDD]

heres a good idea, if you have to cover it up you can at a later date.

 

[BigWil]

You can purchase rigid foam with notches for furring strips. You can attach the drywall to those strips, and you won't lose a lot of space.

Here is a video illustrating what I mean:

 

[thomer]

If I don't need to put up drywall I probably won't. At least not for a while. Can the rigid foam be painted over? I'd like the walls to be white to make the garage brighter.