Ice/Frost issues

[Oreaare]

I have been surfing this site for a couple months now and have found a lot of useful information! I just finished building my 24x24 detached garage in Minnesota. I have it heated with a natural gas "Hot Dawg" 45,000 btu. I finished it off completely. Insulated, sheet rocked, mud and tapped, painted, etc.
I hired out the mud and tapping to a friend of mine. When they started the temps dropped into sub the sub zeros. They heated the garage to 85 degrees trying to bake the mud so they could get it done faster. Obviously with all the moisture in there it was a sona. When I would come home front work I would leave my service door open a little bit to to get some of the humid air out of there. It worked great. Anyway to try and wrap this up.....I have been parking in there with 2 cars for 4 days with it heated around 40 degrees. I tinker out there every night and usually turn it up to around 55. I am getting pretty extensive frost on the 1 course of block that I do have. The temps are in the negative teens right now. I know that I am getting some air leaking in on the corners. I am planning on fixing that when the weather is a little more corporative. The walls have R13 with poly over them. Ceiling is the same due to 2x4 rafters and wanting to use the attic space for storage. Could not find an alternative at the local stores. it holds heat OK.

Any ideas what to do about the frost build up?

Did i do something wrong when doing the exterior?

Thanks for your help!

 

[p_mori7]

The course of concrete block is most likely not insulated, thus it is frozen solid causing warmer / moister air of the garage to condense & freeze.

40* is the temperature at your thermostat height. Lower to the floor will be colder.

I would bring the temp up to 50* and install a cieling fan to circulate the air. A large fan installed high up and pointed down towards the center of the shop could work also (which is what I will be doing eventually).

 

[Gary S]

The course of concrete block is most likely not insulated, thus it is frozen solid causing warmer / moister air of the garage to condense & freeze.
.

Concrete is a lousy insulator, and actually a good conductor. You need insulation to make a thermal barrier between the concrete and the interior.

 

[Oreaare]

Thanks! Could I fill the blocks with spray foam in a can? I am going to add a ceiling fan as well once my inspection is passes.

 

[Highbeam]

Anything you do inside the blocks is mostly useless. The concrete is the conductor. Unless you cover the concrete with some sort of foam board inside or out, the concrete will be a massive thermal bridge.

 

[luke7734]

Anything you do inside the blocks is mostly useless. The concrete is the conductor. Unless you cover the concrete with some sort of foam board inside or out, the concrete will be a massive thermal bridge.

I think your best bet would be to buy a couple sheets of 1.5-2" rigid foam board and line the block on the inside.. filling the blocks with foam doesn't stop the block from passing the cold through the solid parts of it. (just like studs in a wall pass cold around your R13...) Hence the term "thermal bridge"..

What's your gap to the finish wall surface from the block? 1"???

You should check out the last few posts in my HARN build. I've got some sweet pictures of how different insulation does with severe cold we're experiencing this week. (infrared heat gun) The insulated garage doors have frost pushing through the seams of the panels.. it's nuts..

 

[Oreaare]

I think your best bet would be to buy a couple sheets of 1.5-2" rigid foam board and line the block on the inside.. filling the blocks with foam doesn't stop the block from passing the cold through the solid parts of it. (just like studs in a wall pass cold around your R13...) Hence the term "thermal bridge"..

What's your gap to the finish wall surface from the block? 1"???

You should check out the last few posts in my HARN build. I've got some sweet pictures of how different insulation does with severe cold we're experiencing this week. (infrared heat gun) The insulated garage doors have frost pushing through the seams of the panels.. it's nuts..

Your place looks pretty sweet! I am having the same issues with frost pushing through my insulated garage door. Its been negative teens here for awhile so I have not attempted anything yet. I do not have much of a gap between the drywall and the block. I overlapped the poly and set the drywall about a 1/4" off.I then put stained cedar trim around the whole thing. Going to try the ceiling fan for the short term. On the plus side; When i bought the "Hot Dawg" I did a little research but mainly bought on recommendations..... Needless to say I am very pleased. Just received my first gas bill since it has been installed and I cannot believe how low it was. Having it been 85 out there for about a week (outside temps below zero) i was expecting much worse. Pretty efficient little heater!
Thanks for all you help!

 

[luke7734]

That's a pretty sweet deal. A little frost doesn't really hurt anything other than your heating bill.. so the more you do to limit it, the cheaper your bill will become. especially when the temps get back in the 20's+