Insulating inside of concrete blocks?

[BioHazard]

My shop is made out of concrete blocks, most of which are hollow. If you could look down the top of the wall it would be like a bunch of 6" tubes. Would it do any good to insulate the inside of concrete blocks with expanding foam? It wouldn't be that hard to drill a hole in each cavity and fill with foam...

[jklingel]

First off, I am not an engineer. I have read of people filling blocks w/ packing beads or foam, like you are thinking. However, I really can't see much gain because of the huge amount of thermal bridging you'll have; the blocks' webs are continuous w/ the inside and outside, and are going to conduct a ton of heat through them. Any way to put 2" or so of rigid foam on the outside?

[rsanter]

Originally Posted by jklingel

First off, I am not an engineer. I have read of people filling blocks w/ packing beads or foam, like you are thinking. However, I really can't see much gain because of the huge amount of thermal bridging you'll have; the blocks' webs are continuous w/ the inside and outside, and are going to conduct a ton of heat through them. Any way to put 2" or so of rigid foam on the outside?

correct
the thermal bridging will negate most of your efforts

rigid foam on one side would be good, both sides would be better

bob

[BioHazard]

Would it help at all though? Putting sheets of foam on the inside or outside isn't really an option since I'd have to cover it with some kind of wall or siding on top. If I was going to do that I'd just make my shop bigger.

I do know somebody that can get me lots of expanding foam for pretty cheap though...

[russlaferrera]

True, you should cover the sheet with something, and you need some furring strips. I do not understand how making a bigger shop will solve the insulation problem. If you can get foam cheap. Fur the wall out and spray the wall. You still will have to cover it.

Does where you live justify insulation?

[jklingel]

I don't think you need to fir out, necessarily. Many homes up here cover the outer OSB w/ 2" of rigid foam, then put house wrap over that, then siding. I think the house wrap may be sufficient for a while, as far as UV and water protection. Eventually, though, siding of some kind may be necessary.

[BioHazard]

Originally Posted by russlaferrera

I do not understand how making a bigger shop will solve the insulation problem.

If I was going to spend all the time and money to build a false wall on top of the wall I already have, I'd rather just build that wall somewhere else and have a bigger shop with no insulation.

I guess it would probably be more effective to spend money on the attic insulation....

Where I am, if I was insulated better, I wouldn't have to heat or cool for most of the year. Right now it stays at 50* almost constantly, but with my electric heater going full blast I can't get past 52*.

[russlaferrera]

BioHazard, , Sorry but you lost me in your last post. You are going in two directions. Cost is a factor and comfort. Insulation will cost $ and you will save heating/cooling $, and will provide comfort.

Building another wall to make your shop bigger will cost $$$. My reasoning is you can not build a wall to increase the sq ft of your shop, without building 3 walls and a roof. What am I missing?

[Falcon67]

Some info here: http://www.energysavers.gov/your_hom.../mytopic=11570

[bazzateer]

I think he means that if he has to go to the trouble of putting siding or whatever on the existing walls he'd rather spend the time and a bit more money building a bigger garage and do without insulation for now. Yes it will cost a lot more but he'll have a bigger garage, and as we all know, size matters!

[BillGalbraith]

I talked to ny builder today about this subject. He was not in favor of insulating the walls of the garage, at least in my case. This isn't living space, and there is not a need to keep the area at a constant temperature. When I go into the garage, I'll kick the a/c or heat on, and it will take a few minutes to get to the desired temperature. When I'm done out there, the a/c or heat goes off.

In relaly cold weather, the concrete block will get cold-soaked, and since it has such a high thermal mass, it takes a LOT of heat to warm it up. Insulating inside the block isn't going to do anything with prolonged exposure to cold. The heat eventually leaves the block.

As an aside, I'm installing a GE Zoneline unit, similar to the one that you;d find in a better hotel. It's an all-in-one unit that pokes through the wall, similar to a window a/c unit, only bigger. It can do 15,000 BTU. What I like is that it as a remote switch on it. Think about the hotel issue. When you check in, they switch it on. By the time you make it to your room, it's cool in there. If I wire that up, when I start getting ready to go out there, I could switch on the heat or a/c. and it's ready to go when I get out there. It's not a huge deal here in Orlando, and at $1000 it definately a luxury, but I'm thinking there will be times when it comes in handy.

[Falcon67]

You don't say how big your block shop is, but 15K BTU heating in a cold concrete block building is pretty weak. It takes a 24K BTU heater about an hour or 2 to raise up the dead cold temp (45F) in my insulated shop to a reasonable (60F) mark.