Just curious. Why would you not insulate.

[Nivekdodge]

I want to thank all of you for your help over the last year. My garage is built and I have the heat turned on and it seems to be working well. Against everyone's better judgement i've used a heat exchanger off the water heater. it seems to run maybe an hour and a half a day.
I did the insulation thing all around. 2" underneath and on the outside of the walls and foam under the roof deck.
I have a friend building a garage and he won't insulate under the slab because he's just hanging a gas heater. After my experience of how well it holds the heat, I can't see not doing it?

 

[davewo]

Insulate, insulate, insulate.

I have a buddy who works in his totally un-insulated garage, wearing a bulky coat and maybe a propane heater near by. He doesn't want to take the time to insulate. My garage isn't that well insulated (for now) but it is nice being able to work in a t-shirt even when it's freezing outside. I have an old 220 volt heater.

 

[turbowoodworker]

Why not?
CHEAP

 

[Bretny]

Can never add insulation under that slab again so do it per pour. Also even if I wasn't planning on radiant heat I would run the coil in there also.

 

[yeldogt]

You don't know what you don't know ......

Until you live/ work in a well insulated space -- you don't understand the difference .... comfort and maintaining cost. Most have experience with an old garage someplace -- maybe getting heat in it. They think it's "good enough"

There are obviously upfront costs ... that's much of it.

 

[Kaizen]

As for slab insulation...cost. That plus pecans associated materials were out of my budget. Sure I could have put the project on hold to do it but decided above ground insulation would be enough. Also I wasn’t going to heat the shop all winter to spend only a few nights and a weekend day in there.


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[Randy in Maine]

2" of foam under your slab is roughly $1 per square foot. Money well spent.

 

[dcg9381]

I have a friend building a garage and he won't insulate under the slab because he's just hanging a gas heater. After my experience of how well it holds the heat, I can't see not doing it?

We don't insulate under the slab here, but my climate is warm.
The reality of insulation recommendations are that they are based off energy use for "full time" living. So if R30 is recommended - that's probably the right choice if you're going to live there for 20 years.

The answer to your question is economic. I have a shop that's insulated R15. It cost $5000 to insulate it. Should it be R30? Probably, but adding another $5k to insulation costs wasn't in the cards. Instead, I'll pay MORE to heat/cool the building, but since I'm only heating or cooling the building 1-2 days a week on average, it takes a really long time for the energy use difference between R15 and R30 to be $5k.

It very moderate climates, I can see doing a minimal insulation job for structures that aren't used frequently.

 

[Jackfre]

I would not bother with it unless I was doing radiant heat. Then absolutely. If I was maintaining temp throughout the winter, it might make sense, but I go out in the morning and turn on the heater and it is warm through the day and then I turn it off at night. I don't wear slippers or flip flops in the shop either. In real shoes my feet are warm and I am comfortable through the day.

 

[Sokoloff]

WI have a shop that's insulated R15. It cost $5000 to insulate it. Should it be R30? Probably, but adding another $5k to insulation costs wasn't in the cards. Instead, I'll pay MORE to heat/cool the building, but since I'm only heating or cooling the building 1-2 days a week on average, it takes a really long time for the energy use difference between R15 and R30 to be $5k.

That $5K you saved will throw off $250 or so (more if you owe money on higher interest loans) as well, so if the difference in utilities is $500 per year, it will take 20 years to break even (not 10). I seriously doubt the utilities difference is going to be that high.

 

[Kaizen]

2" of foam under your slab is roughly $1 per square foot. Money well spent.

But if you go that far the pex is a given.


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[yeldogt]

Insulation is diminishing return -- and is dependent on climate. Having some thermal break under a slab in a cold climate is important. Even if you do a sheet around the edges it's better vs doing nothing. Obviously in a large building the further inside the building you go the less the really cold ground will effect the slab -- some drop down to 1".

Soil type also affects loss --- with radiant w/o insulation -- you heat the ground. If it's wet clay -- it's going to be more of a problem then dry sand.

 

[75gmck25]

I would insulate and vapor seal under a new garage before pouring the slab because the ground is very major source of cold transmission and water penetration. If I can keep that cold from penetrating through the slab it will be a lot easier to keep the garage temp more stable. I also don't want my slab to be damp because it raises humidity and rusts tools.

I would then insulate the ceiling or roof to the code minimum (or more), and make sure it is fully sealed around any penetrations. If I'm going to heat the garage I want to keep that heat in, and most of it will try to go up and out of the building through the ceiling and roof.

My last task is to completely air seal the walls and doors, and insulate the walls and door up to whatever the budget will allow.

Bruce

 

[JamesW84]

As mentioned, it was a value proposition for me. Like others, I'm a hobby guy, so I'll be out there at most 3 days a week, but likely not the whole day. I wanted to do radiant heat and insulation under the slab, but the cost was prohibitive. I've spent so much on a large shop that it will be a little bit before I can even afford to put stuff in it.

I plan to insulate a "work room" area walls and ceiling and heat only that area...less than 1/2 the shop.

 

[allinon72]

Sounds like a stubborn cheap guy who isn't going to save any money running that heater on overdrive all winter. Being cheap for cheaps sake isn't smart.

 

[chrispyny]

What is obvious is that there is more to consider other than a persons return on investment as far as savings on heating a building like a garage is concerned.

Quick heating from a cold start, zero drafts in a well sealed building, comfort while working in the garage, cheaper more affordable heating and air conditioning units... i could go on.. those all add to a massive value to insulating a building.
It’s not just, “how much i can save heating and air conditioning my garage when i’m using it”.
Ultimately it’s up to the person paying for the work. So to each his own for personal preference. Me, if i was constructing a building like a garage, and low on funds, i’d postpone the build until i had the funds to air seal and insulate everything including the slab,if i were in a zone where it would benefit.

 

[BruceMc]

What is obvious is that there is more to consider other than a persons return on investment as far as savings on heating a building like a garage is concerned.

Yes. If you were to take it to the logical conclusion, why build a garage at all? Just hire out what you need done to someone else. Probably cheaper in the long run.

 

[Sokoloff]

Whatever you do, don't calculate how much you're paying per pound if you fish for bass from a bass boat or raise tomatoes in your garden.

 

[ddawg16]

I live in Southern California....we can get down into the 30's. I didn't insulate the lower walls...but I insulated the south facing upper wall and the ceiling. Combined with the drywall....my garage is comfortable in the winter. If I keep the doors closed, all I need is a sweat top.....

In the summer, the ceiling insulation makes a huge difference upstairs....huge....