I have been searching all over and have not been able to find any reference to this. I am going to start building a garage that I will heat with radiant tubing in the concrete floor. In my research I understand the proper insulation frost wall to slab, etc. What, if anything, have you seen done where the garage door is, as far as insulating the edge of the slab. Location is upstate NY, cold winters. I can see a couple of ways of doing it but wonder what you experts have done / seen done that works well. Am a retired engineer (not in construction) who worked the trades in high school / college and built my own place 30 years ago – so might be over analyzing the problem! Thanks.
Dale
Replies
This is a common conundrum.
The best we've come up with so far is to use vertical insulation, and put a wider pressure-treated "threshold" over it to protect it.
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
Rob -
Thanks. This is one of the options that I had thought of so if you have had success I might well use this method.
Dale
Sorry, hold on. I said this was the best we've come up with.. haven't had a whole lot of testing though, unfortunately. and I may not be aware of some building issue this may impact.-------------------------------------
-=Northeast Radiant Technology=-
Radiant Design, Consultation, Parts Supply
http://www.NRTradiant.com
I asked the same question last year when I was doing mine. I decided the structual advandage of pouring the floor directly on top of the frost wall was worth the loss of insulation at that point. This way, when a vehicle first starts onto the slab (highest stress point), it's fully supported by the rigid frost wall.
I probably won't actually hook up the tubing to a heat source for another year or two, so I don't know how well this will work. There obviously will be more heat loss, and I hope temps stay high enough that I don't get ice forming under the door.
No cracks whatsoever yet on the 24x36' slab.
Don
I wouldn't worry about it too much. We just used a thickened (about 12" tapering back up to 4") slab edge at the threshold over compacted gravel and rebar, then put that 1" fiberboard stuff (can't remember the name) as a isolator between the slab edge and the apron.
It actually works pretty well, as I didn't put a floor drain in, so the snowmelt from the cars after they're driven into the 50° F garage ends up draining under the garage door. There is just enough conduction from the warm slab to keep that snowmelt from freezing really hard. Just turns kind of slushy, easily scraped away, even with below zero temperatures.
I suppose I spend a few dollars every winter to keep 6 - 10 " of apron from freezing, but getting into a totally ice free 50° car EVERY morning is priceless.
Johnny (and Rob) -
Thanks. Good to know that the simple solution works out this well. I have not figured the actual heat losses yet, but I imagine in the big picture the small area with no insulation will have minimal impact on the building as a whole. Will have to decide which of the suggested methods to use.
Dale
I'd say a reasonable approach would be to extend an "ADS" pipe located in a 3/4" stone trench that is wrapped in non-woven geotextile extending from beneath the garage door approach to a "daylite" location. That way, frost would not tend to form and heave the slab beneath the garage door. Having lived in Lockport, NY, you may wish to have the ADS pipe located about 4' below the garage door. (I recall the NYS building code specifed a 4' frost depth).
BTW, you may be over-thinking the situation, but better to think on the front end than to fix the tail end. We have radiant heat in our first floor and basement slabs - you'll really enjoy it!