Replies

1. 
   NormKerr | Sep 02, 2004 07:13pm | #1

   If you pour a new slab you can put the tubing in the concrete:

   1) lay 2" foam over the gravel base

   2) install your tubing in the pattern designed by your heating contractor for best heat balance. You can rent a 'stapler' manufactured by the same company that makes the tubing that easily fixes the tube to the foam with big black plastic stables. Of course, have the tubes exit the floor where you plan to install the heat source (get the 90 deg forms from your tubing supplier, to do this).

   3) if you plan any joints in the concrete, put about 12" long section of 1/2" pipe foam insulation over the tube to prevent any chafing.

   4) lay the 6x6 wire mesh over the tubing.

   5) place the concrete

   You can use a water heater to provide the heat source, others have posted here in the past with instructions how to do that at minimal cost. Your space is small so a small water heater would be pretty economical.

   The floor would be capable of parking a car, just like a normal concrete floor.

   hope this helps,

   Norm

1. 
   DavidThomas | Sep 02, 2004 08:59pm | #2

   I heat my garage with a water heater.  26x28 and it gets down to -40F here (that 's -40C for you Canadians).  1/2" tubing on 1 foot centers.  5/8 or 3/4 tubing costs a bit more but lets you move more water (i.e. heat up the slab faster).  I used a direct-vent HWH so the garage could be as tight as possible and as a safety thing.  It uses outside air instead of inside air so it doesn't need to be on an 18" stand to avoid lighting the gasoline fumes from the car/mower/chainsaw, etc.

   RFH works nicely in a garage because of the uncovered concrete - it gives off heat mroe quickly with less lag than carpet or wood floors in the house.   And it makes great snow-melt for the cars if you're in that kind of climate.  If you might park snowy cars inside, slope the floor towards the center so the snow-melt doesn't run to the walls.

   Other thoughts:  20 x 20 is really small for for a 2-car garage.  Even with no wall in between the side, it only leaves 2-6-4-6-2 where the car is 6 feet.  2 feet on the side is enought to get in and out, but not easily.  And 6 feet is a minimum.  SUV, pick-ups, etc are 7 feet or more with mirrors).  Also, stuff tends to collect in garages!  Those exterior walls would be great places for shelves for storage if the whole garage was 4 feet wider.

   Also check how much return you need at the corners for shear strength.  As one wall becomes nothing but door, their are structural / earthquake concerns.David Thomas   Overlooking Cook Inlet in Kenai, Alaska

1. 
   SamT | Sep 02, 2004 11:37pm | #3

   Jakes garage is already built. He is only going to raise the floor level 5". 

   Jake,

   Most areas require a step up from the garage floor to the interior floor to prevent gas fumes from entering the house.

   What are your plans for the door? Build a ramp from the new floor to the drive? What about ceiling height?

   Is there an existing stem wall under the wall framing? If so, how tall?

   Are you thinking of removing the old concrete floor??? Or just pouring over it?

   If you are pouring over the existing and you have stemwalls at least as high as the new floor, Just lay 1 1/2" foam, another 1 1/2" around the the stem wall, the RH grid, WWM, and pour 3 1/2" of mud. THis will of course leave you with the same drain slope that you currently have. If the existing floor doesn't slope towards the doors, you have another problem.

   If you don't have the needed stem wall height, you MUST leave a 3"-6" trench just inside the existing walls for drainage and to prevent severe water damage to them.

   As to leaky doors, for as long as you intend to use this space as a studio, remove any opening hardware then insulate and DW across the doors, so they disappear on the inside.

   SamT

   Arguing with a Breaktimer is like mud-wrestling a pig -- Sooner or later you find out the pig loves it. Andy Engel

1. 
   DANL | Sep 03, 2004 12:56am | #4

   Good answer, except the part about the doors--I think they want to keep the doors operable in case they decide to still park a car in there once in a while (they said that's why the floor has to be concrete). And I think your idea of drywall would keep the doors from ever being doors, right? Don't quite understand how operable doors can be double clad with siding though.

1. 
   SamT | Sep 03, 2004 05:49am | #6

   If it's gonna park cars once in a while they would want to leave the doors operable, I figured they would realize that without my mentioning it.

   However, if it's just a studio for a time (a time is longer than a while, a coupla years, at least(|:>) some 1 5/8" steel studs or 2x4 flat and DW make sense.

   2" foam plus 5/8"OD PEX with only 5" to work with leaves awfully thin 'crete, that's why I thought 1 1/2" foam. Maybe even 1".

    Naw. 1 1/2".

   But I would put the WWM on top of the PEX to better control cracking. (Ford vs Chevy)

   SamT

   Arguing with a Breaktimer is like mud-wrestling a pig -- Sooner or later you find out the pig loves it. Andy Engel

2. 
   WayneL5 | Sep 03, 2004 01:57am | #5

   Generally, 2" of rigid foam is used as insulation under the slab.  Around the edges you can also use foam as a thermal break.  The foam will be flush with the finished surface of the concrete.

   There's debate about where to locate tubing.  I'm in the camp that says to install the mesh first, then tie the heating tubing off to it.  Raise the mesh up to about the center of the slab with chairs (rebar chairs, not the sitting kind).

   Make sure you get a real mason or skilled person to finish the concrete.  There are lots of hacks around.  For a shop/studio you don't want a bad surface finish.

   It's wonderful to work on a car in winter laying above a heated floor.

   You can add weatherstripping specially made for garage doors to reduce the drafts.

   If you need new overhead doors, Garaga makes excellent insulated doors, as high as R-18.