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New footings around existing slab and adding radiant heat

Question: I have a monolithic slab 35x38 and attached garage slab 20x25 and want to pour new footings around the existing foundation for 2x6 framing around the house and in the garage raise the floor to be level with the house slab and add radiant heat running off a solar domestic hot water systems, I live in the Florida Panhandle where several contractors I've had out said it can't be done and to add radiant heat I would have to tear out the old slab and start again, and to just forget about the radiant heat and just turn up the thermostat.
Opinions please
Sorry I had a fire that left the garage with chard rafters and framing and the house has to be totally gutted down to the studs. So I figured why not just start fresh, I plan on deconstructing the whole structure the add footings are to accommodate 2x6 framing with out making the rooms smaller and add a second floor loft .

The flooring through out the house will be the sealed concrete slab, Even in Florida I'm cold except for during the day in June, July and August . I plan on living out my days in this home, so my comfort is all I'm concerned with and not resale .

Existing Floor Plan188.22 KB
New Floor Plan92.28 KB
New Wrap around Loft27.86 KB
Right Side Elevation with Addition 127.45 KB
Asked by Nancy Giordano
Posted Apr 5, 2011 5:04 PM ET
Edited Apr 6, 2011 12:58 PM ET


5 Answers

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I'm not sure why you are adding new foundations as I assume your existing foundation is monolithic with the slab. As for raising the existing garage floor up to the existing house, it is dependent on how far you have to raise it. If it is one step at 6"-7", you can add 2"-3" of rigid insulation and then place a new slab with radiant heat, making appropriate accomodations for insulating the perimeter. This will be dependent on how you plan on dealing with existing exterior walls that I assume currently sit on the existing slab. As to whether this is all worth it and the best solution, that is dependent on how much work it takes to make it work. Florida heating is not my area of expertise but I would assume it is a lot less than what we need up here in Michigan so even though I love radiant slabs where I live, perhaps it is not the best or most economical solution for Florida, and you still may want cooling.

Answered by Corian Johnston
Posted Apr 5, 2011 6:14 PM ET


Your questions are impossible to answer without a site visit. Among the possible problems is low ceiling height; but I'm just guessing -- just like any GBA reader who tries to answer your question would be guessing.

Answered by Martin Holladay
Posted Apr 5, 2011 7:30 PM ET


Nancy: Raising floors does not often mix w/ existing doors, either. Adding a new foundation (for new walls, to increase R value?) and whatever on top of them is not a simple task. How will this impact the roof? Etc. Maybe it will be more economical to use a different heating and/or cooling method? Solar for heat? Better windows (different solar heat gain coefficient) to help keep the place cool?

Answered by John Klingel
Posted Apr 6, 2011 1:00 AM ET


added more information and photos

Answered by Nancy Giordano
Posted Apr 6, 2011 1:07 AM ET
Edited Apr 6, 2011 2:04 AM ET.


Nancy, your contractors are probably wondering why you are choosing cold-climate strategies for a home in a humid sub-tropical climate - you should probably listen to them. Neither the 2 x 6 walls nor the heated slab are going to be particularly appropriate or valuable in a climate where your more pressing issues are going to be summer heat and humidity. Pack your 2 x 4 walls with cellulose, add a layer of foam slab insulation to the exterior to prevent thermal bridging and concentrate on excellent air-sealing and a good mechanical ventilation system as your home is rebuilt. If in doubt hire a reputable home energy consultant.

Answered by James Morgan
Posted Apr 6, 2011 8:06 AM ET

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