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We have a large family room that was built on a concrete slab. Essentially, the prior owner connected the home to existing garage (with no door to access). During extreme cold bouts, the room will refuse to heat above 55 degrees and you can feel the cold through the carpeting... I’ve researched installing a hardwood floor with radiant heat (we have forced hot water/oil), but the consensus seems to be that it doesn’t generate sufficient heat. Any suggestions? We are tentatively planning to gut the room to add insulation behind the walls, just not sure what to do with floor. TIA
The problem is 90% wall and ceiling insulation and 10% being a slab. Before you put in any kind of additional heating or rework your existing system to feed the room better, insulate it fully. Don't overlook windows and any exterior door, too.
Once the room retains heat, the slab will slowly gain and lose heat with the interior temp and stop feeling so cold. Not to say a more insulated floor wouldn't be a good idea as well.
But don't just dump heat into a room that won't hold it.
The problem is 90% wall and ceiling insulation and 10% being a slab. Before you put in any kind of additional heating or rework your existing system to feed the room better, insulate it fully. Don't overlook windows and any exterior door, too.
Once the room retains heat, the slab will slowly gain and lose heat with the interior temp and stop feeling so cold. Not to say a more insulated floor wouldn't be a good idea as well.
But don't just dump heat into a room that won't hold it.
I agree, it sounds like the addition wasn't insulated properly or the windows and doors weren't. Heat rises, it doesn't fall so the leaks are through the walls, windows/doors or the ceiling. Also look at where the heat vents are, are they at the ceiling (cathedral) or at the floor and where the thermostat is. Is the thermostat that controls the heat in that room controlling the heat in the rest of the house? In that case, once the rest of the house warms to temperature it shuts off leaving the addition still cold. You might look into two zone heating.
You may also want to consider an insulation around the outside of the slab, going down a couple of feet. In this case, insulation means coarse gravel and perhaps a french drain to limit moisture. The air pockets in the gravel act as insulator to keep water and ice from draining as much heat from the slab edges. Perimeter baseboard heat can make a room like that more livable.
I imagine the problem is that the garage slab isn't insulated and the footing for the garage walls isn't insulated. The concrete slab is acting as a big heat sink sucking all the heat out of the room to the uninsulated footings.
You might start with digging out the footing/foundation walls around the garage and insulating. 2" Owens Corning Foamular XPS is R-10.
With an uninsulated slab, the typical fix is to lay insulated panels on the floor and then install the flooring over that. Home Depot has 2"x2'x4' R-7 subfloor panels from Amdry for $22.98. There are other systems out there like ThermalDry the professional installers use. You could also lay down a grid of pressure treated so it won't rot, insulate with Owens Corning Foamular XPS, and put a subfloor over that. With infinite money, you could remove the slab, insulate under it, lay out PEX radiant heat pipe, and pour a new heated floor.
Hardwood is usually not a great idea on a concrete slab. Moisture will get to it and warp/buckle it. If you don't want carpet and can live with it, go with luxury vinyl plank. The Brit company Karndean is what a lot of flooring companies use.
I agree, it sounds like the addition wasn't insulated properly or the windows and doors weren't. Heat rises, it doesn't fall so the leaks are through the walls, windows/doors or the ceiling. Also look at where the heat vents are, are they at the ceiling (cathedral) or at the floor and where the thermostat is. Is the thermostat that controls the heat in that room controlling the heat in the rest of the house? In that case, once the rest of the house warms to temperature it shuts off leaving the addition still cold. You might look into two zone heating.
This room has it’s own zone. Heat vents on “garage wall” and front of house facing wall. We just replaced bay window there. Third wall is where fireplace is (sunroom behind that wall). 4th wall is 3/4 interior (entry to kitchen) and 1/4 to outside. No heating vent there.. Also old sliding window that we’ll be replacing. The thermostat is on that wall as well...
I agree, it sounds like the addition wasn't insulated properly or the windows and doors weren't. Heat rises, it doesn't fall so the leaks are through the walls, windows/doors or the ceiling. Also look at where the heat vents are, are they at the ceiling (cathedral) or at the floor and where the thermostat is. Is the thermostat that controls the heat in that room controlling the heat in the rest of the house? In that case, once the rest of the house warms to temperature it shuts off leaving the addition still cold. You might look into two zone heating.
Quote:
Originally Posted by GeoffD
I imagine the problem is that the garage slab isn't insulated and the footing for the garage walls isn't insulated. The concrete slab is acting as a big heat sink sucking all the heat out of the room to the uninsulated footings.
You might start with digging out the footing/foundation walls around the garage and insulating. 2" Owens Corning Foamular XPS is R-10.
With an uninsulated slab, the typical fix is to lay insulated panels on the floor and then install the flooring over that. Home Depot has 2"x2'x4' R-7 subfloor panels from Amdry for $22.98. There are other systems out there like ThermalDry the professional installers use. You could also lay down a grid of pressure treated so it won't rot, insulate with Owens Corning Foamular XPS, and put a subfloor over that. With infinite money, you could remove the slab, insulate under it, lay out PEX radiant heat pipe, and pour a new heated floor.
Hardwood is usually not a great idea on a concrete slab. Moisture will get to it and warp/buckle it. If you don't want carpet and can live with it, go with luxury vinyl plank. The Brit company Karndean is what a lot of flooring companies use.
Excellent points, thanks. Infinite money would be tearing both room and garage down and building new lol. Will look into insulated panels.
Excellent points, thanks. Infinite money would be tearing both room and garage down and building new lol. Will look into insulated panels.
I'll bet if you put an infra red camera on the floor on a cold day, the middle of the floor looks OK but the outside edge shows really cold. Insulated floor panels will help but you kind of need to insulate the footing, too. Nobody wants to do that project. The ground below the frost line is a fairly constant 50F so the slab once you insulate the footing will be 50F. An R-7 insulated floor panel will work fine for 50F to 70F. Even the cheap 1" R-3 panels you can get at Home Depot will work, particularly if you put carpet pad and carpet over it. I think the fancy 1" stuff the professional basement guys use is more like R-5 so if you don't want to raise the floor too much, you spend the money with an installer.
We have a large family room that was built on a concrete slab. Essentially, the prior owner connected the home to existing garage (with no door to access). During extreme cold bouts, the room will refuse to heat above 55 degrees and you can feel the cold through the carpeting... I’ve researched installing a hardwood floor with radiant heat (we have forced hot water/oil), but the consensus seems to be that it doesn’t generate sufficient heat. Any suggestions? We are tentatively planning to gut the room to add insulation behind the walls, just not sure what to do with floor. TIA
Chase the cold- is it actually the slab? Or is it just poor insulation (walls/ceiling), or air-tightness (doors/windows)? You could be dealing with convection; and/or a deficient "fluid dynamics" issue.
Once you have established the cause, there can be many avenues to pursue that will make the room comfortable-
It could be something as stupid as there was no vapor barrier under the slab- it sucks up water and evaporates in the interior- the result can be a cold slab.
My vote is poor insulation from attaching to an uninsulated wall that isn't heated.
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