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Radiant floor over slab
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Posted by wianno (My Page) on Wed, Oct 31, 07 at 9:51
| I have a small bathroom 6x6 that I am renovationg and thinking about installing hydronic radiant floors. I was going to use Quick Trak directly over the slap but am rethinking this. I have a height concern, so I need to keep the floor as thin as possible. I figure 1/2" for the radiant floor, and 1/2" for the finished floor. Something along the lines of a click in floating floor.
However, I think I will need a thermal break between the radiant panels and the slab. Will a 1/2 Foam insulation (R value 3.3) be sufficient to keep the slab from robbing heat? Could I use roll bubble type insulation instead to get an even thinner thermal break?
Appreciate any thoughts, thanks |
Follow-Up Postings:
RE: Radiant floor over slab
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| You did not note where you are located and how old the home is. All of that information can be used to determine if what you are planning will work. If you have insulation under the slab, it will be either 1" or 2" depending how cold the winters are and the building codes at the time your home was constructed. If the winters are cold and the insulation minimal, you may need some additional heat in the room, base board or a heated towel rack. Your question about the insulation. Use rigid insulation, preferably with a reflective foil covering. R-3.3 is not great insulation if you have an uninsulated slab in a cold climate. Good luck, |
RE: Radiant floor over slab
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| Have you considered electric radiant mats? They are much thinner than hydronic. It is more of a "floor warmer" than a "room heater" but it makes the feet feel nice. |
RE: Radiant floor over slab
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| It's an uninsulated slab. There is only felt paper between the earth and the slab, it was poured about 50 years ago. The home is in Massachusetts south of Boston. The room located in the center of the house surrounded by heated space, no windows, and will have a fan. Its going to be a 1/2 bath. I need the heat to warm the space, warming the floors won't be worth it, so no electric mats. I also found a product that is 5/8 thick called Ipex K-tile. They claim no insualtion. Not sure I buy into that. http://www.sitedocuments.net/radianthome/pdfs/pib_K-Tile.pdf |
RE: Radiant floor over slab
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| If the room is in the middle of the house, you can expect the floor to be about 52 degrees or more. Check the floor temp when it gets cold.. I think you can get away with minimal insulation. The more the better. :-) |
RE: Radiant floor over slab
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| Height is going to be a problem. Check out Roth panels, they come with insulation built in. |
RE: Radiant floor over slab
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| If I had to pick from literature, I would choose the Ipex over Roth. Ipex can float over the floor where Roth suggests a glue/screw down. Also, the Roth panels are 3/4 inch thick, while Ipex is 5/8, not much difference. I am still concerned about insulation with the ipex system. In either case, it is still thinner than the quick trak install I was planning at an inch. How effective is ceiling radiant? Is that an option over floor radiant? I plan to install a copper ceiling over 3/8 plywood. Maybe I can install the Quick track on the ceiling and nail the tin to it. Would this install make noise from the copper expanding and contracting with the heat? FYI, I have radiant in the house on a constant circulation pump and thermostat controlled mixing valve. I intend to add the loop to this system. |
RE: Radiant floor over slab
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| ceiling is effective, but it needs to be larger than floor does, to achieve the same comfort. floor warms you, and the room, ceiling only warms you, and the objects that reflect the radiant. so it takes more heat to achieve the same comfort. would it be worth it to have a section of the slab cut out to save height? oh, add a small section under the jon... nice... |
RE: Radiant floor over slab
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| Yes, Subsequent to me asking the question about ceiling radiant, I found out that it has to run at a higher temperature. Since I am essentially adding a loop to a floor system I cannot up the heat serving this room. I still think that my idea to use 1/2" insulation and the quick traks will work. However, the Roth install appears to do the same but with 1/4" less height. I do not trust the K-tile product with no insulation, or I would at least add a foil faced product under it to reflect the heat back up. Maybe the K-tile works because the heating tubes are not actually in contact with the slab? Interesting comment about the jon. Won't the heated floor cause the Wax ring to get soft and "run" thus breaking the seal? |
Inconsistent:
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| Yes, I see I am not consistent in my views between Roth and Ipex. Ipex looks easier to install, Roth appears more consistent with my knowledge of radiant to use a thermal break. I hope this forum helps me make an educated decision! |
RE: Radiant floor over slab
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| the small loop around the jon will at most heat the bowl and floor to around 90°F. nothing to worry about there. |
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