Hello I recently finished rehabbing a 50 year old single story ranch built into the side of a hill, the basement is walkout and driveway goes around side of the house to garage which is part of the lower level. Above the garage ( which is 25X 25 ) is a room which contains our kitchen and dining / living area. I have a pretty warm garage i.e it is “sort of heated” by several ducts off supply line and good door and stays about 50 some degrees when the outside temp is below freezing. I replaced the subfloor with 1″ T&G and then 1/4″ fiber cement then the tile. Despite the relative “warmth” the floor is still really cold, has a surface temperature ( as measured by probe) of within 5 degrees of the garage. My logical solution is to insulate below and between the joists and then drywall the garage ceiling. I know that would help, but maybe there is a better solution. Above and beyond that I am wondering if it would be feasible,, and in there is any kind of radiant flooring product, that I could install between joists under the floor. If so please let me know and if I did that would it be okay – or unsafe – or even necessary to insulate before drywalling garage ceiling. I am also thinking something like this might cut my heating bills, as the other part of the house is warmer anyhow due to stronger airflow from central heating unit ( I have natural gas heat). Any suggestions would be greatly appreciated. My kids have playing in that part of the house because the floor is so cold. Thanks! -Freezing and snowed in, in Indiana
Edited 12/9/2005 11:06 pm ET by stm
Replies
Adding radiant heat will increase your energy bills, not lower it. But insulation will save you money. It is nearly always better to insulate than throw more heat at it.
Heat loss from through your floor from the room into the garage is probably a large contributor to your garage being so warm, so your garage staying around 50° is not necessarily a good sign.
I would insulate in a heartbeat. One of the easiest ways to do it would be to install fiberglass insulation with the vapor barrier up between the joists. Install a thickness equal to your joist depth. In other words, if your joists are 2 x 12's then install 12 inches of insulation. Then on the bottom of the joists add a thin layer, say 1/2" or 1" of foam board insulation right across the bottoms of all the joists. That would act as a thermal break to reduce conduction through the joists. Then drywall.
Before insulating, seal any penetrations (around wires, pipes, etc.) with low expansion foam.
I can't say whether radiant heat would be necessary in your case.
A nice cushy area rug and pad would make a more comfortable play area. Tile on the skin always feels cold because it conducts heat away so fast.
I'm surprised the ceiling of the garage is not already drywalled, as code would require it as a fire barrier. Check with your local code official to see what is required. Don't be surprised if you are required to have two layers of 5/8" fire rated drywall. Even if you live in an area where codes are not enforced, I would use only fire rated drywall on a garage ceiling.
With costs of natural gas so much higher this year it might not appear your bill has gone down, but if you compare therms or CCF's used I'm sure you will use less than last year for the same average monthly temperature.
well, it sounds like you have FHA heat, so adding radiant would be easiest with either electric mats or by adding a hydronic system, which I would only do if the end plan is to replace *all* or a lot of the FHA with radiant or hydronic heat later. Otherwise adding hydronics makes a small radiant addition pretty pricey, comparitively.
That said, you basically have an uninsulated "wall" at this point. Insulate it, definitely. If you switch the area over to radiant for warm floors on top of that, great, but regardless insulating ANY non-insulated cold plane is necessary!!! Remember, heat doesn't rise. Hot air rises, and heat travels in all directions. So currently your duct leakage may partially be heating the garage, but your floors are absorbing heat (slowly) from your heating system and radiating it into your garage as well. I would also look at sealing your ductwork properly if you stick with FHA.
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