I'm learning many things about our new home. This winter I learned that a room directly above a garage stays much colder than the rest of the house (up to 10+ degrees colder in our case). What options exist to eliminate or reduce this problem? Is there some way I can easily increase the insulation without having to tear floors up, or open up ceilings - or is that the best option available to me?
Jonathan, your problem is very common. Do you know what is in the floor for insulation now? Assuming there is some f/G batts or something similar, it would be hard to try to add anything else, such as high density cellulose directly into the cavities. As much as you probably don't want to hear it, the best way is going to remove the sheetrock from the garage ceiling and remove the existing insulation. With the framing completely open, be sure to seal all holes through joists and floor areas where wires or other components may pass thru with foam. The absolute best insulation would be to have a high density foam sprayed into each bay and into any voids along garage door headers etc. This would give you the maximum R value and absolutely stop any cold air infiltration to the bedroom above. The goal would be to achieve an R value of 30 or more. The alternate method for DIY would be to again, seal any air passage ways and door headers with spray foam, then carefully install the max amount of f/g blanket and cover entire field with 4 mil poly and tape all seams and edges with tuck tape before reinstalling your fire rated sheetrock. This is not the best solution as the r value of the f/g is going to be limited by the size of the joists. 2X8 for example will limit you to about an R 23. A slightly higher R value could be achieved with blown in high density cellulose after sheetrock is installed, in place of the blanket f/g insulation. The spray foam is definitely the best overall, but the most expensive as well.
In response to Sharp Tooth's answer, too long for comment section: I have seen 2 to 4 inches of rigid foam insulation added to garage ceilings in this situation. The only drawback of this method is the problems it causes with garage door openers and suspension hardware. It also can cause issues with overhead lighting and overall head space. I hate to be a nay sayer, but I have to negatively comment on your other suggestions. Insulating a garage that does not have new style insulated, airtight doors is a total waste of money. Likewise, trying to heat a garage that is not build to be energy efficient can be extremely expensive to install and fuel, especially if a separate zone or plumbing needs to be added. This is not a viable solution as every time the garage door opens, out goes all that expensive heat. Carpeting, even over a thick foam pad will not help much either, maybe a gain of 2 to 4 "R", quite negligible. I hope you were not serious about heat tape under the ceiling. Other than electric or forced hot water radiant heat grids that would be installed under the floor, not under the ceiling, there is no safe product to do what you decribed. It would not work anyway, since the source of heat would be on the wrong side of the insulation and the vast majority of the heat would be wasted into the garage air. Sorry to shoot down your suggestions, but I truly believe questions should have informed, proven solutions, not wishful guesses.
Surely the most direct way is to open up the ceiling or the floor and add the insulation there. Other than that you could try the following:
- put a thick carpet onto the bedroom floor so that it covers the entire floor, however this won't help much since carpets are quite thin
- add another ceiling and install insulation above it (or just install insulation onto existing ceiling and leave it uncovered, which might be okay for the garage) - will work, but will consume space under the existing ceiling
- insulate the garage so that it doesn't cool that much
- install a heat source in the garage to compenstate for the heat lost by the garage
- install a heating cable under the ceiling to compensate for heat lost by the bedroom (this should be well thought so that you don't set the house on fire).
Firstly remember that it is the first bit of insulation that has the best payback, so don’t overlook the option of putting down a thick carpet – not the best solution, but it may cut down heat loss in the short time for very little effort.
Another option that not the best solution but will help if you don’t mind the down sides. In the UK (and I assume the USA) you can get insulated boards for boarding lofts, these have a chipboard top that is fixed to solid insulation. You could lay these over the floor in the room, sealing any gaps. However:
- The floor height will be increased, so you will have a step up into the room and the doors may no longer fit.
- You may get problems with condensation forming in the floor.
Everybody is very focused on insulation. While you need to address this and make sure it's everything it can be, the problem could also be the design of the heating system. The heating elements (vents, radiators, etc.) may be inadequate for the heat loss of the room, and/or the location of the thermostat doesn't adequately represent all areas controlled by the thermostat.
If the insulation is as good as it can be, I'd do a heat-loss calculation on the room and compare it to what you're getting from the heating system. And take a look at the thermostat location.
If there is insulation in the space between floor and ceiling, then the cold is probably getting in some other way. If the bedroom is designed to look as though it is "tucked under" the roof, or has dormers, for example, there are nooks and gaps in the framing that are often neglected when the insulation is installed. You need to find the source of the air infiltration first before you spend time and effort on the solution.
Think of an insulated (double pane) window. Thermal windows these days are incredibly efficient, airtight assemblies. But if you do not install it properly, don't insulate the space around the rough opening, and don't properly seal it after installation, there will still be drafts strong enough to blow out the candles on your birthday cake!
I don't mean to dissuade you from your idea - just to caution you to be sure you know the source of the problem before you invest in the solution.