Bedrooms Over Garage Won't Get Cool

Bedrooms Over Garage Won’t Get Cool

Learn why a bedroom over the garage will be hard to cool if there is not enough air being supplied there. You will need to have an HVAC contractor put in additional ducts and returns.

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LESLIE: Wayne in Virginia is dealing with a heating and cooling issue in some bedrooms, tell us about it.

WAYNE: Well, the air conditioning system works fine but the three bedrooms, which are situated over the garage, I can’t seem to get them very cool. They pretty much stay warm; not as cool as the rest of the house.

TOM: Right.

WAYNE: Tried a lot of things; nothing has worked yet.

TOM: Mm-hmm. Well, they’re second-floor rooms. They’re surrounded by unconditioned space; not only on the exterior walls and roof but now also the floor.

WAYNE: Right.

TOM: Where a first floor, you have the cool basement, a slab or a crawlspace, now you’ve got a hot garage. So it really is quite a chore to get enough air conditioning to do that space. What’s the square footage of that space? Can you estimate that?

WAYNE: Well, it’s three rooms: 15×12; the other two are about 10×12.

TOM: Mm-hmm. So, 15×12. Alright, so you’ve got like maybe 400-and-some-odd feet there.

WAYNE: That sounds about right.

TOM: Now, typically, you need about 12,000 BTUs per 600 square feet of space. So if you had three 5,000 BTU air conditioners – one in each room – that should do it. What size air conditioners do you have there?

WAYNE: I have central air.

TOM: So you have central air conditioning in the whole house and everything cools properly except for this space.

WAYNE: Right.

TOM: Well, the problem is you’re not getting enough supply air there, so you need to have additional ductwork done or larger ductwork put in so you deliver more air and you also need, probably, some return work done as well. Because cooling those spaces that are so super-hot because they’re surrounded by three exterior walls plus the roof with the garage underneath is going to require an awful lot of BTUs. Typically, with a house, you figure that you’ve got about 12,000 BTUs for every 600 square feet of house. And so, in your case, you may not have enough tonnage or you may have plenty but you’re just not distributing it right.

WAYNE: Alright, then I would probably need to see an AC expert then to have that figured out.

TOM: Yeah, I think you’re going to need an HVAC guy to add some additional ductwork to the house.

WAYNE: Alright, that does it. Thank you very much.

TOM: You’re welcome. Thanks so much for calling us at 1-888-MONEY-PIT.