Room above driveway is warmer

[Yong Huang]

I have 4 rooms all upstairs. Below 3 are all indoors like living room, etc. They're cool. One is above outdoor driveway. It's noticeably warmer. I can't think of any explanation. One day I used a thermometer to measure floor temperature. It was between 1 and 2 degrees higher than the floors of the other 3 rooms. I think that explains it. But I don't think there's anything I can do.

Probably because this room is warmer, the previous owner noticed it and they didn't want to use this room either. The carpet is much thicker and less used than the rest of the upstairs. If it's because the underside is outdoors this room is warmer, what about those many rooms above a garage? Are they warmer too? What do you do to remedy it? Thanks.

BTW, I remember in winter, this room is a little colder but I'll double check that in a few months.

[jamesgangnc]

Increase the hvac service to the room by adding another run and duct or by increasing the size of the existing runs, ie change the 6" flex to 8". Improve the insulation in the ceiling.

[Yong Huang]

Thanks. More than half the time at night, the AC is not running. I hope the room is not too warm during that time. I'll try to put more insulation in the ceiling above this room.

[jamesgangnc]

Depending on distances involved you could also look at adding a return to that room. Is the room far from the current air handler? Where is the current air return? (Usually where the filter is.) If you leave the door closed on that room a lot then check the gap under the door. Is there enough room for air to get back to the return? Might want to saw a little off the bottom of the door.

I have a room over the garage that has the same problem. I improved it some by replacing the 6" duct with 8" duct. The room already had a

12x20 return in the ceiling. There are still periods when the demand on the hvac is low and that room is a bit hotter or colder than the rest of the house. A variable speed system would help more but that's a pricey solution.

[Bob F]

Check if there is insulation in the floor below that room. If not, fully insulate it.

[HeyBub]

If you can't insulate the existing floor, you may have to build a false "ceiling" on the carport and stuff this "attic" full of insulation.

[Pavel314]

From your description, it sounds like this fourth room is sort of suspended over the driveway. Is that right? If so, that would account for the temperature differences. In the winter, the other rooms have warm rooms underneath them while this one lets a lot of heat escape through the floor into the open air. Conversely in the summer; heat creeps in from outside through the floor while the other rooms have cooled rooms beneath them.

[mkirsch1]

My God, are people really this dumb?

Sun heats the driveway. Driveway radiates heat into floor of upstairs room. Floor in upstairs room is poorly insulated, if insulated at all. Floor of upstairs room is warmer.

You need more insulation in the floor of this room, or just live with it. One or two degrees is hardly what I would consider "warmer." Cheap thermometers have wider variances than that.

[mkirsch1]

That will make it WORSE by trapping the heat that is rising up from the driveway below!

[jamesgangnc]

No, it won't. The room is already conditioned space. It is not conducting heat from below the floor, thru the room, and out the ceiling.

Improving the insulation below the floor would be more effective but I'm assuming that space is unaccessible from above or below without major demolition. In most cases the space above is easily accessed. Improving the insulation up there, while not as effective, would still reduce the overall heat transfer between the room and the surrounding unconditioned spaces. Anything that does that will reduce the load on the hvac service to the room.

Is it possible you don't know what you are talking about?

[ransley]

The reason is its fully exposed, insulation could be better, the AC isnt sized large enough and not enough air circulation. On just insulating the ceiling, My place had little attic insulation, maybe R12, I went to R 60 and the second floor was hotter overall as no night time cooling took effect, it was noticable, but in winter it was much warmer. You should consider everything, what your windows are, floor, wall and ceiling insulation, carpet with foam padding does alot, cellular shades that seal on edges can equal and inch of fiberglass insulation, and a bigger supply for the AC to that room. Running the fan continously on your system will do alot to balance out hot spots, try it while its really hot out. Just running the blower wont add alot to your bill in these hottest days.

[Bob F]

Why would you not be able to insulate it? Worst case, blowing in insulation wshould do it.

[JimT]

No, it won't. The room is already conditioned space. It is not conducting heat from below the floor, thru the room, and out the ceiling.

Improving the insulation below the floor would be more effective but I'm assuming that space is unaccessible from above or below without major demolition. In most cases the space above is easily accessed. Improving the insulation up there, while not as effective, would still reduce the overall heat transfer between the room and the surrounding unconditioned spaces. Anything that does that will reduce the load on the hvac service to the room.

Is it possible you don't know what you are talking about?

===

By the same logic he could drill holes to let the heat out

I was going to suggest a register assist fan or larger duct. Insulation never hurts. Another thing would be to check the condition of the duct work. I have those insulated tubes, and in one of my main tubes, the insulation collapsed inside the tube blocking the air. Easy to check, the tube will collapes when the ac isn't running or feel mushy when squeezed.

[notbob]

That would be my take. That concrete is a big heat sink.

Does the sun hit it in the Summer. Would also explain why colder in Winter. Actually, need more details.

nb

[trader4]

Yes. While the heat that travels through from the floor is one factor, it could also be that this room has the longest duct run, insufficient supply ducts or returns, closed damper in the ducts, collapsed or disconnected ducts along the way, insufficient attic insulation, etc. All that should be checked. But unfortunately only a few of those things can be easily fixed.

A mini-split for that room may be a solution.

[Joe]

The cable TV program "Holmes on Homes" dealt with an identical situation to this. The solution was to remove the carport ceiling and put in the missing insulation as well as some HVAC mods IIRC.

Joe

[HeyBub]

Because the construction MAY be (going down):

• Carpet

• Sub-floor (i.e., 3/4" plywood)

• 2x8 joists

• Air

• Driveway

• Dirt

• China

[Oren]

..." 1 and 2 degrees higher..."

And you are worried about that?! What you describe is what I would call a "carport". Open on two sides with an entrance door to the home.

Does the driveway face east or west?! What kind of siding? Window treatments inside / outside (solar screen, awning, etc.)? Is there a ceiling fan in the room?

Have the floor joist filled with blown insulation. No different than filling wall cavities, IME.

Insulate the garage door, especially if facing east of west: with temps from 90° - 117° (morning/afternoon respectively).

[Oren]

Peel it back from the further most distance from the door.

Drill hole for blown -in insulation. Small hole will show if OP has insulation.

Fill them from the outside... or above.

That's where the insulation is supposed to go.

[clare]

Put in more insulation.