Insulating Ceiling

[fakename]

I have a typical Thai build, Farang home, 2 br, built from cement blocks. We only use the air con in the bedrooms, at night, usually just our own bedroom. It seems the aircon is running most of the time, so would like to insulate the ceiling. I have the insulation, 15cm, so just waiting for cooler days to do the work.

But I have been wondering about other options also. I have seen the adds about insulating the roof, with foam, but dont really understand how that can work. Once the air in the attic is hot, there is no where for it to go, since at least in my home, the roof seems to be completely sealed. I have been thinking of installing an extractor on the roof, just like on a lot of buildings, but the neighbor says it would be ugly! In Scandinavia, we only insulate the ceiling, so the idea of insulating the roof, doesnt seem like the right way to go, but of course we are insulating against the cold, not heat. It just seems that if the attic is filled with hot air, it has to radiate down into the room below, unless the ceiling is insulated.

So, my idea is just to insulate the ceiling, put an extractor on the roof, maybe knock a hole somewhere, for the cooler air to flow into the attic, but am I missing something?

Has anyone installed fiberglass insulation, on the ceiling, and has it improved the cooling in the house? Any thoughts?

[Morakot]

We only use the air con in the bedrooms, at night [...] so would like to insulate the ceiling.

Yes, that a perfect way to keep the cool outside air away from your room at night and keep the hot air inside. Better to look for an extractor fan for your roof space.

Edited September 6, 2012 by Morakot

[Kwasaki]

Insulating your ceiling will make it cooler and reduce noise too, just make sure your roof space has natural through-flow ventilation usually in both gable ends then no need for extractors.

To reduce outside wall heat from day sun heat build up line inside wall or put another skin of brick or block-work to create a cavity on the sun exposed walls.

Edited September 6, 2012 by Kwasaki

[bbradsby]

Correct - insulation is to be just above the ceiling, not under the roof, in hot or cold climate zones. If the batts/blankets have a radiant barrier, it should be facing the attic. Work diligently to eliminate all gaps in the insulation, as they have an outsized effect in compromising your overall ceiling insulation value. Make sure any light fixtures in contact with the insulation are not incandescent or MR-16 lamped or else you could start a fire. If in doubt, change out for fluorescent.

Then, make sure your windows & doors at conditioned rooms are well-weatherstripped, else outside air infiltration will quickly push all that nice, expensive, cold air out through the cracks & crevices and replace it with hot, humid outside air.

[sezze]

Yes, without aircon , put a radiant barrier underneath the roof . Foam might be good also , as i heard positive results from it . And ventilate as much as possible the attick space . For aircon use , insulate the ceiling as much as possible . What you do with the roof doesn't really matter , but best is to ventilate as much as possible also .

[Hssl]

'Micro fiber' blankets many brand names - stay cool being one of them, I used global house's own brand the blankets laid on top of the aluminum ceiling frame supports. They do work but be sure to have some form of venting for the roof.