Preventing overheating due to flat roof ?

[Muzungo]

Out flat is on the top floor, under a flat roof. In summer, we can feel heat radiate off the ceiling at night - the temperature become unbearable.

Would putting 150mm of rockwool or other insulation help ? Can't really afford to give up much more height, but since I want to put in a false ceiling to install halogen lights anyway, I thought it might be worth trying to insulate

Any idea ?

cheers

 

[noseall]

any insulation will make a difference, the more or denser the better.

a modern day compliant roof would use 90mm celotex or kingspan bonded-to-plywood sheeting which would sit on top of the roof joists.

flat roofs conventionally insulated do require ventilation though.

 

[Jasonb]

Depending on the roof covering you could also consider solar reflective paint or white spar chippings though the later tend to encourage moss and block gutters.

Jason

 

[bernardgreen]

How water proof is the roof ?

Keeping it wet on sunny days will cool it. But do not spray cold water onto the hot felt as the sudden cooling will cause differential contraction between the layers and weaken the roof.

Quick fix. Cover roof with "space blankets" ( thin shining foil first aid blankets ) wieghted down with stones.

Long time fix. We built a house with a flat roof over the porch, store room and utility room and the architect's method was to keep the roof wet with about an inch of water by setting the drain higher than the surface. Worked well.

 

[Muzungo]

Many thanks for the suggestions - I can't get put anything on the roof, as its part of the block - all I can do is insulate the ceiling, and was wondering if anyone thinks it will make a difference

thanks

 

[JohnD]

... architect's method was to keep the roof wet with about an inch of water by setting the drain higher than the surface. Worked well.

As a mosquito and tadpole farm?

 

[Nige F]

Many thanks for the suggestions - I can't get put anything on the roof, as its part of the block - all I can do is insulate the ceiling, and was wondering if anyone thinks it will make a difference

thanks

it will .....and space blanket will be the thinnest...maybe the cheapest option

 

[bernardgreen]

As a mosquito and tadpole farm?

Surprisingly not a problem. The architect was Walter Segal and his "temporary" house had the water weighted felt roof ( no gravel or nails to hold the felt other than nailing at the raided edges ) for 17 years without any problems at all. ( other than using the hose to top it up in dry weather )