Roof window in a flat roof

[ruscave]

Hi all, I am having an extension done on my kitchen and because there is not enough elevation to have a pitched roof we are having a flat roof instead. To get more natural light into the room I wanted to have a roof window fitted but the builder who is doing the work expressed some concerns that it may leak slightly due to the water not being able to run away. Was wondering if anyone had any experience of this and if it is a problem, are there any solutions available?

Cheers. R

 

[^woody^]

There is no reason why a properly fitted and sealed rooflight should leak.

The builder will, I assume , construct the new flat roof to the required fall to allow drainage, so I can't understand why he thinks the rooflight may leak.

On seconds thoughts, he may not be confident in doing this, so he is trying the cover himself so that he can say "I told you so" if it does leak.

 

[memor maplin]

Flat roofs aren't and shouldn't be flat, there should be a slight incline for the water to run off and not pool.

Ask your builder how much incline he's going to put on your flat roof.

The figure escapes me at the moment but it should be built to this spec.

 

[nstreet]

The roof light will also have a kerb around it so its actually higher than the roof. As long as a proper felting job is done, there is no reason for it to leak.

Example roof light

http://www.master-plastics.co.uk/index.html?target=dept_353.html&lang=en-gb

 

[memor maplin]

NHBC Standards says.

"a flat roof has a maximum slope of 10 degrees from Horizontal."

or not less than 1:40

Give it a mention next time you see him.

 

[^woody^]

Flat roof pitch is 1:60 or 1 degree for felt coverings

 

[ruscave]

Cheers for the advice guys. I've spoke to the builder again and he agrees it should be fine. A roof window with a kerb should have no problems. Thanks again.