What angle for a flat window on a flat roof?

[pikeynet]

Hi,

I have an extension near finished that has a flat roof, with a (3) flat roof window.

The roof has an angle of about 5 degrees in which the rain water runs away, but the roof windows have one of about 1 degree. The problem with this is the water stagnates and when dries leaves unsightly ring marks (from the 'rubbish' in London rain water!).

My builder says that these have been installed correctly, but I'm not so sure.

Can anyone help?

Thanks

 

[chappers]

What make of window are they if they are fitted direct into a 5 degree roof without an upstand then they are almost certainly fitted incorrectly.Not entirely sure of other makes but velux windows shouldn't be fitted below a pitch of 15 degrees without an upstand.and even greater for some types of roof covering.
they may be correctly fitted and weathertight if fitted onto upstands but idealy these should have some pitch on them to shed water as you say.
The velux flat roof upstands are ideal for the job.

 

[pikeynet]

No specific make. The size the architect drew couldn't be purchased as no-one made it (!), but the builder committed to putting them in so he made some stands and got a glazier to do a window for the top.

This is the box of one of them, in construction. The glass is secured to the top.

 

[chappers]

Probably sound and weather type and yes to all intents an purpose correctly fitted but personally would have built in some sort of run off to prevent the problem you are experiencing

 

[Deluks]

Got a pic of the finished article? I'm wondering how the glass is fixed to the top of the upstands.

 

[pikeynet]

Pictures of two of the windows:

 

[chappers]

Don't much like the look of that, is that just flashbanding sealing those in, if so every chance that the seal will fail at some time particularly due to the flatness of the glass. Admitedly the long window is a strange shape but why hasn't your builder used standard velux flat roof windows for the square ones. looks like a bodge to me. I certainly wouldn't accept that if it were my roof

Have a look here at the flat roof systems

http://www.velux.co.uk/VELUXCommon/...-e710e1c9015d_WebPDPriceGuide August 2008.pdf

 

[and1c]

Pictures of two of the windows:

A neat looking bodge!!
As the others have said, he should have used the nearest correctly sized upstanding velux.
and the architect should have known better....

 

[pikeynet]

Got a pic? I'm wondering how the glass is fixed to the top of the upstands.

Mastic

 

[masona]

Would've been easier to use Velux Sun Tunnel, just fitted one in mine utility room and what a difference!

 

[Xenon]

Thats the same as the old Anderson detail from years ago, but you used to bond the felt to the glass. They never lasted long either. Where's the ventilation?

 

[and1c]

From a security point of view (or lackof) it seems a burglar would only have to slit the gaffer Flash banding and then slice the mastic and lift the window out!!!

The builder should have subbed out the making of some custom Velux' as he got it wrong by not checking the velux size prior to starting the job.

I would say from personal experience with similiar bodges on a house I bought that they wont remain watertight for more than a year or two..

 

[chappers]

.

I would say from personal experience with similiar bodges on a house I bought that they wont remain watertight for more than a year or two..

If your very lucky