ᐅ Are roof windows really not feasible with a roof pitch of about 12°?

Created on: 7 Mar 2018 10:36
A
AnNaHF79
Hello,

we have a single-pitched roof (with a weatherproof underlayment) with a slope of about 12° (a bit more). We would like to install a roof window in the stairwell area; however, our architect tells us this is not possible due to the slope (only from 15° upwards). Raising the gable to adjust the slope is not an option for building code reasons, as we would then exceed the maximum allowed height.

I did some research and so far only found windows from Vitral that are suitable for slopes between 0° and 30°, but the architect says these are only suitable for flat roofs, and so on.

Surely it must be possible to install a roof window on single-pitched roofs with a 12° slope — we can’t be the first in 2018, can we?

Any ideas?

Thanks.
A
Alex85
7 Mar 2018 18:56
Look more at flat roof windows or skylights. They are also available with a motor for opening. These are designed for roofs with a pitch of 0-15 degrees.
Velux is fine by me as well.
A
AnNaHF79
7 Mar 2018 18:59
The construction manager said that installing a flat roof window is not possible due to the required waterproof underlayment – I did not understand why this should be the case.
R
ruppsn
25 Mar 2018 11:35
What type of roofing are you planning to use? A waterproof underlay usually implies roof tiles or shingles. Maybe that’s the reason?

Has anyone explained to you why this approach works for flat roofs but not for low-pitched roofs? I would first ask the architect to explain the technical details.
A
AnNaHF79
25 Mar 2018 12:02
The roofing will be supplied by Braas; the HARZER PFANNE F+ will be used, which for the first time allows the covering of a low-pitched roof starting from 7° with Braas roof tiles.

So far, the architect has argued that Braas would refuse to provide a warranty if a roof window is installed.

Therefore, I contacted Braas myself and was told: "As long as our Braas products are not altered or affected and our installation guidelines are followed, the warranty is valid."

This all seems very strange to me.
R
ruppsn
25 Mar 2018 12:56
Well, this is because Braas systems fall outside the generally accepted industry standards. The standard roof pitch for roof tiles is, as far as I know, 22 degrees, or down to 16 degrees with a waterproof underlay. This is necessary partly because, with a low roof pitch, rainwater can be pushed under the tiles by the wind. The flatter the roof, the more problematic this becomes. From 22 degrees upward, this apparently no longer happens, so a rainproof roof covering is no longer required.

With the Braas 7F system, Braas has come up with a solution that allows them to avoid problems even at pitches as low as 7 degrees, provided their tested sealing membranes for the underlay are used, and one does not just install any waterproof layer in any way.

Of course, Braas might state that the warranty only applies to a closed roof surface, and that no warranty is given otherwise. That makes installing a window in that area tricky.

However, the installer must clarify the details, as they are the ones who ultimately provide the warranty to you. This is my layperson’s opinion as a homeowner who chose the same roof covering, just without a roof window.
A
AnNaHF79
25 Mar 2018 13:07
Well, the point is that Braas, fully aware that we have a roof with the mentioned pitch and will be covering it with the 7-degree tiles, has no issues with the warranty:

"As long as our Braas products are not altered/damaged and our installation instructions are followed, the warranty/guarantee is valid."