ᐅ Installation of Velux Energy Plus Roof Windows in a Hipped Roof
Created on: 28 Aug 2022 17:35
I
Immo2014Hello everyone,
I would like to install a Velux Energy Plus roof window, size 78cm x 118cm (31 inches x 46 inches), in my semi-detached house built in 1986 with a hipped roof. This is a new installation, not a replacement. The rafter width is consistently 84cm (33 inches), which matches exactly the required size by Velux to install the flashing frame EDZ MK06 2000.
I am not a professional in this field, but I have watched a very informative video series on YouTube that covers every step in detail. So, I have decided to take on this job myself. I also do a lot of work around the house on my own.
I have two questions regarding the underlay membrane and the vapor barrier beneath the insulation.
Regarding the underlay membrane:
Today, I removed four roof tiles to check what is underneath (to assess the condition of the insulation and the underlay membrane). The underlay looks like a kind of thin roofing felt. I thought that nowadays it should be a thin overlapping and taped foil membrane. The membrane here is in poor condition, torn everywhere. Where it is still intact, it is extremely brittle.
The rainwater drainage flashing is supposed to be installed over the Velux window and connected together with the underlay membrane and the window apron to prevent water from leaking underneath.
But with a damaged underlay like this, doesn’t that actually make no sense? Should I perhaps only connect the drainage flashing with the window apron and seal underneath the flashing to ensure that no water can enter the Velux window from above?
Regarding the vapor barrier:
The Velux window comes with a vapor control collar. I understand that I have to connect this to the vapor barrier under the insulation with adhesive tape. So far so good.
However, I don’t have a vapor barrier as I expected. The insulation installed is aluminum foil–covered mineral wool. How do I connect the Velux vapor control collar to the roof structure? Should it possibly be glued directly to the rafters with adhesive?
I hope I was able to explain my questions clearly.
Thank you very much for your help
I would like to install a Velux Energy Plus roof window, size 78cm x 118cm (31 inches x 46 inches), in my semi-detached house built in 1986 with a hipped roof. This is a new installation, not a replacement. The rafter width is consistently 84cm (33 inches), which matches exactly the required size by Velux to install the flashing frame EDZ MK06 2000.
I am not a professional in this field, but I have watched a very informative video series on YouTube that covers every step in detail. So, I have decided to take on this job myself. I also do a lot of work around the house on my own.
I have two questions regarding the underlay membrane and the vapor barrier beneath the insulation.
Regarding the underlay membrane:
Today, I removed four roof tiles to check what is underneath (to assess the condition of the insulation and the underlay membrane). The underlay looks like a kind of thin roofing felt. I thought that nowadays it should be a thin overlapping and taped foil membrane. The membrane here is in poor condition, torn everywhere. Where it is still intact, it is extremely brittle.
The rainwater drainage flashing is supposed to be installed over the Velux window and connected together with the underlay membrane and the window apron to prevent water from leaking underneath.
But with a damaged underlay like this, doesn’t that actually make no sense? Should I perhaps only connect the drainage flashing with the window apron and seal underneath the flashing to ensure that no water can enter the Velux window from above?
Regarding the vapor barrier:
The Velux window comes with a vapor control collar. I understand that I have to connect this to the vapor barrier under the insulation with adhesive tape. So far so good.
However, I don’t have a vapor barrier as I expected. The insulation installed is aluminum foil–covered mineral wool. How do I connect the Velux vapor control collar to the roof structure? Should it possibly be glued directly to the rafters with adhesive?
I hope I was able to explain my questions clearly.
Thank you very much for your help
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