Old flat roof, new roof lantern Information, help and advice on maintaining, installing and repairing a flat roof. Post your questions and view answers here

[soundant]

Hi all. I will be as brief as possible - please be patient.

I have at the back of my 1930's semi a 14' x 10' flat roof extension - my neighbor has the mirror image on his side so the flat roof is twice my size. It is in good shape - felt with shingle on top.

I am cutting a 7' x 4' hole and building a 150mm upstand (kerb) around the edge to support a new roof lantern.

I understand that I need to dress up the side of the upstand and cap it with lead flashing before attaching the lantern on top.

My question is : how do I weatherproof the old and new felt? Do I push the new felt under the old by a few inches? What about the four external corners - any tips there for dressing?

I have looked and waited for professional help but I need to move things on if possible. I have done a lot of building work and have many tools but have never attempted roofing...

The construction detail is here:
Google "roof-lanterns-uk.com/installation.html"

Cheers and thanks for looking!

Ant.

[youasked]

I would use *liquid rubber in place of felt and cover joints, extension and evertything , and in fact whole roof. It can be brush or roller applied to 2mm (2 coats) and as our roof is still good after 10 years, I can say as long as its clean when you start, it should outlast everything else. (*Lafarge ). LQGB 0800 630 0010

[soundant]

That's a handy looking product!

Thanks very much - I will look into it asap.