room extension: flat roof
 

I hope to do a room extension, but if I cannot accept an almost flat roof (only a six inch to 14 feet span gradient), there will be a lot more work.

I tend to think that this is a way to make sure that an almost flat roof never leaks. There can be extra work to make sure but I believe it can be done.

What are some established treatment for an almost flat roof to make sure it does not leak.

What do you call the flat sheet, plastic or metal, that one places on the valley of any roof to prevent leaking thru the seam of the valley. I will use this stuff between the existing eave and the new roon extension. I think there will not be leak thru the seam this way, but I also need to make sure that no leak for the flat roof itself, not just at the seam between existing and new roof.

Where are you located?

It's called flashing.
And you can use 90lb "roll" composite roofing.
(comes in 3' wide rolls).

High Desert of SoCal.

There can be up to a foot of snow at any one time. Then it will all melt any in the afternoon.

Tyically two inches of snow once or twice a year. This year no snow at all.

Actually, a few years ago there was two feet of snow, but once in a lifetime thing may be, and may never happen again for 50 or more years. The roof does not have to be considered for this extreme situation.

You will have to use a membrane type roof. Modbit, TPO, PVC, EPDM... depends on your budget and local installers. To tie it into an existing shingled roof you will need to remove some of the shingles and bring the membrane up the deck.

You could also go with a standing seam type roof, again, depends on your budget and design choices.

+1

Go for metal and be done with it once and for all.

The existing roof is tile and I am almost sure that nails instead of screws were used. Do I have to somehow remove one tier of tiles at the seam, the eave of the existing roof? Is there a trick to removed nailed tiles without breaking them?

My garage had a flat tar and gravel roof that wasn't leaking. I replaced it with a rubber membrane roof that hasn't leaked in 20 years. So it is possible.

Tapered insulation
 

90 lb. f/flashing?!:eek: no....Shazzapple gets it, though.
In Miami there are thousands of flat additions called "Florida Rooms". A BUR (eg. two PLY 4 w/Ruberoid Granule cap) hot-mopped over tapered insulation holds up well and greatly improves drainage and energy efficiency.
Low slope/steep slope transitions are Roofing 101 for a pro. Find one.

Do your homework. Pick a system. Get 3 quotes for that system. That's as DIY as you should get.

Yes, matter of fact I do know a "trick" for removing those
pesky lil' tile at the tie-in... :whistling2:

Go to Roof repair Technician for roof extension

i have a flat roof tied in to a steep shingle half. the thread is in here somewhere