Help Me Understand My Flat Roof Installation!

Last year I had a flat roof replaced on my house. The flat is approximately 15’ x 12’.

The contract was setup to install 2-ply bitumen membrane (granular top) and 3/16" Protec board.

I just gutted the ceiling under the flat and can see the membrane through the wood planks. I do not see any evidence of this Protec board.

Can someone please help me understand how this is installed. Do you normally install membrane then protec board then membrane again?

I am confused and worried I am getting ripped off.



ok…so you see the actual membrane or do you see the bottomside of the protec board, remember this board is only 3/16 of an inch…and if the 2ply was put on correctly it is probably alot thinner by now, if not almost flat and transparent…some protec boards are basically just to keep dust and debris from falling thru planks and crevis’…

pics needed

I will try to post some pictures. I just went and had a another good look. The roof is very old (est 1920’s) so there are some gaps in the roof boards.

In between the gaps the material is black and granular, very similar to granual roll roofing (or even house shingles). There is no logo or anything.

I can easily get onto my flat from a walk out, is there anything I can check from on the roof?



is it leaking? did you go with the lowest estimate? did you check your contractors referals? just curious.

He probably left the old roll roofing material in place and installed his system directly to the top of that, which is no problem, since their was no previous flat roof insulation board that could have been wet and as long as the decking boards were not rotted.


Maybe it is the 25lb base sheet that is quoted on my contract.

Anyway, the roofers are back today, there is also a small ponding issue that needs to be resolved. The roof has a slight grade to it which is good, but there is a dip that the collects water and greats a decent puddle about 5 feet in diamter and talk up to a week to evaporate (we are in Toronto).

Any recommendations on how to mitigate the ponding. Can the area be built up and membraned over?

Many thanks.