In alt.home.repair, on Fri, 14 Feb 2020 09:23:09 -0500, micky
wrote:


I need a new roof, or a repair of the old one.

Another question has come up.

It seems the original roof had 3/8" plywood and one roofer wants to
patch it with some sheets of 1/2" plywood, which he says is better.

The other roofer says it will leave valleys that water will collect in,
and that's bad.

I can certainly see if the thicker stuff is below the thinner stuff,
there would be a 1/8" dip, at an angle** which makes the dip a little
less, and a bit of water would sit there until it evaporated or sunk in,
but isn't the roof supposed to be waterproof?

**Roof is 2:5 I think. Prefab trusses.

Will every replacement sheet of plywood be noticeable from the street,
two stories down, because plywood is 1/8" thicker. Should they use
3/8th to patch 3/8ths?