Math Help
 

on slopes not less than 1/4" per horizontal foot. How much drop would that be in 25 feet? Would it be 25 times .25? 6.25 inches? If so the roof someone is trying to sell me is not recommended by this web site Here :smack:

Think of it as a 1" drop per four feet of run. For guesstimates, there are six "four-feet runs" in 25' so make it a six inch drop. For precision, add the 1/4" for the extra foot (25 - 6*4 = 1) for a precise answer of 6-1/4"

1/4" per foot is basically flat. That's also, as I recall, the minimum slope for drain pipes making it the bare minimum angle to encourage the flow of water.

I assume you are not using shingles since the min rise to run for shingles is 3:12 (3 inches per foot).

What is the roofing material?

They're looking for positive drainage which they define as So no low spots for puddles are allowed.
At least Modified Bitumen would be melted down and form a continuous cover unlike shingles which have to have more slope. :cool:

Looks like the answer is 25 times .25 for 61/4 or 6.25. What is the roofing material?
It's in link above thanks.

They're showing 3 different materials in that link, Buster. :confused:

Nor does it explain why what he is being "sold" falls short of what is being recommended. I'll see your :confused: and raise you one :confused:

My bad all he put on bid was Modified Bitumen. So that's what lead me to look around.
A roofer, I'm not.

I was in roofing for almost 14 years, Buster...what, specifically, are your questions on this roofing issue? The water evaporation within 48 hours thing is a stipulation for the sake of the warranty. Basically, you need enough slope to ensure that all standing water will drain off in that time. In reroofing situations, that is nearly impossible without replacing the substrate, because original roofing substrates sag unevenly over time, and you get "potholes" where the water will stand. 1/4" per foot average structural slope will *not* typically drain an older roof, but you can have a tapered insulation system installed to fix that. It greatly adds to the cost, though.

I assume you have some flat roofing involved, here, if you are looking at Mod Bit?