During the last big rain here in AZ, I noticed a significant amount of ponding in the newly renovated areas of our roof. I first noticed the sitting water while it was still raining and about 2 days later the water was still present. I contacted my general contractor, but he's questioning how long the water was present.

Is there a way I can measure the slope of the roof to determine if it is at least at the minimum for a flat roof (1/4" per 1')?

1 Answer 1


If water is ponding on the roof, there is essentially no continuous slope to the edge. It doesn't matter what the slope is if the water can't run off the roof. How long it was there isn't really relevant in my opinion.

But if you want to measure the slope in a localized area, take a level - for convenience, say it's 1 foot long. Put it on the roof and raise the low end until it reads level. Now measure the height that you raised that end to make it level. That's you're slope.

So if you lifted it 3/4", that would be 3/4" rise per foot of run.

If you had a 3' level and lifted it the same 3/4" to get level, you'd have 1/4" rise per foot of run.

  • Thanks, I had issues with General Contractor in the past and had to get the State involved before they would make obvious corrections. I think they will want to try to say they did their job correctly if I can't explain exactly where the issue is. This will help.
    – Eric S
    Commented Jan 29, 2019 at 21:54
  • If you had issues of that significance with this contractor before, why'd you go with them again? Commented Jan 29, 2019 at 22:01
  • 1
    Same renovation, found new issues after a big rain. Believe me we wouldn't use them if they paid us to do work now.
    – Eric S
    Commented Jan 30, 2019 at 17:18

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.