Is It Normal for a Flat Roof to Have Some Standing Water?
BERKELEY FLAT ROOF BLOG
Is It Normal for a Flat Roof to Have Some Standing Water?
A little water right after rain is normal. Water that’s still there two days later is not.
Flat roofs aren’t perfectly flat — they have a slight built-in slope toward drains, and it’s completely normal for water to take some time to fully clear after a storm. The generally accepted threshold in roofing is 48 hours: water still standing after that points to a drainage or slope problem worth addressing.
Ongoing ponding accelerates membrane wear at that spot and adds weight the roof structure wasn’t necessarily designed to carry indefinitely. It’s worth fixing even if it hasn’t caused a leak yet.
Water sitting on your roof longer than it should?