10/09/2026
FAQ Friday: What is tapered insulation?
This one is for the commercial building owners, and it is a good one to know. A flat roof should not actually be flat. If water just sits up there, it finds a way in.
Tapered insulation is rigid insulation board that we cut and lay at a slight slope, usually about a quarter inch per foot. That built-in slope steers rain water toward the drains instead of letting it pool in the middle of the roof.
Why it matters: standing water, what we call ponding, is one of the hardest things on a flat roof. It breaks down the membrane over time, adds weight and stress to the structure, finds every weak seam, and a lot of manufacturer warranties will not cover a roof that ponds.
When we did the commercial TPO on Homer Street, the drainage layout was a big part of doing it right. A flat roof that moves water to the drains like it should is a flat roof doing its job.
Own a building with a flat roof that holds water after it rains? Get a second opinion. We are happy to take a look.
📲 (410) 677-4975