It’s **legal in limited cases and rarely a good idea** — particularly in Houston’s heat.
Code generally permits a maximum of two layers total, so an overlay is only possible on a roof that currently has one. Beyond that, here’s what an overlay actually costs you:
– **The decking never gets inspected.** Rot, soft spots, and old leak damage stay hidden under the new roof until they fail.
– **Heat gets trapped.** Two layers hold more heat in a climate that already shortens shingle life, and an overlay typically loses several years of service.
– **Weight adds up.** A second layer adds roughly 250 pounds per square to the structure.
– **The surface isn’t flat.** New shingles telegraph the contours of the old ones, and the finished roof looks it.
– **Manufacturer warranties are often reduced or void** on overlay installations.
– **Flashing usually gets reused,** which is where most future leaks begin.
The savings are real but modest — typically the tear-off and disposal portion of the job — and you’re trading years of roof life for it.
We don’t recommend overlays and won’t quote one without walking you through the tradeoff first. If budget is the constraint, financing preserves the roof and solves the actual problem.