Seam Rollers & Probes

On a flat or low-slope roof, the seams are the roof. Once TPO or PVC sheets are fused with hot-air welders, that weld still has to be checked by hand — every foot of it — before the membrane can be trusted to shed water for years. That check is what seam rollers and probes are for.

What This Step Confirms

Roller pass — a hand roller run along the fresh weld to confirm the two sheets have fused into one continuous layer, not just touched.
Probe test — a blunt probe drawn along the seam edge to find any spot where the weld is thin, skipped, or not fully bonded.
Full-length coverage — every seam on the roof gets this treatment, not a sample section, since a single weak inch is enough to let water in.

Why It Matters

A membrane roof can look finished from a distance and still have a seam that isn't sealed all the way through. Rolling and probing catches that before the roof is closed up, while it's still simple to re-weld a section. It's a hand-checked step, done alongside the welding equipment, on every flat roof job this practice completes.