The 48-hour rule for commercial flat roofs

Summer holidays are in full swing. The weather isn't taking one.

Heavy rainfall followed by a blistering heat wave is one of the hardest tests a commercial flat roof faces. Water that can't drain sits and bakes, and heat accelerates the breakdown of the membrane underneath it.

Meanwhile the warm, damp margins around drains and flashings become ideal ground for algae, plant roots and nesting animals — all of which go to work on the seams.

Four checks worth making before the next downpour, especially with staff away:

1. Clear every drain, scupper and gutter.

    After heavy rain the roof should be dry within 48 hours. If it isn't, something is blocked or the drainage is undersized.

2. Check seams and flashings for organic growth.

   Roots get into membrane overlaps and lever them apart. A weed on a roof is not cosmetic.

3. Look for nests and debris

   At parapets, curbs and equipment bases — where a blockage forms fastest.

4. Scan the membrane for UV damage

   Blistering, crazing, or splits where it meets a curb or changes plane.

None of this needs a contractor. It needs someone on the roof before the next storm, not after.

If you'd rather not send someone up, that's what our inspections are for — we'll photograph what we find and tell you what's urgent and what can wait until fall.