Flat Roof Decks (Why they always leak)

The “Modern” Look

Everyone wants a modern box house. Flat roof. Roof deck party area. It looks great on Pinterest. It’s a nightmare in the Philippines.

Water always wins

If your roof is flat, water sits. If water sits, it finds a microscopic crack. Gravity pushes it through. Drip. Drip. Drip.

If you MUST have a flat roof…

1. It shouldn’t be flat. It needs a 1-2% slope. You shouldn’t feel the slope when walking, but water should run to the drain. If you have puddles after it rains, your contractor failed.

2. The Waterproofing Myth “Sir, we used Plexibond!” Waterproofing paint lasts 2 years. The sun cooks it. It cracks. You need a physical membrane (Torch-on bitumen) or a roof over your roof deck.

3. The Parapet Trap You know those walls around the roof? They trap water. If the drain clogs (leaves, rats, tennis balls), your roof becomes a swimming pool. Water gets heavy. Roof collapses. Install a Scupper (Emergency Overflow Drain). A hole in the wall 2 inches above the floor. Just in case.

Summary

Pitched roofs shed water instantly. Flat roofs hold water hostage. Choose wisely.