Membrane Decks Over Garages: Common Leak Points
A deck on top of a garage or living area is a popular way to get outdoor space on tight Wellington sections, especially around Miramar, Kilbirnie and Lyall Bay. Underneath the tiles or timber, the deck is really a flat roof with a waterproof membrane. When that membrane fails, water ends up in the garage or room below.
Problems are often fixable without starting again, but they need someone who understands flat roof and membrane deck repairs to find the actual entry point before work starts.
Where they usually leak
- Outlets and scuppers that block with leaves and sand
- Upstands where the deck meets walls and balustrades
- Under ranch sliders and doors with a low threshold
- Fixings for balustrades that pierce the membrane
- Joins in the membrane that have opened up with movement
Signs to look for
Watch for staining on the garage ceiling, water sitting on the deck after rain, tiles that sound hollow or have lifted, and swollen skirting or flooring inside the doorway. Rust stains below balustrade posts can also point to water getting in at the fixings.
Repair options
Small failures at outlets or upstands can often be patched and resealed. Where the membrane is old or has many faults, it may need to be replaced, which usually means lifting the deck surface. Improving falls to outlets and adding an overflow helps the new membrane last.
Keeping it working
Sweep the deck regularly, keep outlets clear and avoid dragging heavy furniture across exposed membrane. A quick look after each big storm is worth the few minutes it takes.
Read next: What to Do When a Tree Comes Down on Your Roof and An Annual Roof Check for Wellington Rental Properties.