Water pooling inspection of an elevated tiled deck in Avoca Beach

The brief

Our client in Avoca Beach reported water pooling on an elevated tiled deck at their house. The deck is about 5.6 m long, has a glass balustrade, and has a room directly below the area where the water collects. Avoca Beach is one of the Central Coast suburbs listed on our service areas page.

The client asked for an inspection to assess the structural condition of the deck in relation to the water pooling.

Why it needed a structural engineer

Water sitting on a deck above a room raises two questions: is the deck structure damaged or moving, and is water getting into the room below? The explanatory information in NCC 2022 Volume Two, Part H2 notes that decks and balconies, particularly over internal spaces, can be susceptible to water getting into the building and causing damage.

A structural engineer can check the deck for visible structural defects or deterioration, look for signs of moisture in the ceiling below, and recommend what should be investigated and fixed.

What we inspected

The inspection was visual and non-destructive. It covered:

• the accessible tiled deck surface;
• the area where the water pooling was reported;
• the deck, for visible structural defects or deterioration;
• the ceiling of the room directly below the reported pooling location.

The report is based on the information the client provided and on what was seen on site. Only elements exposed during the inspection were observed, so nothing under the tiles was seen. The original structural design capacities were not verified beyond the scope of the visual inspection.

What we found

Area checked	What the report found
Tiled surface	Localised water pooling near the outer corner of the deck, next to the glass balustrade
Tiles in the inspected area	No significant cracking, lifting or visible movement
Ceiling of the room below	No visible water staining, sagging, cracking or other evidence of moisture damage at the time of inspection
Deck structure	No obvious structural damage, deformation or deterioration in the visual inspection

The site photos also show leaves and staining on the tiles near the glass balustrade and around a pot plant at the corner.

What could be causing the pooling

The report lists four possible causes. They are possibilities, not confirmed findings: the recommended water-flow test and level check are there to confirm whether a localised low point or insufficient fall is causing the pooling.

Possible cause	What the report says
Localised low point	The affected area may be slightly lower than the surrounding tiles, causing water to collect
Insufficient surface fall	The tiled surface may not have enough slope to direct water away efficiently
Uneven tile installation	Individual tiles may have been installed at different levels, forming a shallow depression where water collects
Tile or substrate settlement	Minor settlement or movement beneath the tiles may have created a localised low area after installation

The result

The report recommended six steps, in this order:

1. Clean the affected area. Remove the pot plant, leaves, dirt and other debris from the pooling area, and keep the surface and drainage path clear.
2. Carry out a controlled water-flow test. Under the tiler's guidance, apply water carefully to the cleaned surface to confirm the direction of flow and find where water remains.
3. Measure the tile levels and falls. Use suitable levelling equipment to confirm whether a localised low point or insufficient fall is causing the pooling.
4. Remove the affected tiles if required. If inadequate falls are confirmed, carefully remove the affected tiles to expose the underlying screed or substrate, and correct the screed with suitable engineering guidance.
5. Reinstate the tiled surface. Install suitable tiles with compatible adhesive, grout and flexible sealant, so the finished surface drains freely without localised low points.
6. Conduct a final drainage test. Carry out another controlled water-flow test to confirm that water drains toward the outlet without significant ponding.

The report concluded that further assessment and appropriate rectification by a suitably qualified tiler and engineer are recommended. The aim is to prevent continued water pooling and reduce the risk of future water ingress or material deterioration.

The steps give the client an order of work to brief a tiler: test and measure first, and lift tiles only if inadequate falls are confirmed.

Water pooling on your deck or balcony?

Our inspection reports and certifications include general building inspections of a structure's condition, with a written report. Send us photos of the deck, the spot where the water collects and the ceiling below it. If the fix needs engineering input, structural design and consultation covers structural remedial and alteration design. You can request a no-obligation quote online or call 02 4326 9026.