Balcony Waterproofing

Balcony Waterproofing

This guide will show you everything you need to know about balcony waterproofing.

Sound good? Let’s dive right in…


If you have a balcony situated above other living areas in your house, waterproofing can save you from a multitude of problems.

Rain run-off from balconies is a very common issue in new and existing builds and if the waterproofing is not done to standard, using the correct products extensive damage can occur.

If the waterproofing membrane has failed, and there is already signs of water ingress, there are three courses of action that you will need to consider, as to prevent extensive damage from occurring that can lead to very expensive repairs.

Option 1: Applying clear coat or siloxane sealant products to the tiles and grout of the tiled balcony. This will however only work if tiles are in good condition or if the underlying substrate is in good and sound condition. Where there's obvious damage such as erosion, cracks or extensive structural timber rot, applying over-tile products should be avoided and the damages repaired.

Option 2: Epoxy grout or epoxy injection is another option to stop water leaks without removing tiles. It is more effective than clear sealers and costs on average twice that of the clear sealers.

Option 3: Remove the tiles and re-apply waterproofing. If you remove the tiles and sand cement bedding you will need to assess any structural damage and if present will need to repair this before re-applying waterproofing. You will need to contact a professional waterproofing contractor to ensure the job is done correctly and obtain a guarantee. Sometimes other contractors such as carpenters or plumbers will need to be engaged to carry out these repairs before the waterproofing can be carried out.


The most important factor in balcony waterproofing is the drainage system, the balcony needs to have a fall to the edges or to the drain to ensure water is always moving away from the living areas.

Inspect balconies to assess signs of damage or failure, including

  • Missing or cracked grout
  • Popped tiles or damaged sand cement bedding
  • Insufficient drainage
  • Signs of efflorescence
  • Damage or cracks in the substrate
  • Missing or failed waterproof membrane
  • Excessive movement
  • Water damage from underneath

Efflorescence is now considered a building defect!

Efflorescence mentioned in the list above refers to salts and minerals that are present in concrete substrates or sand cement beddings. Once wet, the salts and minerals wick up and through grout lines and between tiles giving a white to yellow appearance. The buildup can become quiet severe and begin to engulf whole tiles and cause irreversible damage to floor finishes. Waterproofing on-top of screeds or sand cement beddings can eliminate efflorescence as can admixtures used by tilers in the sand cement mixture.

It is important to waterproof your balcony correctly during the construction stage.

A good contractor will ensure the correct membranes are used and that they are applied to the manufacturers specifications.

It is said that prevention is better than cure. In this case, repairing an already damaged balcony is more expensive than doing it initially.


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