Leaking Balcony Repairs: Waterproofing & Leak Detection Guide
Why balconies leak
The most common reason balconies leak is membrane failure. Improper application. Incorrect product selection. We often see membrane failure with incorrect thickness. Applied in a way that allows it to perform correctly. Not enough curing time – failure occurs.
If the balcony is left to deteriorate for a long period, it can lead to major problems, such as:
- Decay and rot spreading down external walls
- Discolouration on walls or ceilings
- Electrical issues
- Structural failure, including collapsing areas
What to check when locating the leak
It can be challenging to determine where balcony leaks are coming from. Here are practical hints to look for:
- Is the balcony drain blocked, or has there been a plumbing failure nearby?
- Has the joinery of the door leading out to the deck failed?
- Is the leak visible on the underside of the balcony?
- Has tile grouting putrefied, allowing water through a join in the waterproofing membrane under the tiles?
- Is water running back across the joists under the deck from the outside edge?
- Is the base of the cladding touching the deck? Water can potentially back up into the bottom plate of the timber wall frame.
- Has the waterproofing membrane been correctly installed underneath the door frame to prevent wind-driven rain from getting underneath the door and down into the wall below?
- Is the water coming down from the roof and running down the external walls?
- Are there any cracks in the plaster cladding around the balcony or the external walls nearby?
- Is the tiled area sealed correctly?
If you can tick any of these, it’s time to get the cause identified properly.
The correct repair and waterproofing approach
The best way to repair and waterproof a leaking balcony is with a sandwich membrane system:
- Two coats of membrane on the surface of the substrate
- Then the screed
- Followed by another two coats of membrane
This system is especially secure because water has to pass through two membrane layers to fail.
To install this correctly, there must be enough room at doorways and openings to accommodate the added thickness of the screed and tiles beneath those areas. A true sandwich membrane build-up isn’t possible due to access or height constraints. Effective solutions can be recommended using heavier-duty membranes.

Leaking Balcony Repairs
Get a professional assessment and quotation
A properly trained team can assess the situation, identify the source of the leak, and recommend a solution designed to protect your structure—and help prevent the same issue returning. The goal is to avoid unnecessary cost while not taking risks with your property.
For the professional contractor of the DYI a free solution, onsite assessment in some cases, call or submit a quotation request.
Review the damage, locate the leak(s), and provide clear options for rectifying the problem.
Quality of the material purchased is guaranteed for Leaking Balcony Repairs
Repairs and waterproofing should be carried out with proven materials and workmanship standards, because balcony waterproofing is only as reliable as the system installation.
Contact the team today to get your leaking balcony investigated and repaired.
Leaking Balcony Repairs
The solution is right here for your leaking balcony repairs.
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