How to repair balcony timber edge board separating from base?

Question

Hi everyone,

I'm looking for advice on how to repair this section of my balcony.

I just bought the house 8 months ago. I've noticed that the horizontal timber board along the edge of the balcony has separated from the structure below it, leaving a gap of around 5–10 mm in some areas. The old sealant has cracked and pulled away, and there are brown water stains running down from the gap. Water has been leaked to the living room.

I've attached several photos showing:

* The gap between the upper and lower sections.
* Failed/cracked sealant.
* Water staining.
* Some areas that appear to have deteriorated or possibly rotted.

I'm not sure what this component is called, but it appears to be a timber board attached to the balcony edge rather than structural framing. Before I start removing old sealant and filling gaps, I'd like to understand:

* Does this look like water damage and timber rot, or could it simply be movement/shrinkage?
* Should I remove the existing sealant and inspect behind the board?
* Is this something that can be repaired with filler/sealant and repainting, or does the timber likely need replacing?
* Are there any signs that suggest a more serious structural issue?

The balcony is exposed to weather and receives direct rain.

Any advice on the best repair approach would be appreciated.

Nailbag · Answer

Hi @leslie.ng143

Unfortunately, I'm in the same camp as @MitchellMc in that the water ingress into the living space is a clear indication of more than just a simple repair project.

A few of those photos also indicate that the floor substrate isn't a masonry one as the edges are splitting open. So possibly a ply product that along with the waterproof seal are compromised.

I would recommend that you get a couple of quotes from specialist companies. Put into Google "Leaking Balcony Repairs Near Me". This will bring up companies within your area that can help. And as there is a living space below, please take seriously the recommendations by these companies. As @MitchellMc mentioned, leaving the repairs to long or taking shortcuts will only result in more significant damages and costs when it comes to this type of issue.

Please keep us in the loop of your progress.

Nailbag

MitchellMc · Answer

Welcome to the Bunnings Workshop community @leslie.ng143. It's terrific to have you join us and many thanks for your question on balconies.

I can see the balcony is located directly above the living room, I think the primary issue is likely a failure of the waterproofing system rather than just a failed bead of sealant.

The board itself appears to have been exposed to moisture for some time, and the staining and separation suggest water has been getting behind the coating. It's also possible that the sheeting used for the deck surface is not suitable for long-term exposure to the weather, or that it has deteriorated to the point where it is no longer providing a sound substrate for the waterproofing membrane.

Given that water is now entering the living room below, I'd recommend speaking with a builder who has experience with waterproofed balconies. They should be able to determine whether the damaged area can be cut out and repaired locally, or whether the more appropriate long-term solution would be to re-sheet the entire deck and install a new waterproofing system.

Unfortunately, once water has made its way through a balcony assembly, patch repairs are not always successful, particularly if there is hidden damage beneath the surface. A thorough assessment now could save significant repair costs down the track.

Let me tag @Nailbag to see if he has any thoughts.

Please let me know if you have any questions.

Mitchell