How to stop balcony efflorescence rotting our timber deck below?

[StuartD]

The balcony above our apartment is seeping mineral salts onto our deck below. These salts are eating into the timber deck boards and they are rotting.

Other than getting our neighbour to apply some sort of water repellent sealer to their tiles/balcony. Is there anything we can do to the balcony from below ?

 

 

 

[EricL]

Hello @StuartD 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about stopping a leak from your neighbour's balcony.

It sounds like you're dealing with a challenging situation with mineral salts seeping onto your timber deck. In this particular situation, I suggest speaking to your neighbour in regards to the leak that is happening on the balcony. The best way to repair this is from above as any product placed under the balcony is subject to hydrostatic pressure.  In your case, where the moisture and mineral salts are coming from above, applying a membrane of any kind to the underside of the balcony could be less effective if hydrostatic pressure builds up. This pressure could cause the membrane to delaminate or fail over time.

There is a product you can place underneath the balcony called Sika® Damp Proofing Slurry, which is designed to withstand hydrostatic pressure. This product forms a crystalline structure within the concrete or masonry to block water penetration, making it suitable for areas exposed to persistent moisture. This is a special-order product and is subject to availability. 

But if you manage to convince your neighbour to waterproof their balcony, then there is no need to apply a sealer under your balcony.

Let me call on our experienced members @Dave-1 and @Nailbag for their recommendations.

If you have any other questions we can help with, please let us know.

Eric

[Dave-1]

Good Evening @StuartD 

Thats a tight situation to be in 😕 Hard call all around.

The hole in your neighbours upstairs balcony looks like a weap hole? I am not sure of the ruling about if they are acceptable or where acceptable when it was originally built. With the rotting of the deck in that one spot? It seems that it has been going on for a long length of time. How many spots across your balcony are there? Short term fix would be to have a mat/dish/potplant filled with rocks to dissapate the drip and also stop it always being wet. Long term It be looking into the ruling and also having a chat to body corporate for your complex as a first step.

BTW how old is your decking?

Dave

[StuartD]

Good evening @Dave-1  / @EricL 

Thank you for your prompt reply, truly appreciate it.

I have engaged the neighbour and they have agreed to help rectify the situation. From reading other Bunnings workshop questions, it is my understanding that the Crommelin Penetrating Sealer & Water Repellent is the recommended product to apply from above? Does this work on tiles? How much would be required for a roughly 12m squared area or does it only get applied to weep area? Would it also be advisable to also apply the Sika® Damp Proofing Slurry on the underside of the balcony?

We have in fact this week replaced the whole deck below, hence why this issue is concerning me. In the mean time I have placed a plastic paint drop sheet under the balcony.

There are two main weep areas, I have attached recent photos. One is on the front side of the balcony, should I also apply Crommelin Penetrating Sealer & Water Repellent to front facing side of the balcony too?

regards

Stuart

[EricL]

Hello @StuartD 

Please allow me to double check with Crommelin in regards to the compatibility of Crommelin 1L Natural Finish Penetrating Sealer And Water Repellent with grout and tiles. Another product you can use is the CPC 1L Shower Plug Sealant. It can be used over tiles and grout and has a coverage of 25 square meters. Once you've placed the sealer over the grout and tiles, it will technically need to be tested to make sure that the waterproofing is effective. Please make sure to give the sealer enough time to cure before testing it.

In regards to the Sika damp proofing, if the waterproofing works properly then there will be no need to apply the slurry. 

If you have any other questions we can help with, please let us know.

Eric 

[Dave-1]

Good Evening @StuartD 

Wise having a chat to the neighbours, much easier when there is communication going on

I would use the product @EricL has suggested (I havnt had this type of issue so dont know something I could recommend that I have used myself) 

Id also keep an eye on it after you have used the sealer. Just as a caution type deal.

Dave

[EricL]

Hello @StuartD 

Thank you for your patience. I've just been in contact with the Crommelin technical department, and they have confirmed that the Crommelin 1L Natural Finish Penetrating Sealer is not compatible with glazed or sealed tiles. The penetrating sealer can only be used on porous substrates such as masonry, concrete, natural stone, paving or timber surfaces. I therefore suggest using the CPC 1L Shower Plug Sealant.

If you need further assistance, please let us know.

Eric