What is salt damage?
Just like rust in steel, once salt damage starts, it’s hard to stop. The salt appears on walls, floors and ceilings as stains, solid build-ups, salt crystallisation and salt blisters at the surface.
What causes salt damage?
The most common causes of salt damage are rising damp, leaks, and water leaching through tile beds and render. Generally these issues are caused by bad workmanship or the use of inferior products, but with older properties (over 50 years old), often it’s simply a case of the damp course breaking down due to age.
What is airborne salt damage?
Since so many of Sydney’s buildings are close to the water, I see a lot of salt damage caused by airborne salt. This results in the surface of the stonework or brick fretting (flaking off).
The softer lime mortar used in external brickwork and stonework prior to the 1960s can also be substantially affected by salt deterioration.
How do I know if I have salt damage?
Commons symptoms of salt damage include bubbling plaster, ceiling stains, flaking paint, crumbling bricks or stonework, or visible leaching of salt on tiled areas.
How can I prevent salt damage?
As with all building problems, prevention is better than cure. For a new build, ensure that you use a reputable Sydney builder who uses top-notch materials.
For example: To avoid salts leaching from tile beds, it’s vital that your builder keeps the base material dry when laying tiles to stop any salt forming in the first place. I actually apply a second membrane over the tile screed to keep it dry. The tiles are then glued to the second membrane layer (using a compatible glue, of course).
With render, any builder worth his salt (!) knows that a salt-retardant render works best in external areas; combine this with a decent membrane paint system such as Dulux AcraTex and you’ll have a salt-free long-lasting finish.
With an existing property, stick to a strict maintenance schedule, ensuring render, grouting and tiles are all well looked after. A common result of salt leaching from tile beds is a build-up of salts in the drainage system. I have seen pipes completely blocked due to this. On exterior balconies, take off the drainage grates at regular intervals and clean out the salt deposits in the pipes below.
How can I fix salt damage?
Each type of salt damage requires a different fix, so it’s vital that you assess the cause of the damage before you attempt any remedial measures.
Warning: Painting over the damage is NOT a solution. Yes, you can cover up the stains or flaking with paint and hope it all goes away, but the dampness will just reappear at a later date.
Here’s a brief outline of some salt damage solutions:
- Rising damp: Unfortunately there’s no easy for fix for a rising damp issue. First, a new dampcourse must be installed either using sheet type such as Alcore or using an injection system.After this, the affected plaster (and at least another 300mm past the last sign of salt damage) must be removed and replaced. Be sure to use salt-retardant render mix, as it acts as a barrier preventing any more salt from reaching the brick surface. It’s critical that your plasterer doesn’t use any additives such as lime or plastermaster renderer’s clay. Using even a tiny amount will prevent it working and the salt will bleed through. (Most renderers are not aware of this!)
“Standard render mix won’t work – the salt damage will quickly reappear.”
- Leaks: With a leak, again, it’s a case of repairing the leak source, and then removing and replacing the affected render using salt-retardant render.
- Leaching: If you have salt leaching from tile beds, unfortunately this can be a big problem. It’s important to check that the tiles are sound, fully bedded (tap to make sure there is no hollow sound), expansion joints are in place, the tiled area has the correct fall (slope) and so on. If all this is ok, cleaning off the salt and sealing might work.
“‘Read the Fine Print.’ The so-called 10- or 12-year warranty the tile-sealing companies provide is void if there is movement or there are other issues below the tiles.”
- Stonework: If you have salt damage to your exterior stonework, there are several products on the market that aim to remove as much salt as possible. (Several applications are required.) A stonemason will then need to cut away the damaged surface and re-dress the stone.
- Painted brick: This can cause a real problem and the only 100% fix is to grind off the paint using special tools (make sure there is no lead in the paint) and re-render with a coat of salt-retardant render at least 10 mm thick.
If you’d like to learn more about salt damage, check out these links and resources:
Over to you
Have you had an issue with salt damage on your property? What was the cause and how did you fix it? We’d love to hear so please comment below:
Got a question?
If you have a problem with salt damage on your property, give Peter a call on 0412 355 887, or contact us for an obligation-free quote..