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The exterior render around our hose keeps bubbling and breaking up. We have had it repaired several times but it keeps happening. The chap who has repaired it advised us to use brown vinegar to wash away the powder that comes through the paint (efflorescence?). We had a quote to repair it at $10,000 with no guarantee it would work. We don't believe there is a damp course - is this possible? There is no interior damp. We are on a hill on clay soil. Any permanent repair ideas??
Hello @JulieW
I totally agree with my colleague's assessment. Water or moisture is getting trapped behind your wall, notice that the damage only appears in a very specific spot on your wall. Not only does it appear in one spot, but in a straight line and then it flows downwards as this type of damage often tends to do.
I suspect that behind your wall a small amount of water is finding its way toward the unsealed side of the wall. It then enters the cement substrate where it tries to find a way out. Due to the surrounding clay soil in your area, the water instead of being absorbed into the soil is being diverted towards the wall. An unforeseen series of events has led to this particular set of circumstances.
What are the options for repairing the wall? Cutting into your exterior wall is possible but not the best way to repair the wall. Cutting from inside the house is messy and will cost a fair bit. You'll be able to waterproof the inside of the wall, but the source of the water must be tracked and diverted away from your wall. You can also cut out a ventilation window in the wall to allow the water to evaporate. But there is no guarantee that it will be able to get rid of all the water.
One other option is to put a sealer on the bare concrete wall. I recommend using Dunlop Damp Proof Waterproofing, this product will have to be specially ordered at the special orders desk in your local store. It prevents rising dampness, efflorescence, and negative hydrostatic pressure. The best part is that it can be painted over once you have a thick enough coat placed on the surface.
Please keep us updated with your progress, we look forward to seeing your wall sealed and repaired.
If you need further assistance, please let us know.
Eric
