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I have what looks to be a big problem with water flooding in my crawl space after big bouts of rain which leaves the water sitting against highlighted yellow brick wall leaving a must smell in the living space behind it. On the other side of the blue highlighted wall the side of the house consisting of concrete and a concrete/brick set of stairs. Am I right it saying the water is seeping in under the external stairs section of brick work? I have a steep backyard that slopes into the house. On both sides if the house it is the same (concrete and concrete/brick and stairs. How do I go about fixing this? Is better backyard drainage the solution or is there more that needs to be done?
Welcome to the Bunnings Workshop community @ashleyj. It's wonderful to have you join us, and many thanks for your question about water drainage.
The water is finding the easiest route into your crawl space, quite possibly through a junction where the exterior concrete stairs meet the brick wall. Another likely cause is subsoil water or groundwater moving through the soil beneath your house and coming out along the slope, which can be hard to fully block with surface solutions alone.
In this kind of situation, the best approach is to get in touch with a drainage specialist who can assess the site and install proper drainage systems. This usually involves creating an active way for water to be directed away from the crawl space instead of just allowing it to pool and cause dampness and smells.
One effective solution is to install drainage pipes or a French drain around the affected area to collect and channel water away. Additionally, you might consider installing a sump pit in the crawl space where water collects, paired with an automatic pump that activates to remove water during heavy rain events. This system helps keep your crawl space dry and prevents ongoing moisture problems.
Improving backyard drainage by regrading or adding surface drains can help reduce the volume of water getting near your house, but because of the slope and the subsoil water, it’s likely that a more comprehensive drainage setup will be needed.
However, looking at the wall behind the stairs, there is a great deal of moisture leaking down from the stairs; you can actually see their outline, the algae building and watermarks on the wall. I would suggest taking a flathead screw driver and scraping out any debris between the wall on the outside and the stair treads and risers. Use Sikaflex 11FC to fill the gap between the stairs and the wall. It needs to be a continuous bead of filler across the top of the stairs, down the face of them and across the next stair, right down to the bottom. I feel this will reduce much of the water ingress.
Please let me know if you have any questions.
Mitchell
