How to direct water away from house?

Sameer

Hi -

I need a suggestion on whether I should install a strip drain on the left side of the house, in the side alley. The slope is adequate for water flow, but the home inspector told me when I bought the house that rainwater can pond or flow toward the house wall and then flow out. So, later I asked the plumber to install a strip drain to direct the water to the stormwater system. Weep holes are also obvious and cleaned, and there is no moisture inside the house. I am only concerned about whether I should order a premium strip drain, which is an expensive solution, in case of windy rain. Even if the strip drain is installed, water or moisture may still enter the weep holes during windy or monsoon rains. Alternatively, I could use Sikaflex to seal the gap between the concrete and the wall, leaving the weep holes open before and after applying Sikaflex. Or I could do nothing and leave it as is, since there are no signs of moisture, mold, etc., and water flows toward the side gate. I know the slope isn't ideal, but it's acceptable. I used the water hose to see where the water flows. Attached are pictures and a video for reference. I really appreciate any help you can provide.

Does anyone share the experience and guidance on that? 

MitchellMc

Welcome to the Bunnings Workshop community @Sameer. It's terrific to have you join us, and many thanks for your question about drainage.

It sounds as though you have a few possible paths forward, but the first thing to weigh up is the fact that you are not currently seeing any signs of moisture, mould or internal dampness. In many situations, if there are no symptoms, nothing urgently needs to be fixed. The slope you have described is at least allowing water to move away from the wall.

The concern I have is that the concrete is sitting right up at the base of the weep holes. That is not ideal, and in many cases it is not compliant because the weep holes should sit above a clear gap so moisture has a free point of escape. When the concrete surface is level with the lowest point of the weep holes, there is always a risk that during a heavy downpour the path will briefly hold water, the gradient will not keep up, and water will lap straight into the weep holes or be drawn into the brickwork. You may not see these events from inside because water can travel in the cavity and evaporate before it ever leaves a mark. The problem usually only shows up after prolonged or torrential rain.

Installing a strip drain is the most effective preventative measure. It gives you a guaranteed low point for the water to fall into, which helps compensate for the fact that the concrete has been poured too high. It also creates some separation between the slab surface and the brick line so the damp course is less likely to be overwhelmed. While it is an added cost, it is a sensible long-term fix and removes the risk of water reaching the weep holes during storms.

Using Sikaflex to seal the joint is not a good idea. It would bridge the tiny gap that currently exists and create a continuous surface for any water to sit against. That can encourage moisture to track into the wall rather than letting any small amount drain down the expansion joint. It also does nothing to change the fact that the concrete is still too high relative to the brickwork.

Given everything you have described, doing nothing does carry some risk during exceptional weather. Installing a strip drain is a proactive solution that helps offset the height of the concrete and reduces the likelihood of water entering the wall cavity in heavy rain. If you want to protect the home for the long term, the strip drain is the best option.

Let me tag @Nailbag to get his thoughts.

Please let me know if you have any questions.

Mitchell