How to improve drainage?

mschipper

Hi All,

I had some new carpet installed the other week and the installer found water has gotten into my property (see images). The cause looks to be that the previous owner installed pavers at the damp course level outside the bedrooms.

I have removed the pavers (see image) which a can already see should fix my water ingress issue. I still intend to dig down/reduce the level another 20-30mm, then lay 10cm or so of quarry gravel.

The question I have is what should I do for drainage? The soil has a lot of clay and doesn't absorb water well. There is already 90mm stormwater running along the path (as you can see in the image). Should I add more drains along the stormwater length or install some other drainage system (french drain, etc)? Should the drains be under the gravel or level with the top of it? 

Any suggestions would be appreciated.

MitchellMc

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

After it rains, is there much standing water on the soil's surface? If so, adding a drainage channel would be a good option. However, if you are adding gravel to the area, then the water will fall through it, and socked agline placed on or directly below the soil level and covered by the gravel would be a better solution. 

Your soil level is already below the level of the concrete slab, and the pavers do not look like they extended much above the slab. I think removing 100mm of the soil and replacing it with gravel would do the trick, and I certainly wouldn't advise you to remove 300mm if it starts to undermine the retaining walls. Speaking of retaining walls, is there adequate drainage installed for them, and does much of the water come from the elevated property?

Here are a couple of helpful guides: How to fix a muddy lawn and How to install garden drainage.

Please let me know if you have any questions.

Mitchell