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How to improve drainage on side of house?

Hi there. I am redoing the 'dead side' of our house with a particular emphasis on improving drainage. The area doesn't get a lot of sun in Winter and we've had some dampness issues down there to do with high soil levels and poor surface drainage. All downpipes are connected to an existing soak well the issue I want to rectify is that when it buckets down we get water coming under the fence and down the limestone wall which pooled on the old concrete. I've dug out down to foundation level and am redoing the entire side. I was looking at two options to handle the wall overflow, either a surface drain along the limestone connected into the existing stormwater system, or alternatively using agpipe and aggregate to do a French drain style connected to the stormwater. I will be using paving against the house with a nice runoff angle to the new drain or aggregate, also has eaves the full length. Soil is very sandy northern Perth style, so I think if I can get the water off the surface it will drain quick. Any advice on surface grate or French drain?

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JacobZ

Hi @Johhno16,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

Based on what you have described, the issue sounds like surface water flow rather than groundwater pressure. When heavy rain hits, water is physically moving under the fence and along the limestone wall before it has a chance to soak into the sandy soil. In that situation, the priority is to intercept the water immediately at surface level before it can spread and pool.

A surface channel drain installed along the base of the limestone wall and connected into your existing stormwater system is likely going to be the most effective solution. It will capture sheet flow as soon as it enters the area, which is far more efficient during heavy downpours than relying on water filtering down through aggregate into an ag pipe. French drains are better suited to subsurface seepage, whereas your problem is fast moving runoff. A grated channel also gives you predictable performance and is easier to maintain, especially in sandy soil where fine material can migrate over time.

As long as the channel is set slightly below paving level and falls correctly into the stormwater system, it should resolve the overflow issue effectively.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob

Johhno16

Thanks @JacobZ. That confirms my approach, always like to check these with someone else.

Appreciate the reply, I'll head to Bunnings for the gear over the next couple weeks.

Johhno16

@JacobZ sorry two more questions.

With the chanel drains do you need to angle them down to flow the water or are the internals already set for this. Basically do you install it level or on a slight slope to the stormwater connection?

Secondly, if paving up to them would you concrete the drain in place or just rest it in sand?

JacobZ

Hi @Johhno16,

Channel drains are perfectly straight, so you have to set the fall in the base material to ensure water flows to the drainage point. It is recommended that for every metre of run, the channel falls by 1 centimetre.

They are also typically set in place with concrete to ensure they do not shift and they maintain that fall along their full length. Installation instructions for our channel drains can be found here - EasyDRAIN Instructions.

Have a read and let me know if you have any further questions.

Jacob

EricL

Hello @Johhno16

Here are some rendered images using AI to give you a bit of an idea and some inspiration of what it can look like. One with cement and one with pavers.

Eric

Johhno16

Thanks @EricL.

Is it deliberate that the drain is set off the wall a little? I was going to but it right up to the wall?

EricL

Hello @Johhno16

Yes, the set off is deliberate, it is technically in accordance with the suggested installation process of the EasyDRAIN product.

Here is a handy step-by-step guide: EVERHARD EasyDRAIN Installation Instruction

If you need further assistance, please let us know.

Eric

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