What is a Spoon Drain in residential construction and why do structural engineers specify them.

A spoon drain is used to collect and carry stormwater at ground level before it soaks into the ground.
At Cornell Engineers, we specify a spoon drain to protect a house from slab heave. When surface water is able to soak into the ground it could be a problem so we use a spoon drain to take the surface water away and discharge downstream of the house we are trying to protect.
A spoon drain is different from an agricultural drain because agricultural drains are used to collect water that has already soaked into the ground.
This is a Cornell Engineers - Structural Why Files video. Check out our other videos on why structural engineers do what they do.
Also, you might like this page about improving drainage on sloping blocks:
cornellenginee...
What is a spoon drain?
How do you make a spoon drain?
What is surface drainage?

[@malyboyle223]

Thank you so much. This is just what I need and I think it'll move a lot of water away quicker than other grated drains available....plus I can do it myself😊 cheers

[@CornellEngineers]

Thanks for the feedback. These are all excellent reasons for using a spoon drain over a grated drain. Matt

[@wh9247]

Hello, Thank you so much for this video. I’ve learnt a lot from it and others. We had a structural engineer come out and inspect our house, which has helped identify issues with water getting in underneath in ways we wouldn’t have thought of. He suggested an agi drain in our backyard (our house slopes down to the street from top left to bottom right). Or possibly a swale. I don’t think either option is perfect as we’re on very reactive clay soil which cracks in summer and swells in rain. So water doesn’t travel easily under surface and a swale is about moving water slowly. I think the engineer really meant a spoon drain. We don’t want a big concrete drain right across our backyard near our house. Would digging out a natural spoon drain to divert water around our house (we have a lot of room on one side) work? Is there an easy way to work out how much water is being diverted? Thank you for your time.

[@CornellEngineers]

The idea of keeping surface water on the surface and handling it with a natural spoon drain is a great way of managing the bulk of the runoff coming down the hill. A swale is about moving water slowly but we too have used the term to describe the land formation required to improve stormwater protection of a building. So, yes, it would look like a spoon drain except formed in the ground. it also will help that as part of this landscaping work the ground will be graded away from your dwelling which is always a good idea. As far as working how much water you have to handle, you can get scientific about it which is complicated, or just try improving things and watching where water overflows when it rains and then improve the width of the drain in that area. Best of luck!

[@wh9247]

@@CornellEngineers Thank you so much. We would’ve used you guys for sure but we’re not in Queensland.

[@johnandrewbalandra9298]

Do you have a website? I want to get in touch and seek help for the retaining wall I’m building around my house.

[@CornellEngineers]

Hi John. We sure do. Our website is at cornellengineers.com.au/

[@nataliecrocker4963]

What if your house block is lower than the road and there is no storm water drain

[@Matthew_Cornell_Photography]

Hi Natalie It depends on a few things. How old is your house? Where is your legal point of stormwater discharge? Rules vary with different areas. Only very rarely do councils ask you to make water flow uphill. Matt

[@bbasian]

Just got a question that bothers us a lot. Appreicate any thoughts you could share on this: The backyard area next to my house foundation is paver , and then sitting further out from the paver is yard. My plumber recommended us to install a spoon drain between the paver and the yard. I feel confused. The material underneath the paver is soil. And the yard ground is soil too. So, what is the point to install a spoon drain between two sides of soil? Wont the rainwater soak into soil and the render spoon drain to be useless? Or we should install an AG drain? Location: North Brisbane

[@CornellEngineers]

Flat pavers, rock pathways gardens and flat yards are all equally likely to allow water to soak into the ground. The effect you should be trying to achieve is to drain water away from the house and let it soak into the yard downstream of the house. So on the upstream (higher) side of the house grade the ground away to a spoon drain which discharges the water beside and away from the house. The downstream side of the house is not so much of a worry so long as water (again) drains away from the house. For people who really like pavers and won't replace them with concrete paths, we have recommended plastic under the pavers falling to a grated drain or ag drain away from the house. Ag drains are still are leat preferred option when trying to move surface water. it is better to move surface water at the ground surface and collect water already in the ground with ag drains. Hope this helps.

[@bbasian]

@@CornellEngineers Totally agree, we have considered concrete too. But there is a drainage pipe just next to the house foundation. If we concrete over the drainage pipe, then it could complicate the matter for plumbers? The plumber inspected our underground pvc pipes and replaced one broken/ collapsed section, and said others are fine now , but because of many rocks under ground, other section "could" collapse in future and need replacement. So on one hand, concrete around the house seems the best option for fending off rainwater. On other hand, concrete over the drainage pipe, will add the cost to our future pipe replacement. So we wonder if we could ask the concreter to add a long narrow "manhole"/ cover to allow plumber can open the shaft and replace the pipe easily? Much appreciated for any thoughts on this dilemma

[@CornellEngineers]

@@bbasian If you have the money have the pipes re-done now and maybe even sleeved so that the water pipe is inside another pipe so they can be replaced again later if needed. It's getting complicated so you'll probably need a formal inspection and advice to resolve your dilemma. Best of luck. Matt Cornell

[@bbasian]

@@CornellEngineers Got two follow up questions: 1) when u mentioned plastic, what kind of plastic are u referring to? I mean, when we talk to the paving contractor, just ask them to put an impermeable plastic sheet under paver , so they will know what to do? 2) Could you email your service fee ( for site inspection of a 3br house in North Brisbane) to my email: [e-mail]. Love how you are willing to educate your youtube channel audience about some basic knowledge. Thanks Cornell!

[@CornellEngineers]

@@bbasian plastic sheet = 0.2mm heavy-duty polyethylene membrane. It's standard under concrete slabs and available from Bunnings (and other hardware suppliers).