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What drain system do I need: Trench or French drain?

Hello,

After replacing barge boards at the base of my house as they were rotten through water damage, mainly from the rain, I want to install a drainage system to help flow water away from the boards. I have a nice slope to work with but just wondering should I use a French drain (dug below the surface) or a surface drain system like a channel drain or trench drain. I intend to have gravel going up to the barge boards, not a garden bed as previous as I think this contributed to the water damage. There is a large bush at the end of the house that concerns me with its roots potentially finding its way into a French drain system, so was thinking a surface drain system would be better? What are your thoughts? I will enclose pics.

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Comments

Dave-1

Good afternoon @KeithNeely

Thats a nice old school garden edge you have and that goes up against having those barge boards stay in one piece.

How high is the inside of your garden comapred to the stonework? I am hoping its built up over time and mulch ect has been thrown on top which caused it to stay against theboards and caused them to rot. Would it be possible to reduce the height of the garden material in the garden bed to be below the barge boards?

I once was told by a plumber that any tree will seek out drains as they have good stuff in them let alone water. The roots will travel a LONG way and I believe this now after replacing my drains.

Instead of a dish drain and french drain could you put a back edge along the garden bed to keep the soil/mulch off the boards?

If you really want a drain Ilike the sound of a dish drain as French drains will still have water on top for at least a little before it soaks in.

Dave

KeithNeely

Hi Dave, thanks for replying promptly. I'm actually going to do away with any garden between rock wall and barge boards and have the garden bed in front of the rock wall instead. I want to lay a tasteful gravel mix in the space between barge board and rock wall, but the eve overhang is not enough to stop rain hitting the barge boards and pooling in the area between boards and rock wall. To me, it's a question of should I have an exposed channel/trench drain or dig deeper for a French system, which will probably need to be lined to stop roots? Or something else?

Neil

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/30119#Comment_30119

Afternoon @KeithNeely

Ahhh Bingo! Then I will change my recomendation 🙂 If you are going to lay a tasteful gravel mix between the rock edge and the barge board then a French Drain for sure. Nothing will be above it bar the gravel so it will really drain well. I was urprised when I did some stormwater pipe work and lined the trench with gravel at how well the gravel works just by itself in draining the surrounding area. I wouldnt go too deep (as long as the pipe is covered by an inch or two at least) as all the gravel would feed towards the french drain. Roots into will take a long time and if the drain is shallow you can pull it up if you need to.

Alternativly you could have a couple of inspection points along the pipe so you can get into the pipe to easily clean it out or a plumber with their high pressure waterjet cutters.

Do you know where the exit for the french drain or dish drain will be?

Dave

KeithNeely

https://www.workshop.bunnings.com.au/discussion/comment/77533#Comment_77533

Dave,

I will take your recommendation, it was my first thought but good to get confirmation.

The outlet will be at the very end through a hole or removed stone in the wall, then flowing down the driveway into stormwater.

Do you think I should line the trench with pond liner or will just gravel be sufficient? I plan to use a socked aggie pipe for the actual drain.

Neil

EricL

https://www.workshop.bunnings.com.au/discussion/comment/102793#Comment_102793

Hello @KeithNeely

Welcome to the Bunnings Workshop community. It's wonderful to have you join us, and thank you for sharing your question about what drain system to use.

It's great that you've received fantastic advice from @Dave-1. Putting in a pond liner will block the roots from immediately seeking out the pooled water. However, it will also act as a channel and direct the water to the lowest point in the drain. It will also prevent water from passing through and getting absorbed in the soil.

Personally, I'm a big fan of surface drain systems, easy to clean and blockages are easily removed. I suppose the only drawback to it is that you can easily see where the debris gathers when water flows down the drain, and it leaves the debris on the surface.

My other suggestion is to use Everhard 3m EasyDRAIN Polymer Grate And Prejoined Channel. This combines the ease of a surface drain system and redirects water towards the area where you want it to drain.

I've placed an image below to give you an idea of how it can be installed.

If you have any other questions we can help with, please let us know.

Eric

KeithNeely

https://www.workshop.bunnings.com.au/discussion/comment/118406#Comment_118406

Thanks Eric, I guess from the knowledgeable responses I’ve received, either option would work! I must say it’s great you guys have taken the time to respond and provide usable options, many thanks! Cheers

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/102793#Comment_102793

Morning @KeithNeely

I have installed a socked agg pipe under some pavers with gravel next to my garage and seriously I am impressed at how that area drains now. It was once a pool and now it dries so fast. I didnt use anything other then gravel and the socked pipe. I have it leading to my stormwater pipes.

I do like @EricL 's suggestion 🙂 It was something I hadnt thought of and would work nicely and take care of root issues down the track!

Dave

KeithNeely

https://www.workshop.bunnings.com.au/discussion/comment/118409#Comment_118409

Morning,

There was one thing concerning me about the channel system, they are technically used for moving surface water, but if they sit on a bed of gravel the water would drain through the gravel before the channel drain takes effect. They seem more effective on more solid surfaces like paving or driveways where the water rolls off the hard surface into the channel drain? Is this logical or am I overthinking this? Cheers N

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/127626#Comment_127626

@KeithNeely

It depends on how much water you get and how it travels, if you had the time and resources then both could be an idea to capture stormwater instances and also down the hill creep of water? Lots more effort required tho.

I have had a huge ampount of water come down in a short time and that has been factored in to the way I have made paths and channeled my gardens. Gravel lined drains for the subsurface water and channels for the above ground stuff. Now I expect the stormwater events rarely so its debatable to have them but hey its an experiment. 🙂

So the question is, how much general rain and how much storm instances do you have?

Dave

KeithNeely

https://www.workshop.bunnings.com.au/discussion/comment/133670#Comment_133670

The water I get is never a torrent as the bed is partially covered by the eves. The natural slope of the garden directs most of it, but historically it has found its way to the stumps and barge boards so the main aim is to direct the water away and into a channel or drain as there never was one originally. I like both options and happy to do either, just wondering which is the more effective? I’m thinking the French drain may be more work in the digging? Not sure if to go 100mm or 65mm pipe? Cheers N

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/137413#Comment_137413

Afternoon @KeithNeely

100mm pipe for sure, the extra volume in area makes me sleep better at night... lol Love stormwater but hate the issues it causes. Either way will require digging to some degree. Since you are the one who gets to dig 🙂 It probarly will come down on how much effort and dollars you want to spend.

Here is the project where I used the ag pipe with sleeve and also a grill to capture the extra runoff if there was an extreme storm inundation .

Fixing water ingress issues in garage

Would like to see the project and hear how it helps when you do it 🙂

Dave

EricL

https://www.workshop.bunnings.com.au/discussion/comment/137413#Comment_137413

Hi @KeithNeely

I totally understand your worry on the flow of water. I've re-drawn the channel drain so that you'll have a better idea of how it works. Should your lawn area get fully soaked, any excess water will begin to overflow towards the channel. You'll see that the concrete has a little kickstand at the end to protect your barge boards.

If you have any other questions we can help with, please let us know.

Eric

keith drain2.jpg

KeithNeely

https://www.workshop.bunnings.com.au/discussion/comment/139978#Comment_139978

Thanks Eric, your drawing has made it very clear now, cheers Neil

KeithNeely

https://www.workshop.bunnings.com.au/discussion/comment/139977#Comment_139977

Great work and nicely documented. Lucky you didn’t have to contend with large tree roots as well!

Neil

Dave-1

https://www.workshop.bunnings.com.au/discussion/comment/141779#Comment_141779

@KeithNeely

hahahahah and some more insane laughter 🙂 I hit a bunch of gum tree roots up the side of the house on stage 1 of stormwater rectification 🙂 And yes they were seeking out the old crappy fractured stormwater pipes. (And so many stones! I felt like a quarry!)

Dave

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