Green Building Forum - Perimeter Drainage Options Tue, 19 Dec 2023 04:41:31 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=269964#Comment_269964 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=269964#Comment_269964 Wed, 22 Aug 2018 14:09:38 +0100 Doubting_Thomas
Initial plan was a slot/channel drain with localised ‘shoes’ connecting into it at each downpipe. Visually though, the preference would be a simple French drain, geotextile lining with a perforated pipe coil below gravel. The weakness I see with the latter approach is ‘reverse drainage’ whereby we end up with the rainwater off our roof saturating our foundations before it percolates down into the pipe...

What I’m wondering now is if there’s anything out there that could do both. Some form of channel with grating that’s then buried under gravel, so water can either trickle down off the facade or be directed down off the roof.

Anyone got any ideas/product links or am I over thinking this?]]>
Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=269966#Comment_269966 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=269966#Comment_269966 Wed, 22 Aug 2018 16:31:11 +0100 Peter_in_Hungary
If you were worried about water seeping out to the foundations then line the french drain with impermeable plastic sheet which will direct everything to the attenuation storage. I would put geotex on top of the french drain (and then put a couple of inches of shingle on that) to keep stuff from being washed into the french drain over time.

I would connect each down pipe directly to the french drain,either above ground to the top of the drain or below ground above the pipe. Above ground would be more flexible in the maximum down pour that could be catered for.]]>
Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=269967#Comment_269967 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=269967#Comment_269967 Wed, 22 Aug 2018 16:41:44 +0100 gyrogear
The fall connects directly into the surface drain (vertically, no shoe) - for this, a cut-out is required in the cover...


P.S. Watch out for slotted covers in front of building entrances etc. as they can catch out stick- or crutch-users...

gg]]>
Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=269969#Comment_269969 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=269969#Comment_269969 Wed, 22 Aug 2018 18:49:27 +0100 djh Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=269974#Comment_269974 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=269974#Comment_269974 Thu, 23 Aug 2018 08:08:55 +0100 Doubting_Thomas Posted By: djhWhy not just connect each downpipe to a drain pipe that goes to the attenuation crates? Multiple downpipes can share a single drain if convenient and sized properly. Then have a separate French drain if desired.

It just seems like doubling up - the attenuation is a block of crates adjacent to the house (imagine an exclamation mark on its side, our house is the dash and the crates are the dot). In other words the direction and location the roof draining pipes would run around the house is the same as the French drain so they’d naturally sit above each other anyway.

I think Peter’s solution is probably the most workable but I don’t know if the flow rates along a perforated pipe would be dramatically different to the channel drain that our drainage design was based on.]]>
Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=269990#Comment_269990 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=269990#Comment_269990 Thu, 23 Aug 2018 16:29:23 +0100 Peter_in_Hungary Posted By: Doubting_ThomasI don’t know if the flow rates along a perforated pipe would be dramatically different to the channel drain that our drainage design was based on.
When I have seen the out flow of french drains with perforated pipe at the base there has been more water coming out of the french drain than the pipe ! A perforated pipe in a french drain is specified (mostly) to give the builders and planners a warm feeling. If the drain is properly constructed then the pipe is largely superfluous but having said that I always chuck one in as its cheap insurance.]]>
Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270107#Comment_270107 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270107#Comment_270107 Tue, 04 Sep 2018 19:34:15 +0100 CWatters
http://www.pavingexpert.com/drain07.htm

Not used them myself. We went for regular linear drains for the patio. Where I built a French drain around a shed I have problems with leaves rotting on top of the gravel causing weeds and grass to grow. Looks untidy and hard to mow over due to the stones.]]>
Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270108#Comment_270108 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270108#Comment_270108 Tue, 04 Sep 2018 19:42:13 +0100 CWatters
You can get half perforated pipe. It can be installed with perforated side up or down depending on your objectives. Perforated side up seems to match what you are asking about.

This is 150mm diameter. Not sure how to mate it with say 80mm down pipes.

https://www.drainagesuperstore.co.uk/product/6m-twinwall-half-perforated-drain-pipe-150mm.html]]>
Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270109#Comment_270109 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270109#Comment_270109 Tue, 04 Sep 2018 19:43:59 +0100 CWatters
https://www.draindepot.co.uk/110mm-x-3m-single-socket-half-perforated-soakaway-pipe.html]]>
Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270110#Comment_270110 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270110#Comment_270110 Tue, 04 Sep 2018 21:18:17 +0100 Doubting_Thomas
For anyone interested, I also found this: https://www.drainage-channel.co.uk/category-6090/DC975.html
which appears to be a linear channel with gravel tray on the lid. In theory adding a few downpipe connectors would then achieve the setup I was proposing above.

However they weren't too keen on the idea of sticking roof runoff into this channel too - they were concerned over the chances of it overfilling and flooding since, I guess, it's designed to only take percolated surface water. Personally I think the overflow is unlikely in our situation, but either way they're not exactly the cheapest solution...]]>
Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270113#Comment_270113 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270113#Comment_270113 Tue, 04 Sep 2018 23:17:59 +0100 goodevans
The French drain can be connected to the storage crate via the perforated pipe(s) and the granular fill of the French drain which should be contiguous with the granular fill surrounding the crate (which will be covered by geo-membrane to prevent the fill getting into the crate). In this way water in the granular fill and water in the perforated pipe go into the store.]]>
Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270116#Comment_270116 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270116#Comment_270116 Wed, 05 Sep 2018 11:46:40 +0100 djh Posted By: goodevansI plan to have my downpipes finish above ground level with a shoe and discharge into a gravel strip/French drain that surrounds the house.
That's what I've done with a view to easier maintenance (unblocking of downpipes etc if ever required). Do check the arrangements with your BCO first. Mine tooka little bit of persuading that it was OK.]]>
Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270120#Comment_270120 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270120#Comment_270120 Wed, 05 Sep 2018 13:58:55 +0100 goodevans Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270122#Comment_270122 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270122#Comment_270122 Wed, 05 Sep 2018 17:32:38 +0100 djh Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270123#Comment_270123 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270123#Comment_270123 Wed, 05 Sep 2018 17:37:35 +0100 Nick Parsons ]]> Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270133#Comment_270133 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270133#Comment_270133 Thu, 06 Sep 2018 15:40:31 +0100 gyrogear Posted By: goodevansA little easier for me as I have piles so there is little need to move the water away from the foundations.

this is probably a good argument for annular retention...

gg]]>
Perimeter Drainage Options http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270136#Comment_270136 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15844&Focus=270136#Comment_270136 Fri, 07 Sep 2018 10:40:04 +0100 CWatters
Think I'd want the twin wall stuff as a minimum.]]>