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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthordelprado
    • CommentTimeOct 17th 2017
    Hi All

    Does anyone know anything about them as an alternative to a soakaway? Approved document H doesnt not mention them and when I asked my local building control they advised to speak to my local water company.

    There is therefore no official guidance as to whether or not I can just run my gutter (1 of 3) into my garden (which is my plan)

    • CommentTimeOct 17th 2017
    Posted By: delpradoThere is therefore no official guidance as to whether or not I can just run my gutter (1 of 3) into my garden (which is my plan)

    I think you have to meet two criteria:
    (1) rainwater must be led away from your house
    (2) you mustn't allow water to flow over your property boundary into adjacent properties (although there are exceptions)

    So your soil would need to be permeable 'enough' to absorb the rainwater in the rain garden rather than overflowing. I expect there are permeability tests and calculations that could be done to deem conditions OK in return for a wodge of moolah crossing somebody's palm, but it might be simpler just to do it then ask permission if it works. JustMHO.

    FWIW, my downpipes discharge into the French drain around my house. We're on clay, but we are fortunate that there's a ditch at the side of our property and there was a land drain connecting the [filled] hole my house was built on to the ditch. My BCO hummed and hawed a bit but eventually let me put another piece of drain pipe from the hole to the ditch and then signed off. I have an inspection hole so I can check the depth of the water table in the hole under my foundations. It all seems to work.
    I think it's very much down to the BCO you have and your ground conditions. I was allowed to discharge rainwater directly onto the road by the Highways Dept. and BC.
    • CommentAuthorMike1
    • CommentTimeOct 18th 2017
    Sounds perfectly reasonable to me, provided you have suitable soil. For info, try https://raingardens.info/ for starters...
    • CommentAuthorgoodevans
    • CommentTimeOct 18th 2017
    I'm on clay - so a soakaway seems to make no sense however I will need to use a no dig construction method up my driveway (200mm deep geocell/webcell filled with a no fines single size aggregate, with a filter membrane between the soil and the aggregate). Being no dig the top soil will continue to do it's infiltration job (and oxygen/water will continue reach the soil to keep it healthy).

    I am planning to use a similar constuction all around the house paths and patio's and intend to use a downpipe shoe to discharge the roof water onto/into the layer of aggregate - in effect creating a very thin, but wide/long soakaway. My engineer seems to think it will work and will create calcs if necessary. If I have to do a perculation test I guess I will need to dig a 300x300x300 hole in the top soil - which will be the bottom of the "soakaway" - which will have the necessary results (but I may have to create a 200mm high polythene wall in the drainage layer downhill of the house to create a store).
    • CommentTimeOct 18th 2017
    goodevans, it sounds 'interesting'! Or should that be 'fascinating'. What does the Geocell product cost, if you don't mind my asking? My drive has a Terram membrane, then a sub-base, then a smaller honeycomb filled with gravel. But they used the wrong material for the sub-base so I'm going to have to dig it all up and start again :(

    I guess levels will be very important. Unless your land is very smooth, you'll need to trim and/or fill some bits.
    • CommentAuthorgoodevans
    • CommentTimeOct 18th 2017
    The "cellular confinement system" to use its generic name (and google searching) is horrendous in price - for 200mm deep about £350 for 20m2 plus the angular aggregate which is difficult to source in Cambs. But I have no choice - I need it for root protection. The geocell drapes easily and can be topped with either a no fines gravel or permeable paving - the cells can be over filled to level up - and I will use it as a reduced dig base for the garage raft with a simple 200mm of RC on top with no thickening around the skirt. The cells can be stacked up if more depth is required.

    It can also be used for earth retaining walls - I'm considering using it in several layers with a no fines concrete mix for free drainage retaining wall with a flexible rendered finish and slate coping - but that's for after the build. It looks like it comes in two basic flavours - a perforated plastic based membrane or a non-woven web like membrane - for bonding with a no fines concrete I think the non-woven looks best the end cells could be cut and embedded for a really good edge bond.
    • CommentTimeOct 19th 2017
    Posted By: goodevansthe angular aggregate which is difficult to source in Cambs

    Try Bilney crushed gravel.

    The geocell drapes easily and can be topped with either a no fines gravel or permeable paving - the cells can be over filled to level up

    If you over-fill then you will have loose gravel which will spread and rut. Also, how do you plan to confine the edges?
    • CommentAuthorgoodevans
    • CommentTimeOct 19th 2017
    Thanks for the Bilney reference - I've also seen reclaimed railway ballast - which doen't seem as 'sharp' as the crushed gravel - reuse good, containments bad - but I don't know how 'dirty' railway ballast is.

    For unsupported edges I was going to shutter, partially cut the outer cells next to the shutter and fill the cut cells with a no fines concrete mix through to the shutter. I'm hoping that the free drainage will prevent frost damage. This is why I like the non-woven variety of the webcell - using it as reinforcement fibre tied back to the mass of the driveway. Alternativly an extra strip of geotextile laid under the drive poking out the side, cut into strips which are embedded into the concrete would also work. I think exposed cells / textile would deteriorate due to UV hence the reason for embedding.

    Too much loose gravel on top may move if not further covered with paving. There is the option of levelling up with aggregate under the the web but on top the the geotextile - this would be locked in. Soil levels can also be levelled slightly as well.

    My plan is to have an area on the driveway to be able to have a petanque court (boules).

    apologies to delparado this has drifted well away from the original posting.
    • CommentTimeOct 19th 2017
    Posted By: goodevansI don't know how 'dirty' railway ballast is

    I forget exactly but you need a reliable supplier and I think it is steam cleaned or something. Much larger pieces though.
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