1. Visiting from the US? Why not try DIYnot.US instead? Click here to continue to DIYnot.US.
    Dismiss Notice

Damp proof course and dry channel - needs concrete 'bed'?

Discussion in 'Building' started by fogster74, 6 May 2013.

  1. fogster74

    fogster74

    Joined:
    9 May 2012
    Messages:
    17
    Thanks Received:
    2
    Location:
    Berkshire
    Country:
    United Kingdom
    Hi guys, since buying our house last year work has continued unabated. We're just getting round to sorting the garden - when we bought the house, the damp was horrendous - paving on paving on concrete put the ground level of our 1900's Victorian detached home about 6 inches above DPC!

    Very first task was to rip up all the old concrete and paving and voila, within weeks the damp had virtually disappeared. I excavated down to almost foundation level - a year later, no damp, but a garden that looks like Fred Flintstone's back yard.

    I'm not in the process of putting the garden back. We have a number of problems with the damp proof course level - the biggest issue is that the connection to the mains sewers is high, meaning our waste pipes are relatively high (in relation to DPC) and hence I have no option but to restore ground level to close to DPC.

    Having looked here: http://www.pavingexpert.com/dpc01.htm I think I can keep ground level to 75mm below DPC and was considering a dry channel arrangement. My question is does the base of the channel need to be bedded on concrete, or can I just edge the channel and let whatever water enters the channel drain naturally (the channel will be backfilled with 10-500mm decorative gravel). Getting a run to a drain is difficult, but the gutters all drain well away from the house and the house sits on chalk (the ground is like a sponge - even in the heaviest rains last year I never once saw a puddle)? I know this is far from ideal, but I'm really quite limited in options. Even a French drain with a perforated buried soakaway pipe is not an option as the sewerage waste pipes run parallel to the house wall on the side most affected, and aren't deep enough to allow the French drain / drained channel "on top".

    I've attached a picture of the sort of arrangement I'm considering, albeit I'm simply thinking of not lining / bedding the channel along the base where it says "concrete" in the pictur, but allowing the water to drain straight into the chalk.

    Thoughts and alternate options or things to consider would be most appreciated!!!!
     
  2. Sponsored Links
  3. pinenot

    pinenot

    Joined:
    4 Jan 2013
    Messages:
    1,728
    Thanks Received:
    230
    Location:
    Angus
    Country:
    United Kingdom
    Can you put the relationship of these drains on this sketch? and a plan of the drainage might shed something else...pinenot
     
  4. johnMCG

    johnMCG

    Joined:
    10 Oct 2013
    Messages:
    1
    Thanks Received:
    0
    Location:
    Lanarkshire
    Country:
    United Kingdom
    Hi fogster, I had just read the same article on pavingexpert.com when I found this post.

    I'm planning on putting in something similar to yourself: my drains are also very shallow, due to the fixed height of the flow to my septic tank and then the runoff from the tank coming back towards and under the house.

    Coupled with the limited distance between the top of these drains and DPC, I’ve decided that the ‘dry channel’ method is the way to go.

    Currently we have a French drain running parallel to the house, perforated drainage pipe in a gravel filled trench.

    I was essentially looking to leave this in-place and set a row of kerb stones parallel to it; using them to define the trench and contain the patio sub-base on the other side.

    Similar to yourself I was going to avoid the concrete base to the dry-channel.

    I wondered how you had got on with this, did you stick to your plan?

    Or does anyone else have any comments on this?


    Thanks
     
  5. mattice

    mattice

    Joined:
    5 Feb 2013
    Messages:
    130
    Thanks Received:
    12
    Location:
    Worcestershire
    Country:
    United Kingdom
    Same issues for me, ground level, shallow drains etc. I have 500mm difference in ground height so opted for a 9" retaining wall on a concrete footing. I left 100mm soil gap between the wall and the edge of the footings, a spade width in total between the house and retaining wall. I have left it to drain naturally but intend to put a perforated drain on the garden side of the retaining wall and take it off down the garden to a soakaway. I have heavy clay so this is probably essential.
     
  6. Sponsored Links
  7. fogster74

    fogster74

    Joined:
    9 May 2012
    Messages:
    17
    Thanks Received:
    2
    Location:
    Berkshire
    Country:
    United Kingdom
    I ended up going for the simple route. As the house is on chalk, the soil is incredibly free draining - we've never had so much as a puddle, even in the heaviest of rains. I just needed ground level to be below the DPC.

    I bought a load of Victorian edging tiles off ebay (£150 for about 30m - bargain!) and set these in mortar about a brick's length away from the house. Due to the way the house sits too low in the chalk, the garden level on one side is up to DPC (or near enough); the drain is backfilled with cotswold stones but these are about 3" below the DPC (so below the level of the garden on the other side). I was concerned about the edging tiles toppling in but they proved very sturdy. The mortar slops in - I was careful to shoulder it at the bottom of the trench to allow enough surface area for water to drain through into the chalk below.

    I know this isn't really enough of a drop below DPC but it was the best compromise I could find. My very rough drawing is attached... this has been in situ for six months now and all damp has disappeared. Very happy with the result.

    [/img]
     
  8. fogster74

    fogster74

    Joined:
    9 May 2012
    Messages:
    17
    Thanks Received:
    2
    Location:
    Berkshire
    Country:
    United Kingdom
    Cheers for sharing. I'd agree - there's no way I'd do what I did with clay - I think I'd have achieved nothing more than making myself a very small moat had the house not been sitting on chalk!
     
  9. ban-all-sheds

    ban-all-sheds

    Joined:
    27 Aug 2003
    Messages:
    69,782
    Thanks Received:
    2,858
    Location:
    London
    Country:
    United Kingdom
    I reckon I could grow rice in my back garden during the rainy season.

    :evil:


    An outdoor LED ropelight would be a cool thing to have in that trench.
     
    • Thanks Thanks x 1
  10. fogster74

    fogster74

    Joined:
    9 May 2012
    Messages:
    17
    Thanks Received:
    2
    Location:
    Berkshire
    Country:
    United Kingdom
    What a cool idea - I'll suggest it to the missus! thanks!
     
  11. DIYnot Local

    DIYnot Local

    Joined:
    3 Sep 2019
    Country:
    United Kingdom

    If you need to find a tradesperson to get your job done, please try our local search below, or if you are doing it yourself you can find suppliers local to you.

    Select the supplier or trade you require, enter your location to begin your search.


    Are you a trade or supplier? You can create your listing free at DIYnot Local

     
Loading...

Share This Page