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Groundwork & Foundations

French drain/ decking??

Hi, my back garden ground level is higher than house floor level, with resultant damp problems. A french drain was put in a while back which helped. I would now like to put decking at the back of the house- should i remove french drain and dig away all dirt from around house edge, with decking over it?? Hope this makes sense!

4 Answers from MyBuilder Groundworkers

Best Answer

no keep drain in place if its working water will still go underneath decking boards


Answered 7th Mar 2011

Hi Kirsteen
In response to your question,yes.The ground level should be no higher than 150mm below the damp course ( two bricks ).This is standard practise.
Many thanks


Answered 7th Mar 2011

Hi, removing of the soil/dirt at least 2 bricks below the damp course is a positive step in the right direction and then reinstate the french drain as an extra precaution. the drain may in fact be working but the damp may be also be that the original damp course has broken down and needs replacing.
It is bad practice to have any soil or dirt near the wall as it acts like a sponge so remove it any way it can only help, then fit the decking and enjoy the summer as its on its way.
regards rob


Answered 8th Mar 2011

Hi Kirsteen, i am currently building a large rear garden decking for a customer who had the same problem as yours........i basicaly reduced the ground level 150mm below the dpc level of the house and installed a french drain running along the rear of the house.......the decking will come right up against the house so they are able to open the rear doors and step out directly onto the decking.......its the only correct way to do it.


Kaz Suleman
Senior Construction Engineer


Answered 8th Mar 2011

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