DPC Building Regulations Guidance After Extension Added to Property If you want to know how your DIY projects could be affected by building and planning regulations, click here to post questions and view answers

[snow1507]

Hello All - I'm looking for some guidance around DPC. We have a detached house that we have just had extended on one side. The side that has been extended now has a narrow 1m passage that goes from the front to the back of the house. The contractor that we used 2 years ago to do the work has built the 1m passage up to the neighbours ground level which is about 150mm above our DPC. We are looking to get building regs sign off however Im concerned that the inspector will pick this up as an issue.

I intend to dig a trench in advance of the inspectors visit is drop the ground level to 150 - 200mm below DPC, my question is how far away from the wall does the trench need to go? once Ive dug out the trench I will put in a retaining wall (250mm), put weed fabric down and cover with a some shingle or stones. To help explain this, Ive drawn a rough diagram attached. It also maybe worth adding that this passage way will not be used, even for foot traffic.

diagram.png (3.45 KiB) Viewed 7770 times

Ive read through Building regs and can only find details to the depth below DPC but not the distance away the ground level needs to be. Any advice would be greatly appreciated.

Tony

[welsh brickie]

its best if you install an aco drainage system, its made of plastic with a metal grill, easy to install and ideal for this situation, available at most building suppliers

[snow1507]

Thanks Welsh Brickie, if you dont mind a couple of questions. If I install an aco system, it would be around 20m in length and I'm guessing still need to be 150mm below DPC? secondly, the aco will sit in soil and the run to it will be flat and soil. Would the water actually reach the aco drain before being soaked into the ground?

[welsh brickie]

you will have to dig out the soil, lay a plastic membrane and run it up the wall,place the drain in position and concrete it in place, and it can be laid at dpc height, it can also be laid level, its probably best to concrete or pave the path so the water runs into it,