Land drain/ french trenc

[Lagoonablue]

My side return path runs water against the side of the house due it's incline. I want cavity wall insulation but they won't do it as they are afraid the damp will get through to the wall via the pooling water. Firm have advised a french trench. I have no idea who would do this for me. Essentially the concrete along the path will need to be cut away, and this trench dug.

Who would do this? A paving specialist or a builder?

why not add cement on the side of the path next to the house so the water drains away from the house? DIY

Thanks. That would look a bit strange. The path is concrete imprint so is a particular colour. I like the idea of a long drain along there or this gravel filled trench but just not sure who does these things!

A builder would do it.

Any general builder or handyman. You just need to hire a cutting implement from tool hire shop and excavate. We had one done down the side of our house by a handyman general builder (not a specialist in any way), cutting out concrete paving laid on concrete base (so very hard work) and then backfilled with large Cornish pebbles. I think the point is that the water should not collect in the gulley and the air can get to the house wall through the irregular spaces in the pebbles. I may be wrong but it has worked for us and the damp has gone.

I'm planning a very similar job at the moment. Probably DIY as I've struggled to find interested tradespeople.

This website is very useful and authoritative:
www.pavingexpert.com/dpc01.htm

Especially read the Workarounds section on the above page in relation to your damp proof course (DPC) and the depths you need to dig to.

This video is udeful in terms of seeing the process:

Are you going to put a pipe in the bottom of the trench? I probably won't - just dig 20/30cms down and fill with pebbles to well below the DPC.

It's tricky getting into the gap between a paved area and the house wall. Especially if it is narrow - mine is 20cms max.

Will end up using narrow digging tools and lots of backache.

I wouldn't use a cutting machine near the wall of my house unless you are very, very, very sure about where all the GAS - WATER - ELECTRICITY pipes and cables are located.

Be very careful about all of these - dangerous and expensive to fix if cut.

If using tradespeople, builders and paving or groundworks people, even landscapers are often skilled at this. If you put drainage or landscaping hard into checkatrade - you will find local firms and can check their websites to see if they do drainage.

Thanks all for your help. All really useful. No way it is a job for me as useless at DIY! Off to checkatrade!

You have not said where the DPC is. It should be about two brick courses above the ground or paving, which is nine inches. If you can achieve that, with a fall away from the house, you might not need the french drain.

It is very common for stupid people to heap flowerbeds, or lay concrete, against a house wall above the DPC, causing damp.

The reason for the 9" gap is so that rain does not splash up and wet the wall.

BTW a French Drain is filled with cobbles, pebbles or clean large broken brick , not gravel. The larger stones have airgaps so drain quickly and do not permit water to rise through capillarity. There should be a barrier to prevent mud from the garden washing in, landscape fabric is usual. Mud or sand will block the gaps between the stones.

The trouble is that people who used to own the house laid concrete imprint stuff over an existing path which means the ground is too near the DPC. This is why the insulating people won't do the cavity wall. The decking is too near the wall too. It's a pain.

grrrrr.