Trench

[Wieas]

I need to get someone in to dig a trench on one side of my property due to high ground levels causing a damp problem. There is currently a concrete path there.

I was just wondering what width and depth of trench would be needed. Also before the gravel is added is there some kind of fabric that has to be laid first?

Your question is actually "how to make a French Drain"
(See goggle)

Usually a couple of feet, against the house wall, but not going beneath the foundations.

You use cobbles or pebbles, which do not support capillarity, and are safe to walk on.

Line with landscape fabric to prevent mud washing in and clogging it, or clearing a fine texture which supports capillary ("rising damp").

You need to lead it away from your house, preferably downhill, otherwise sloping deeper, and preferably have a soak away unless the soil is porous enough without it.

Look out for buried pipes and cables.

If you have glazed clay drains and gullies you will probably find the broken one causing the damp while you dig. I'd recommend digging them first.

Paving Expert calls it a Land Drain and has good diagrams.

www.pavingexpert.com/drain16.htm

PigletJohn, thanks for your helpful reply.