French drain and pea gravel patio

[El Greyo]

Hello all

We've recently bought a wonderful 17th century cottage and have plenty of work to keep us happy in it for quite a while.

The highest priority is to sort out the damp problems. To the rear, the garden slopes up away from the house, so water drains down to the cottage. Also, immediately behind the house was a concreted area (I hesitate to call it a patio) approximately 9 inches higher than the internal floor level. So it's no wonder that the back wall of the house suffers from damp.

So far we've ripped up the concrete, and the plan is to lower the ground level and put in a french drain. Once that is done, we have thought that the best surface to replace the concrete is pea gravel as this would provide the best drainage. The area to cover is approximately two meters wide and runs the length of the house. At the end we'll have to put in something to retain the gravel as the ground drops down around the side of the house. Otherwise the area is well contained.

Does anyone have any advice about laying the gravel? Particularly what depth of shingle is required, what size of shingle you recommend, what should we put under the gravel and any other tips anyone might have? Or if you have another suggestion for this area? We don't intend to use it as a patio, it'll be more of a path.

Thanks very much for your help.

 

[Feltwell]

Welcome to the forum! Post some pictures up of your house, people will be interested.

I'd definitely lay a permeable membrane under your new shingle "patio" - at my last house we had an area of gravel without one (done by a previous owner) and weeds kept on coming through. Here, most of our front garden is laid to gravel over a membrane - we get very, very few problems with weeds.

The best place to point you to for advice on any paving is the website below, pavingexpert - it's very good, and has a forum as well for any queries - the forum has lots of landscapers contributing to it, I got very good advice on some paving & drainage problems I had.

http://www.pavingexpert.com/fabrics.htm

http://www.pavingexpert.com/gravel01.htm

You don't have to have gravel if you don't want it - you could intercept the run-off from a hard paved surface with a Aco channel or by other means. Again, the Pavingexpert site has loads of drainage stuff on it.

 

[JoceAndChris]

Glad you posted that question El Greyo as it pertains to me too. Good luck with your new project, and it would be lovely to see some pics of the house.

 

[Penners]

Hello, El Greyo, and welcome.

I broadly agree with what Feltwell has said. A gravel surface will help to allow some water to permeate away before it reaches the house, but may not be the complete answer. As you're at the bottom of a slope, sub-surface water is still likely to permeate down to the walls of the house. So your plan for a French drain seems very sensible.

The choice of gravel can be a difficult one. Larger gravels (20mm and above) are more stable and less prone to being carried or kicked about, but they can be uncomfortable to walk on. Very small gravel gets picked up on shoes and walked about, often into the house. My own preference for a compromise between these two is 10mm shingle.

As Feltwell has said, a permeable membrane underneath the gravel will help to stop it sinking and help to deter weeds.

 

[El Greyo]

Hello and thanks for the advice. The links posted by feltwell were particularly useful and I think I'll listen to the practical advice on pea size by Penners and go for a 10mm gravel size.

The french drain is going to be vital - having dug down a bit, we've already encountered water even in this very dry summer. It looks like it's seeping down the hill in the soil and the soft sandstone bedrock. Next door - where the hill has been cut back for an extension, water is continually pouring out of a hole in the 4ft high retaining wall.

I'll take some photos and post them if people are interested. I'm sure to to have more questions as we bumble along in our gradual inprovement of the house.

Thanks
Steve

 

[JoceAndChris]

Definitely interested. Good luck!

 

[Penners]

I'll take some photos and post them if people are interested.

Of course we're interested!

 

[El Greyo]

OK then, when I have a spare minute I'll sort out and post some photos. But it might not be very soon, after all I've got a french drain to install, and after that I've got a lot of pointing to do, and after that then hopefully the planning permission will have come through (touch wood) so I can build a shed and after that we'll be looking at insulation in the roof and making secondary glazing for the winter and the front door needs stipping and painting and so does the back door and we need to look at the window frames and ...

One thing with a period property: I can't remember the last time I was bored.

 

[Penners]

hopefully the planning permission will have come through (touch wood) so I can build a shed

Planning permission for a shed? Surely that's not necessary, if it's a "temporary structure".

 

[robgil]

remember that a french drain soak away will not work very efficiently if at all in clay, what is your ground like?

 

[Moo]

OK then, when I have a spare minute I'll sort out and post some photos . . .

Don't wait until you've done the work - we like to see Before, During and After pictures.

 

[El Greyo]

Planning permission for a shed? Surely that's not necessary, if it's a "temporary structure".

It is if it's within the curtilage of a listed building. Since 2008 apparently.

It's a steep learning curve buying a 350 year old listed cottage; I didn't even know what a curtilage was before. Nor a french drain come to think of it.

 

[El Greyo]

remember that a french drain soak away will not work very efficiently if at all in clay, what is your ground like?

I think we'll be alright. The rock below is sandstone and the soil, while a bit clayish will drain reasonably well I think. The main purpose is to intercept water draining down the hill and divert it round the side of the house into the drainage system. Thanks for the tip though.

 

[EricD]

remember that a french drain soak away will not work very efficiently if at all in clay, what is your ground like?

I think we'll be alright. The rock below is sandstone and the soil, while a bit clayish will drain reasonably well I think. The main purpose is to intercept water draining down the hill and divert it round the side of the house into the drainage system. Thanks for the tip though.

thats good idea and hopefully will divert the water around the house to help