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Posted: Wed Mar 12, 2014 1:09 pm
by n_fuller
Hello,
Just stumbled across this forum and its got some great information, but haven't been able to find anything to help me with my problem so I was wondering if anyone had any advice.
Basically I live in an 19th century Cornish cottage which has very poor drainage and some damp problems. To alleviate this I want to install a linear drainage system around the perimeter of the house right up against the external walls.
Having looked around on line there are quite a few of these systems but none seem to go that deep. To actually prevent the moisture reaching the walls I want to dig approximately a foot below the floor level so that it cannot rise into the walls.
So my question is are there any systems that would allow me to have a drain deep enough that anyone knows of?
If not if I construct one using a concrete channel and brieze blocks, should I put a membrane between the house external wall and the edge of the drain?
Any advice on this issue would be gratefully recieved.
Regards,
N.
Posted: Wed Mar 12, 2014 5:49 pm
by r896neo
It sounds like you need to think about tanking the walls rather than linear drains?
Linear drains are to deal with surface water run off.
You may need to tank the walls to stop penetrating damp which can be done from the inside or outside.
Then perhaps you may also need to install land drains along the walls. You need to be careful though directing water to run along near the footings of a building so perhaps may need some expert advice on site.
Posted: Thu Mar 13, 2014 9:21 am
by Tony McC
There are linear channels that reach down 300mm and more, but as the preceding poster says, this may not be the right drainage solution for your property.
What might make more sense would be an interceptor drain which will divert any groundwater before it gets to the sub-surface walls of your property, and take surface water too.
There are ways of creating a sort-of interceptor drain using linear channels, which involves core drilling holes every 300mm or so in the sides of the channel and then affixing a permeable geotextile to the channel to allow water through but keep silt and roots out. Quite honestly, the simpler gravel-based interceptor drain is a much easier option!
Posted: Thu Mar 13, 2014 1:49 pm
by n_fuller
Hello and thank you for taking the time to reply.
Perhaps I should expand a little on my thinking of the linear drain system (I would like to add that in no way do I consider myself knowledgable in this area to start with).
We will be tanking the walls on the inside, but the drains are to stop the moisture collecting or even reaching the walls in the first place. The back garden slopes steeply down towards the house, which itself is sort of cut into the hillside a little. In many areas the ground level outside is above the floor level inside. On top of that there is no DPC and the house itself is built straight onto granite, so no foundations or anything like that.
Maybe I am using the wrong terminology, but I wanted to build a drainage system that would prevent any water reaching the external walls of the house, either from run off or seeping up from below to the edge of the house.
My plan was to dig the drain about a foot below ground floor level.
I have attached what may be mistaken for a child's drawing but is in fact supposed to be a pictorial diagram of what I am planning and the layout of the house.
I am interested to see whether your initial thoughts remain the same.
Regards,
N.
ps. sorry can't seem to be able to attach a picture to the post.
Posted: Thu Mar 13, 2014 7:02 pm
by r896neo
That makes sense. Tanking is easier to do on the inside anyway if your rennovating.
In that case tony's example of an interceptor drain is your best bet.
Ideally it the land drain pipe at the base needs to flow to somewhere if the lie of the land allows it.
Posted: Fri Mar 14, 2014 8:48 am
by Tony McC
Yep, the interceptor is the best option.
Posted: Fri Mar 14, 2014 9:09 am
by n_fuller
thank you all for your advice much appreciated.
I have contacted a couple of professionals and going to wait and see exactly what they say, and then make a decision on whether I think I can do the work myself or if it is just easier paying for it.
regards,
N.