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Posted: Sun Dec 16, 2018 12:02 pm
by Shambo
Hello I have a stone terraced house with a concrete back patio. The concrete is all the way up to the stone wall at the back of the house & bordered by a stone wall on 1 side (1 neighbour) & a brick wall on the otherside (the other neighbour). There is a drain in the middle of the patio where surface drainage from some guttering down pipes are angled towards. My question is I would like to have a wide stone border around the house wall & then some gravel beyond it. The house is 200+ years old, the stone walls are very thick there is no damp proof course. There is some damp here & there in the house (mainly because there are 5 bedrooms and we don't heat it enough) but no obv rising damp. Can I pave up to the old stone wall at the back of the house? Make it slope appropriately? Should I attempt a drainage channel? The inside floor levels are much much higher than the outside level. Any input appreciated
Thanks.
Posted: Sun Dec 16, 2018 1:08 pm
by Tony McC
A commonly used tactic with these older properties is to create a free-draining area immediately adjacenet to the stonework/brickwork/masonry. The idea is to prevent any moisture residing against the house so it can't find a way in.....in theory.
The simplest way to achieve this is by using the equivalent of a 'splash strip', the 200-300mm wide strip of gravel you often see laid between paving and masonry. However, unlike far too many so-called splash strips, this one needs to go down to a depth of at least 300mm, and, preferably, be lined with a suitable geo-textile before being completely filled with a clean angular aggregate, a bit like that shown in the drawing here.
Other options rely on the use of a fin drain, drainage composite or "waffle board", as discussed here but these are often a more expensive solution, requiring greater depth and are pronbably best suited to what we might term "heritage" projects with generous budgets.
Posted: Sun Dec 16, 2018 6:33 pm
by Shambo
Hi Tony thanks for the reply. The first option sounds reasonable but wouldnt the water just collect in this stoney gulley by the side of the house, seeing as the rest of the patio is concrete? Im a good diyer but as you can see I know nothing about drainage.
Posted: Tue Dec 18, 2018 4:52 pm
by Tony McC
Yepo the water collects, and so you need an outfall.
Depending on ground conditions, it may be that the sub-grade itself, at depth, is highly permeable. We see this a lot around here where the porous Old Red Sandstone lies under half-a-metre of boulder clay - dig through the clay and you have ideal drainage.
For those not that lucky, the simplest fix is to use a perforated pipe at the base of the trench and direct that to a soakaway or SW system or local ditch, whatever is available.