Posted: Mon Mar 04, 2013 2:17 pm
Hi everyone, first time poster here so apologies in advance for any faux pas.
I currently have a damp problem in two walls in my kitchen which back out onto my patio. I suspect part of the problem is poor design and drainage of the patio, along with inappropriate rendering of the wall down to ground level and possibly a bridged/broken DPC. I've had a new chemical DPC injected to no avail and so need some advice on whether to/how to rectify the patio drainage issue. I've got a few pictures to help explain:
This is the rear face of the house, and the damp problems are on the other side of the white rendered surface. As you can see, the patio step is laid pretty high up, the top being less than 2 inches below the internal floor level. The step is sloping slightly to the right, such that water poured on the left half of the step runs away from the house towards the main patio area, but on the right it runs towards the gulley where the green iron soil pipe is. Once it hits this gulley it flows towards us along a concrete base towards the end of the step then seems to flow into soil, draining quite slowly. The house is built on London clay, which might explain this.
This next picture is a better view of the gulley on the right.
This next picture shows the height of the patio step in relation to the doors and the surrounding patio level. As you can see, the step comes right up to the wall.
Now what I'm thinking is that this damp in the kitchen could be caused by one or a combination of all of the following:
1) Degraded DPC, in which case I don't know what more I can do after having a new DPC injected.
2) External render bridging the DPC, in which case I think I need to hack off the waterpoof cement render to about a foot above the ground level and finish with a bell cast to stop capillary action and allow the lower brick courses to breathe.
3) The patio step bridging the DPC, in which case I'm not sure what to do. Do I need to remove the step in it's entirety, cut it back by a distance from the wall so it becomes a floating step, or install something like a linear drainage channel between the step and the wall.
4) If I install drainage, where can I drain the water to? Is there a way of draining it into the green soil pipe on the right, or do I need to run the channel round to the left of the building where there's an actual drain which takes the guttering run off?
For further info, this next picture shows the side return patio with the rainwater drain and an airbrick visible on the left.
The patio slopes away from us down towards the garden but it still looks fairly high compared to that airbrick. Also down at the end where those grey plant pots are is prone to pooling of water when a high volume of water comes down the patio (think torrential rain or pressure washing, not normal British everyday rain).
I'd really appreciate any thoughts on where I go from here. Am I barking up the wrong tree with my diagnosis? What trade do I need to install drainage - a paving expert or a builder? Is this likely to be an enormous, expensive, or even necessary job? Any advice gratefully received! Thanks for reading!
I currently have a damp problem in two walls in my kitchen which back out onto my patio. I suspect part of the problem is poor design and drainage of the patio, along with inappropriate rendering of the wall down to ground level and possibly a bridged/broken DPC. I've had a new chemical DPC injected to no avail and so need some advice on whether to/how to rectify the patio drainage issue. I've got a few pictures to help explain:
This is the rear face of the house, and the damp problems are on the other side of the white rendered surface. As you can see, the patio step is laid pretty high up, the top being less than 2 inches below the internal floor level. The step is sloping slightly to the right, such that water poured on the left half of the step runs away from the house towards the main patio area, but on the right it runs towards the gulley where the green iron soil pipe is. Once it hits this gulley it flows towards us along a concrete base towards the end of the step then seems to flow into soil, draining quite slowly. The house is built on London clay, which might explain this.
This next picture is a better view of the gulley on the right.
This next picture shows the height of the patio step in relation to the doors and the surrounding patio level. As you can see, the step comes right up to the wall.
Now what I'm thinking is that this damp in the kitchen could be caused by one or a combination of all of the following:
1) Degraded DPC, in which case I don't know what more I can do after having a new DPC injected.
2) External render bridging the DPC, in which case I think I need to hack off the waterpoof cement render to about a foot above the ground level and finish with a bell cast to stop capillary action and allow the lower brick courses to breathe.
3) The patio step bridging the DPC, in which case I'm not sure what to do. Do I need to remove the step in it's entirety, cut it back by a distance from the wall so it becomes a floating step, or install something like a linear drainage channel between the step and the wall.
4) If I install drainage, where can I drain the water to? Is there a way of draining it into the green soil pipe on the right, or do I need to run the channel round to the left of the building where there's an actual drain which takes the guttering run off?
For further info, this next picture shows the side return patio with the rainwater drain and an airbrick visible on the left.
The patio slopes away from us down towards the garden but it still looks fairly high compared to that airbrick. Also down at the end where those grey plant pots are is prone to pooling of water when a high volume of water comes down the patio (think torrential rain or pressure washing, not normal British everyday rain).
I'd really appreciate any thoughts on where I go from here. Am I barking up the wrong tree with my diagnosis? What trade do I need to install drainage - a paving expert or a builder? Is this likely to be an enormous, expensive, or even necessary job? Any advice gratefully received! Thanks for reading!
