pebble dashed wall

Postby headroom » Thu Jan 31, 2008 10:57 pm

I have a ground floor extension which is rendered and pebble dashed the rendering goes down to the floor level of the yard which is concrete. The wall is not a cavity wall and it is very damp inside would knocking off the pebble dash rendering up to maybe 6 inches and cutting a groove in the concrete of the yard of 6 inches abutting the wall then filling with gravel stop the problem? Thanks in anticipation.
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Simply Build It

Postby Perry525 » Tue Feb 05, 2008 7:13 pm

The first thing to do, is to ascertain if there is a damp proof course and, where is it.
The norm is for the DPC to be above the outside ground/path whatever by about 6 to 9 inches.
This is to avoid splashing from heavy rain.
Find the DPC and go from there.
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Postby headroom » Tue Feb 05, 2008 8:12 pm

Hi Perry, The wall doesn't have a damp proof course, I am thinking of knocking off the rendering upto about 6-9inches, channeling out the concrete of the floor in the backyard and putting in loose gravel and maybe drilling and injecting some damp proofing materials (there seems to be alsorts on the market ) - - - what do you think? - - - thanks for your thoughts.
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Postby LCL » Sat Feb 16, 2008 12:39 pm


From reading your post, it sounds like you have a low level penetrating damp issue.

What you suggest you will be carring out is correct, but i would doubt the need for a chemical dpc. Try not to add any water proofing agents to the wall and this will upset the natural moisture movement rthrough your structure.

One quite significant issue that you have not raised, is the internal floor construciton. If you have a suspended timber floor, you should be looking at reducing the ground levels externally to at least 6" below this floor level. PD at this location can very easity affect floor joists, especially when they are built into the external wall and are not protected with a DPC. In 1877 is was made law to include a DPC in buildings so i am also assuming that your property pre-dates this. If it does not, your property may contain a slate DPC which is contained within the bed joint and concealed from view.

Hope this helps

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