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Hi everyone

First time buyer here who is keen to listen and learn from the experienced people. About 8 months ago we bought a 1930's end of terrace property. Since then we have noticed a significant issue with 'rising damp' and as such we have some dry-rot in the floor joists and floor boards. The main source of the damp appears to be on the gable end wall. There is a boundary wall which starts off around 2 foot from the property and the space narrows to around a 6 inches. Boundary wall is retaining 3 or 4 foot of soil.

Also there has been an extension built at some point at the rear of the property - the impact is that there is no ventilation across half of the rear of the property.

It appears that the DPC, if still in tact, has been bridged by a previous owner, who has rendered all the way to the ground. There are also only two air bricks in the entire length of the wall.

I am looking for some feedback on an appropriate route forward. My initial thinking is that I need to install more air bricks. I understand that I should have an airbrick every 1.5 - 2 metres? Are there any repercussions of having too many. The reason I ask is; a major area of dampness is around the base of the stairs, I would like to put one in either side of that location to increase the air circulation.

The next action will be to remove two courses of render to bring it above the expected DPC. I will then apply a damp proof course cream. I am planning on using something similar to Dryzone - does anyone have any suggestions as to a particular brand? Is there any harm, apart from cost, in over applying - i.e. injecting more regularly than suggested.

A third question. It is suggested that the internal render and plaster should be knocked off. I know that this due to the salt crystals within the plaster. However, will this have any impact on the damp proofing? If the internal render/plaster is not breaching the DPC then there should be limited amounts of water being transmitted up the wall, or am I missing something? I am planning to get the wall re-plastered professionally, but I am trying to prioritise my limited budget.

I am also considering installing French drain around the base of the wall to reduce the any standing water between the boundary wall and the house. Am I being a bit over overzealous?

Many thanks
 
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8 months ago what did your mortgage surveyor's report show and tell about the conditions you ask about above?
Have you had a Damp & Timber salesman's "survey" and report?
Can you post photos of the "dry rotted" timbers?
Can you post photos of the gable wall at ground level?
 
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Hi Vinn, the surveyor identified damp and also decay. We have had a damp proofing company come in and take a look. They suggested, removal and repair of infected timber. Knocking plaster off to 1.5m. Knock back external render to remove bridging. Chemical DPC, they did not specify what type. Installation of forced underfloor ventilation. I'll take some pictures before work tomorrow and upload them.

Cheers
 
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If you can also post the Damp company's diagram it would help?

Penetrating or rising damp will introduce salts into the plaster - the salts will remain, so the plaster has to be removed and replaced by a 3:1 sand & lime mix of render - never gypsum plaster.

Your DPC is probably in great condition but other factors such as ground levels might have altered since new build. Debris in the cavity can also bridge any DPC's.

Your boundary wall is a retaining wall? Are you located on a hillside?
 
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