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Released On 10th Sep 2018

Rising and penetrating damp discovered by survey at a lower ground floor flat, London NW6

In July 2018, we carried out a full building survey on the lower ground floor flat at 10a Mill Lane, London NW6.  Parts of the flat in this terrace of Victorian-era properties were below the external ground level, and three causes of dampness, both penetrating and rising dampness, were discovered within the property.

10a Mill Street, London NW6

Penetrating dampness due to rainwater downpipe leakage

To both the front and rear elevations to the property, there had been prolonged leakage from the rainwater downpipes. Some of the downpipes were still in the original cast iron, and were fractured; other, more modern, PVC downpipes simply hadn't been maintained, resulting in open joints and leakage.  One of the rear downpipes actually had a hole within in, and water was spewing out of the hole every time it discharged.  

The result was that brickwork adjacent to these areas had become saturated over time, to the point where plant growth had received sufficient moisture to establish itself, growing out of the brickwork.  Such plant growth can only occur where the brickwork has been damp for many months, and clearly there was no effort or will on behalf of the current owner of the flat, or any other lessees within the building, to maintain the property to an acceptable standard.

Plant growth on external brickword 

Plant growth caused by leaking drainpipe

The principal cause for dry rot developing to the interior of any property is when brickwork becomes saturated due to rainwater discharge from leaking downpipes. This property was therefore at risk of a dry rot attack until such time as the pipes were repaired.

Penetrating Dampness From the Front Walkway

The kitchen to the subject flat was not only located below ground level, but running directly above it was the asphalted walkway leading up to the communal front entrance door to the other flats within the property.  

Asphalt walkway in poor condition

Whilst the asphalt was in fair condition, the render to the guard wall on the left side of the walkway was so badly fractured that it was admitting water through to the interior of the kitchen each time that it rained.  This had been ongoing for a long period of time, with damp staining visible within the kitchen at high level.  

Cracked render allowing damp penetration

Penetrating dampness visible

There were also some random cracks to the kitchen ceiling, suggesting strongly that the joists above, supporting the ceiling plaster, were likely to be decayed.  

Major works were therefore necessary to the guard walls, in order to repair the render, tighten up the joint between the asphalt and guard walls, and also provide a proper capping on top of the walls, with the cappings seated on a damp-proof course.

Rising Dampness

Despite the fact that the vendor maintained that damp-proofing works had been carried out to the interior of the property, with a 20-year guarantee available, there were numerous areas where there was significant rising dampness, with the dampness actually visible at low level, as can be seen in the photograph below.  

Evidence of rising dampness

Clearly, any works previously undertaken had been completely ineffective and the guarantee was worthless.  

Our survey recommendations

It was clear from the survey of this lower ground floor London flat the whole property needed to be properly damp-proofed.

Taking into account our observations of three areas of penetrating/rising dampness and the works necessary to carry out the required repairs, both externally and internally, we would estimate that a figure of approximately £15,000 was needed, in order to carry out the repairs.  We recommended to the prospective purchasers that they sought to obtain the £15,000 off the purchase price.

If you think you would benefit from a building survey on a property you own or are thinking of buying, get in touch for jargon-free advice and a quote.

Call us on 07711 491000 or email


Category: Case Studies

Tags: Older properties, London, Basements, Damp penetration, Full building survey, Terraced houses, Damp-proof course, Drains / pipework, Root growth, Price negotiations, Rising damp, Cracks, Penetrating damp

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