Derby Surveyors

PVC Cladding to Timber – Hidden Defects

It is often said that ‘that one waits ages for a bus, then two come along at the same time’. Just last week, at the end of June, something similar happened when carrying out a survey and assessing the cause of a largely hidden defect.

It is easy to miss defects, perhaps even serious, particularly hidden, when a dwelling initially presents very well.  The 1986 film, The Money Pit, starring Tom Hanks and Shelley Long, should, perhaps, be central to every Surveyors’ training, and even count as CPD.

A property I recently surveyed for a Home Buyers Report was nothing like The Money Pit home, but the initial impression was of a home that had been nicely updated and extended, including new a kitchen, bathroom and carpets.

It became apparent, not all was as it seemed during the survey, when a small area of black mould, at the base of a dormer bedroom wall, was observed, as seen in the picture below.

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Further investigation revealed additional defects to both the front and rear dormer external facing timber framed walls: a gap opening between the front and sides dormer walls, the wallpaper covering losing adhesion and elevated moisture readings, as seen in the pictures below.


External observation did not reveal defect, (see property picture below), and although flat roof coverings are prone to failure at any time, it appeared to be in reasonable condition and no dampness was observed to the ceiling. PVC cladding can though, also disguise defects beneath, and given the evidence available the following advice was included within the report.

There is some black mould growth to the small front bedroom. Mould forms as a result of water vapour condensing in stagnant air spaces. The growth of mould can be reduced by increasing ventilation, which can sometimes simply be achieved by keeping windows open. Any existing mould should be removed as this can be toxic. If the problem continues, you should consider installing an extractor with a humidistat built in, that helps reduce excess moisture within the air.

However, elevated moisture levels were measured to external walls of the dormer, which are clad in PVC, and it is likely that there is moisture penetration behind the cladding and potentially deterioration to the timber frame. We also observed significant cracks, to the dormer walls, particularly at junctions with the gable end elevation, and window frames. As noted previously, the dormer walls are thought to be timber framed, and we believe the cracks and damp, are associated with deterioration of the timbers behind the PVC cladding. It will be necessary to have the cladding, or plasterboard, removed to facilitate further inspection of the fabric materials beneath. Any rot will need to be chopped out and replaced.

The following day, a Saturday, whilst out walking with the dog, by happenstance, I walked past a property where the PVC cladding to original timber soffit and fascia boards, had been removed, (see scaffolding picture below). Removal of the cladding had revealed significant deterioration to the timbers beneath, including extensive wet rot. It is likely that deterioration to internal finishes was the first indication of a more significant defect.

I shared the photographs of the second home, on the Gold Crest Surveyors What’s App Group, for general information, and there was some interesting feedback, particularly that Insurers might well not cover damage behind PVC cladding.


Assessment of the defect also served as a reminder that defects, are not always immediately apparent, and vigilance is required despite first impressions being good or, especially when they are.

An additional aspect was, as is often the case, that the client had noticed something was wrong and would have been, quite rightly, disappointed had the report only, included the standard advice to increase ventilation, albeit, that it has been my observation that most properties are inadequately ventilated, and internal air qualify is often poor.

Reluctance to ventilate is, typically, a response to perceived security issues, and consequent of poor advice on heating. Operating heating from a thermostat, setting the minimum temperature at 15oC, retains heat held in the building fabric, thermal mass. Stale air can then be ‘purged’, even in the coldest months, without significant heat loss i.e. most heat is held in the building fabric, walls and ceilings.

The defect also served as a reminder that vendors unknowingly hide defects, with furnishings and sometimes, placement of themselves.

Finally, it’s worth making time to watch or re-watch, The Money Pit, and not just for CPD but because it’s hilarious. There are many funny moments but particularly memorable for me, is when Tom Hanks informs Shelley Long, whilst their home is falling apart round them, that ‘the Turkey’s done’.

By Andrew Maw.