Structural problems in empty properties

The longer a property lies empty, the greater the risk of further devastating dilapidation, compounding the cost and timing of eventual remediation. So, to understand the problems that arise with a dwelling that has been unoccupied in the long term, we must consider why it became empty in the first place.

Disrepair may also be caused by landlords' access being restricted over a long period. I was once involved in a case where an old man didn't allow anybody inside his flat. His rent was always paid on time and there were no immediate external signs to warn his local authority landlord of problems. However, we had to force entry under emergency powers when there was a serious water escape from his property, which resulted in flooding and damage to the flat directly below during a period of freezing outside temperatures. We found his property to be in a severely distressed state, including a collapsed ceiling caused by a burst water tank. The local authority had to place the house on its long-term void list as the repairs had not been budgeted for.

It is not just local authorities that cannot afford to properly maintain a property. I have performed many surveys in Central London where a house is worth millions of pounds but the homeowner cannot afford to maintain it. The cycle of degradation can happen in expensive homes and council flats alike.

I have seen whole streets of vacant council houses that eventually had wholesale refurbishments, including chemically injected damp-proof courses, retrofit cavity wall insulation and waterproof renders. However, when investigating subsequent problems, I found poor original diagnoses; for instance, original damp-proof courses had not failed so walls did not require chemical injections. With no budget available, these houses again sat empty and so the cycle of degradation continued.

Problems may also recur in once-vacant properties due to poor-quality repair work. Acute skill shortages mean that labour can be expensive, while tight project budgets may lead to less-experienced workers being employed or work being done too quickly. Until work is completed correctly, a property may remain empty.

Retrofit solutions may also be ill judged, poorly diagnosed and badly executed. I am presently handling a case where a council decided to pebbledash a 1920s cottage, but the work had to be redone five times because workers had not properly adhered the pebbledash to the substrate walls. The final coat also contained and leaked pyrites, which resulted in rust-like streaks running down the wall. It is difficult to prevent pyrites from leaking as they are hard to detect in certain gravels, so it is important that constructors source materials from reputable suppliers. One attempt at pebbledashing also used non-galvanised chicken wire mesh as a key to the substrate, to which the new cementitious render could adhere. However, this later corroded and caused whole sheets of render to fall off.

Damp and subsidence are the types of problem that recur because there has not been an holistic review of the property and its environment. Yet this is imperative to prove causation and the true source of a problem. Identifying symptoms without considering other defects, the building's design or use and occupation factors means you run the risk of making a misdiagnosis that will lead to inappropriate remediation and unnecessary delays and costs.

The starting point to reduce this figure should be preventing a dwelling falling into disrepair in the first place. But where there are problems, there needs to be a full pathological assessment of the issues. Such an holistic and independent review may involve a degree of destructive and intrusive testing to fully understand the particular defects. If the diagnosis is correct, the remediation – often requiring a multidisciplinary approach – is more straightforward and should avoid problems returning.

Related competencies include: Building pathology, Housing maintenance repairs and improvements