Damp management and remediation

Management

Key features

• Only symptoms are targeted.
• Requires less physical upgrade/repair of the building.
• Often less disruptive in the short-term.
• May require a change in lifestyle/behaviour of the building user.
• The source of dampness could continue unchecked, resulting in later problems.
• Cheaper in the short-term but can be more expensive in the long-term.
• Quickly and cheaply achieves a satisfactory habitable condition, often when occupiers must remain in situ (e.g. in tenanted property).

Examples

• Unproven retrofit damp courses.
• Cause of damp wall not confirmed, but internal surfaces given a new, often waterproof, coating, which dams the damp.
• Internal linings or plaster systems installed to dam the damp are vulnerable to damage; repairs to patent systems can be problematic.
• Wet basement walls and floors are lined (tanked) internally to produce a dry internal finish.
• Condensation mould is cleaned off and surfaces redecorated using anti-fungicide paints or wallpaper adhesives.
• Condensation mopped up as it occurs.
• Dehumidifiers are used to help reduce vapour in the air. But remember in the UK approximately 40-50% of a cube of air contains moisture and therefore the dehumidifiers will continue to draw moisture from the air, even in normal conditions.
• Space used differently, where a room suffering a damp problem is used for a less damp-sensitive use.
• Fine tuning of heating or ventilation systems to help reduce condensation problems.
• Occupier changes washing and/or cooking habits to reduce adverse moisture generation effects.
• Materials, equipment, etc. vulnerable to damage from damp are moved.
• Specialist patent repair or improvement systems installed, often with a limited life compared to the life expectancy of the property, and causing problems if the system breaks down or fails.
• Pumped drainage systems that require annual maintenance.

Stop the rot

Why the practice of passing clients to salespeople from damp-proofing companies must end, by Mike Parrett

At best, dampness in buildings is misunderstood and, at worse, it is completely misdiagnosed. For almost 50 years, dampness surveys have been predominantly undertaken by commercial companies with products or services to sell. Diagnosis has relied on individuals who earn commission based on the results of their findings – often geared toward the services they provide.

Successive government English Home Condition Surveys (and similar ones for Northern Ireland, Scotland and Wales) have identified that dampness, in all its forms, accounts for over 50% of building defects. We regularly see Home Buyer Survey reports containing recommendations for low-level, wall-based dampness to be further investigated by specialist organisations, even suggesting that they should be members of bona fide associations.

However, few surveys are conducted by individuals trained in building pathology and with nothing to sell but the truth. The commercial ‘interference’ in damp diagnosis has continued to grow based around the misleading notion of a long-term damp guarantee.

A professional opinion?

What happens in practice is that a surveyor will examine building elements using only an electrical resistance or capacitance (moisture) meter. Where high readings are indicated, the next stage of the investigation is passed to commercial companies who send in salespeople. These usually subject the building to the same examination as the surveyor, but they now form a professional opinion of causation with remedial recommendations. See the panel opposite for an example of how this is not the best approach.

So, how could this practice of commercial reliance have flourished? I believe the answer lies at the heart of building surveying and falls into three categories:

What is required to become a chartered building surveyor?

In the medical profession, someone wishing to become a GP is fully trained on the whole of human pathology.

Within this group, emerges a peer group of specialists to which GPs refer specific cases.

Imagine if none of the GPs wanted to become specialists. Would they send their patients to drug companies for the next stage of treatment?

The normal route to becoming a BS is through a Bachelor of Science honours degree. If we look closely at the curriculum, they don’t cover pathological surveying, building failure investigations or undertaking dampness surveys to ‘Level 4’ detail (see Diagnosing Damp1). There are therefore limited opportunities for under- and postgraduates to develop into specialists to fill the shortage in the profession. We need to mirror general medical practice and develop surveyors with a similar approach. The BS should and must play a pivotal role in caring for both the building and the occupiers, by referring the client to an independent expert to undertake the next stage of the building investigation, while remaining in the loop to deliver the specialist’s findings.

What is practiced as a chartered building surveyor?

I’ve found that most BSs are reluctant to undertake invasive testing and they have largely supported inviting commercial organisations to advise on remediation to cure dampness. The reality is that most would never dream of undertaking any invasive testing because they feel this is way beyond their remit, especially in the Home Buyers market. This begs the question of what value a BS adds to this part of the process?

What PII cover is in place?

Do BSs not perform pathological damp surveys because these are actually outside their remit, or is it because they think they don’t have (or can’t get) the correct PII cover? I fear that PII is not the issue and the reason for not performing detailed damp surveys has been lost in custom and practice that has gradually evolved over time.

What’s the answer?

So what is needed to help surveyors help stop the rot? I often describe dampness pathology as using one hole through a suspended timber floor board on the ground floor of a property. Through this hole, I can insert a hygrometer, a temperature probe and an optical borendoscope to observe a good section of the sub-floor void and comment upon the:

• air temperature and moisture content;
• presence of any timber decay, wet rot, dry rot, etc.;
• presence of any wood-boring insects and rodent infestations;
• depth and condition of the void;
• presence of any physical horizontal DPC to the walls;
• height of the local water table or evidence of water (possibly);
• condition of support walls;
• type and location of the mains water supply pipe;
• routing of heating pipes and whether they are insulated; and
• risk that through-wall air vents are blocked..

I can usually extract 3 or 4 pages of valuable information, giving the following benefits:

• greater protection from PII claims than standard methods;
• huge savings from not undertaking unnecessary remedial work;
• higher client satisfaction;
• gradual elimination of dampness in buildings by greater understanding of the true causes;
• increased public awareness;
• develop cohesive planned preventative maintenance schemes;
• targeting resources to manage or cure the damp will contribute to achieving sustainability goals; and
• justice through accurate expert evidence in claims for disrepair and statutory nuisance.

Case study

At the Metropolitan Housing Trust, around 80 ground-floor flats were examined by a damp-proofing company. Their diagnosis revealed that all the flats suffered from rising damp, due to a failure of the existing physical DPC, and required a chemical DPC injection, associated internal waterproof plaster, replacement timber skirting boards and redecoration. These free surveys took just over a week to complete.

We were brought in because the Trust wanted an independent in-depth survey and we undertook a thorough pathological review of each flat, which took three of us over four weeks. Our surveys were chargeable at an agreed average cost per dwelling. Rarely were the results of our electrical resistance or capacitance meters taken on their own. These results are a valuable tool to identify patterns of potential dampness in masonry and plaster, and of the percentage of moisture content, but are only a first step.

Many of the dwellings were subjected to a full Level 4 survey and involved invasive testing using calcium carbide, testing for the presence of salts (chloride and nitrate ions), use of an optical borendoscope, a listening stick for water main leakage, floor hygrometer, etc. In a number of the flats we found:

• serious rising damp caused by leaking pipes;
• failure of the solid floor damp proof membrane;
• raised abutting external ground levels;
• penetrating damp caused by fractured cast iron rainwater and soil vent pipes;
• mould on walls caused by internal plumbing leaks; and
• the effects of active internal condensation due to the use and occupation of some of the dwellings overcrowding, etc.

The importance of this case study cannot be underestimated. Had the recommendations of the free surveys been adopted, the average remedial cost of each dwelling would have been between £4-6,000 and would not have solved the problems.

In addition, the guarantee from the damp-roofing company would have only covered their waterproofing process (injection system and plastering). Therefore when the dampness returned, and a claim made under the guarantee, a subsequent thorough survey would have confirmed that the cause of the rising damp was everything other than a failure of the original physical DPC to the walls.

Back to the future

The Public Health Act of 1875 identified the link between dampness problems in buildings and ill health. Surveyors must address and take some professional responsibility for this link.

Claims for ill health caused by mould and damp are rising globally, none more so than in the USA where these claims could eventually shadow those for tobacco- and asbestos-related illnesses. We have also seen an increase in disrepair and statutory nuisance claims against landlords over the last 15 years, as tenants become more aware of their rights.

We cannot continue with the antediluvian practice of passing our clients to salespeople without any

further connection with them; this is failing in our duty of care. We must take a lead on developing a more in-depth understanding of dampness in buildings by making this part of qualifying as a BS. This will also herald a new era of professional independence that steers away from the practice of recommending commercially led investigations.

Yes, there is a lot to do but, in time, the results will speak for themselves.

Stop the Rot, Building surveying journal (January/February 2009), RICS