Period Property Advice

RICS has collaborated with Historic England and the PCA to produce a Joint Position Statement - Investigation of moisture and its effects on traditional buildings: Principles and competencies.

The document has been additionally supported by Historic Environment Scotland, Cadw, Historic Environment Division Northern Ireland, SPAB and IHBC.

For the first time ever, these organisations have come together to agree on the set of principles and competencies that should be used anytime there is a need for an assessment of moisture within a traditional building. This is most typically likely to be during a pre-purchase building survey, and investigation into a moisture related problem or when a contractor undertakes repairs and alterations to a building.

In the context of a building survey on a traditional building or any historic building, it should be within the competence of the surveyor to be able to make a professional judgement on the building and not simply make a recommendation. This document establishes a position of best practice throughout all levels of surveys and inspection of traditional buildings.

The surveyor should take a ‘whole building’ approach, look for the source of any excessive moisture, not rely on potentially misleading data and should then provide the client with advice to manage the situation. The document goes into detail in a step-by-step format of what the surveyor should do and ultimately to take responsibility for the advice given.

The JPS 2022 will be taken into consideration in any potential disputes and claims against surveyors and the whole profession, at whatever level, is encouraged to adopt it.

For most surveyors, this will be nothing new and it will already be standard practice during surveys and report writing.

For others, it is a reminder that the building should be looked after to the best possible standard and that clients expect the very highest impartial and unbiased professional service.

Damp

The incorrect diagnosis of damp is perhaps the biggest area of concern to period property owners in the UK.

For worried property purchasers, problems are compounded by advice commonly given by surveyors that a free-survey be
undertaken by a contractor thus passing the buck to a person who only gets paid if he can show that there is a need for work to be done.

Many properties which are said to have a "history of damp" are actually fine; past treatments have proved ineffective simply because either the problem being treated did not exist, or because the cause has been misdiagnosed.

For example, damp at the base of a wall can be caused by moisture descending unseen through the core of a wall until it reaches an impervious layer, such as a previously injected damp-proof course, forcing it to spread outwards.

Re-injecting a damp-proof course will not cure this problem. Likewise, a high reading on a "damp"-meter does not necessarily indicate damp since these meters measure electrical resistance not moisture content.

However, damp can be a real problem, and when viewing a period property there are some key areas which should be noted because they can cause or compound dampness:

Are the external ground levels higher than the internal floors? Has a concrete path been laid around the property? Has the exterior been covered in a new cement render?

In timber framed properties, purchasers should be wary of dampness causing sole plates to rot and rotate, leading to stud walls to slope outwards and floor joists becoming unstable, while any potential owner of an earth building such as cob or clay lump should be aware that cement renders can trap excessive moisture levels
within the walls, leading to the wall's total failure in extreme cases.

Another area of particular concern is traditional brick, pamments or flagstone floors which have been laid directly onto earth

and are perceived to be a source of damp.

Non-specialist consultants may well recommend lifting such floors to construct a standard modern concrete floor incorporating a plastic damp-proof course. Yetoften all that is required is to remove the impervious floor coverings such as lino as, once these are removed, traditional floors tend to dry out and thereafter present very few problems.

In contrast, constructing an impervious concrete floor which does not breathe can result in moisture concentrations in adjacent walls. Similarly, modern impervious finishes and sealers often used on floors and masonry walls only exacerbate problems elsewhere, by not allowing moisture to escape through the fabric of the building, and can cause the treated surface to flake and spall.

Wood Boring Insects and Timber Decay

Show me a period house without a history of insect attack! Do not be deceived by the findings of a free survey from a company specialising in rot eradication: extensive replacement of original fabric and chemical spraying is rarely needed.

So, take advice from an independent expert such as a surveyor or architect before taking drastic action.

He or she will be able to establish whether the infestation is still active. If action is necessary, it is possible that adjusting environmental conditions in the property - increasing natural ventilation, for example - could cause the infestation to die out naturally, saving you expensive and needless repairs and treatments, as well as avoiding unnecessary fears about what effect these toxic chemicals and solvents might
have on your family's health.