Knowing where to begin can be the hardest part of dealing with damp in an old building. This article explains how to prioritise repairs, avoid costly mistakes, and tackle problems in a logical order to achieve the greatest long-term benefit.
The starting point for many people who come to me is that they have become aware that their house has damp problems, but they are unsure how they should begin tackling them. Quite often they have already received conflicting advice from different trades or have spent time reading on the internet and have ended up more confused than when they started. This is something I encounter regularly when carrying out damp investigations in Cornwall, where traditional buildings vary enormously in their construction and exposure. What they are really looking for is a way to cut through the noise and establish sensible priorities.
In my experience, that is often the best position to be in. Most damp problems in old buildings have developed over many years. They are rarely emergencies and they are seldom caused by a single defect. More often, several relatively minor issues are acting together. The first step is not usually to repair the building. The first step is to understand it.
Understand Before Spending
It is surprisingly easy to spend a lot of money on the wrong thing. As with so many things in life, taking time to understand the problem before acting generally leads to better outcomes.
One of the difficulties with damp is that symptoms and causes are not always the same thing. Damp patches, mould growth and deteriorating plaster are symptoms. Even the visible defect itself may simply be another symptom. I frequently encounter buildings where failed render has been blamed for water ingress, only to discover that the render itself deteriorated because overflowing gutters or defective eaves details had been introducing excessive moisture for years. Replacing the render without addressing the underlying cause may improve matters for a time, but there is every chance that the same defects will gradually return.
Water rarely behaves in the neat and predictable way we would like. Symptoms may appear some distance from the source and one defect may quietly drive several others. Understanding how problems are linked together is often more valuable than immediately trying to repair the most obvious issue.
It is also worth remembering that most tradespeople naturally view problems through the lens of their own trade. A roofer may focus on roof details. A mason may focus on the render. A damp proofing contractor may focus on membranes or tanking. This is not because anybody is being dishonest. Proper diagnosis takes time and thought, and it is rarely economically realistic for a contractor to spend hours analysing a building before carrying out work. Buildings, unfortunately, do not separate themselves neatly into trades.
We live in an age where there is no shortage of information. The difficulty is no longer finding it, but deciding which sources deserve to be trusted. In my view, a good book from a reputable publisher explaining how old buildings deal with moisture is often more valuable than spending hours reading internet forums. The aim is not to become an expert. It is simply to gain enough understanding to avoid spending large sums of money in the wrong place.
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Manage the Living Environment While You Make a Plan
Major repairs can take time to organise, but there are often things that can be done immediately to make the building more comfortable and reduce the symptoms.
I tend to think of this as two related campaigns. One is reducing the moisture load the building is subject to. In other words, reducing the amount of water arriving at the building from outside. The other is managing humidity within the building itself. The two are closely linked, but they are not quite the same thing.
Even before external repairs are undertaken, or sometimes even before they are required, it is often possible to improve conditions indoors. A faulty bathroom extractor fan can contribute more moisture than people realise. Avoiding drying clothes indoors, using a dehumidifier and maintaining gentle and reasonably consistent heating can all help. Small changes in everyday habits often improve comfort while larger decisions are being made.
Ventilation helps too, although more ventilation is not always better. Throwing every window open may reduce humidity levels in the air, but it can also cool the walls in the process. Heavy walls respond much more slowly than the air around them, and colder wall surfaces may actually encourage condensation by increasing the temperature difference between the air and the wall surface. In many cases the aim is simply to create stable conditions and keep humidity at manageable levels while a longer-term plan is being developed.
Easy Wins Are Worth Taking
Something that is worth bearing in mind, particularly where budgets are limited, is that relatively modest interventions can sometimes make a surprisingly large difference. Not every problem needs an immediate or expensive solution.
If something is inexpensive, easy to do and has very little downside, it is often worth trying even if you are uncertain how much difference it will make. Clearing gutters, repairing damaged drain surrounds, extending downpipe discharge away from the building or reconnecting an extractor fan are all fairly simple jobs. They may not solve the whole problem, but they can often improve matters.
I frequently encounter buildings in Truro where deteriorating render, pointing or other external finishes on a sheltered elevation have convinced the owners that major remedial work is urgently required. In many cases the internal face of the wall is damp and it is easy to assume that the failing finish is responsible. However, it is not unusual to find that the finish itself has deteriorated because excessive moisture has been introduced from elsewhere, perhaps by defective gutters or poor eaves detailing. Since the wall itself is relatively sheltered, the finish may not actually be performing a particularly demanding weatherproofing role. Once the defects above are corrected, internal dampness often improves dramatically, even though the render or pointing may still look poor. The appearance can then be addressed when budget allows.
It is a useful reminder that the obvious problem is not always the problem that matters most. Cosmetic defects are not always urgent defects. Particularly where funds are limited, simple measures with little downside are often worth trying because the potential benefits can be surprisingly large.
Understand the Building as a System
Although a damp problem may begin with a single defect, it rarely stays that way. One issue often creates conditions which allow others to develop. A defective eaves detail may introduce water onto a rendered wall. The additional moisture causes the render to deteriorate, allowing more wind-driven rain to penetrate. Increased moisture levels may raise humidity within the building, encourage timber decay and eventually even contribute towards movement. What started as one relatively minor defect may gradually develop into several different problems. Damp problems rarely have a single cause, and they are rarely solved by dealing with one thing in isolation.
I often say that the devil is in the detail. The most expensive repair is not always the most important one, and large defects are not always responsible for the greatest damage. A small fault in a gutter, flashing or eaves detail may have more influence over the performance of a building than a large area of tired render or worn pointing.
Thinking about buildings as systems also helps explain why diagnosing and curing damp can sometimes be difficult. A chimney defect may reveal itself in a downstairs living room, particularly where an upstairs room has been dry lined and the symptoms have effectively been hidden. A drainage problem may appear as mould on an internal wall. One defect can exacerbate another and several relatively minor issues acting together may create symptoms which appear out of all proportion to the individual causes.
This is one reason why understanding cause and effect is often more valuable than simply reacting to symptoms. It is tempting to focus on the most visible problem, but successful repairs usually come from understanding how different parts of the building interact with each other.
I have also learned to be wary of what I sometimes think of as romantic repairs. French drains, complete re-rendering projects and wholesale repointing are all tangible and satisfying pieces of work. They look impressive and they feel decisive. Sometimes they are exactly what is needed. In many cases, however, smaller and less glamorous repairs hidden away in gutters, eaves and drainage details can have a greater effect on the long-term health of the building. The devil, as ever, is usually in the detail.
Cluster Related Remedial Work Items Together
When planning remedial works, it is generally worth thinking about how related items can be clustered together. Access equipment is expensive, and there is little sense in replacing render only to disturb it again a year later when windows, sills or rainwater goods are renewed. Grouping related work together makes better use of access and helps avoid paying twice for the same disruption.
Clustering work also tends to make projects more attractive and efficient for contractors. Many trades are perfectly capable of dealing with a range of related defects in one area, and having a written scope of work helps ensure that details are not missed or misunderstood. The aim is not simply to save money. It is also to avoid undoing completed work and to make sure that different repairs complement each other once the project is finished.
Act and Observe
One advantage homeowners have over consultants and contractors is that they live with the building every day. I may only see a property for a few hours and can only ever provide a snapshot in time. Occupants, on the other hand, observe how the building behaves over months and years. They know which wind direction brings problems, how rooms respond to different weather conditions and whether symptoms are improving or getting worse. In many ways, understanding a building is a partnership between professional knowledge and long-term observation.
This is one reason I generally prefer introducing the minimum number of variables that it is practical and economical to introduce. There is little sense in carrying out work twice and, if scaffolding is already in place, it makes perfect sense to deal with related items such as gutters, sills and render together. Equally, there is value in understanding what effect repairs are having. Making major changes to heating and ventilation, installing a French drain and stripping internal finishes all at the same time may eventually solve the problem, but it becomes difficult to know what has actually made the difference. Particularly where budgets are limited, it often makes sense to undertake a group of related works, observe the effect and then decide what should happen next. In that respect, damp diagnosis is often a gradual process rather than a single event.
Buildings also dry slowly. Damp staining, salts and mould do not disappear overnight and historic defects often leave evidence behind long after the original problem has been corrected. I frequently encounter situations where homeowners are keen to strip internal finishes immediately, when patience and observation would often provide more useful information. External defects frequently drive internal symptoms, and allowing the building time to respond can sometimes avoid unnecessary work.
In my experience, the most successful campaigns of damp remediation are rarely the result of one dramatic intervention. More often they are the result of a series of sensible decisions, made in the right order and reviewed over time.
Knowing Where to Stop
There is always another improvement that could be made to an old building. Ground levels alter, trees and vegetation grow and previous generations will often have left behind a mixture of old and new materials. In many cases there are dozens of desirable repairs, but far fewer that are genuinely necessary. Unless budgets are unlimited, the aim is not to achieve perfection. It is to understand the building, identify the issues contributing most to the symptoms being experienced and obtain the greatest benefit from the resources available.
The way buildings are occupied changes too. Many houses which were once heated by open fires experienced a high rate of air exchange simply as a consequence of the heating method. Today, the same buildings may be heated by radiators and occupied very differently. People generally wash more frequently, produce more moisture and expect a warmer and less draughty environment than previous generations. The building itself may not have changed greatly, but the conditions it is expected to perform under often have. This is particularly relevant in Cornwall, where many traditional buildings now provide levels of comfort and occupancy which would have been unfamiliar to their original occupants.
In my experience, damp problems are rarely caused by one thing and they are rarely solved by one thing either. The most successful programmes of remedial work are usually the result of a series of sensible decisions made over time. Sometimes complete cures are possible and sometimes management and compromise are the more realistic approach. Living with an old building has always involved understanding how it behaves and accepting that maintenance is part of the process. There will nearly always be another desirable improvement waiting in the wings, but that does not mean that it needs to be undertaken immediately.
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