At the first sign of a damp problem in a home, the initial response is often to identify the cause of the damp (rising or penetrating) and then implement the appropriate measures. While a damp proof course can offer limited benefits for certain situations, this isn’t a catch-all solution for all damp problems.
Many companies have turned a quick profit on the popularity of the injectable chemical damp proof course, often recommending this without sufficient exploration into the origins of the damp problem. If the DPC is implemented in a cavity wall that hasn’t sufficiently dried out, then it could be rendered useless. The cosmetic problems are covered up and the damp problem continues.
A better solution to damp proofing a property against rising damp would be to properly investigate the origins of the damp. The causes of damp are not always straightforward and simple. It takes an expert with extensive experience to be able to make links between the evidence and provide an actionable plan.
In this guide, we’re looking at some of the common causes of damp and potential treatment options beyond the obvious damp proof course. Added insight into the process of addressing damp problems will result in improved outcomes for residents struggling with moisture ingress in their homes.
What causes rising damp?
There is a common misconception that a faulty damp proof course is the only cause of rising damp. While this is one factor that might contribute to rising damp, it’s not the only issue to consider. There are other construction and maintenance factors that should be explored before assuming that the damp proof course is the only possible issue.
It’s also not uncommon for other sources of damp to be misattributed to rising damp. This could lead homeowners to address the wrong problem and ultimately continue living in a damp home.
One of the signs that homeowners will look for when diagnosing rising damp is the “tide mark”. This is something referred to as a water line. It occurs when moisture dissolves soluble salts in building materials. The moisture evaporates into the air, leaving a darkened deposit of salts on internal walls.
While rising damp is often to blame, it’s not the only cause of moisture buildup and salt deposits. Poor ventilation in the home can lead to the same outcome. These tide marks can also remain, long after the original moisture ingress has resolved.
The most common cause of moisture ingress into homes is not from rising damp due to a faulty damp proof course, but from poor ventilation and drainage around the home. The use of concrete finishes around homes along with absent drainage slopes can direct excess moisture towards the property, leaving it with nowhere to go.
Drainage, ventilation and damp
Modern homes are designed to offer ventilation through multiple sources, and this helps to prevent moisture build up in the home. Homes should also be constructed with proper drainage in mind. Groundwater is often more likely to blame for damp that looks like rising damp.
Moisture reservoirs can occur in properties and this will be counterproductive to the aims of keeping your home dry and warm. Common moisture reservoirs include:
- Undrained ground
- Builders rubble under foundations
- Thick walls
- Mass masonry
These can all be managed with adequate ventilation, but issues may arise if these measures fail. It’s often not a single solution that will help to bring your damp problem under control, but a combination of solutions that support your aims.
Even something as simple as excess condensation in your home can lead to the appearance of rising damp. This can occur when moist air in the home condenses on to cold surfaces, which are usually close to the ground on external walls. If there are hygroscopic salt deposits already on your walls, this can further aggravate the issue, leading to cyclical efflorescence.
While we’re looking for issues in the construction of a property, it’s also possible that the cause of the excess moisture could be the result of a plumbing issue or a broken roof tile. Rather than jumping to conclusions and assuming that rising damp could only be from a faulty damp proof course, it’s a good idea to explore all of the options.
Treatment for rising damp
Rather than jumping straight to a chemical injection barrier as the only possible solution, it’s worth exploring a few different possibilities to help address a damp problem. Getting to the true cause of the problem will deliver improved outcomes and reduce the need for follow-up treatment. Here are just some of the potential treatments for rising damp in the home.
Assess external drainage
Draining around your home is an essential part of keeping your home dry and warm. Modern building techniques often neglect some of the simplest methods for preventing rising damp. French drains are a popular method for preventing moisture build up around the home, but without maintenance or proper construction, they can actually make the issue worse.
The use of materials like concrete and sand at the base of external walls can lead to poor draining that has nowhere to go but inside. They also prevent moisture from evaporating from this area, allowing it to become trapped in the home.
Review ventilation methods
Ventilation refers to more than just windows, doors and extraction fans. Under-floor ventilation, dry lining in walls, roof ventilation, eaves ventilation and chimney ventilation all work together to ensure moisture can evaporate from the home. Before assuming that a new damp proof course is in order, it’s worth checking that these methods are present and functioning.
Damp proof course repair
When there is clear evidence of a faulty damp proof course, rather than resort to replacing the entire DPC, this can be repaired locally. This can be achieved by “cutting in” a new layer of damp proof materials at the failure site, rather than repeating the chemical injection throughout the entire masonry.
There is a far greater risk for further complications when the masonry is repeatedly drilled for this chemical injection process – and this is particularly true when carried out by an inexperienced or untrained individual.
Physical barriers are often more beneficial than chemical barriers and will be less susceptible to failure. An expert can advise on how to use physical barriers to prevent damp, and also how to isolate remaining materials (which may remain damp for some time) to avoid the appearance of the problem returning.
Final thoughts on damp causes and treatment
It’s tempting to diagnose all tide marks and salt deposits as the result of a failed damp proof course, but the reality is often much more complex. Before shelling out for a new damp proof course (which could be ineffective in materials that are already damp and saturated) consider the other potential causes that might be contributing to this issue.
The solution might require a number of interventions, as the origin of the problem might be more complex than first thought. Working with a trained and experienced professional to address the damp problem in your home will put you in the best possible position to eradicate damp and prevent further damage from excess moisture in your property.