Client: Architect, Ridge and Partners
Our client tasked Timberwise with completing rising damp treatment on a rural property in Oxford. The survey was requested due to a suspected case of black mould in several rooms on the ground floor. This property was a large, detached farmhouse of a solid brick construction, and was both occupied and fully furnished at the time of our inspection. The weather was overcast and damp.
Challenges
Our inspection was restricted by the fixtures and fittings within the home. Items such as fitted units, tiled walls, and furniture can all limit access to certain areas of a property, making it difficult to create a complete picture of a damp or condensation issue. Thankfully, this is also quite common in furnished properties, and our surveyor called upon their years of experience to work around this concern and ensure a thorough and accurate inspection was conducted for our client.
Observations
Our inspection began with an assessment of the exterior of the property. Our surveyor noted three potential defects: Vegetation within the guttering, an area of missing stonework, and an abutting wall, all on the front elevation of the farmhouse. All of these can be factors in penetrating damp, where an external defect allows water to ingress into a property. As the property was of a considerable age, this is likely down to wear and tear or a lack of maintenance. However, penetrating damp can also be a consideration if a new installation is present: Something as simple as installing a hanging planter on a wall can create an opening where water can enter if it’s not installed correctly or if the correct materials aren’t used.
A further inspection of the property also yielded a further concern. Our surveyor could not confirm if a Damp Proof Course (DPC) was present due to the stonework pointing, which had covered the expected line of the DPC. It is not uncommon for older buildings to have a slate or bitumen DPC, both water-resistant materials used to combat the possibility of rising damp. Some older buildings do not even have a DPC, and instead relied on the inhabitants heating or ventilating a property to control the moisture levels within.
Moving inside the property, our surveyor found the results of the damp concerns identified outside the property. A large amount of black spot mould growth was present in several ground floor areas. This was likely caused by cyclic damp, most likely due to condensation build-up over time. The property was found to have adequate passive ventilation, but mechanical ventilation was present but old, and identified as a likely reason for moisture building up within the ground floor rooms.
Our surveyor conducted a further examination of the walls with an electronic conductivity meter. These meters do not provide a true measurement of moisture in plaster or masonry, but can indicate where damp is present. With this, our surveyor was able to establish moisture profiles in several sections of the ground floor, suggesting the presence of rising damp.
Differing from penetrating damp, rising damp is the result of moisture rising from floor level through capillaries in plaster or masonry. This moisture often surfaces on walls in the form of damp patches or tide marks on lower sections of plaster. Rising damp may occur when water levels rise beyond a certain level outside, or if damp bridges a DPC through materials in contact with the ground, such as external render. In this case, our client confirmed that recent flood water had been a contributing factor in the damp, and had likely broken down the existing DPC due to the excessive ingress of water within a short period.
Rising damp also carries with it the risk of further damage. Several sections of the wall had areas of bubbling or peeling plaster. These areas reveal where damp rises to the wall’s surface, causing the plaster to fail. This damp also carries with it salts from groundwater. Over time, these salt deposits remain in the wall when moisture evaporates. When more moisture enters the atmosphere, the salts attract it back into the wall. Over time, this cyclic behaviour weakens the plaster to the point where it can blister or even fall off the wall.
Solutions
Given the age and current condition of the property, our surveyor designed a solution to both remedy the current damp issues and provide relief from the atmospheric damp currently invading the property.
First, our technicians removed all damp-affected plaster. This would not only provide the ideal base to rejuvenate the property from, but also ensured the removal of any historic salts. As a result, no further moisture would be drawn into the walls once work had finished on the ground floor rooms.
Next, our technicians installed a new DryTek DPC solution. This involves drilling into the mortar between the stonework, horizontally and just above the floor level. A water-resistant cream was then injected into these holes, creating an impermeable barrier that stops damp from rising through a wall. With the inconclusive presence of a DPC or the likelihood of an existing DPC having previously failed from flood damage, this provided ideal remediation and ensure the protection of our client’s property.
However, just installing a new DPC would not be enough if flooding were to occur in future. Therefore, our technicians also installed a damp proof membrane on the walls most at risk of future flood damage. When combined with a gulley at the base of the wall, this would prevent any future floodwater ingress, instead running off the membrane and being either pumped away or drained into the property’s existing wastewater channels. In areas where the risk was considerably lower, a plaster slurry would provide adequate waterproofing and protection alongside the newly installed DPC.
Finally, the walls were finished with a salt-retardant specification plaster. Unlike historic plasters, our specification would not allow salts to gather within the plaster, ensuring that cyclic damp would not cause the plaster to fail once completed. Our surveyor also recommended upgrading the existing extraction units within the property, as this would help to prevent condensation issues such as black mould from reoccurring.
Results
Our client was delighted with the results from Timberwise’s surveyor and technicians. They were impressed by the agility displayed by our surveyor when asked to amend the proposed plan to suit their needs, and were overjoyed with the results. The finalised remediations protected as much of the original building as possible without the need for extensive remodelling. Our client was satisfied with the result, and had peace of mind that their renovation would be safe from the onset of damp-related concerns in the future.
Do You Want Help with a Rising Damp Solution?
Our dedicated and experienced team in Oxford are ready to talk to you about your options for property preservation. Don’t hesitate to call us on 01865 389 720, or you can request a survey online.
