Client: Domestic
Our client, a homeowner in Cardiff, contacted Timberwise to consult on the condition of their new property. This property was a basement-level flat and of a solid brick construction. The property had some historic signs of both damp and condensation damage, resulting in the spread of black spot mould in some areas.
The property was unoccupied and unfurnished at the time of our inspection, and the weather was sunny and warm. We were not limited to any specific areas of the property during our inspection, meaning that our surveyor could diagnose the full extent of moisture damage within the property, as well as the contributing factors.
Observations
Our surveyor began by inspecting the external areas of the property, which highlighted several concerns. Primarily, the external ground levels were higher than the interior floor in the entrance hallway. This can cause moisture to pool, and if given an ideal path, allow it to penetrate laterally into the flat. There was a small grate at both the front and rear of the property where this water could drain away, but without further damp-proof measures, this would not be enough to solve the concerns.
Our surveyor’s fears were compounded upon examining the external walls. Here, it was confirmed that the render was in contact with the ground. As render is more permeable than masonry, this allows a direct route for water to ingress into the wall and bridge over a Damp-Proof Course. This is also known as rising damp. They also found that the paint applied to the render was flaking and debonding in some areas, which would contribute to damp ingress within the property.
In addition to the risks associated with rising damp, our surveyor also noticed areas of potential penetrating damp. Primarily, an external wall was abutting the rear elevation, and there were also areas of vegetation growth outside of the property. Penetrating damp occurs when moisture finds its way into the property through an external defect. In this case, both the abutting wall and the vegetation were likely to be penetrating the rear walls in some form, and as such were allowing moisture an easy path into the home.
The results of this damp ingress were clear to see inside the property. High humidity levels were present throughout, with an average of 58-64%. This isn’t too far from the ideal humidity range of 50-55%, but even a small difference in how humidity is handled can have vast differences in the outcomes. High humidity is one of the major factors in how both mould and rot grows, and this was evidenced by a case of black mould in the skirting boards near the rear entrance of the property. The contributing moisture was likely down to the bridging render and high ground levels identified outside the property.
Another factor in mould and rot growth is ventilation. Though this property was found to have adequate extraction units, there was a lack of passive ventilation such as trickle vents on windows or passive vents in the walls. Mechanical ventilation is ideal for extracting moisture when undertaking moisture-generating activities like cooking or showering, but often these units are only turned on during those activities. Without accompanying passive ventilation, any remaining moisture is retained within the property. Our Condensation Control page has helpful tips on how to actively and passively reduce moisture retention within your property.
With this contributing moisture in mind, our surveyor also used a conductivity meter to assess the moisture content of the walls, and found high levels within the plaster and skirting boards. Though conductivity meters only give an indication of moisture content on masonry or plaster, they can be useful for creating a map of damp spots, or moisture profiles, to help diagnose a case of damp within a property. They do give a true indication of moisture in timber, and are ideal for assessing the moisture content of skirting boards, joists, and floorboards.
Assessing each of these readings, out surveyor concluded that not only were the rising and penetrating damp factors prevalent, the method of interior plastering had also contributed to the continued damp environment within the property. The interior walls were plastered using a dot and dab method using a gypsum-based plaster. This plaster is very absorbent, and when in direct contact with masonry draws moisture to the finished surface, leaving behind salts in the plaster. These salts then draw in more moisture as it accumulates. This cycle of moisture retention and drying causes the plaster to weaken, bubbling and eventually chipping away.
Solutions
Considering the information gathered during their thorough survey, our surveyor recommended damp repairs that would not only remedy the current humid conditions of the property, but also reduce the possibility of a recurrence in the future. However, considering all the overlapping factors, they also recommended a further resurvey upon completion of the work to ensure that all contributing factors were caught and actioned successfully.
First, our technicians removed the existing plaster in most of the property. This plaster was not of a salt-resistant specification, and the presence of historic salts would only allow moisture to remain within the property long-term, causing further mould to propagate.
Once removed, our technicians installed a new Damp-Proof Course in areas where the external ground level were high compared to the interior floor. This involved injecting a gel into the mortar joint just above floor level and at regular intervals. This gel creates a barrier that prevents water from rising above it, ensuring that rising damp would not be a factor once the remediations were completed.
Next, our technicians installed a wall cavity drain membrane on top of the exposed masonry. This membrane provides a waterproof barrier where moisture runs off instead of through a finished wall. This water then collects in a gulley at the base of the wall and drains away. This method provides a complete waterproof solution for the property, and would not allow moisture to ingress and cause any damage to the newly finished walls once completed. You can find more about this and other methods we use on our Basement Waterproofing page.
Once the waterproof membrane was installed, a final coat of plaster with a salt-retardant specification was applied to each wall. This provided the ideal finish to combat humid conditions of the property, and would ensure that salts could not collect in the walls from atmospheric moisture. Combined with moisture control from mechanical ventilation already present, this was the ideal finish for the customer to decorate once the plaster had completely dried.
Results
Our client was delighted with the standard of our work, praising both our surveyor’s thorough diagnosis and design, and our technicians’ clean and efficient damp repair work. Our combined team provided the ideal solution for our client, and once implemented, ensured that the customer’s new property was guaranteed to be free of damp for the foreseeable future.
Our client also had peace of mind that should any other damp issues present themselves, they knew who to turn to. They could now look forward to living in their property and decorating it to their taste without fear of damp damaging the final look of their home.
Do You Want Help with a Basement Waterproofing Solution?
Our dedicated and experienced team in Canterbury are ready to talk to you about your options for property preservation. Don’t hesitate to call us on 02920 290 558, or you can request a survey online.
