Client: Domestic
Our client, a homeowner in Chepstow, contracted Timberwise to design and install a waterproofing solution to protect their lower ground floor of their property from water ingress. This property was a semi-detached house of concrete construction, and was both occupied and furnished at the time of our inspection. The weather conditions were overcast but dry.
Challenges
As the lower floor of the property was built partially into a hillside, it was essential to plan this solution around the risks of hydrostatic pressure behind the wall, such as from changing water tables and heavy rainfall. Hydrostatic pressure will increase due to high water levels, and can cause defects to form in masonry over extended periods.
As an additional concern, there was an area of vulnerability between the wall and floor junction on the upper floor where the potential for water ingress was greater. Leaving this area exposed could allow water to penetrate, putting the ceiling and floorboards at risk.
Observations
Our surveyor first assessed the current condition of the property to identify any defects that may be contributing to the internal condition of the property. However, they found no obvious defects to the property’s structure, and continued their inspection inside the property.
Internally, the client’s property was currently undergoing renovations, and the bathroom had been stripped back to reveal the concrete floor and walls. Our surveyor identified a previous damp proof membrane that had been installed on the walls. However, the membrane had been punctured by the timber framing installed on top of it, rendering it ineffective at preventing water ingress.
While the basement was dry during our inspection, and the previous plasterboard had been removed, some evidence of damp remained. The membrane was stained in several areas where the timber frame has been installed, and some damp staining was evident at the base of the wall and on the concrete floor.
In the adjacent bedroom, our surveyor identified no current evidence of water ingress. However, remedying one section of the wall and not the other might encourage the water to ingress through the easier path, eventually showing through on the walls as it had in the bathroom prior to our client’s renovations.
Our surveyor finally assessed the ventilation methods used in both rooms. As the bathroom already had mechanical ventilation, and wall vents were present in both rooms, our surveyor concluded that the rooms were likely capable of removing any atmospheric moisture once the renovations were completed.
Solutions
Having assessed the property, our surveyor believed that the lower floor required a full Type C waterproofing system to manage water ingress within the property. Unlike the previous method used in the property, a Type C waterproofing method allows moisture to pass through the wall rather than preventing it. This moisture is then diverted into a channel at the base of the wall with a cavity drain membrane, which is then pumped away.
The advantages of a Type C solution would prevent hydrostatic pressure from building behind the wall. This would reduce the likelihood of defects forming within the wall. Even if a defect were to form, the membrane would divert any residual water away, preventing it from showing through the plasterboard walls as it had previously. A Type C waterproofing system also conforms with BS8102 waterproofing regulations, ensuring that any solutions are designed with existing defects and challenges in mind.
To install the system, our technicians first removed the failed damp proof membrane from the walls. In the bedroom, this also meant removing the existing plasterboard and laminate flooring.
Once cleared, our technicians applied an anti-lime coating to the concrete walls and floors. This would provide an additional layer of protection behind the new membrane, preventing water from flowing through in large amounts and overloading the pump in heavy rainfall. Our technicians then dug a channel in the basement floor at the base of each wall to collect any water ingress.
Next, our technicians installed the new cavity drainage membrane to both the walls and floor, with an overlapping joint at the base of each wall. Unlike the previous flexible plastic sheeting, this membrane is much sturdier, and used a series of plugs with gasket seals. These plugs also allow for either a plasterboard or plaster screed finish without penetrating the membrane, preventing moisture from penetrating the membrane and showing on the walls.
Once the membrane was secured, our technicians installed a sump chamber in the corner of each room. Any future water ingress would collect in either chamber, which would then be pumped off site through the existing wastewater system. Once installed, these pumps were tested to ensure they were functioning, and fitted with an alarm system to warn our client in the event of a fault or failure.
Results
Our client was delighted with the work of both our surveyor and technicians. They were happy that our expert team worked with them, and provided a system that allowed them to continue renovating the property without fear of water ingress in the future. They were also satisfied by our surveyor’s knowledge of maintaining the system once it was installed, providing peace of mind whenever inspection or testing would be required in future.
Do You Want Help with a Basement Waterproofing Solution?
Our dedicated and experienced team in Bristol are ready to talk to you about your options for property preservation. Don’t hesitate to call us on 0117 322 4938, or you can request a survey online.
