Our client for this project was a construction firm based in Fulham, London. They requested Timberwise to complete a survey on a property due to problems associated with damp. Our surveyor found that immediate attention was required for the abutting structures and walls and external ground levels.
It was also noted that it wasn’t immediately apparent if there was a damp proof course. The property was a commercial property of solid brick construction and was both unoccupied and unfurnished at the time of our inspection. The weather conditions were overcast but dry.
Challenges
Our inspection was restricted to the ground floor rooms and areas only, as per the request of the client. During our inspection, we were unable to establish the presence of an existing damp proof course (DPC) and advised the client to have it assessed by a third party. The potential sources of the moisture were complex enough that rising damp could not have been completely ruled out until other environmental factors were controlled.
Another challenge to contend with was that the building was actively under construction. As such, we had to be mindful of other workers and equipment and ensure everything was completed safely and mindfully.
Observations
We found that the property was suffering from lateral damp penetration. Often referred to as penetrating damp, it is the process of water moving horizontally from outside the property into the interior walls. This was due to an external wall abutting from the rear elevation. We had also noted that the high external ground levels that were relative to the internal floors situated at the rear elevation were also causing the lateral penetration of ground moisture.
We identified the cause of the moisture due to the fact that the rear elevation wall was an earth-retaining structure that had been built onto the back of adjoining gardens of surrounding properties. We also noted that the electronic meter readings confirmed exceptionally high moisture levels in the lower sections of the rear wall.
We noticed the presence of bridging plaster in the rear wall areas, which was also likely to cause water penetration, as the bridging backing coat render and plaster was not in contact with the floor. Damp migration and some spotted were found on the internal painted brickwork, despite previous owners’ attempting to seal the walls with a liquid membrane. Overall, the dampness appeared to be a direct result from penetrating damp rather than due to free-flowing water. Due to the presence of other moisture sources, we could not completely rule out the presence of rising damp until these factors have been brought under control and a suitable drying period has taken place. We took damp readings with a non-intrusive conductivity meter.
Solutions
We began by securing the designated work area by using dust sheets and hardboard raped to the floor. We also applied polythene sheeting over any remaining large fixtures. As the property was unoccupied and unfurnished, there weren’t any additional preparatory measures in this regard.
Our goal was to provide the client with a wall cavity drain membrane to manage water penetrating through to the brickwork. For the waterproofing solution, we sourced and installed an 8mm air gap membrane lining system to the face of the rear elevation wall. This membrane contained air glow gaps at the top and the bottom of the membrane installation. We would then apply a 3mm mesh membrane, before applying the area with a HydraDRY tanking slurry, which acts as a strong waterproof barrier for walls and floors.
Completion of the project was finished with the installation of timber battens which we affixed directly onto the face of the membrane. We then secured new plasterboard to this timber framing. We then applied a final skim plaster coat over the new boards.
Results
We provided the client with a thorough specialist survey that helped them to identify structural defects in the property and what has been causing the damp issues. We delivered a successful remediation strategy that tackled the lateral penetration the building was suffering from due to the earth retaining walls. We also used a DryTek Finishing System which will manage moisture and salt migration.
Do You Want Help with a Waterproofing Solution?
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