Our client, a construction firm in Kincraig, Perthshire, tasked Timberwise with inspecting the drawings of the basement in order to provide a design and recommendations for a waterproofing system to protect against water ingress. This property had a basement of poured concrete construction and was both unoccupied and unfurnished at the time of our inspection and throughout our construction of the solution.
Challenges
As far as challenges on this project are concerned, there were no immediate issues concerning stored items, fittings, or residents, as it was an unoccupied property that was getting ready for conversion and reconstruction. However, the area was an active building site, so we had to be mindful of other work happening, other people, and our own staff and equipment.
Other main challenges include having to design and develop a full waterproofing system that is compliant with BS8102:2022 Grade 3 performance levels. Grade 3 is the highest level for below-ground waterproofing, which requires a completely dry space which is crucial for inhabitable sub-level spaces.
To achieve this, we had to consider the potential hydrostatic pressure from changing water tables, localised flooding, or blocked drainage systems. What was also important was that the system needed to work with the client’s pre-existing Type B waterproofing concrete installation, without damaging it during construction.
Observations
This project involved waterproofing a new-build basement structure, which included a raft foundation and retaining walls. Inspection was conducted on architectural drawings to develop a compliant waterproofing strategy. A Type A (Barrier Protection) waterproofing solution was identified as the necessary complement to the Type B structure to achieve the required grade of protection, creating an effective combination waterproofing solution.
Solutions
To prepare the area for waterproofing, we installed a Koster KSK SY15 membrane to the affected area’s concrete blinding, re-applying where necessary. We then applied a Koster KBE liquid film, which acts as a sealing compound.
For the structural element of the project, we installed a Koster Quellband Waterbar after the pouring of the appropriate structures. The Waterbar is essentially a swellable joint tape which helps to prevent swelling in structures and acts as a waterstop in concrete construction joints.
We then set on the external tanking and finishing of the project. We applied two coats of Deuxan 2C to the external retaining walls. Deuxan 2C is a bitumen thick film sealant that is used for waterproofing solutions. We then incorporated a reinforcement of a glass fibre mesh into the first coat of tanking, which increased the thickness of the solution to 6mm. We then installed a Delta Geodrain Quattro protection board over the tanking coating.
For the drainage side of the solution, we created a specification for an external land drain which sat below the raft foundation which was linked to a maintainable drainage system. We also advised the client to complete regular maintenance and servicing of their pump system to ensure it is working correctly.
Results
Timberwise successfully designed and installed a Grade 3 waterproofing system that was fully compliant with BS8102:2022 standards, overseen by a CSSW (Certified Surveyor in Structural Waterproofing) qualified surveyor. We provided our client with a 10-year guarantee covering the waterproofing system and workmanship.
Do You Want Help with a Waterproofing Solution?
Our dedicated and experienced team in Perth are ready to talk to you about your options for property preservation. Don’t hesitate to call us on 0800 288 8660, or you can request a survey online.
