Client: Construction Firm
Our client, a construction firm in Edinburgh, enlisted Timberwise with surveying their property to provide a lift tanking solution to protect against water ingress. A lift pit is a recessed area underneath a lift shaft, which provides a gap for the lift car and mechanism when the elevator reaches the bottom floor. We had to design a solution that would be able to withstand wear and tear and still remain watertight
The property was a commercial building, made of brick and concrete. It was under construction, and therefore it was unoccupied and unfurnished. The weather conditions during the time of assessment were not recorded as they were not relevant to this particular case as it is a construction rather than a remediation of persisting issues.
Challenges
This project presented us with a number of interesting challenges. A key requirement was for us to achieve a Grade 2 waterproofing protection level in accordance with BS 8102:2022. BS 8102:2022 is the UK’s standardised practice for protecting below-ground structures such as lift pits from water ingress.
It offers guidance on how to effectively design and construct systems that prevent groundwater and surface water from entering structures below ground level. In the construction and waterproofing industry, it’s often considered the key standard for basement waterproofing design. BS 8101:2022 is a comprehensive piece of legislation that covers site investigation, construction detailing, waterproof design and risk assessment, and any maintenance and repair considerations. It also covers the selection of waterproofing systems that are deemed appropriate depending on what it needs to be waterproof, such as lift pits, basements, and so on.
With that in mind, we also had to account for potential hydrostatic pressure that could result from changing water tables, localised flooding, or instances of heavy rain. A key thing to contend with was managing the risk of water entry through vulnerable wall-to-slab junctions and potential voids behind brickwork. We also had to design the system to be able to accommodate micro-movements and hairline cracks caused by lift vibrations to ensure that our system would not sustain damage and become susceptible to moisture infiltrating.
Observations
Our inspection and proposed works for this project were solely limited to the lift pit. The lift pit structure consists of brickwork walls and a concrete slab base. Internal surfaces, we noted, would require significant preparation to remove paint, debris, and friable materials that could hinder the waterproofing’s effectiveness. The lift was in a fairly sheltered part of the building, but care would still need to be taken when assessing how water and damp could infiltrate, and making sure the area remained dry during installation.
Solutions
Timberwise set to work on designing and installing a waterproofing system that would conform to BS 8102:2022 regulations. Preparatory works prior to installation included grinding and preparing brick walls to remove paint and friable material in order to prepare the slab base surface for work.
For the waterproofing system, we drilled and injected resin into the construction joints at the wall-to-base junction to fill voids and reduce moisture entering through any gaps and weakening the structure over time. We then applied Koster Polysill TG500 anti-lime coating to all concrete and brick surfaces, before forming a 45-degree concave fillet using Koster Repair Mortar Plus at the wall-to-floor junction which sealed the vulnerable area. After that was completed, we applied a 6mm thick Koster NB1 Grey crystalline slurry as the primary waterproofing layer up to damp proof course (DPC) level. Kosters NB1 is a slurry system with crystallising and capillary-plugging agents. We then applied a further two coats of Koster NB1 Elastic Grey at a 2.5mm thickness to provide a flexible seal against vibrations and micro-movements.
Results
We successfully delivered an installation of a Grade 2 waterproofing system for our client, which is fully compliant with the BS 8102:2022 code of practice for below-ground structures. The tanking system we installed also comes with a 10-year guarantee, ensuring long term peace of mind for the client. The client was pleased with the results.
Do You Want Help with a Waterproofing Solution?
Our dedicated and experienced team in Edinburgh are ready to talk to you about your options for property preservation. Don’t hesitate to call us on 0131 278 3583, or you can request a survey online.
