Overview

The client was replacing an above-ground-level pool house with a below-ground one. The brief included a plant room (servicing the main pool and hot tub), WC and changing area.

Delta Registered Installer, Dryside Ltd, was appointed as the waterproofing specialist to collaborate with Palladium Homes to provide a reliable, watertight solution for the reinforced concrete structure.

The water table was identified at around 1.8-2m below the finish ground level. Sub-soil conditions were clay, so a perched water table with variable heights was anticipated.

The Waterproofing Design Stage was between May and Dec 2021 and designed to BS 8102:2009, the British Standard for the protection of structures against water from the ground, Grade 3 (no dampness or water penetration acceptable).

Attention to detail is critical when designing a robust waterproofing approach. Working with the ground works team, Dryside was able to ensure all construction joints and service entry points were sealed to a high standard.

Throughout the project, Dryside was onsite and able to amend and modify the waterproofing approach to achieve the client’s requirements.

Methodology

After its site inspections, Dryside recommended a combined Type A and Type C waterproofing solution. Combined waterproofing systems can offer optimal structural protection against water ingress.

Installation of Delta Type A external drainage was specified as a primary waterproofing solution. Due to the known water table, this would function as the first line of defence. Dryside started alongside the ground workers on site in Jan 2022, during the construction phase.

Dryside proposed incorporating a Delta Type C cavity drained system including basement drainage to ensure the structure would be watertight for its life-cycle.

Koster NB 4000 is a hybrid product that combines the properties of a polymer modified bitumen sealant and a flexible mineral waterproofing slurry which was applied over the concrete, further protected by Delta Geo Drain Quattro, a drainage and protection membrane, which was flashed in and buried just below external ground level. Dryside preferred Koster NB 4000 for its ease of application and versatility to work alongside Koster NB 1 as the first coat.

The internal Type C system was a standard installation, with modular drainage to the sump. Dryside added a provision to mitigate a flood from the pool room plant, including an extra incorporated floor drain.

4m² external area of the stairs was incorporated into the specification for ground water sump pump chambers, ensuring the entire area was specified correctly.

Once the construction was complete with third-party finishing contractors undertaking dry lining and finishings, Dryside returned to site to install the pumps and commission the basement drainage system.

Products used

  • Delta Geo-Drain Quattro

  • Delta MS 500

  • Delta MS 20

  • Koster Polysil TG 500

  • Koster Repair Mortar Plus

  • Koster KB Flex

  • Koster NB 1

  • Koster NB 4000

  • Delta Qwik-seal plugs

  • Delta Corner strip and double-sided tape

  • Delta V3 Ground Water Sump

  • Delta V3 Foul Water Sump

  • Delta High Level Alarms

  • Delta Battery Backups

Outcome

The project was delivered on time and to budget.

The client was delighted with Dryside Limited’s ability to collaborate with the groundwork team throughout the build process. Establishing collaborative practices ensured the smooth running of the project and offered a robust detailed approach.