The Damptec team has recently finished work on an existing barn being converted into 2 habitable dwellings. We were asked to determine a viable tanking/dampproofing solution for the walls and R/C floors.
We recommended installing a cavity drain membrane on the ground floor walls and floor. Any water ingress would fall into a maintainable channel and be managed out of the property via gravity.
The waterproofing solution is defined in “BS: 8102 2022 Protection of Structures against Water from the Ground” as a “Grade 3” environment where no dampness is permitted and where the internal environment needs to be managed using appropriate environmental controls.
Type C Waterproofing System (drained protection)
This system allows water to enter into the building as it would normally, therefore not changing the dynamics of the structure. It is commonly called a cavity drain system as the waterproofing membrane is dimpled and therefore creates a cavity which allows water to run behind it leading to a concealed drainage system which then leads to a point of removal. The cavity drain system is installed from the DPC down.
The system is maintainable and therefore offers long term protection to comply with BS 8102: 2022.
PROPOSAL AND SPECIFICATION
Internal Waterproofing
Drainage
The effectiveness of the waterproofing system is dependent upon discharging free water before pressure can build up behind the system. The system in this instance drains via gravity, exiting via a 50mm pipe at the front of the property.
- Access/Flushing points:
These are located at key periodic locations around the perimeter channel system to enable the system to be maintainable.
Wall Cavity Drain Membranes:
Walls: We mechanically fixed the 8mm cavity drain membrane and PT mesh cavity drain membrane to the earth-retaining walls (floor to ceiling) and non-earth retaining walls (to 1.2 m high)
Waterproofing the concrete slab:
Closed-cell thermal waterproof insulation board:
Newton Fibran XPS 500-C was placed below the Newton flooring membrane as a fully drained supporting spacer.
Floor membrane:
Newton 508 (8mm) eco floor membrane was installed over the insulation board in conjunction with cornerstrip.
