Some of the wettest basements we've seen
Two apartments in a mill conversion adjacent to a river
The original floor construction was very thin (weak), yet had received mastic asphalt tanking
When water pressure came to bear, the space flooded significantly resulting in a claim for NHBC insurance
Trace designed a combined protection waterproofing system using internal tanking and cavity drainage
Work included fully renewing the floor structure with a reinforced concrete slab
Work undertaken in 2015 and dry ever since
Because of the extent of water accessing the space, we sought to block water out in the first instance via Type A tanking. Any internally applied barrier tanking system, has to hold back water pressure, the structure which receives the tanking must also be capable of absorbing these pressures.
In this case it meant a replacement floor slab in reinforced concrete, the walls were already sunstantial with this being a large mill.
The walls were stone and to ensure a good key/bond between the tanking and the walls, we raked out the mortar beds and installed 3:1 render, correctly batched and cured, also using cem-1 cement which has a much higher cement content that what you would buy from your local builders merchants.
The render then received a spray applied polymer modified cementitious tanking system.
The new floor slab was treated with a post applied crystalline slurry which migrates into the concrete and functions like a waterproofing admixture.
Type C Cavity Drainage
Internal of the Type A Tanking, we installed a Type C cavity drainage waterproofing system, which would deal with any water bypassing the tanking. Fixing details through the tanking were avoided, and because of known issue with power outage, we installed battery back-up and generators configured to recharge the batteries when they reach a set stage of depletion (avoids the generator having to turn off/on every time a pump turns on.