What we do and do not undertake
This article is written as impartial guidance, because owners are regularly quoted one of these systems without being told why. It is not an offer of the work. Procure Group does not undertake full basement or cellar waterproofing installations. Our waterproofing work is limited to appropriate localised applications encountered as part of damp investigation and remediation — the base of a wall where ground sits against it, a floor-to-wall junction, a short below-ground return. Where a designed system to a whole below-ground room is what your property needs, we will say so and tell you to instruct a specialist who does that work every week.
Three forms of protection, not three grades
BS 8102:2022, the code of practice for protecting below-ground structures against water ingress, describes three forms of protection: Type A, barrier protection applied to the structure; Type B, protection integral to the structure itself; and Type C, drained protection that manages water which enters. They are strategies, not quality rankings, and the right one depends on the structure, the water and the use of the space.
Type A: resist the water at the face
A barrier system — cementitious multi-coat tanking, a liquid-applied membrane or a bonded sheet — resists water at the surface of the structure. It needs no power, has no moving parts and takes up very little space, which is why it suits the shallow depths where the water load is modest. What it depends on is a sound, properly prepared substrate and absolute continuity: water under pressure will find the half-metre that was not treated or the pipe penetration that was not detailed.
Type C: accept the water and manage it
Drained protection lines the structure with a studded membrane that holds a drainage void against the wall. Water entering the structure runs down that void into a perimeter channel and away to a gravity outfall or a sump and pump. Because nothing depends on bonding to dry masonry, it tolerates the friable, salt-laden and rubble-filled masonry that older solid walls so often turn out to be once the finishes come off.
What each one asks of you afterwards
A barrier system asks very little, provided it was correctly applied — but if it does fail, finding and repairing the breach behind finished surfaces is disruptive. A drained system asks for maintenance: channels rodded through inspection points, any sump chamber and pump checked and cleaned, the alarm tested, typically annually. At shallow depths a gravity discharge is sometimes available, which removes the dependence on power altogether.
How the choice is made
By assessing the water the structure faces, the condition and form of the structure, the consequence of any element underperforming, and the environment the finished space has to provide. A store and a habitable room justify different levels of protection. Before either system is priced, the avoidable water outside should be dealt with: ground levels, paving falls, rainwater goods, gullies and land drainage. It is not unusual for that alone to change the scope, and it is the part of the job we would investigate for you.
The honest summary
Tanking suits sound structures, modest water conditions and simple geometry, and it is a poor choice on friable, salt-laden or rubble-filled masonry. Drained protection suits retrofit work on imperfect substrates, provided the discharge route and the maintenance are accepted as part of the design. Anyone offering one system for every situation is selling a product rather than designing waterproofing.
Limitations of general guidance
This article is general guidance. It cannot confirm the cause of dampness in a specific property. Recommendations should follow an inspection of the building, its external environment and its internal conditions.
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