Located on an excavated sloping site leading down to the canal basin, all that was left of the building section involved was a stone and brick ground retaining wall, seen in Photograph 1, with ground water escaping through it.

A new building was constructed, with the lowest level incorporating the retaining wall.

Our brief was to advise on a way to waterproof the original the stone and brick wall, whilst leaving them exposed.

Rotafix Aquachem resin based primer was chosen, and whilst this leaves a sheen finish, this was agreed as being acceptable by the client.

Knowing that pressure is best relieved in association with any tanking medium,  we formed drainage channels in the concrete slab at the wall and floor joint, leading to a redundant stone filled canal channel that extended into the barrel arch seen below, and from there drained to low ground.

Because any tanking medium is only as good as the substrate it is applied to, we raked out the stone beds, widening them where necessary, and structurally pointed them, with Photograph 2 showing how ground water readily escaped during the raking out period.

Aquachem is applied by brush or sponge, is milky white when first applied, turning clear once set.

Difficulties were found in that if the substrate is too wet it fails to make this change perfectly, and some areas still today show evidence of this.

However, the situation was mitigated by inserting pipes into the walls temporarily to encourage water to escape in planned areas, relieving pressure from areas being worked on.

The stone and brickwork outside of the two barrel arches were to be treated with the resin based Aquachem, whereas the arches were to be cementitiously tanked in three coats, with Setcrete 1 waterproofing additive.

Therefore, the Aquachem was applied first and extended into the arches, after which the cementitious tanking was lapped back over at the joint.

All during the work rain-fall was heavy and almost constant, with this and site waste water escaping from the compound and building site above, encouraging water pressure against the ground retaining wall, and whilst this made application very difficult, it highlighted suspect areas in the application.

Any such application must be on a wait and see basis, because water being extremely heavy and seeking, will find any defect in the system.

We initially applied two coats, but in areas had to snag, undertake additional structural pointing and apply up to four coats before the dam eventually held watertight.

The original brickwork seen was particularly porous, but eventually held, and new brick sections where cavities were formed proved to fill up with water from the site compound above. All was eventually held back successfully by the Rotafix Aquachem.

It was only minimally extended onto the new concrete soffits forming the floor level over, that area being least vulnerable to ground water pressure.

Whilst from seeing the rest of our site you will see that we do not advocate 'tanking' as our first choice for waterproofing, Aquachem served the purpose admirably, and today during and after heavy rain, one can actually see water running behind the  material on the face of the wall. This may be strange, but Aquachem does work.

USING

OUR

IMAGINATION

Trace Basement Systems