Basement Tanking - Project 1

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An ordinary property in Exeter suffering from so many problems we were unsure how it stood up.

Just a few of the problems were 'infestations' by wood destroying beetles:

Woodworm (Anobium Punctatum)
Deathwatch Beetle (Xestobium Ruffouillosum)
Wood-boring weevil ((Pentarthrum Huttoni)

A few fungal attacks:

Dry rot (Serpula Lacrymans)
Wet rot (Coniophora Puteana, Fibroporia Vaillantii, Asterostroma)

With a good coating of black spot mould 'condensation' (Penicillium) all washed down with a good bit of 'damp'. To list a few:

Rising damp
Lateral damp
Basement flooding
Descending damp 'roofing defects'

Needless to say that once the property was inspected we soon realised that the main support timbers holding up the ground floor and internal timber walls had dropped about 50 mm, and that during its slow decline all the internal joinery was re-set to its structural collapse, without anyone addressing the main water problems.

A close working partnership with our membrane suppliers, Triton Chemicals, quickly established a construction and installation method to overcome the basement flooding. On the left is David Whichello, Triton Chemicals, Chris Barratt on the right.

The first job was to remove everything, including the basement wall plaster.

Breaking up the floor, you can see the damp area where water was penetrating through. The wall and the central post were responsible for holding up the carrier beams and joists. The post was completely rotted at its base.

Not really much to this floor construction - just broken bricks with 40 mm of concrete.

Once all the floor and plaster work was removed the sub-site was excavated to allow for a concrete base, and the membrane composition floor build up.

Here 100 mm of concrete was laid with drainage channels cast into the floor.

A sump pit was excavated to the rear of the room and a sump with drainage gravel surrounding it was installed.

The concrete floor was laid up to the sump, with the drainage channels discharging into the gravel.

Sump filling up with water from water table and penetrating dampness though the basement walls.

The following photographs are the floor membranes being laid and sealed.