Tony Bingham tells the story of the pianist whose basement dampproof system failed, the court case that ensued, and the intriguing role eggs and dimples played in it
This is a nice little case because it's all about building buildings, (or more accurately, basements), and about hens' eggs and quails' eggs and a man who plays the piano rather well. He is Jean Louis Steuerman. His piano is a Steinway Grand. He wanted to move it from his first floor to his basement. The judge in the case visited the house and the room. "It is a very pleasant house," said Technology and Construction Court judge, His Honour Peter Bowsher.

Tom Luke was the builder. Three walls made contact with wet ground. Bituthene was the "tanking" solution, but it failed. Luke said he would do it again but couldn't promise success. So Dampcoursing Ltd was brought in. It recommended a system called Delta MS Cavity Drain. This uses large sheets of plastic with "dimples" at intervals. The judge said it looks like egg trays, some with dimples the size of quails' eggs and some the size of hens' eggs. The small eggs go on the walls and are covered in blockwork, the big eggs go on the floor, dimples down; the water runs between them on the sloping slab. The Steinway would look very smart if it all stayed dry and the system worked.

And now, dear reader, you are asking yourself where the water runs to. It flows across the sloping slab to a drain outlet. Within months this outlet was blocked. A waggle with a broom handle sorted that. Six months later it blocked again. Then deposits of lime built up. People got tired of waggling the broom handle. The client told Luke to rip out the second effort. A third system was installed at no mean expense – and is working well.

If I buy a washing machine that doesn’t work, I don’t have to hire an expert to find out why in order to get my money back

Now came the reckoning. The piano player's barrister said the case was simple: "You sold me a system that does not work, therefore you are liable." Dampcoursing's barrister said: "That is not enough." The judge said: "It may not be enough, but it is a good start." He went on: "Of course, the claimant has to show a breach of contract … But it does not follow that he has to prove the mechanism of failure. If I buy a washing machine that does not work, I do not have to hire an expert to find out why in order to get my money back."

Dampcoursing said it wasn't its fault if the drain failed. "That I do not accept," said the judge. "They did not make the outflow, but they asked for it to be made, and if it was not sufficient, they should have said so." In short, it was up to Dampcoursing to ensure that the drain would suit what they were installing. It was impossible to refute liability. The whole idea of the system was to have flowing water around the hens' eggs to avoid the build up of lime, but Mr Steuerman had lots of little mountains under his floor. The Delta Cavity literature told the installer to first ensure that the substrate had falls to the drainage outlets to prevent ponding. Done well, the idea comes with a 30-year guarantee.