Waterproofing: the record that outlives the tiles

Waterproofing is the only trade whose work disappears completely the moment the next trade starts. Tiles go over it and nobody sees it again.

A failure surfaces years later as a stain on a ceiling below, and by then the evidence sits under a finished floor.

The record is the product, as much as the membrane

A waterproofer without a record carries every later failure, whether the membrane caused it or not. A waterproofer with one can answer in minutes.

Six facts cover nearly every question that arrives later.

• The product and its batch, read off the tin rather than remembered.
• The number of coats, with a photograph of each.
• The drying time between coats, and the conditions that day.
• Where the membrane turns up, at the walls, the hob and the door.
• The bond breaker and the angles, which is where most failures start.
• The date and the person, so the work has an owner.

Photograph each coat, not the finished job

One photograph of a finished grey floor proves that a floor was grey. A photograph per coat proves each layer exists.

Colour differences between coats make this easy, and most manufacturers supply the coats in different shades for exactly this reason.

The angles cause the failures

Membranes rarely fail across a flat floor. They fail at the junction between floor and wall, at the hob, and around the waste.

Those are the photographs worth taking carefully, because those are the places anybody investigating will look first.

Record who came next, and when

A membrane damaged by a tiler's trowel or a plumber's bracket is a common cause of failure, and the waterproofer usually wears it anyway.

Noting the date the membrane finished and the date the next trade started gives the timeline a shape. A gap of an hour tells its own story.

Hold the records where somebody finds them in year seven

A phone gets replaced, a laptop dies, and a folder in a van goes to the tip with the van. A warranty question arrives long after all three.

Store the record against the job in a system that outlives the hardware. Our guide to site safety paperwork makes the same argument about filing by job rather than by date.

A callback with a record is a short conversation

Most waterproofing disputes turn on whether the membrane went up the wall far enough, and whether it cured before the tiles arrived.

A business that can answer both with dated photographs settles the matter quickly. A business that cannot pays for somebody else's mistake.

Flood testing proves the work while it can still be fixed

A flood test on a finished membrane costs an afternoon and finds a failure before the tiles hide it.

Photographed with the water in and the level marked, it becomes the strongest record the trade can hold.

Builders often resist the day it takes. The cost of skipping it lands years later on somebody, and usually on the waterproofer.

Substrate preparation causes the failures nobody photographs

A membrane over dust, laitance or a wet screed fails however carefully somebody applied it.

A photograph of the prepared substrate, before any product, is the one that answers a manufacturer's first question in a warranty claim.

What to change first

• Product and batch come off the tin and onto the record
• Each coat gets its own photograph, not just the finished floor
• The angles, the hob and the waste get photographed closely
• Drying times and the day's conditions go on the job
• The date the next trade started sits beside the date the membrane finished
• Records live against the job, somewhere that outlives a phone