Rising damp occurs when moisture from the ground is drawn up into a building's walls through capillary action, which happens when there isn't any DPC (damp proof course).

This is called DPC (Damp Proof Course), a water-repellent silicone resin that is usually injected at the bottom of your walls to protect your home’s pores.

The idea of dampness bypassing a damp-proof course by “bridging” is greatly overstated, says Jeff Howell.

However, rising damp is something of a mystery. Modern houses have a horizontal damp proof course (DPC) and membrane (DPM) under the floor.

Hyload Insulated DPC, the structural waterproofing product from Ruberoid Buildings Products, has been designed to minimise cold bridging when closing masonry cavity walls.