scope:

Introduction

Several Good Repair Guides deal with rain penetration and rising damp in existing buildings. This Good Building Guide looks at ways of preventing the problems occurring in new cavity wall construction. In driving rain, water leaks through the outer leaf of most cavity walls, often in quite large quantities. Provided the damp-proofing measures are correctly designed and installed and the wall itself is reasonably free from defects, the water does not reach the inner leaf, but flows harmlessly down the cavity face of the outer leaf until it reaches the footings or is directed out of the cavity via cavity trays or window/door lintels.