Introduction

Damp proofing sits firmly in Part C of the building regulations. ‘Site preparation and resistance to moisture’ may sound a little long winded, but in reality this section of the building regulations exists to make sure that the properties we live in are not built on top of hazardous materials (be they natural or man made) and that the lower levels of the building are adequately insulated from the effects of water.

It is the latter that many of us will encounter through a number of different building projects, or through simply buying an older house, however it is the former that can present significantly more problems if not addressed properly. To this end it is recommended that you should always consult your local council with any queries you have relating to this topic.

Damp Proofing

For the majority of home owners, the effects of water will be encountered via rising damp. To help prevent this building regulations require a damp proof course (DPC) to be installed in all habitable buildings. This consists of a layer of impervious material built into the mortar bed at least 150mm (6in) above ground level. As a general rule when you build a new wall its DPC must coincide with the DPC in the existing structure.

It is relatively easy to spot the signs of rising damp on interior walls due to the obvious damp on the walls, however it's not always so easy to spot the causes on the outside walls. That said by having a root around outside the offending area you can usually find the cause. The most common causes are blocked drains and/or gutters, plants growing on the outside walls, and soil from flower beds sitting against the wall higher than the damp proof course.

When it comes to the effects of water to walls (particularly external) and floors, the building regulations are very detailed and cover all aspects of insulation and moisture prevention to ensure health and safety standards are upheld. Again, no matter how bad or difficult the problem may seem, this is one of those jobs when it's advisable to seek professional assistance.

• If you do find you have Damp of one form or another, its best to consult a building contractor, and/or your local council, for advice in dealing with the problem correctly.

Further Information and useful links

• Full guide to the building regulations
• Making structural changes to your property

• Find a Builder near you
• Find a Surveyor near you

• Part C: Site preparation and resistance to moisture (odpm.gov.uk)
• Party Wall Guidance (rics.org)
• Find your Local Council