Substructure and ground-bearing floors

Also see:

5.1.19Damp proof course

Damp proof courses shall adequately resist moisture from reaching the inside of the building. Issues to be taken into account include:

  1. positioning of DPCs
  2. DPC materials.

Positioning of DPCs

DPCs should be:

  • positioned a minimum of 150mm above finished ground or paving level
  • linked with any DPM
  • of the correct width and fully bedded
  • either welded or lapped by 100mm minimum
  • impermeable.

Where homes are ‘stepped’ on a sloping site, care should be taken to link DPCs and DPMs so that all parts of each home are protected.

DPC materials

Acceptable materials for DPCs include:

Bitumen based materialsBS 6398
Polyethylene (should not be used below copings, in parapets or for tanking)BS 6515
0.5mm minimum
Proprietary materialsTechnical Requirement R3

DPCs and flexible cavity trays should be of the correct dimensions. At complicated junctions, preformed cavity trays of the correct type and shape should be used.

Brick DPCs are only suitable to resist the upward movement of moisture and should:

  • consist of two courses of engineering bricks, laid broken bond
  • be bedded and jointed in a 1:¼:3, cement:lime:sand, or equivalent, mortar.