Flat roofs, terraces and balconies

7.1.2Provision of information

Designs and specifications shall be produced in a clear understandable format, include all relevant information and be distributed to all appropriate personnel.

Design and specification information should be issued to NHBC, site supervisors, relevant specialist subcontractors and suppliers, and include the following:

  • extent and direction of falls, and position of outlets to provide effective drainage with no back falls. A roof deflection analysis should be provided for medium to large roofs and those with complex roof layouts.
  • sections through the construction, including how falls are formed.
  • method of ventilating voids where ventilation is required.
  • size, specification and position of the components, including treatment for durability and the position and extent of the air and vapour control layer, insulation and waterproofing layers.
  • details at critical junctions.
  • details of fixings, their frequency and fixing method, including those for insulation and surfacing.
  • specification for intensive and extensive green roofs, biodiverse roofs, or Blue roofs.
  • details and fixing methods of balcony support and guarding components.
  • survey requirements and preparation treatment of deck before application of waterproofing.
  • method of testing the integrity of the waterproofing layer.