SAP Assessments

A SAP Assessment is required for an extension to a domestic dwelling. If the glazing area required in the extension is 25% or more of the floor area then a full assessment is required to satisfy Building Regulations.

Area Weighted

  • These are simple calculations if the glazing area is only slightly above 25%
  • To prove that the average u-values in the proposed extension are better than in a notional extension with standard u-values and openings.

Extension plus existing building

  • Two assessments are undertaken, one with the existing building plus the proposed extension and the other with the existing building plus a notional extension with 25% glazing and standard u-values.
  • if the CO2 produced in a year from the existing plus proposed exceeds that of the existing plus notional then compensatory measures must be taken in the existing buildings. This could be increasing the insulation or changing the space heating system.

SAP checklists are available in the download section which will help collect all the information required.

Once the SAP Assessment is completed we can send it to Building Control Officer to ensure that you can get your completion certificate as soon as possible.