Comparative SAP

Want more glazing in your extension? Comparative SAP can help achieve your design

Comparative SAP Calculations

Under Building regulations, the area of glazing allowable in extensions is ordinarily limited to 25% of the floor area + the area of existing doors and windows that are no longer exposed because of the extension. Because this can be quite prescriptive, the Approved Document does give alternative ways in which compliance may be demonstrated whilst achieving a more desirable level of glazing

One way of complying is to show that the area-weighted insulation value of all the elements in the extension is no greater than that of an extension of the same size and shape that complies with a notional extension that does comply.

Where even greater design flexibility is required, SAP 2009 calculations can be undertaken to show that the calculated carbon dioxide emission rate from the dwelling with its proposed extension is no greater than for the dwelling plus a notional extension which conforms with the minimum standards.

We can undertake the necessary heat loss calculations as detailed above to demonstrate the provision of excessive glazing within an extension as required under Building Regulation Approved Document L1B

You may require a comparative SAP if

  • You have an extensively glazed extension.
  • An area weighted U-Value Calculation fails.

For a free no obligation quote or advice please contact us.