SAP Calculations for Extensions and other 'Notifiable Works'

Extending or altering domestic property? You may need a SAP Calculation for your Building Regulations submission. The Building Regulations provide guidance on the thermal performance of extensions, 'material change of use' applications and alterations but do allow for flexibility if there is a design which does not strictly meet the requirements. These allow for an 'area weighted' approach or a 'notional extension' approach. Coles Knapp can assist with calculations in any of these scenarios.

Coles Knapp are fully qualified and accredited to provide SAP Calculations and offer a quick, reliable and competitive service. Simply call us today for a quote, then send us your plans and specifications.

 Contact us now for a free quotation.


Area Weighted U Values and Substantially Glazed Extensions

The most common scenario of the above is the 'Substantially Glazed Extension'.

The Buildings Regulations Document L1B allows for an extension to have glazing up to a maximum area of 25% of the floor area of the extension, plus the area of any openings in the existing dwelling that are now covered by the extension. If the extension has more glazing than this it is possible to comply with Building Regulations by either calculating the actual extension has an area weighted U Value no worse than a 'just compliant' extension OR by proving that the whole house including the extension (plus any other improvements elsewhere) is no worse than the whole house with a 'just compliant' extension that is the same size and shape, but meets the Regulations. 

Coles Knapp have provided many such calculations and can meet strict deadlines to ensure that any proposed work is not delayed. Please contact us for more information.

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