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Commercial Windows


1 Sample Specification

Draughtproofing existing sash windows

When specifying draughtproofing for existing sash windows please consider the following wording to avoid the risk of a poor quality imitation system being used:


  • An approved draughtproofing system meeting the highest requirements (Class 3) of BS6375 Part 1, 2004 in relation to air leakage which tests to 600Pa – the equivalent of 71mph winds.
  • The system must incorporate a two-piece parting bead to facilitate removal and refitting during future painting.
  • The replacement parting bead section must be available in a variety of colours to suit the chosen paint colour for the windows.
  • The draughtproofing system shall incorporate a Sash Removal System including cord brake and housing, to allow sliding sashes to be removed internally for future painting and maintenance.
  • Energy performance of the windows to be no less than 80% of that achieved by a double glazed unit.

2 Sample Specification

New sash windows

When specifying new sash windows please consider some or all of the following:


  • New sash windows by Bolger Sash Windows
  • Frames & sashes to be manufactured in Accoya® wood
  • Windows to be guaranteed for a minimum of 50 years against rot
  • Windows to be manufactured to traditional details including pulleys, cords and weights, fork jointed meeting rails, and having all dimensions and mouldings to exactly match the original windows / neighbouring properties / to exactly replicate all details found in typical properties from the same period / to exactly match architects details.
  • Spiral or spring balances will not be allowed.
  • Pinned on meeting rails will not be allowed.
  • New windows to incorporate Ventrolla or equal approved. (see above).

Sash Windows

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Casement Windows

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Window Refurbishment

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