Modern sash windows can only be considered secure if they have passed PAS24 


It was our deisgn team that assisted BSI (British Standards Instituion) in formalising the standards to which all sash windows should comply. Therefore it was a Bygone window that was the first sash window of any material to pass BS 9750, the predecessor to PAS24 in 2006.  Shortly after this, the windows obtained the police preferred Secured by Design endorsement.


To pass the test, the windows were subjected to vigorous attacks, with each corner and locking point being tested in turn.  Unlike many inferior systems where keeps are simply screwed to the glazing beads (which takes seconds to break into), ours are secured directly into the steel reinforced sash frame.


If you examine the claw lock section of Bygone cams you will notice that they are handed which means that when two are fitted they come as a left and right handed pair.  This helps to centralise the sashes in the frame preventing them from being forced to one side. 


The locking keep is screwed into the meeting rail using four fixing screws, two vertically and two horizontally to maximise the resistance to the shear forces.  On the top of the top sash there are two metal rider blocks which hold the top sash in place so that it cannot be moved backwards and forwards.




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Premier Partner For October

Cherwell Windows 




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“The windows have now been in a month or two and have made such a difference to the warmth of our house"

"I wouldn't hesitate to use this company again in the future”

Mr D.R - Reading

These sash windows are only sold through our national network of premier partners, all of whom are certified and approved Bygone sash window installers




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Accreditations >

Learn why you get better windows because of these

  • BBA - British Board of Agrément Certified
  • ISO 9001:2015 Certified Organisation
  • SBD - Secured By Design Approved Windows
  • British Fenestration Ratings Council - A Rating
  • Energy Savings Trust Recommended Windows
  • CE Compliant Windows

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