I take issue with Steve Menary's article ‘Fire in the Hole' (CM, May 2006). NHBC requires a cavity to be provided when insulated render systems are used on timber or steel framed buildings for good reason.

Experience from the British Columbia ‘Condominium Crisis' and in other countries confirms that insulated

render systems do leak in certain circumstances. Rain penetration through insulated render systems led to the timber decay in a large number of apartment buildings in British Columbia.

NHBC seeks to avoid potential problems of timber decay and steel corrosion in the UK. We see the provision of a 15mm cavity as an essential second line of defence. NHBC Standards require compliance with the statutory Building Regulations and, ultimately, it is for the Building Control Body to assess whether the design proposals for the particular building satisfactorily address fire concerns.

Neil Smith, group head of technical, NHBC

Source

Construction Manager