Published on 12 June 2019 13:43

A Guide to Replacing Heritage Rooflights

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Key Learning outcomes
  • Recognise the criteria for satisfying listed building consent
  • Identify different period styles
  • Understand how to match existing layouts with modern performance
  • Know how to re-use decorative features
  • Understand the different options for glazing on heritage rooflights
Heritage rooflights provide an aesthetically-pleasing and effective source of natural daylight. However, there is strict regulatory best practice when it comes to replacing them. Contravening regulatory requirements in the replacement of heritage rooflights can be a costly mistake, with construction teams having to re-undertake replacements compliantly, if key standards are not observed.

The following guidance provides a comprehensive overview of the required approach to replacing these valuable historic features, to ensure that structural changes are compliant, and serve to complement the style of the building.

1.0 Meeting the criteria to satisfy listed building consent

As with all potential changes to a listed building, replacement of heritage rooflights is governed by specific criteria which serves to maintain the period aesthetics of the structure. As a bare minimum, any new rooflights fitted need to match both the shape and size of the existing fittings. Further conditions for compliant replacement depends upon the status and historic listing of the building, which may require additional more detailed features to be replicated.

The following rooflight features may be subject to restrictions, depending upon the building being restored:

• Framework material
• Glazing bar spacing
• Glazing seal
• Glazing finish
• Pitch/slope degree.

When it comes to replacing heritage rooflights, each of the above criteria is required to maintain the same dimensions and finish as the original. As a result, Historic England suggests that repair to any historical windows is often better than replacement, especially if the glass is rare. However, if the windows are not of particular interest, and can be replaced in a way that complements the building in an appropriate style, replacement may be approved. Sensitive selection of an appropriate rooflight which retains the period style and qualities of the original will ensure that the completed replacement will be compliant.

All replacement rooflights also need to meet various standards for performance and durability. They also need to be compliant with environmental performance criteria. Government regulations state that if heritage rooflights have deteriorated to the extent that repair is no longer viable, replacements should be fitted in the same plane as the originals, with the profile and dimension matching the originals. If applicable, meeting rails need to be in the same position, and mullions (vertical dividers that separate windows) should be retained. It is also important to retain the original method of opening the rooflight.

Each listed building has its own distinct features, meaning that there is no set list of changes that can or cannot be made.

Somerset House was built in the neo-classical architectural style and has a very distinct designs of rooflights.
Somerset House was built in the neo-classical architectural style and has a very distinct designs of rooflights.
 
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About

Europa House
Alford Road
Cranleigh
Surrey
GU6 8NQ
Rob Hamblen
Tel +44 (0)1483 917580
rob.hamblen@whitesales.co.uk
The information contained in the CPD article web pages is not intended and accordingly shall not be relied upon either as a substitute for professional advice or judgement or to provide legal or other advice with respect to any particular circumstance. RIBA Enterprises accepts no responsibility for loss occasioned to any person acting or refraining from action as a result of the information contained.
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