Where cladding is being removed, it is likely that the windows and doors will also be removed. They may then need to be repaired or replaced.
Where windows require extensive work (replacement of sealant, new glazing rubbers or the replacement of reveals to accommodate cavity walls) to bring them back to near-new condition or where modification of the rough opening is required to allow the window to be fitted, it may be more cost-effective to specify new joinery. This is because of the time involved to repair the existing windows to the required performance level and the costs of storage.
The energy performance of new windows requires careful consideration. One useful tool is the Window Energy Efficiency Rating System (WEERS), a voluntary 6-star rating programme for thermal performance developed by BRANZ in conjunction with the Window Association of New Zealand (now called the Window & Glass Association). You can find more information in BRANZ Bulletin 579 WEERS – Window Energy Efficiency Rating System.
Where windows are being removed for reuse, they need be removed undamaged. The ease of removal will depend on:
- the window reveal – windows with slimline jambs require more care and work to remove than those with architraves
- size and weight of the window – will the window have to be deglazed to allow it to be removed by hand or is cranage required?
- the location on the face of the building
- the shape of the window – faceted and curved windows are much harder to remove and store.
When removing windows with slimline jambs, there is an additional cost of installing architraves as the plasterboard has to be cut to allow the windows to be removed.
Windows that are to be reused should be checked for signs of water penetration through the window itself. Where the window has leaked, can it be repaired to ‘as new’ condition or must it be replaced? Replacement would be a contingency item unless the original assessment of the causes of the problems had identified the failure and the need to replace windows – getting new windows priced as an option at tender stage is recommended to allow comparison.
Before windows are reinstalled:
- back seals will need replacing
- the glazing rubbers that hold in the glass may need to be replaced
- the reveal will have to be replaced or an additional bead (see Figure below) added to accommodate the remediated wall thickness
- hardware may be worn and need replacing
- clean off plaster and paint debris
- the BCA may require a producer statement verifying the condition of and performance of the upgraded windows.
When detailing the windows:
- prepare the opening as shown in E2/AS1 – where a window is being reinstalled, check that sufficient reveal-to-frame clearance will be available to install the air seal
- consider replacing windows that have shapes that are difficult to weatherproof such as those with curved or raked tops or raked bottom edges
- ensure stop-ends are specified for head flashings in cavity systems
- incorporate air seals between the reveal and the frame
- incorporate sill tray flashings with direct-fixed claddings
- ensure the requirements of NZS 4223 Part 3 for human impact on glass are complied with. This standard was updated in 2016.
Updated: 27 April 2016