Windows – draughts

Cause

Deteriorated seals to aluminium joinery

Repair

  • replace seals around aluminium joinery. Replacement seals are available from hardware suppliers or window frame manufacturers. Take a sample of the existing seal to ensure a correct profile match

  • remove old seals by starting at one corner and prising out a section of the seal. Once a section has lifted, the rest of the seal will generally easily pull out

  • cut a replacement seal longer than the size you want

  • starting from the top centre of the frame, push the seal into the gap between the gasket groove or bead and the glass. Spraying soapy water on the seal can help installation

  • work the seal into the gap all the way around the perimeter of the frame. Take care to ensure that that the seal is properly fitted into the corners of the frame

  • do not stretch the seal as it is being inserted. If a seal is stretched during installation it will eventually retract, leaving a gap where the two ends of the seal meet

Cause

Gaps around timber doors and window sashes

Repair

  • insert self-adhesive PVC foam draught strips in timber door and window frames to block gaps

  • ensure that catches pull doors and windows tightly into the frame

  • consider secondary glazing on windows. With this, plastic film, magnetically attached plastic sheet, plain or low-E glass is installed inside the existing glass with a still air gap between them. Proprietary products are available. Research has found that secondary glazing can be used as a functional alternative to retrofitted double glazing in existing domestic single-glazed window frames. (In fact, the performance exceeded the expected performance of double glazing retrofitted into the existing framing due to the secondary glazing effectively insulating the framing.) Some products allow secondary glazing to be removed during the warmer months

  • for more guidance on improving the thermal performance of timber windows, see BRANZ Bulletin 659 Upgrading the thermal performance of timber windows