Timber or steel window – cracked or loose putty

Causes

Putty is not protected by paint and has dried out

The glazing rebate was not primed before the glass was installed

Common

Listed under: Exterior, adhesives and sealants, sealants, glass, metal, steel, timber and wood-based, putty, windows

Cause

Putty is not protected by paint and has dried out

Repair

  • replace putty:

    • carefully scrape out the damaged putty with a hacking knife or a chisel

    • remove the glazing tacks (from timber frames) with a pair of thin-nosed pliers and remove the glass

    • remove any remaining putty from the rebate. Check there is no rot in the timber. Prime the rebate

    • insert new putty in the rebate then gently press the glass into the putty. (New glass will need to be measured for and purchased if the existing glass is broken or breaks during removal. Size new glass to give a gap of 2–3 mm between the edge of the glass and the glazing rebate – e.g. for a gap of 450 mm the glass should be 445 mm)

    • in timber frames, install new glazing tacks then press putty around the edge of the glass

    • smooth the putty to a consistent slope (around 30–45°) around the window edge with a putty knife

  • paint putty after 2 weeks, ensuring that all the exterior putty and 2 mm of the glass is painted

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Cause

The glazing rebate was not primed before the glass was installed

Repair

  • as above

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