Windows – casement sash won't open

Causes

Paint may have sealed window shut

Timber sash is rotted or sash corner mortice and tenon joints are loose

Hinges are corroded/have seized 

Building has settled

Previous owner may have nailed window shut

Windows or frame may be warped causing sashes to stick

Sash is binding on frame 

Listed under: Interior, finishes, timber and wood-based, paint, timber, windows, durability, corrosion, rot, fixings and hardware, fixings, hardware

Cause

Paint may have sealed window shut

Repair

  • run a blade or a power tool with an oscillating blade between the sash and the frame to cut through the paint. Gently tap around the sash to free it. 

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Cause

Timber sash is rotted or sash corner mortice and tenon joints are loose

Repair

  • if the amount of rot is small, scrape out all the rotted timber – the glass may need to be removed first. Treat the area around where the rot was removed with a hot air gun to dry the wood then apply two coats of paint-on timber preservative. Allow to fully dry

  • apply a two-pot epoxy resin wood sealer

  • fill the excavated area with a polyester fibre reinforced filler, finishing 2–3 mm below the final surface. Complete the filling with an exterior-grade timber filler and allow to harden

  • sand and prime as required with a timber primer, then finish with two coats of enamel paint

  • if rot is extensive the options include using a timber patch, replacing a section of the sash or replacing the entire sash

  • loose joints should be repaired to keep the window weathertight and prevent rot developing. If the opening is small and there is no rot, fill the gap with an exterior grade of timber filler, prime and repaint with a minimum two coats of enamel paint. If the joint opening is more serious, the joint may need to be rebuilt

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Cause

Hinges are corroded/have seized 

Repair

  • spray accessible parts of the hinge with a penetrating lubricant. Leave time for the lubricant to work, then gently prise the sash open. Remove the sash, clean and lubricate the hinges if they can be restored

  • if the hinges are badly corroded, replace them

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Cause

Building has settled

Repair

  • if the building has settled, consider relevelling and/or repiling if major renovations are planned

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Cause

Previous owner may have nailed window shut

Repair

  • locate and remove nails or other fixings

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Cause

Windows or frame may be warped causing sashes to stick

Repair

  • remove the sash from the window and plane or machine sand the edge to allow it to open freely. Prime and paint exposed timber

  • check hinges are not corroded or loose

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Cause

Sash is binding on frame 

Repair

  • tap along length of sash with hammer and wooden block to release bound window. Remove the sash and plane or machine sand the edge to allow it to open freely. Prime and paint exposed timber

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