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Conservation Repairs

Conservation repairs are essential for long term preservation of sliding sash windows. This work would be carried out before preparation for painting begins.

What are sash window conservation repairs?

Conservation repairs to sash windows are carried out to prevent or considerably reduce wood decay. This is achieved by the strengthening of the joints around the box sash window and closing any gaps that have appeared at the joints. The top of the windows are generally less susceptible to moisture ingress.

The parts of the window where the most common conservation repairs are carried out include : -

  • the bridle or haunched mortise and tenon joints to the top and bottom sashes.
  • the housing joint of the pulley stile.
  • the joints to the inner and outer linings.
  • any gaps between the window sill and the stone threshold.

Carrying out these repairs will stabilise movement in the timber and prolong the life of the sash window by preventing moisture ingress.

In addition to the Conservation repair to the joints, repairs to glazing lines to the outside of the sashes is very important especially where we identify missing or loose putty around the glass. Taking appropriate action will ensure that there is no moisture ingress. The end-grain is very susceptible to moisture and should be sealed. Sealing of exposed end-grain areas to the window sills and sash styles will help prevent wood decay.

Below is an insight into the process of conservation repairs to sash windows.

  1. Removing the existing paint finish and any filler around the shoulders of the joints the area is sanded back to bare timber, to a minimum of 10mm from the epoxy resin repair.
  2. We open the existing joint to a width of at least 4mm and a depth of at least 10mm.
  3. We sand the bridle or haunched mortise and tenon joints and remove any dust and dirt.
  4. We check the moisture content of the wood.
  5. We apply the 2 part wood primmer stabiliser thoroughly into the joint using a small brush and wipe off the excess.
  6. We apply the "Window Care Epoxy Resin System".
  7. Once the epoxy resin is cured we sand and seal the joint to a smooth and even finish.