Repairing and Repainting Sash Windows

Sash windows first began to be used in the United Kingdom towards the end of the 1600s and are still being used today, although modern ones will be double-glazed and will be harder to repair. Although sash windows look mysterious they are in fact quite simple in construction and once you know a few tricks they are easy to take apart and repair.

Sash Window Repair

In this article we’ll be covering repairs to the wooden parts of sash windows rather than broken glass. The repair of glass in sash windows is no different to any other single-glazed windows and is covered in our article in this section. The only possible difference is that you might want to use some wedges to hold the sash tight while you perform the repair.

The word ‘sash’ refers to one of the two wooden frames that hold the glass, so there is an inner and outer (also known as upper and lower) sash in each window. They are held in at the sides by the two guide tracks (‘runners’) that they slide in and the vertical movement is checked by weights on cords that run over pulleys at the top of the frames. These constructions at either side of the frame that hold the runners, cords and weights are known as the ‘boxes’.

Removing the Inner Sash

For many repairs to sash windows you will need to remove one or both of the sashes and this is really a two person job. Working from the inside of the house, open the upper sash, lowering it as far down as it will go. Then carefully lever out the staff beads that run from top to bottom of either box to hold the inner sash into the boxes.

It’s worth running a sharp knife down the join to cut the paint layer. This means that they can be replaced with just minor touching up if the paint on the beads and boxes is in good condition.

Detaching the Cords

The inner sash can then be lifted away at the top (leave it in at the bottom) to reveal the connections where the sash cords are attached at each side. The cord is usually held with pins or staples. One by one your helper should hang on to a cord, detach it then tie a knot to prevent it from disappearing into the box when they let go.

If you don’t do this the weights on the other ends of the cords will draw the whole cord into the box and you will have to re-thread it. Keep supporting the inner sash as this is being done then remove it and put it to one side.

You will now see the parting beads that separate the runners for the inner out outer sashes. Lever these out of their boxes and remove the outer sash in the same way as the inner one. Support the outer sash with blocks of wood because if it falls the rest of the way to the bottom of the frame it may shatter the glass.

Repairing and Repainting the Components

Once sash windows are broken down into their main components the woodwork on the frame, boxes and sashes can be repaired or replaced and then painted using the techniques outlined in the relevant articles in this section of the site. If you find faces that aren’t painted, don’t be tempted to paint them, they are meant to be that way.

The main point is to keep the sashes out until the paint is properly dry or they will stick once they have been replaced. Prepare suitably sized boards that you can screw to the frame for security if you have to leave the sashes out for a few days.

Reassembling Sash Windows

When all the repairs have been done put the sashes back in the frame, replacing the beads if necessary. Re-fitting is the reverse of the removal procedure but remember to hold and secure sashes until everything is back together again to prevent them dropping and smashing the glass.

Cords should be refastened at the same place as before, using three flat headed nails driven through the cord into the side of the sash. These will be easier to remove next time than staples.

Dealing with Stiff Sashes

Stiffness with sash windows is usually down to warping of the bead or poorly applied paint in the runners of the box, sometimes a badly replaced staff or parting bead. Unfortunately all of these will entail removal of the sashes to effect a repair. So take care when renovating and replacing everything and you should have a snug fitting window that slides smoothly.