Problems and Maintenance with Traditional Sash Windows

The traditional hardwood sash window frame is found in properties built from around the mid 19th century to the early 20th century. They are operated by a mechanism of weights, cords and pulleys which cause the sash to move up and down. One end of the cord is nailed into a groove at the side of the sash, and the other end has a weight attached. The weight itself is tucked into a weight box.

Due to the age of these traditional windows, it is inevitable that some problems will occur. However, with proper regular care and maintenance there is no need why they should not last many years more. An appearance of rot or warping in the wood is generally only superficial as good quality hardwood can usually be renovated. The problem arises with cheaper, poorer quality replacement wood sashes. The cheaper the wood is, the less likely the possibility of it being restoring your window.

Do not be put off by chipping, dirty paintwork. If the material beneath is quality hardwood then your sash can still be restored.

Why carry out an annual window inspection? Deterioration of the windows is likely to begin at the joints and on horizontal surfaces, as this is where moisture will collect when your windows are open.

Renovate before replacing. Hardwood sash windows are designed to be easily taken apart so that they can be repaired or replaced as they were made during a time when products were built to last many generations. Be aware that modern UPVC sash windows are not made for easy dismantling and will need expert attention. Getting a newer version is not always as advantageous as it seems.

Problems

Some of the most common complaints that arise with old sash windows are:

Draughts
Rattling
Sticking
Rot

Draughts - Around old sash windows the gaps can be substantial, costing you more in heating bills and using up more energy. Good draught proofing is essential, especially finding a discreet proof that does not overshadow your authentic windows. Draught proofed beading can be fitted, and there are now many specialised joinery firms who can insert brushes or seals that are very effective.

Brush seals are fine nylon fibres, though you can also purchase seals which consist of urethane foam in polypropylene. Your savings on heating bills will recoup the cost of fitting draught proofing in 5 to 25 years; less time than that of replacement UPVC. Draught proofing measures are also effective against rattling, as any gaps in the sash window will have been sealed.

Sticking - Firstly ensure that your window is not sticking due to a slightly messy paint job. If this is the case, carefully draw a knife or chisel along the edge to free it. If the reason for sticking is unknown, rub some wax into the channels and sash stile. It may also be advisable to gently oil the top pulleys and replace the sash cord, checking the beading is correctly seated.

If you find excess dirt or paint in the window channels prior to waxing, gently chisel them out and sand the area. If you feel that this is not adequate, strip the paint from the frame's channels and coat it in teak or linseed oil, as these were the original protection methods used.

If all else fails, inspect the sashes for warping or swelling. To rectify wood abnormalities, you will need to remove the sashes and plane a little wood off if necessary.

Rot - Superficial damage from rot can be easily rectified by applying wood treatments. First remove any dirt and debris, and then apply a wood hardener to strengthen the window. Use a two part epoxy filler and then re-prime with an undercoat and up to two top coats.

Significant rotting will require you to dismantle the sashes and strip all paint with a chemical stripper, carefully knocking the joints apart. You will then have to sandpaper and treat the parts of wood you wish to keep. For serious damage a specialist will be required.

Removing Window Sashes

To carry out major renovations to restore rotting wood, replace a broken cord, or release internal sticking, you must first extract the sashes from the window frame.

Prise off the outer stop bead with a chisel either by leverage or by trying to tap it back sharply to cause the securing pins to come loose. Before removing the lower inner sash, mark with a pencil on the sash and on the frame where the ends of the sash cords come. Then gently lift out the lower sash, taking care not to drop the weights if the cord is broken.

Again, use the chisel to ease out the parting bead and then lift off the upper outer sash. Do not forget to repeat the markings as above. Weight box covers or "pockets" can then be unscrewed so that the weights can be fed through the pocket openings.

Replacing the cord - Feed the new cord over the pulley as used by the original cord, passing it through from the window side, into the boxing toward the weight box. The new cord can now to be tied as the original one was.

On an upper sash, put the side that has the existing cord back into its place in the frame, and position the sash itself around 4 inches up from the window sill. Then pull the replacement cord until the weight goes into the box and hits the top. Once in this position, nail the cord in place and tie the same way as the original cord. As the sash is replaced and pushed up, the cord will fall. On a lower sash the weight should be at the top of the box when the window is on the bottom.

To complete, reattach the centre parting bead, replace the bottom sash and attach the outer stop bead.

Re-glazing Plain Glass

If the glass has been broken or you just want to renovate the entire window at once, replacing plain glass can be relatively unfussy. Always wear thick gloves.

First, carefully knock out the glass and chip out the putty. If the putty proves difficult to remove, soften it with paint stripper or bleach covered with Clingfilm.
Remove the nails (sprigs) that hold in the glass.
Measure the inner window frame and subtract 3mm from the height and width.
Roll the putty in your hands until it becomes a rope and press it into the frame.
Position the glass into the window and press firmly around it. Tap the sprigs back into place.
Press a second putty rope around the edge, and smooth using a wet putty knife.