Can my rotten sash windows be repaired?

Rot is not a pretty sight, particularly at the front of your house. However, if you leave your home maintenance for even a few months it’s something that can set in, particularly in window sashes, where moisture can collect and set in quite easily.

Weatherproof finishes and paints are a great way to keep the rot at bay, of course, but they will wear off eventually and if you’ve forgotten to reapply and find yourself with rotten window sashes, you might want to run through your options.

Of course, you could always have your windows replaced entirely but there are less drastic measures to consider too.

Minor rot problems

Rotten wood is a blight that digs away at your window sash until there’s no good wood left. So, the best way to ensure a minor problem doesn’t evolve into a major problem is to cut away the rotten timber before it has a chance to dig in further.

If you cut away the rotten wood until just solid wood remains, you might then be able to repair what remains and apply a wood preserver to hold back the rot a while longer.

Major rot problems

Consult your local window specialists and see what your options are. New timber can sometimes be spliced into a sash box or the windowsill itself can be repaired without affecting the window itself. But it will, of course, depend on the individual case.

New window sashes can also be created, though if you are going to that much trouble you might as well go for brand new windows – unless there is something special or unique about them that can’t be replicated or replaced.

Preserving character

Nine times out of ten, if a window is rotten and the homeowner is adamant they don’t want it replaced, it’s because they are of some architectural or aesthetic significance.

There’s also a certain charm to older window sashes that can’t be adequately matched by modern uPVC models.

Removing rotten timber windows in 5 steps

Investigate – First, examine the extent of the problem by prodding at the wood with a screwdriver or a Stanley knife.

If it’s relatively solid, with just a few timbers falling away, it might just be minor rot. If the implement sinks into the wood, however, you’ve got a case of rot that might require more severe measures.

Unscrew and prepare – Unscrew the window and cut away the parts of the frame that are beyond repair. Note that you’ll need to leave a space to fit in any new pieces of wood.

Filling in – After any new necessary timber has been spliced into the frame, you’ll need to use a decent wood filler to secure it in place and round it out.

Be careful not to use too much as when the wood expands it will lead to cracks. The amount of filler required will depend on the quality of the timber and the accuracy of the cut.

Glazing – The seal of the putty around the glazing needs to be absolutely air-tight, particularly if your windows are double or triple glazed.

If even a small amount of moisture gets caught between the panes it can lead to mould and that will always lead back to more rot. So ensure you’ve replaced any cracked or loose putty before painting.

Colour up – Finally, use a strong prime layer (at least two or three undercoats) and water-resistant paint to finish off your windows and bring them back to life.