How to free a sash window that’s been painted shut

sash windows 3

Traditional sash windows are an original feature of many period properties. They can take a little effort to maintain but it’s well worth doing since they look so much nicer than modern uPVC windows, particularly in an older building.

A common problem within sash window repair is a sash window that’s difficult to open. It’s typically caused by having been painted badly, so that paint has got between the sash and the frame. Numerous layers of paints applied by careless painters over the years will have built up and effectively sealed the window shut.

Add to that the likelihood that the frame and/or channels won’t have had any cleaning or lubricating attention either, and it’s no wonder that your sash window will no longer open.

Luckily, this is not a terminal condition. Unsticking a sash window may need a bit of elbow grease and the right technique, but it can be done. Here’s what you do:

Tools you will need

The main tools you’ll need for freeing up a painted shut sash window are

·        Sharp Stanley knife or similar razor knife

·        Flexible steel scraper or putty knife, or deglazing/splitting tool

·        Wide chisel

·        Hammer


In order to find out if it’s the paint build-up that’s causing the problem, it’s a good idea to give your sash window a general inspection.

First, make sure the sash cords are still working OK. Give them a pull and see if they are still attached to the sash weights in their pockets. If the pulleys turn and you’re able to feel the tension from the sash weights, then there’s no problem. However, if the cords are missing or are no longer attached to the weights, the window will need fixing – which is a separate problem we won’t dwell on now.

Next, take a close look down the lines where the window runs in the frame runners. Many old windows have been painted shut from both sides, so check both the interior and the exterior of the window. Can you see that it’s been sealed with paint?

sash windows 2

Step 1: The Inside

Now use the razor blade of your Stanley knife to score a straight line between the sash and window stops on both sides. Push the scraper into the space along the line and apply gentle pressure to break the bond. If you’re using a deglazing tool, you can simply cut the line in one step.

Sometimes the paint has penetrated deeper than you think and it’s difficult to get a Stanley knife in without damaging the paintwork. In this case, a scraper or professional deglazing/splitting tool is your best option. They’re tough, flexible and very thin – the ideal tool to force into the gaps. Hold it up to the gaps all around the joins inside and out, and gently tap with a hammer. You may feel the window give a little when it’s freed up.

Under no circumstances should you use a hammer and chisel to free up the sides. A chisel is too thick and will ruin the wood, while too much brute force can actually break the glass – you have been warned.

Next, repeat the process at the meeting rail (i.e. where the top and bottom sash meet when the window is in a closed position). Make sure you have the sash lock unlocked so that you can separate the two sashes.

While cutting the windows open, take great care not to cut yourself or gouge the wood – these tools are sharp!

sash windows 4

Step 2: The Outside

Using the same method as above, repeat the entire process on the outside, except this time you will be cutting the paint between the sash and the parting bead, the square trim piece just outside of the sash.

Next move on to the underside of the meeting rail, then tackle the bottom of the sash where it meets the window sill.

You should now be able to open the window. If you still have no joy, a hammer and chisel may be required as a last resort. For the lower window, place the chisel on the outside at the base – from the outside only. For the upper window, place the chisel on the top – from the inside only. Using a hammer very gently so as not to damage the woodwork, carefully tap a little at each side to free the window.

Step 3: Opening the window

Having removed all obvious paint obstruction, try to slowly wiggle the window open from the inside. Any luck? Chances are that even if you’ve cut all the paint out of the seams, the window will still struggle to be opened.

The trick is to be patient – don’t rush it and don’t be too rough. The last thing you want to do is to break the glass or damage the mortise and tenon joints that hold the window frame together! Use your scraper to keep cleaning out the remaining paint and, with a bit of perseverance and some elbow grease, you should be able to get the sash window open.

Once you get the window moving a little bit, keep opening and closing it carefully to free it up fully. It will become easier to slide each time. Once you have the window fully open, you can use a chisel or sandpaper to remove the remaining excess paint build-up on the inside of the runners.

Finally, apply some dry lubricant such as a graphite spray, or use the tried and tested traditional method of vigorously rubbing an old candle all over the runners up and down the frame. It should make opening and closing your period sash window as smooth as the day it was fitted!

Of course if you struggle and this doesn’t work you can always call in an expert. Sash window repairs Brighton could advise and help.

Written by Julie Hanson

Julie is passionate about property – development, investment and portfolio planning. Along with husband Alec, Julie is actively building a property portfolio while helping others to do the same.

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