How to Paint a Sash Window

Summary: How to paint sash windows in the right order to ensure that you get the best possible finish. Advice about how to painting techniques to avoid windows sticking.

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Painting a sash window can lead to all sorts of trouble. If it is not painted in the correct order the sashes will stick together or each sash may stick in the frame rebate. This demonstration is one example of the best order to paint the various parts of a sash window. There are other ways but this is the one we have found to be best.

Different stages of painting a sash window

Different stages of painting a sash window

  1. Remove all locks and handles from the window frame. Its hard enough to paint as it is without painting round all the ironmongery. See our project on replacing a sash cord if the window does not open or shut in a balanced way. Just as with every decorating job these windows will need proper preparation. Sash windows fit very tightly together and the more paint you put on them the tighter they get. At some point in the decorating life of a sash window one has to start again and strip the paint back. If this is the time it may be best to follow the instructions in the project above and take the window to pieces.
  2. To get at all the parts of the sash window its necessary to reverse the sashes. Lift the bottom sash as high as it will go and pull the top sash down. Many people try to put masking tape on the glass but this causes more problems than it solves. Don't worry about a bit of paint on the glass, we will deal with how to get that off later. Make sure you remove all dust when you have sanded down. Use the hoover on the window to be certain of this. One of the reasons for painting windows and doors in the order we do is simply to do it in a way which keeps your fingers and elbows out of the wet areas you have just painted. Its not a scientific as it seems and most of it is just common sense!
  3. Start painting the bottom section of the sash which you have pushed up to the top. The mullions come first. Mullions are the division strips within the frame that hold the individual panes of glass. Paint carefully but don't worry about a little paint on the glass. As already said we will deal with that later. If you are right handed start at the top left corner and work across to the right just as you do when writing. Many people prefer to paint one side of all mullions first, then go back to paint the other side and finally the front. This is a good way to do it as the job is time consuming and painting all of 1 mullion can lead to the paint getting a little "sticky" as you finish. This makes it harder to get a really smooth finish. We tend to paint the left hand side of each mullion first, then go back to painting the right side.We also paint the underside of each horizontal mullion separately before going back to do the top.
  4. Paint the mullions in the lowered to sash. You wont be able to get to them all but paint the ones you can get to easily. Use the same method as above.
  5. Paint the face of the frame on the lower sash which you have pushed to the top.
  6. Paint the underside of the rebate into which the top sash will push when the job is finished. Push the top sash back up now but do not push it all the way into the rebate. Stop short of any painted surfaces meeting.
  7. Window scraper

    Window scraper

  8. Paint the remaining mullions and frame faces. Anything you could not reach before is now accessible.
  9. Finally the frame casing and the cill can be painted and the special weapon bought in to tidy up the paint on the window panes. Push the blade of the scraper onto the glass and run gently in towards the mullions. Now hold the blade vertically and run it carefully along the edge of each mullion where it meets the glass. This will cut through the paint so when you scrape the surplus paint will lift and leave a clean edge.

Another common problem with sash windows are the draughts caused by gaps in the frames. Once your paint is fully dry, this can easily be overcome by installing Gapseal leaving you with beautifully painted and draught free windows!

Take a look at our video section on painting and watch a film on how to paint window frames for a visual demonstration on this common DIY task.

Don't fancy doing this project yourself? We work with Checkatrade to ensure that we recommend only reliable and trustworthy tradesmen.

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