How To: Maintain Sash Windows

As a window restorer I get called in to restore badly neglected windows. After decades of little or no care things have gotten so bad that that these windows usually don’t operate anymore, are riddled with rot or termite damage and look pretty ugly. The sad thing is that none of this would happen is people knew how to maintain sash windows properly.

Most people think that it’s the age of the window that makes it look and operate so poorly. It is actually not the age but the lack of regular maintenance.

Don’t be fooled by claims of a “no-maintenance” window. No matter what materials they are made of every window needs some level of maintenance on a regular basis.

In this post, I’ll walk you through the basics of how to maintain sash windows to keep them looking great and functioning smoothly for hundreds of years. You heard me right, if you have pre-war wood sash windows like a double-hung wood window or a single-hung wood window they will outlive you by hundreds of years with only a few minutes of maintenance each year. Keep reading to learn how.

Annual Cleaning

Looking through a sparkling clean window is an underestimated joy in my opinion. When you give that glass a good cleaning the sun seems brighter and the neighborhood looks happier to me.

An annual cleaning is also the step to maintain your sash windows for a long time. Wash the exterior of the window including the sash, jamb, sill, and glass with soap and water and wipe it down with a towel or chamois.

This cleaning keeps the paint looking good and helps it shed dirt and water better over the year increasing the life of the paint and reducing the chance for rot.

Unless you have little kids with sticky fingers the interior of the glass doesn’t usually need cleaning as much or as often as the exterior but a good wiping down with a damp rag of the window elements always makes things look better and helps remove any unwanted dust.

If you’ve got things growing on the outside of your windows (never a good sign) use this post to help you get rid of mildew and mold growth effectively. Watch the quick video below to show you how easy it is to remove mildew growth from windows.

Inspect for Rot

One of the biggest issues with wood windows is the potential for rot. If you think of rot like you would cancer you can understand that early detection is key. Inspect the exterior of your sash windows annually for soft spots, paying particular attention to the joints of the sash and jamb where water can get trapped.

If you see signs of rot or sense soft wood, scrape the small area clean of paint and any damaged wood and apply a small amount of a borate treatment like BoraCare to stop the rot in its tracks. Then once the borate has dried, fill in any of the damaged wood with a good wood filler.

Touch Up Paint

The exterior paint on your sash windows is meant to be a sacrificial protective layer designed to eventually wear out and need replacing. Doing an annual inspection and touching up little chips or bare spots will keep the windows protected from water penetration.

Carefully inspect all painted areas and touch them Up as needed, paying special attention to the paint line between the glass and glazing putty which can fail earlier than other areas. You want to maintain that 1/8” line of paint that laps onto the glass and helps seal the putty. This simple act will extend the life of your putty into decades of additional use.

Be careful during your painting to not paint things like hardware, pulleys, or ropes. Getting paint on these mechanical elements can compromise the smooth operation of your windows.

Touch Up Putty

The glazing putty seals the glass to the wood sash and is beveled to provide easy water shedding. If the putty has been chipped out or is missing then water has an opportunity to pool and cause rot.

When you are inspecting your sash windows remove any loose or crumbling putty and lay in some new glazing putty to seal those areas. Once the putty has developed a skin (usually 3-5 days) put two good coats of paint over it to protect it as well.

If you can do these simple things to maintain sash windows once a year your windows will remain beautiful and won’t have the typical issues associated with old wood windows.

Extend their life, and keep your costs down dramatically by completing these annual checks which should take no more than 5-10 minutes per window each year. Keep in mind that if you skip a year (or two) then you compound the time you’ll spend the following year. Maintenance time doesn’t go away if you skip it. It builds up year after year and by breaking it into simple, inexpensive chunks like this you make the costs and time commitment more manageable.

If your looking to restore your old windows and you’d like help with your project consider my DIY Assist program. We’ll send you a care package of all the tools and supplies you’ll need to restore your old windows and it comes with 2-4 hrs of one-on-one coaching with me or one of my Window Pros. Learn more about DIY Assist here!