Peeling paint is never a good thing, and in an old house, one of the most typical places you’ll find peeling paint is on your windows. But if you knew what caused this incessant peeling, you could stop it in its tracks. That’s what I’ll help you do today!
The picture above is from a recent project my company is working on in Apalachicola, FL, but it’s an all too familiar scene with peeling paint along the glass of windows.
The room where the picture was taken had a window AC unit on full bore. It kept this little room at about 60 degrees! It really felt like an ice box in there, especially when it was around 95 degrees outside.
This huge difference in temperature and the excessive humidity caused the windows to constantly be sweating with condensation (in this case on the humid outside) and that’s the main culprit of peeling paint.
The Condensation Conundrum
Wood that is constantly getting wet doesn’t hold paint well. The water gets into the wood, spreads throughout the wood, and tries to escape again. If the wood is bare, the moisture can escape, but when it’s painted, any moisture trying to escape the wood will start to push the paint up off the surface of the wood. That’s the most typical cause of peeling paint on wood, period.
In the case of the fort, it was cold dry air inside and warm humid air outside. The dew point was reached on the surface of that glass and voila, dew (otherwise known as condensation!)
In most temperate climates, the condensation occurs on the inside of the glass during the winter.
Outside is cold dry air all winter and inside we keep it warm and toasty. And it’s always a little humid inside because of the activities we do like, say, breathing. Seriously though, breathing is one of the causes of humidity indoors along with steamy showers, cooking, washing, etc. Any time you use water inside, there is some evaporation.
That condensation on the glass collects and rolls down onto the wood sash and profiles of the window where it seeps into any cracks in the paint and from there, into the wood it goes.
How to Stop Condensation
So, if condensation is the main culprit that causes peeling paint, how do we stop it? I’ve got some great solutions for you and most of them are very affordable.
- Bath Fan – A bath fan is the easiest way to get rid of that extra humidity in your house. Install a bath fan with some serious CFM (cubic feet per minute) power to suck out all the shower steam. A few important things to know:
- First, make sure you size it correctly for your bathroom. This will tell you what CFM rating you need for your fan.
- Calculate the number of cubic feet in the bathroom by multiplying the room’s height x width x length in feet.
- Divide the number of cubic feet in your bathroom by the number of minutes in an hour (60).
- Make sure it is vented outside your house! Some people just vent it into the attic which causes high humidity in your attic and just moves the problem upstairs.
- Use it! If you don’t remember to turn the fan on, it won’t do much good. Turn it on with each shower and let it run for 10-20 mins afterward.
- First, make sure you size it correctly for your bathroom. This will tell you what CFM rating you need for your fan.
- Dehumidifier – Whether you use a room size dehumidifier or a whole house option, a dehumidifier is a great way to keep humidity at bay.
- Indow Inserts – These are panels that install easily on the interior of your windows and air seal old windows. I’m a dealer in my area for Indows, but that’s only because I have seen how well they work. They make a huge difference in the war against window condensation. In my experience, they have all but stopped any condensation on the windows where they are installed. If you don’t believe me, check out this post.
What to Do If Your Paint Has Already Peeled
If you’re already the victim of peeling paint, you need to fix your condensation issues likely, but how can you repair the peeling paint and help keep it smooth in the future.
Here are some simple steps to repairing the peeling paint and keep things looking good.
- Scrape any loose paint off with a pull scraper.
- Sand the surface smooth with 120-grit sandpaper, being careful not to scratch the glass. Be sure to follow lead safe work practices if your house was built before 1978.
- Clean off any sanding dust with a tack rag.
- Prime the surface with an oil-based primer.
- Brush on 2 coats of finish paint. You can use either oil-based or water based paint depending on what your existing paint is already.
These tips should help you get your windows back into good shape and keep that problem causing condensation at bay.
For more on repairing and restoring old windows, you can visit my resource page How To: Repair Old Wood Windows
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I love old houses, working with my hands, and teaching others the excitment of doing it yourself! Everything is teachable if you only give it the chance.
My windows are becoming moldy and the paint is flaking off on the outside due to the heat and humidity of S.C. summers. My home was built in 1964. Would I follow the same method to correct them?
My bathroom window has this issue, how do i dry the damp wood before sanding an painting it?
I think, as in putting linseed oil on bare wood on all “channels”, and bare wood, it prevents the dry wood from pulling oil from putty, or oil based primer, preventing possible cracking of putty or paint popping off, in future.
worked for me. ????
had paint popping off down to bare wood on my bottom window sill. 1973 wood windows double sash , side frames are aluminium channels with springs inside that has red plastic clip that holds the spring to the bottom of window. 4 springs per window. 9THEY DONT MAKE THE RED PLASTIC clips anymore)……popped off within a year. 2006 I sanded each window down, feathered out, put heavy coat of linseed oil ,wait 24 hrs, put second coat linseed oil on. used oil based primer/w/linseed oil in it. 2 coats laytex ontop. good for 10 years now. all brick house with storm windows.
I hope someone can advise me on this wood window mystery. In the spring, I hired a contractor to reglaze all the house windows. Now, in the Fall, I am about the business of painting the beads before the storm windows go in, and I notice that on the lower sashes, the upper horizontal plane is not glazed. It appears that plane was never done over the years. Is there a reason to leave one plane unglazed? The top sashes (leaded glass design) are glazed on all four planes. Help! It will get cold fast here, and it looks like this project will go on until next spring!
I do hope I am using the correct terminology to describe my dilemma. These are double hung windows; 1929 house.
Mary Ann, not to worry! The top of the bottom sash is not supposed to be glazed. The glass sits in a small kerf in the wood there to hold it securely in case the meeting rail is ever torqued too much. Sounds like everything was glazed correctly and is ready for paint.
Thank you, Scott. I was confused, as all the tutorials about glazing windows show all four planes being glazed. This will save me a lot of time, but to be honest, I have glazed a few of the undone panes. Not to late to undo them, as the glaze can’t possibly have “skinned over” yet.
Love your site!!
Instead of peeling paint I have peeling and cracked shellac(I think)with black, mold, on the wood underneath in some areas.
Can I scrape off shellac, sand to get below the old stain and mold and then re-stain and use a polyurethane over that?
Is it realistic to sand mold out?
Michelle, shellac is even easier to remove! You can almost wipe it away with Denatured Alcohol which dissolves shellac. Once that is gone treat the mild with a mild killing spray or some bleach water. Then once the wood dries you can sand, stain and poly. Make sure to use spar urethane instead of regular poly because the expansion and UV rays on windows will wear out regular poly too fast.
10 years ago I sanded, re-stained and 3 coats of oil poly on inside of my 1973 wood windows. none of my windows are back puttied. should I take all window panes out and back putty ? no glazing pins either. A LOT of the old factory putty is still in good shape. have taken one window completely out and have it in garage to work on. am retired and have the time to do it right. ordered variable heat hear gun with attachments, and also ordered 705 steam machine.
do I sand poly on inside of windows and use spar urethane ? I got the time to do it right