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How To Restore Steel Windows

Historic Steel Window
Image Credit: Scott Sidler

Historic steel windows are all across America. They became popular in big cities to combat the fires that were so common around the turn of the 20th century. Then, from the 1930s until the 1950s, they were a popular choice in residential housing due to the decreasing availability of quality lumber.

Many steel windows sit and deteriorate across the country. While much attention has been paid to restoring traditional wood windows by preservationists, historic steel windows have fallen through the cracks. Well, that is something I would like to remedy here at The Craftsman.

We have put together a comprehensive guide to walk you through the process of how to restore steel windows. I’ll discuss the highlights here in this post to give you a primer on the subject.

If you really want to get down and detailed about working with historic steel windows, you should purchase and download my picture filled e-booklet. It is 12 pages of everything you’ll need to know about restoring steel windows. It includes:

  • Materials list
  • Detailed photos and breakdowns of each step showing exactly what and how to do it
  • How to get old hardware working again
  • Time tested techniques we use everyday

Pick up your copy right here!

The Craftsman’s Guide to Restoring Steel Windows


How To Restore Steel Windows

Putty removal

Historic steel windows are best restored in place, though with some effort, they can be removed from their opening and restored in a shop. The process is pretty straight forward and mostly focuses on removing the old glazing and paint down to bare metal before applying fresh coatings.

Step 1 Putty Removal

Old glazing putty on steel windows is often much harder than on historic wood windows. There is also a possibility that it contains asbestos so you should have it tested before large scale removal.

The best way we have found to remove the old putty is using an inexpensive wood chisel and hammer, but be careful of the spring clips that hold the glass in place. Once all the old putty is out, you’re ready for paint removal.

Step 2 Paint Removal

Scraping paint down to bare metal is essential here if you want your new paint to last. Use a ProScraper to remove any old paint. Once the paint is gone, sand the surface smooth and wipe all the sanding dust down with a damp cloth when you’re finished. Then, clean the glass as best you can before proceeding.

Step 3 Pre-treatment & Priming

Treat any rusted areas with a rust treatment like Ospho (this step is fairly complex and is described in more detail in the e-booklet). Then prime all the metal surfaces with a quality metal primer.

Step 4 Glazing

Glazing steel windows

Once the primer is dry, you can proceed to putty glazing. You’ll need a putty designed for use on metal sashes like Sarco Dual-Glaze or DAP 1012. Press the putty into the glazing rabbets and finish the putty with a smooth bevel and clean 90 degree corners.

Follow the manufacturer’s recommendations for painting the putty. Some putty can be be painted right away, while others require a couple weeks to skin over before painting.

Step 5 Finish Paint

Top coat with a quality exterior paint. The paint should be lapped onto the glass about 1/16″ in order to seal the putty. You need to cut in a straight line with your paint brush and let the paint dry naturally in order to create a good seal. I recommend using an oil-based paint whenever painting a metal surface.

Complete all these steps (other than putty glazing) on the inside as well and your historic steel windows should be ready for another 50 years with only minimal maintenance other than regular paint jobs.

For a more in depth explanation of the process you should definitely pick up my e-book The Craftsman’s Guide: Restoring Steel Windows

Subscribe Now For Your FREE eBook!

83 thoughts on “How To Restore Steel Windows

  1. Looking at buying a building in Detroit that has one larger steel frame window with 60 individual panes. I’d like to restore this building but it’s in a less than desirable neighborhood and I’m afraid if I redo the windows, bricks will be thrown thru them the next day.

  2. Hi – we have some old Steel casement windows made by Hopes that are really beautiful. I have done most of the restoration but I am going to need a couple of the old window cranks to operate them. Please let me know if anyone might have a source for my project.

    Thanks so much!

  3. Im actually over-joyed to read this…along with stressed. I bought a 50’s ranch cottage (750 soft) and there is 10 of these gorgeous metal casement windows (flange) in the concrete. I don’t know who can help me refurbish them ..(new glass, efficiency film, and of course keeping it from leaking on the inside and deteriorating anymore) which is what happened to the last owner and a mold problem arose! Ive since town out the drywall. Im in Ocala, FL …middle of nowhere. To replace is sooo expensive with these custom sizes and it looses its charm, I’d rather spend the $$ on whats already there and keep its historic nature! Please help!! Thank you, Rita

  4. Need recommendation for someone to help me restore my 1939 steel casement windows. I’ve started on my own but it may be too big a job for me. I am in Tucson. Thank you.

  5. I have a set of interior steel doors, am I able to keep the metal frames bare without painting? If so what is the best putty to use ?

    Thanks, E

  6. Can I use a heatgun to help strip off the paint on the casement windows? Can they be painted with latex or acrylic instead of oil paint?

  7. I’m looking for a company that does repair and restoration work in the Chicago area for my 1930s Tudor home. The steel casement windows are beautiful and still functional, but badly need some TLC before they deteriorate. My husband and I could possibly putty and paint, but there is a lot of rust and build up, in addition to missing machinery and frame issues, that we want someone who specializes. Any recommendations for our area?

    1. Check out Old Country Steel Windows

      They’re doing our window restore now in the south Chicago suburbs but are based out of Wonder Lake.

  8. Scott
    I gave in to my wife and in the process of replacing our old steel casement windows with new clad double hung units.
    I have removed all the screws,scraped out caulk at masonry and seem loose from the inside, but cannot get the frames out – I was hoping to not cut them in half and actually trying to leave all the glass in place with hopes of passing them on to someone’s restoration project.
    Am I missing something with removal? Do you know anyone in the Charlotte. NC area that would want them?

  9. Do you know anyone who would do restoration work for steel casement windows circa 1940 in the bay area, CA? The Wooden Window referenced here appears to be out of business.

  10. Just bought a 1947 brick veneer house with steel casement windows. Looking forward to restoring the windows but would like to reduce heat loss through the panes and the effects of the steel thermal bridge. What type of glass pane should I be looking for and are there any paints that I could use to reduce the thermal bridge? Great guide!

  11. Hi Scott! I purchased your book to guide me through restoring the steel windows in our “new” 1950 ranch home in Oskaloosa, IA. I am starting on the inside but last fall I cleaned the outsides of the windows and noticed a now crusty, probably once fluid substance that has randomly seemed to seep from the top of some of the glass panes. I scraped it off with a razor and it’s pretty persistent, to say the least! And now, it’s back ?Do you have any ideas on what this might be and if I can do anything in my restoration process to prevent it in the future? Is there a step I need to add somewhere?

    Thank you for your help. Your guide has been a blessing.

  12. So much interesting info here. Im learning to love my old steel casements in my 1932 english tudor even though i hated them not so long ago!. Does your ebook talk about the steps in fixing up the interior of the steel casement windows? im actually trying to figure out how to remove layers of paint from the interior steel windows & then what the next steps are in finishing the steel & then to paint in a tudor dark brown or black paint. i see this look in many design & home magazines ….french casement window look & would love to recreate it myself if possible.

  13. Hi there,
    I have a 1930 home with many steel casement windows in NY. I love them but OMG – are they drafty. The cold just blowing right in. Remember NY winters get really cold! We put up the frost plastic, heat shrink, sheet barrier which helps some but not great. Are there any tips, beside reapplying the putty to help stop the drafts??? I read somewhere about applying silicone to the inside of the window, take baking sheet and cut strips, place on top of the silicone, then close the window, let it dry for a day….. open and take off the baking sheet….and the silicone would form a air barrier in the gaps …..what do you think of this??? I know Skeekicher is good company – but they won’t even come out unless it’s a big job worth thousands.

  14. I’m purchased a 1930’s home with 35 metal casement windows. They are all rusted but appear to be solid. Since this is my future office vs. my future home cost is more Important derry. I had a contactor recommend sand blasting the windows then apply the primer. My 3 questions are:. 1) your thoughts on sandblasting, 2) going back with individual double pane vs. single pane and 3) do you have a Contractors name in Knoxville, TN or the East TN area? Thanks

  15. Scott, I’m buying a 1930’s house with single page metal Casement windows. A total of 35. What are your thoughts of replacing the glass with a double pane windowm and second, do you have any recommendations of Contractors around Knoxville TN or East TN area?

  16. I have a 1930s home with steel windows. I am in Albemarle NC,near Charlotte. Glazing is cracking, although most still hard. Does all glazing need to be removed or can it be repaired?
    Any names of restorers in area? Thanks.

  17. My grandfathers house, built in 1947-1948 I believe has steel casement windows. I’m in need of assistance in locating a restoration and rehabilitation contractor to not only restore, but to possibly add screens or additional glazing for energy efficiency. The house is located in Reno, Nevada and I’ve not been able to locate anybody close to Reno that knows anything about these types of windows. Any advice would be helpful. Thank you.

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