Why would you repair a metal window? Let's ask the experts:
There is not a single and simple answer, because the repair depends on:
Repair goals can range from minimal to extensive. In fact, the less, the better!
Have a plan
The How to Do It section shows what things can be done, from minimal to full restoration. Know what the goal is, then plan just the repair needed to get there.
Don't overdo it.
What do you need to know?
You need to know only how to do the repairs the windows need. Nothing more. What you need depends on the goal and the plan.
What needs to be done for steel windows falls into three categories.
The main thing is knowing what to do and how to do it.
The two courses of action...
Repairs to steel windows usually are not complicated.
Many repairs require only simple skills and common tools. A Do-It-Yourself owner can save money doing some or all of the repairs. Many historic homeowners are more familiar with working with wood than with metal. Nonetheless, with knowledge about steel windows, the DIY owner can do many repairs.
Major repairs, however, are more likely to require a window repair professional with more metalworking capacity than owners have.
The first step is to figure out the condition of the windows. Remove surface dirt and grease and scrape away loose and flaking paint. Only then can any metal deterioration be assessed.
Surface imperfections do not necessarily indicate actual deterioration of the window material. Even if there is paint build up, cracked or broken glass, missing hardware, and some evidence of rust, the steel windows still are not likely to be seriously deteriorated. What looks like a badly deteriorated window may just be a window that needs some deferred maintenance.
A good overview of preservation of historic steel casement windows is City of Phoenix, Steel Casement Window Repairs.
The guiding reference on historic steel windows is U. S. Secretary of the Interior, National Park Service, Preservation Brief 13, "The Repair and Thermal Upgrading of Historic Steel Windows" (Sharon C. Park, AIA).
Steel windows, like anything else, require maintenance and occasional repair to remain in top working condition. Routine maintenance includes
For repair and weatherization of historic wood windows, see the article on Historic Window Repair and Rehabilitation
Repair of steel windows differs in important ways from the repair of wood windows. Materials made specifically for steel windows are needed, as noted below.
Paint poses two problems.
Loose paint and light rust can be scraped or sanded off readily. A wire brush is useful, or even an electric drill with a wire brush.
Heavy paint build-up between the movable sash and the fixed window frame can prevent a window from closing tightly.
Removing all paint from a window usually is not necessary. Any existing paint that still is tightly bonded to the metal still is good. However, full restoration of a steel window would strip off all paint and start fresh.
If any bare metal gets exposed, it needs to be painted immediately with a rust-inhibiting primer. NOTE: a primer especially for metal is needed, and the primer and the finish paint need to be chemically compatible. This means from the same manufacturer.
Other repairs need to be addressed before final painting.
Windows may not open for a variety of reasons, although the principal problem usually is that they are painted shut. First, be sure the window is unlocked. The paint seal will have to be broken. Work a putty knife or a utility knife along the edges of the movable sash until it breaks free. The paint seal could be inside, outside, or both.
Another common problem is that a casement sash is not sitting squarely in the window frame. The problem most likely is the hinges. Often, just tightening the hinge screws will pull the sash back into alignment with the frame.
If paint is not the problem, it may be a frozen crank mechanism (see below).
Loose or missing glazing can allow air infiltration, and it looks bad. Any loose glazing can be chipped off, the surface cleaned with a wire brush, and reglazed. The This Old House web site includes how to reglaze.
NOTE: a glazing compound specifically made for metal windows is needed, such as DAP 1012 (readily available). (Wood window putty won't last on steel.)
While the following demonstrations of glazing techniques are for wood windows, they are essentially the same as for steel windows.
A complete restoration would remove all glass from the window, clean and prime the frame, reset the glass, and reglaze.
Hardware may not work because it is clogged, needs oiling, or is broken.
How to Fix Casement Window Cranks provides guidance on getting cranks to work better.
Damaged or missing hardware can be replaced. There are numerous sources.
A complete restoration would remove all hardware, clean (and polish if possible), oil, and repair or replace.
Sills & Casing
Houses with steel windows usually have masonry window sills. If these are damaged, then there is a masonry problem, not a window problem.
If the sills happen to be wood, they may have deteriorated. Sills get the most exposure to weather and need the most routine maintenance or repair. The usual reason is that paint has not been maintained and has deteriorated, exposing the wood.
For information on repairing or replacing wood sills, see the section on "sills and casing" in our Historic Window Repair article.
Once windows will operate smoothly and are repaired, then the finish paint can be applied.
When corrosion is extensive, or when metal window sections are misaligned, then major repair is required. Sometimes major repairs can be done with the windows in place. Other times, windows may have to be removed to a shop.
Fortunately, major repairs rarely are needed for steel windows in houses. And severe deterioration is unlikely to happen for more than a few windows.
The scope of major repairs is presented in Preservation Brief 13 Steel Windows.
Generally a contractor with specialized knowledge and skills will be necessary for major repairs.
A good storm window is an essential.
For information on storm windows, see our article on storms.
Exterior caulking is needed everywhere around the window frames and sills.
For general instruction, see How to Caulk Metal"Most small gaps up to 1/4 inch may use a 100 percent silicone caulking for metal, such as GE Silicone II Aluminum & Metal. Larger gaps should use a polyurethane caulk, such as SeamStitch Polyurethane Elastomeric Caulk."
Interior caulking is needed around interior window frames.
There are reliable contractors who specialize in the window repair and restoration. They know how to do it correctly. Several well-known ones are listed below.
Since many of the repair and weatherization tasks are simple, general contractors, handymen, or house painters may be able to do them. However, employing non-specialized contractors for window repair can be risky.
There are two reasons why employing non-specialized contractors for window repair can be risky.
Replacement window companies will advise you that your windows cannot be repaired and are energy inefficient. Their advice: buy their new windows!
Don't Believe It!
Advice. You need to know what work you need and how it should be done!
Here's how: study the DIY information. Even if you cannot DIY, it is the information that you need to understand what work you need contractors to do, and how they should do it.
Contractors can learn! There are reliable contractors who just doesn't know about windows. They can learn what they need to know here in order to do good work.
Having a plan is very important here again. With a plan that prioritizes the work to be done, an owner can work with a contractor and get the most important work done first and within the budget. Also, if work must be spread out over time for financial reasons, the plan will help the owner and contractor set up the work in a series of affordable stages.
Disclaimer. The window repair and restoration contractors listed here have credentials for windows and have been recommended by building owners in Historic Districts. Neither the Historic Boston-Edison Association nor the Detroit Historic District Commission can guarantee your satisfaction with any contractor. Every owner must find contractors with whom they can work satisfactorily. Check their references yourself.