Send me a FREE trial issue Plus a FREE gift
Old-House Online » Old-House Tips, Restoration Stories, & More » Repairs & How To » How To Repair a Steel Window

How To Repair a Steel Window

Replacing broken glass in a steel casement window requires specialized tools and processes. By Steve Jordan | Photos by Andy Olenick

    Repaired steel casement windowReplacing a broken pane of glass on a steel casement window isn’t like repairing wood sash. It takes different tools, special materials, and a fine-tuned process. But once the former are assembled, the job is easy enough for anyone with a little DIY experience and a willing attitude.

    Step 1

    Assemble your materials, starting with the glass. Unless your glass is ordinary 1⁄8″ double-strength sheet glass, purchase 3⁄16″ or 1⁄4″ plate glass at a glass supplier to match the existing. (The new pane of glass should be about 1⁄8″ narrower than the opening’s height and width.) Steel sash should be glazed with putty specifically made for metal windows, such as DAP 1012. (Wood window putty won’t last.) You’ll also need an awl and hammer, metal sash clips, duct tape, a wire brush, needle-nose pliers, a small window suction cup, and whiting.

    Materials for repairing a steel window

    Step 2

    Wearing eye protection and a respirator and using basic lead-safe work practices, begin removing the old putty. Because old putty can be hard and may contain lead, Portland cement, or asbestos powder, use an awl and hammer, not heat, to loosen it. Look for areas where the putty is loose or missing, insert the awl point between the putty and steel, and gently tap the awl with your hammer; the force needed will depend on the condition of the putty and its composition. If the putty is intact, start from the middle.

    Removing old putty

    Step 3

    Once the putty is removed and the edges of the glass are exposed, look for two metal spring clips on each vertical side of the opening; pull them out with the needle-nose pliers. These clips are fragile and easy to lose; if you can hold onto them and they remain intact, you can reuse them. Otherwise, purchase new ones at a glass company. Next, with the ground and floor protected to catch glass shards, old putty, and dust, cover both sides of the glass with wide masking or duct tape to contain breakage. If the pane isn’t badly cracked, pull it out using a small window suction cup, or by tapping gently from the inside out. With the glass out, finish removing the old putty. If the sash rebate is rusty, use a wire brush or a drill and wire brush attachment to remove as much rust as possible. Brush or vacuum the dust away, and prime the cleaned area with a coat of oil-based rusty-metal primer.

    Cleaning up rust

    Step 4

    Since DAP 1012 is usually oily on top of the can and dense at the bottom, remove all of the material and knead it into a pliable ball, using whiting if necessary to firm it to an appropriate consistency. (If the putty is dry on the top of the can, return it for fresh material.) The new pane of glass can’t touch the metal frame in any direction, so back-bed a thin layer of putty in the frame to seat the glass, protect it from thermal movement, and create a weather seal. Install the back-bed with your fingers or a putty knife, pushing the putty into the frame (warm putty is more pliable). Next, insert the pane of glass, and gently push it into the putty until it is well-seated. Using needle-nose pliers, install the metal sash clips on each side to secure the pane.

    Inserting sash clips

    Step 5

    Before glazing, remove excess back-bedding material from the interior side with your putty knife. Next, glaze the exterior—I like to push the putty into the frame and glass tightly with the putty knife, but the common method of rolling putty into a snake and then inserting it also works. Take care to respect the interior sight lines of the sash—putty and paint on the outside shouldn’t be visible from the inside. Tool the putty, pushing it tightly to the frame and glass while cutting the edge away at the sight line. To finish, sprinkle a little whiting or plaster dust on a clean cotton rag, and carefully wipe away all the smears. After the putty dries, paint with two coats of oil-based paint.

    Applying putty
    Published in: Old-House Journal February/March 2013

    { 2 comments… read them below or add one }

    Catherine Brooks, Eco-Strip June 20, 2013 at 10:47 am

    Why wouldn’t low infrared heat (Speedheater), which does not vaporize lead, be used? With glazing on wood windows, it safely softens the glazing and therefore, reduces the risk of breaking the glass with an awl, sharp chisel, and a hammer. Scraping SOFT, heated, old lead-based paint and putty generate less lead dust and further reduce the risk of lead poisoning than does dry scraping.

    Linda Forrest September 21, 2014 at 3:26 pm

    I have a house with metal windows and can’t find anyone who can repair. Where should I go? Can you help me out?

    Leave a Comment



    Get your FREE Trial Issue of Old House Journal and a FREE gift.
    Yes! Please send me a FREE trial issue of Old House Journal and a FREE gift.
    If I like it and decide to continue, I'll get 7 more issues (8 in all) for just $16.95, a savings of 53%. If for any reason I decide not to continue,
    I'll write cancel on the invoice and owe nothing. The Free Trial Issue is mine to keep, no matter what.
     
     Full Name:
     Address 1:
     Address 2:
     City:
     State:
     Zip Code:
     Email (req):
     
    Offer valid in US only.
    Click here for Canada or here for international subscriptions

    Products & ServicesHouse ToursHistoric PlacesHouse StylesOldHouseOnline.comMagazine
    Architectual ElementsKitchen & BathsHistoric HotelsArchitectural TermsRepairs & How ToSubscribe to Old-House Journal
    BathsInterior & DécorHistoric NeighborhoodsAmerican FoursquareFree NewslettersBack Issues
    Ceilings & WallsGardens & ExteriorsHouse MuseumsBungalowSubscribe to Arts & Crafts HomesDigital Editions
    Doors & WindowsColonial RevivalOld House CommunityAdvertise
    Exterior Products & LandscapeGothicAbout Us 
    FlooringQueen AnneContact Us 
    FurnitureVictorianPrivacy Policy
    HardwareLand for Sale
    Heating & CoolingSite Map
    Home Décor
    Kitchens
    Period Lighting
    Real Estate
    Repair & Restoration
    Roofing & Siding
    Tools & Equipment

    EXPLORE OUR HOME GROUP BRANDS:
     
    Designer Sourcw e bookDesigner Craftsman Historic Home Show Logo

    Copyright © 2011-2014 Old House Online