Skip to content 
Aluminum single hung windows are popular in Dublin homes for their durability and low maintenance. However, when glass breaks or mechanisms fail, knowing how to handle repairs can save you time and money.
Understanding Your Window’s Lifting Mechanism
Your aluminum single hung window uses one of three systems to keep the lower sash in position when opened. Identifying which type you have is the first step to successful maintenance.
Block and Tackle System
If you don’t see visible mechanisms on the window sides, you likely have a block and tackle system with internal springs and strings. Look for thin metal clips in the side jambs just above the sash. To remove the lower sash, pull the bottom of these clips outward using a screwdriver or your fingernail on both sides. Remove any rubber stops at the top, then raise the window completely. The clips will catch the block and tackle assemblies, allowing you to lift out the sash.
String and Pulley System
Some windows feature a visible system across the top with strings running down each side, screwed into the upper corners of the sash. Before removing these screws, you’ll need to take out one of the black plastic side jamb covers. Raise the window fully, insert a flat screwdriver at the bottom of the plastic piece, and pull outward until you can grip it with your fingers. Slide it out carefully.
Hold the string firmly while unscrewing it—these strings are under tension and will snap back quickly. Let the string retract slowly after removal. Pull the panel toward the side where you removed the plastic cover to extract it.
Spiral Balance System
Windows with spiral metal rods require professional attention. These mechanisms can be damaged easily during DIY repairs, potentially requiring complete replacement of the balance system.
Replacing Glass in the Lower Sash
Once you’ve removed the sash, glass replacement follows standard procedures. Remove the frame screws from opposite corners—never adjacent corners, as this can damage the frame. Carefully extract the broken glass, clean the frame channels thoroughly, and install the new pane with fresh glazing.
When reinstalling the sash, reverse the removal steps. For block and tackle systems, position the window, close it fully, and push the metal clips back into place. Replace the rubber stops at the top. For string systems, reinstall one string screw first, then remove the opposite corner screw to maintain frame integrity during reassembly.
Repairing the Upper Fixed Sash
Upper sashes in single hung windows are typically fixed panels, making them easier to access without disturbing the lower sash. Start by unlocking the window and raising the lower sash several inches. Remove the screen, then unscrew the horizontal mullion bar between the two sashes.
Tap one corner of the bar downward with a hammer and screwdriver until it releases. Grasp the bottom of the upper sash and wiggle while pulling down. After moving it down several inches, grip both top and bottom edges and pull left or right until one side releases from its track. Swing the panel out for glass replacement.
Installation reverses this process. Seat the sash fully in the top frame channels, then tap the bottom upward with a rubber mallet. Reposition the horizontal bar and tap it onto the sash frame before reinstalling screws and the screen.
Maintenance Tips for Longevity
Regular maintenance extends the life of your aluminum windows significantly. Clean tracks and jambs every few months, removing dirt and debris that can interfere with smooth operation. Lubricate moving parts annually with silicone spray—never oil-based products, which attract dust.
Inspect weatherstripping for wear and replace it when you notice drafts or moisture infiltration. Check that drainage weep holes at the bottom of the frame remain clear to prevent water buildup.
When to Call the Professionals
While many repairs are manageable for DIY enthusiasts, some situations warrant professional expertise. Complex spiral balance systems, severely damaged frames, and modern double-pane sealed units often require specialized tools and knowledge.
Need expert help with your window repairs or considering an upgrade? The team at Expert Windows specializes in aluminum window repair and replacement throughout Dublin. Whether you need a simple glass replacement or complete window installation, our experienced professionals deliver quality workmanship backed by reliable service. Visit our completed projects gallery to see examples of our work, or contact us today for a free consultation.
