How to Replace a Broken Window Stay Arm on a Casement Window

Replacing a broken window stay arm on a casement window is a job most handy homeowners can tackle in under an hour with basic tools. The stay arm is the hinged metal bar that holds your casement window open at a set position — when it breaks or seizes, your window either won't stay open or can't be secured properly, which is both a safety and a ventilation issue.

What Is a Window Stay Arm?

A casement window stay arm (sometimes called a window stay or friction stay) is the adjustable arm mechanism that controls how far a casement window opens and locks it in position. Most NZ homes use either a peg-and-slot stay (a simple bar with holes that pegs onto a fixed pin) or a friction stay (a more modern sliding-track type). Identifying which type you have is the first step.

Tools and Materials You'll Need

• Flathead and Phillips screwdrivers
• Tape measure
• Pencil or marker
• Replacement stay arm (matched to your existing type and size)
• Optional: drill and appropriate drill bits if new screw holes are needed

Step 1 — Identify and Measure Your Existing Stay

Before buying a replacement, take careful measurements of the old stay arm:

• Overall length of the arm when fully extended (measure pin-centre to pin-centre)
• Fixing hole spacing on both the arm and the mounting plates
• Material and finish — most NZ window stays are aluminium or steel, in silver, white, or bronze powder-coat to match the window joinery
• Note whether it's a left-hand or right-hand fitting (which side the hinge pivot sits on)

If possible, remove the old stay first and take it with you to the hardware store for a direct comparison.

Step 2 — Source a Replacement Stay Arm

Replacement window stay arms are widely available in New Zealand. Check the hardware aisle at Bunnings or Mitre 10, or visit a specialist joinery hardware supplier. PlaceMakers also stocks window hardware. If your windows are a specific brand (e.g. Altherm, Metro, or Vantage aluminium joinery), contact the manufacturer or a joinery supplier directly — they often sell matched replacement parts.

Tip: Take a photo of the old stay, the window frame, and any visible brand markings on the joinery before you shop.

Step 3 — Remove the Old Stay Arm

1. Open the window to a comfortable working position.
2. Locate the screws on the casement plate (fixed to the window sill or frame) and the arm pivot plate (fixed to the window sash).
3. Unscrew and remove both plates, keeping the screws in case they're reusable.
4. If the stay has a peg pin, this may be a separate component — note how it's fitted before removing it.

Inspect the screw holes in the timber or aluminium frame. If they're stripped, you'll need to use slightly larger screws or fill and re-drill the holes.

Step 4 — Fit the Replacement Stay Arm

1. Hold the new casement plate in position on the sill or frame, aligning it with the existing screw holes where possible.
2. Screw the casement plate down firmly — don't overtighten on aluminium frames as you can strip the thread.
3. Attach the arm pivot plate to the window sash, again aligning with existing holes.
4. Connect the stay arm between the two plates, inserting the peg pin or sliding the friction mechanism into place as per the manufacturer's instructions.
5. Open and close the window several times to check the arm moves freely, holds the window open at the desired position, and doesn't bind or rattle.

Step 5 — Check Window Security

Once fitted, make sure the window closes and latches fully. A poorly fitted stay can prevent the window from sealing correctly, which affects both weathertightness and security. NZ's BRANZ provides guidance on window performance and weathertightness if you want to understand how window hardware fits into the bigger picture.

If your home is a rental property, note that under the Healthy Homes Standards, windows in certain rooms must be openable for ventilation — a working stay arm is part of meeting that requirement.

Tips for a Long-Lasting Repair

• Lubricate the new stay arm pivot points with a light spray lubricant (e.g. WD-40 or a silicone spray) once fitted, and annually thereafter.
• In coastal or high-humidity NZ environments, choose a stay arm with a quality powder-coat or stainless steel finish to resist corrosion.
• If the window frame itself is rotting or damaged around the fixing points, address that before fitting new hardware — a stay arm is only as good as what it's screwed into.

When to Call a Professional

Replacing a stay arm is not restricted work under the NZ Building Code, so homeowners can do it themselves. However, consider calling a qualified handyman or joinery specialist if:

• The window frame or sill is rotted, cracked, or structurally damaged
• You can't identify the correct replacement part and the window is a security or weathertightness risk
• The window is large, heavy, or at height and safe access is a concern — always follow WorkSafe NZ guidelines when working at height
• The joinery is under warranty and DIY work might void it

A skilled local handyman can usually complete this job quickly and cost-effectively. You can find qualified tradespeople in your area on tradedirectory.co.nz.

Sources & Further Reading

• BRANZ — Window and door performance
• Tenancy Services — Healthy Homes Standards
• WorkSafe NZ — Working safely at height
• Bunnings — Window hardware
• Mitre 10 — Window stays and hardware
• MBIE Building Performance — NZ Building Code