Why Won’t My uPVC Window Close?

Here’s a common conundrum that often has homeowners scratching their heads: Why won’t your uPVC windows close?

It can be pretty perplexing and worrying when you need to shut your windows, and they won’t cooperate. Your home security can be compromised, especially if it is a ground floor window that won’t close.

But fret not; we’re here to provide you with some of the reasons your uPVC windows refuse to close and provide practical solutions to address them.

Problem 1: The Window Hinges Have Worn Out.

Is there a visible gap between the sash and casement at the corners of your uPVC windows? If so, worn-out hinges could be the culprit.

Hinges on your windows bear the brunt of constant usage year after year. And let’s not forget the punishment they must endure from the elements.

Strong wind and harsh weather can take a toll on these hardworking components. Even the sturdiest hinges can succumb to wear and tear over time.

Solution: Replace the Hinges

Fortunately, you can fix your stubborn uPVC windows without replacing the entire unit. Replacement hinges are readily available online or in your local hardware store.

But how do you know what hinge type to buy? Consider these tips:

  1. Determine whether the hinge is top-hung or side-hung. Top-hung hinges attach to the sides, while side-hung hinges sit at the top and bottom. Here’s another trick: Check the position of the handle to identify your window’s orientation. 
  2. Measure the outer track width of the window hinge. The standard size is 18mm, but some hinges for older double-glazed windows are 15 mm.

Note: You can switch to a different friction stay, like egress or restrictor hinges. Just make sure to get the track width right. 

  1. Get the total length of the hinge track, including the end cap. Older 10-inch side-hung hinges can be hard to find, but you can use a 12-inch hinge instead.
  2. Determine the hinge thickness. If the supporting arm has a dip, then it’s 17-mm thick. Meanwhile, a flat arm is 13 mm and is the most common.

Once you have the replacement hinges, it’s time to roll up your sleeves for a switcheroo:

  1. Unscrew the hinges from the frame to remove the window sash. The sash can be heavy, so have someone hold it while detaching the hinges.
  2. Remove the screws that fasten the hinge to the sash.
  3. Clean the hinge areas on both the window sash and frame. Wipe away any dirt or debris and inspect for signs of damage that might need your attention.
  4. Attach the new hinge to the sash. You can adjust the position of the hinge along the slotted holes.
  5. Replacement hinges come in pairs. Repeat steps 2 and 3 on the other side of the window sash.
  6. Screw the hinge track onto the existing holes on the frame, just enough to hold everything in place.
  7. Close the window to do a test fit. The joint at the corners of your sash should align with the joint on the window casing.
  8. Tighten all screws if you’re happy with the fit.

Problem 2: The Window Has Sagged.

Your window sash should fit snugly within the frame. But what if the bottom of the panel is rubbing against the bottom of the frame? Well, that’s a clear sign the window has sagged.

Because your window won’t close properly, the gap will invite pesky draughts and unwanted noise into your home.


Sometimes, a dropped uPVC window is a structural issue and needs professional servicing. Before reaching out for help, you can try a simple trick to see if it solves it.

Here’s what you can do:

  1. Remove the screws on the bottom hinge.
  2. Move the hinge along slightly to make some clearance off the bottom of the sash.
  3. Replace the screws and check if the window closes okay.

Do you have a tilt-and-turn window that catches on the bottom when you close it from an open position?

A temporary fix involves lifting the bottom of the window and easing it along the frame.

Or you can raise the window panel by adjusting the hinge on the side (or both) that sticks against the frame. Follow these simple steps:

  1. Loosen the screw on the problematic side of your window sash. Get a tight grip on your window to support it from its weight.
  2. Lift the window slightly and tighten the screws.
  3. Check the alignment of your window.

Problem 3: The Window Lock Won’t Engage Properly or Has Failed.

If the locking mechanism is still intact but won’t seal tightly, there’s a possibility the drive gear and keeps don’t align properly.

However, if your window won’t lock at all, it’s likely the gearbox is falling apart. 

Solution 1: Tighten the Grip

To tighten the seal of your lock, all you need is an Allen key and a minute of your time. Here’s what you need to do:

  1. Locate the roller cams on the edge of your window sash. You’ll find a lock adjustment head with a hex hole and a tiny dot or line on the side.
  2. Fit the Allen key on the slot and turn it clockwise. The dot should be closer to the rubber seal to tighten it.

Solution 2: Replace the Broken Handle/Lock

To replace a broken uPVC window handle, check out these steps:

  1. Gather your tools: a flathead screwdriver, Phillip screwdriver, and measuring tape.
  2. Pop off any screw cap with a flathead screwdriver.
  3. Unscrew and remove the handle.
  4. Measure the length of the spindle protruding from the underside of the handle.
  5. Order a new handle online with the correct spindle size. You can also bring your old handle to your local store for a matching replacement.
  6. Install the new handle.

For a broken lock, it’s best to contact a service engineer or a professional locksmith.

uPVC Window Problem FAQs

How Do You Fix a uPVC Window That Won’t Close?

You can try one of the following solutions if your uPVC windows don’t close properly:

  • Replace damaged or worn-out hinges.
  • Tighten the lock or replace it if it has failed.
  • Adjust the alignment of your window panel.

What Are Common Problems With uPVC Windows?

Some common problems with uPVC windows include:

  • Stiffness when opening and closing
  • Faulty or damaged hardware (screws, locks, and hinges)
  • Sagging window panel
  • Expanded frame
  • Damaged seal

uPVC Window Closure Problem Conclusions

Typically, uPVC windows won’t close because of a sagging window, worn-out hinges, or failed lock. Luckily, these common issues can often be sorted with some DIY enthusiasm.

However, there may be occasions when you need to call in some expert help or have to replace your windows. This where Klic Home Improvements can be the window company you need with a full range of window replacement options that will perfectly complement your home.

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