Why Is My uPVC Window Letting in Draughts?

If your uPVC window is letting in draughts, it usually means the window is no longer sealing properly against the frame. Even a small gap can make a room feel colder, let outside noise in, and make the window less comfortable to live with, especially during windy or colder weather.

In many cases, the problem is caused by worn hinges, damaged rubber seals, poor alignment, a faulty handle, or a locking mechanism that is not pulling the window tight enough when closed. It does not always mean the whole window needs replacing.

Below, we explain the most common reasons a uPVC window lets in draughts, what you can safely check yourself, and when it is best to call a window repair specialist.

Quick Answer: Why Is Cold Air Coming Through My uPVC Window?

Cold air usually comes through a uPVC window when the opening sash is no longer sealing tightly against the frame. This can happen even if the window looks closed from inside the room.

The most common causes include worn hinges, damaged rubber seals, poor alignment, a faulty handle, or a locking mechanism that is not pulling the window in tightly enough. Dirt, debris or a damaged trickle vent can also create what feels like a draught.

In some cases, the issue is easy to spot, such as a visible gap, loose seal or open trickle vent. In other cases, the window may need checking more carefully to find out whether the hinges, locks or keeps are out of line.

Common reasons include:

• Worn or damaged window hinges

• Loose, split or flattened rubber seals

• A dropped or misaligned window sash

• Locking points that are not engaging properly

• A stiff or faulty handle

• Dirt or debris in the frame

• An open, loose or damaged trickle vent

• A failed double-glazed unit

If the window still lets in cold air when it is fully closed and locked, it is usually a sign that one or more parts need adjusting, repairing or replacing.

Worn Hinges Can Stop the Window From Sealing Properly

Worn hinges are one of the most common reasons a uPVC window starts letting in draughts. The hinges do more than simply open and close the window. They also help pull the opening sash tightly back into the frame so it seals properly.

Over time, hinges can wear out, loosen, bend, or stop holding the window in the right position. When this happens, the window may still close, but it may not pull tight enough against the rubber seal. This can leave a small gap through which cold air can get in, often along the hinge side of the window.

You may notice the window feels loose, catches slightly when closing, or makes a whistling noise when it is windy outside. In some cases, you may also see a visible gap between the sash and frame.

The good news is that worn hinges can often be replaced without replacing the full window. Once the correct hinges are fitted and the window is sitting properly again, it can help reduce draughts and make the window easier to close and lock.

Damaged or Flattened Window Seals

The rubber seals around a uPVC window are designed to help stop cold air, water and outside noise from getting through. When the window closes, the sash should press neatly against these seals to create a tight fit.

Over time, window seals can become worn, loose, flattened, split or hardened. If this happens, the window may not seal properly, even if the handle turns and the window appears to be closed. You might feel cold air around the edge of the frame, notice more outside noise, or see sections of seal that have pulled away.

In some cases, damaged seals can be replaced. However, it is important to check why the seal has failed. If the window has dropped, the hinges are worn, or the sash is not sitting correctly in the frame, replacing the seal alone may not solve the problem.

A repair specialist can check whether the draught is being caused by the seal itself, the window alignment, the hinges, or the locking mechanism.

The Window Has Dropped or Moved Out of Alignment

A uPVC window needs to sit squarely inside the frame to seal properly. If the opening sash has dropped or moved out of alignment, it may still close, but it may not press tightly enough against the seals to stop draughts.

This can happen gradually over time, especially if the hinges are worn or the window is used regularly. You may notice the window catching as it closes, a larger gap on one side, or the handle feeling harder to turn than it used to.

When the sash is out of position, the locking points may also fail to line up properly with the keeps in the frame. This means the window may not pull in as tightly as it should, leaving small gaps where cold air can get through.

In many cases, a dropped or misaligned uPVC window can be adjusted or repaired. It is best to deal with it early, as forcing the window closed can put extra strain on the handle, hinges and locking mechanism.

Faulty Locks, Handles or Closing Mechanisms

The handle and locking mechanism help pull the window tightly into the frame when it is closed. If these parts are worn, stiff or out of line, the window may look shut but still not seal properly.

This can happen when the locking points do not line up with the keeps in the frame, or when the internal mechanism is not moving as it should. You may notice that the handle feels stiff, does not turn fully, or the window does not feel as tight as it used to when locked.

A faulty handle or mechanism can also be caused by another issue, such as worn hinges or a dropped sash. If the window is not sitting correctly, the lock has to work harder to pull everything into place, which can lead to wear or damage over time.

If the handle feels stiff or the window will not lock smoothly, avoid forcing it. The locking mechanism, gearbox or keeps may need adjusting, repairing or replacing to help the window close securely and stop draughts.

Could It Be the Trickle Vent?

Before assuming there is a fault with the window itself, it is worth checking the trickle vent. Trickle vents are small vents usually fitted at the top of the window frame. They are designed to allow controlled airflow into the room, even when the window is closed.

If the trickle vent is open, loose, damaged or missing its cover, it can feel like a draught coming through the window. This is especially noticeable in colder or windy weather.

However, trickle vents should not usually be permanently blocked. They help with ventilation and can reduce the risk of condensation and damp by allowing air to circulate. If the vent is damaged, broken, or letting in too much cold air, it may need to be repaired or replaced rather than sealed shut.

If the draught is coming from around the frame, hinges or seals rather than the vent itself, the issue is more likely to be linked to the window alignment, hinges, seals or locking mechanism.

Is It a Failed Double-Glazed Unit?

Not every draughty window problem is caused by the frame, hinges or seals. In some cases, the issue may be linked to the double-glazed unit itself, especially if the glass is no longer insulating the room as well as it should.

A failed double-glazed unit usually happens when the seal around the glass breaks down. This can allow moisture to get between the panes, which often causes misting, condensation or a cloudy appearance inside the glass. While this may not always create a direct draught, it can make the window less effective at retaining heat.

If the window also feels cold around the edges, has visible gaps, or does not close tightly, there may be more than one issue. The glass unit, hinges, seals and locking mechanism may all need checking to find the real cause of the draught.

The good news is that a failed double-glazed unit can often be replaced without replacing the full window frame. This can help improve the window’s performance while keeping the existing uPVC frame in place.

What Can You Check Yourself?

There are a few simple checks you can do before calling someone out. Start by checking whether the trickle vent is open, loose or damaged, as this can sometimes feel like a draught from the window.

Next, look around the edge of the frame for any obvious gaps, loose seals, dirt or debris. If anything is trapped in the frame channel, gently clean it out and close the window again without forcing it. You can also check whether the rubber seals look split, flattened or pulled away from the frame.

When the window is closed, check whether the handle turns fully and whether the sash feels tight against the frame. If the handle feels stiff, stops halfway, or the window still feels loose when locked, there may be a problem with the hinges, alignment or locking mechanism.

It is also worth feeling carefully around the hinge side and handle side of the window to see where the cold air is coming from. This can help determine whether the draught is linked to the seals, hinges, trickle vent, or another part of the window.

Avoid forcing the handle, pushing the window hard into the frame, or permanently blocking ventilation. If the window still lets in cold air when closed and locked, it is likely to need adjusting, repairing or replacing parts.

When Should You Call a uPVC Window Repair Specialist?

You should call a uPVC window repair specialist if the draught is still there after basic checks, or if the window does not feel like it is closing properly. A draught can be a sign that part of the window is worn, damaged or out of alignment.

It is worth getting the window inspected if you can see a gap around the frame, the handle feels stiff, the window will not lock smoothly, or the sash feels loose when closed. You should also get help if the hinges look worn, the seals are damaged, or there is misting between the panes of glass.

Leaving the problem can make the window less comfortable, less secure and harder to use. It can also put extra strain on the handle, lock and hinges if the window is being forced closed.

In many cases, the cause can be repaired without replacing the full window. A specialist can check whether the draught is coming from the hinges, seals, alignment, locking mechanism, trickle vent or glass unit, then advise on the most suitable repair.

Can a Draughty uPVC Window Be Repaired?

In many cases, a draughty uPVC window can be repaired without replacing the full window. The right repair depends on what is causing the draught in the first place.

If the issue is caused by worn hinges, these can often be replaced so the sash pulls back tightly into the frame. If the rubber seals are damaged, loose or flattened, they may need refitting or replacing. If the handle, lock or mechanism is not pulling the window shut properly, those parts can usually be adjusted or replaced.

A failed double glazed unit can also often be replaced without changing the whole frame, especially if the uPVC frame itself is still in good condition.

A full window replacement is usually only needed if the frame is badly damaged, warped, cracked or no longer worth repairing. In most cases, it is best to have the window checked first so you know whether a repair is possible before paying for a full replacement.

Need Help With a Draughty uPVC Window?

If your uPVC window is letting in draughts, feels cold around the frame, or no longer seals properly when closed, it is worth getting it checked before the issue gets worse. Many draught problems can be repaired without replacing the full window, whether the cause is worn hinges, damaged seals, poor alignment, a faulty handle, or a locking mechanism that is not pulling the window tight enough.

At LRM UPVC, we repair uPVC windows, doors and locks across Runcorn, Widnes, Frodsham, Halton and the surrounding areas. We will always look at whether the window can be repaired first, helping you avoid unnecessary replacement costs where possible.

For advice or a free, no-obligation estimate, get in touch with LRM UPVC today.