Adjusting uPVC windows for winter: why they draft and how to fix it

With the onset of cold weather, many notice cold air coming in from closed windows. Often, the window is not broken; it is simply set to summer mode or the rubber seal is worn out. In this article, we will explain how to determine the cause, what you can do yourself, and how much window adjustment and repair costs.

How to check if a window is drafty

A simple test: open the window, place a sheet of paper between the sash and the frame, and close it. Then, try to pull the paper out. If it comes out easily, the sash is not pressing firmly enough against the frame in that spot. Check all sides of the sash: top, bottom, and sides.

1. Summer and winter mode

Most modern uPVC windows have small round or oval cams on the edge of the sash. By turning them, you can change how tightly the sash presses against the frame:

• Summer mode: The sash presses loosely, which provides minor ventilation and causes less wear on the rubber seal.
• Winter mode: The sash presses tightly and retains heat better.

How to switch to winter mode: Cams are typically turned with a hex key or wrench, and they often feature a mark. Which position corresponds to winter mode varies by manufacturer, so turn one cam first and use the paper test to see if it has improved. Then, turn the others in the same way.

Not all windows have adjustable cams, and their type varies by manufacturer. If you are not sure, do not force it: replacing damaged hardware is much more expensive than adjustment.

2. Worn-out rubber seal

If the sash is adjusted tightly but the window is still drafty, check the rubber seal around the sash and the frame. Over time, it dries out, cracks, and flattens.

• If the rubber is soft and intact, simply clean it and apply a special silicone product. This maintains its elasticity;
• If the rubber is hard, cracked, or missing in places, it must be replaced.

3. Sagging sash or difficult to close

If you have to lift the sash to close the window, the handle turns hard, or the sash hits the bottom of the frame, the sash has sagged. This often happens with wide or heavy sashes. The sash is aligned by adjusting the hinges.

Do not turn the handle with force. This damages the internal mechanism, and instead of a simple adjustment, you will need to replace the hardware.

4. When the problem is not the window

If cold air is coming in not from the sash, but from around the frame at the junction with the wall, the cause is likely improper window installation: the space between the frame and the wall is improperly or insufficiently filled. Adjustment will not help here, and a technician needs to assess it on-site.

Aluminum windows and balcony doors

Sliding aluminum windows are common on balconies. If they move with difficulty, make noise, or do not close completely, the cause is usually worn or dirty rollers and damaged hardware. Repairing such windows is a separate service.

Prices: Window and balcony door repair

Prices include only labor, excluding materials and parts.

Frequently asked questions

How much does uPVC window adjustment cost?

Adjustment and repair of a uPVC window or door cost 50₾. If the rubber seal needs to be replaced, it is a separate service and costs 80₾.

Can I switch to winter mode myself?

If the window has adjustable cams, you can. Turn all cams equally and do not force them. If the sash has sagged, the handle turns hard, or you are not sure, leave it to a technician: improper adjustment can damage the mechanism.

Why does window glass fog up in winter?

Fogging is often a result of high humidity in the room, not a window defect. Regular ventilation of the apartment and exhaust fans in the kitchen and bathroom usually reduce this problem. If the fog appears inside the glass unit, between the panes, the unit is damaged.

How often does the rubber seal need to be replaced?

Rubber dries out, cracks, and loses elasticity over time. If it is hard or cracked, or if the window is still drafty despite the sash being tightened, it is time to replace it.

Is your window drafty? A Profi Masters technician will adjust your windows for winter and replace the rubber seal if necessary.

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