Why Do uPVC Windows and Doors Expand in Heat?

uPVC, or unplasticised polyvinyl chloride, is a popular material used in modern home construction for windows, doors, and guttering. It is known for its durability and affordability compared to other materials like wood or aluminium. However, one common concern with uPVC is its tendency to expand in heat, which can cause problems with closing and locking windows and doors in hot weather. 

At Bluemanor Windows, we sometimes receive calls from local homeowners during warmer weather with the same concerns about struggling to close their windows and doors. That’s why we have generated this guide to answer all of your queries surrounding uPVC in warmer weather. So, why do uPVC windows and doors expand in heat? Read on to learn more!

Heat Expansion of uPVC Windows & Doors

When the temperature rises, uPVC undergoes thermal expansion, meaning it expands in size. While the plastic will return to its original form when it cools down, this expansion can be problematic, especially during warm summer nights when securing properties is essential. Luckily, uPVC only expands at hot temperatures of 25 degrees and above and reverts to its original form at 23 degrees and below. As the average UK temperature ranges between 9-18 degrees, you really don’t have to worry about your uPVC windows and doors expanding in hot weather. 

However, there are some preventive actions that you can take when those heat waves ripple in. 

1. Adjusting the Hinges of uPVC Windows & Doors 

This can provide a temporary solution by allowing for the expansion. By loosening the screws on the hinges and slightly repositioning them, you can create a small gap between the door or window and the frame. This extra space allows for the expansion of the uPVC without affecting the operation of the door or window. However, it's important to note that this is a temporary solution and may need to be repeated if the expansion occurs again.

2. Open Windows & Doors in Shaded Areas

It’s important to ventilate your home, especially during warmer weather. Yet, during peak times of the day, we would advise opening windows and doors in more shaded locations of your property and avoiding direct sunlight. So, if the sun is hitting the front of your property during the day, ventilate your property by opening rear windows and doors. 

As well as this, with advancements in double glazing technology, new uPVC windows and doors are expertly crafted to thermally regulate seasonal temperatures by reducing heat transfer. Compared to outdated windows and glazing, you can help keep your home cool by closing windows and curtains. 

Impact of Color on Heat Expansion

Heat expansion is more common in darker uPVC or woodgrain models. The darker colours absorb more heat from the sun, leading to more significant swelling. If you're considering uPVC for your windows and doors, especially in areas with high temperatures, it's important to be aware of this potential issue.

Benefits of uPVC Windows and Doors

Despite the normal swelling process of uPVC windows and doors, they offer several performance benefits. They are easy to clean, resistant to cold and wet weather, more affordable compared to alternatives like wood or aluminium, energy efficient, secure and durable. uPVC is popular amongst our customers for these reasons. As our modern range is crafted with market leading materials and design, a majority of our homeowners don’t experience issues with windows and doors swelling. Typically, older uPVC models will be susceptible but advancements in window and door technology mean that heat expansion only occurs at high temperatures with minimal expansion. 

Is It Normal for Windows & Doors To Swell in Heat? 

uPVC windows and doors expand in heat due to the nature of the material. While this expansion is not permanent and can be reversed when the temperature cools, it can cause inconvenience and difficulty in operating doors and windows. Adjusting hinges or waiting for the temperature to cool down can provide temporary solutions, but recurring expansion may require further investigation. It's important to weigh the benefits and drawbacks of uPVC and other materials to make an informed decision for your home.

Choose Bluemanor Windows for Quality Solutions

Here at Bluemanor Windows, we have decades of experience in the fenestration industry. We specialise in manufacturing, supplying, and installing double glazed home improvement products. Our team of experts can guide you through the process, ensuring you make an informed decision and enjoy your windows and doors for years to come. Get in touch with us today for a free personalised quote or to discuss your requirements. Use our free online quoting engine to get started on your home improvement journey.