uPVC (unplasticised polyvinyl chloride) has become the go-to material for modern window and door installations thanks to its strength, thermal efficiency, and low maintenance. However, one common question we hear at Premier Windows especially during warmer months, is: “Is uPVC supposed to expand in heat?”
In short, yes. uPVC naturally expands when exposed to high temperatures. While this is a normal and temporary response, it can occasionally make doors or windows harder to open or close during heat waves. In this article, we explain why uPVC this happens, what to expect, and how we at Premier Windows help ensure your products perform optimally in every season.
Why Does uPVC Expand in Heat?
Just like many materials, uPVC expands as temperatures rise. This process, known as thermal expansion, is not a fault or manufacturing defect, but a normal physical response. When temperatures exceed around 25°C, uPVC frames may expand slightly. Once the temperature drops below 23°C, they contract and return to their original size.
This expansion is most noticeable during hot summer days, particularly with darker coloured uPVC finishes that absorb more heat. Fortunately, in the UK’s relatively moderate climate, this is usually a short-lived issue. But in extreme heat, it can temporarily affect the operation of doors or windows, especially if they haven’t been properly fitted.
Common Signs of uPVC Expansion
If your uPVC windows or doors become stiff or hard to operate during a hot spell, thermal expansion could be the reason. You may notice:
• Doors that stick or won’t close easily
• Windows that become difficult to open or lock
• Minor gaps or alignment changes around the frames
These signs are temporary and often resolve once the temperature drops. However, there are smart ways to manage or minimise these effects.
How to Manage uPVC Expansion
1. Adjust the Hinges
A quick, effective solution is to slightly adjust the hinges on your windows or doors. By loosening the screws and repositioning the hinges slightly, you can create just enough space to allow the frame to expand without sticking. This doesn’t damage the product and can make a noticeable difference during warm spells.
2. Use Shaded Openings
During hot days, try opening windows or doors that aren’t in direct sunlight. If your south-facing door is sticking, open a window or door on the shaded side of your home to ventilate instead. Not only does this help manage expansion, but it also keeps your home cooler overall.
Additionally, closing curtains or blinds during peak sun hours can lower interior temperatures and reduce frame swelling.
Do Certain Colours Expand More?
Yes, darker uPVC colours, such as anthracite grey or black, are more prone to noticeable expansion because they absorb more heat. If you live in a sun exposed area and are concerned about expansion, lighter colours or woodgrain effect uPVC may be a better choice.
At Premier Windows, we offer a wide range of colours and finishes, all engineered to handle the UK’s fluctuating weather with ease.
Are Modern uPVC Windows Still Affected?
Newer uPVC windows and doors, such as the ones we install at Premier Windows, are significantly more advanced than older models. Modern frames are crafted with high-performance, multi-chambered profiles, enhanced reinforcement, and improved hardware that accounts for seasonal movement.
While all uPVC expands to some degree, our products are designed to minimise the impact. Most of our customers report no operational issues, even in the summer months.
The Benefits Still Outweigh the Downsides
Despite the occasional expansion in extreme heat, uPVC remains one of the best materials for doors and windows in the UK. Benefits include:
• Excellent thermal efficiency
• Resistance to moisture and corrosion
• Affordability compared to timber or aluminium
• Low maintenance and long lifespan
• Security and strength
At Premier Windows, we tailor every installation to suit your home, taking into account thermal movement, frame positioning, and finishing to avoid common pitfalls.
Trust Premier Windows for Reliable & Long Lasting uPVC Installations
With years of experience in double glazing and home improvement across the UK, Premier Windows is your trusted local partner for high performance uPVC windows and doors. Our expert installers take every detail into account, from weather conditions to material behaviour, so you can enjoy reliable, year-round performance.
If you’re looking for uPVC solutions that stand up to the elements, contact us today or get a free, no-obligation quote.
