How can you help prevent uPVC windows or doors from expanding in the heat?

UPVC is used for many home improve­ment prod­ucts as it is tough, main­te­nance free and has a long lifes­pan. All uPVC prod­ucts respond to high-tem­per­a­ture changes more dra­mat­i­cal­ly than tim­ber and alu­mini­um products.

At 40ºC your UPVC can expand by up to 2.4cm, which is like­ly to affect nor­mal use. In real­ly high tem­per­a­tures you may notice that your win­dows or doors become stiff, and they may not open and close prop­er­ly. This is like­ly to be because the UPVC has swollen.


Your win­dows and doors are not bro­ken and do not need replac­ing. This is a per­fect­ly nat­ur­al occur­rence and can affect dark­er-coloured uPVC prod­ucts more seri­ous­ly due to the amount of heat being absorbed.

Where heat has affect­ed your uPVC frames, the issue will dis­ap­pear once tem­per­a­tures return to nor­mal. When the sun sets, your win­dows and doors will retract, return­ing to the nor­mal size and position.

expanding upvc french doors
expanding upvc french doors from outside

So how can you pre­vent uPVC heat-expansion?

Should you real­ly need to inter­vene, you can cool down your uPVC doors/​windows by spray­ing the out­side with water, or by pat­ting it down with a cold, damp cloth. This will help the mate­r­i­al to shrink back down to size so that it’s once again with­in its nor­mal work­ing parameters.

Here at Evan­der, we ensure that all our uPVC prod­ucts have had exten­sive test­ing so that they are able to work with­in nor­mal tem­per­a­ture ranges. Of course, with tem­per­a­tures as they are at the moment, you may find that this is now an issue.

Should you only expe­ri­ence these prob­lems in extreme tem­per­a­tures, Evan­der does not need to attend to make adjust­ments, as this will only cause you fur­ther issues down the line. If the prob­lems with your uPVC prod­ucts do not rec­ti­fy them­selves once the tem­per­a­ture drops, we can assist with repairs, replace­ments and advice.

Please call 0345 145 0130 or get in touch via our con­tact form below if you would like any fur­ther assistance.

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