The difference between PVC and uPVC – By double glazing Edinburgh experts
PVC, or polyvinyl chloride, is a polymer, a material made up of long molecular chains.
Manufacturers can change its properties to suit different products.
Adding plasticisers makes it softer and more flexible for uses such as cable coverings, flooring and some shower curtains.
uPVC stands for unplasticised polyvinyl chloride, the rigid plastic material used for many window frames, external doors and roofline products.
uPVC contains no added plasticisers, so it retains its rigidity.
Window and door manufacturers use this rigid PVC because a frame needs to support its fittings and hold its shape during everyday use.
PVC can describe either rigid or flexible plastic, although comparisons between PVC and uPVC often use “PVC” as shorthand for flexible PVC.
A product labelled “standard PVC” therefore needs a closer look at its specification before you can judge its properties.
How manufacturers make uPVC frames
Window manufacture starts with a PVC compound that contains ingredients chosen for outdoor use.
Stabilisers help the material withstand processing and exposure to daylight, while pigments provide colour.
Impact modifiers improve its resistance to knocks. Unplasticised plastic still contains additives.
The formulation matters because a window exposed to sun and rain has different demands from an indoor plastic trim.
During extrusion, machinery heats the raw material and pushes it through a shaped opening to produce long uPVC profiles.
The profiles cool before being cut and joined into frames.
Internal chambers divide the hollow sections, and reinforcement can provide the stiffness needed for the window’s size and design.
uPVC windows and doors around your home
In uPVC windows and doors, the plastic forms the profiles around the glass or door panel.
Hinges, locks and seals are separate components fitted to those profiles. A window also has an outer frame fixed into the wall and, where it opens, a moving section called the sash.
Our uPVC window range includes casement windows, top-hung designs and tilt-and-turn options.
Casements open on hinges, while a tilt-and-turn window can tilt inward for ventilation or swing inward from the side.
uPVC door frames can surround several kinds of door, including a composite door leaf. The leaf is the part you open, and its construction may differ from the frame.
Our door range includes both uPVC panel and composite options.
Roofline and other building uses
uPVC is also used in construction for drainage pipes, guttering and exterior cladding, sometimes called siding or weatherboarding.
Around the roof edge, fascias support the guttering and soffits cover the underside of the eaves.
A window sill or roofline board made from uPVC needs a profile suited to that job. These products share a material family, but their shape and construction differ.
Our roofline range covers fascias, soffits and guttering.
Energy efficiency in double glazed windows
uPVC conducts heat poorly, which helps limit heat transfer through a window frame. The chambers within the profile also contribute to insulation.
Around the opening sash, seals restrict draughts when the window closes against them.
Double glazed windows have two panes separated by a sealed gap, usually filled with air or an insulating gas.
Low-emissivity glass coatings reduce heat loss through the glazing.
The frame and glass work together, so the material name alone cannot tell you how energy efficient a window will be.
Comparing the complete window
A whole-window U-value measures heat passing through the glass and frame together. Lower figures mean less heat loss.
Check that quotations use this figure consistently, because a value for the centre of the glass leaves the frame out of the comparison.
A window energy rating also accounts for heat gained from sunlight and air leakage.
Our windows are available with double glazing or triple glazing.
Your existing windows, heating use and the rest of the property’s insulation will affect the difference you notice after replacement.
Low maintenance and everyday durability
uPVC doesn’t rot, and its surface needs no routine protective coat of paint.
For a homeowner comparing it with painted timber, avoiding repeated sanding and repainting can be a substantial advantage, particularly on upstairs windows.
Clean the frames with a soft cloth and mild soapy water, rinse away residue and follow the manufacturer’s care instructions.
Abrasive pads and unsuitable solvents can damage the surface, especially on a coloured finish.
Hinges and locks need their own maintenance, and seals should be checked for damage.
Clear drainage openings allow water to escape from the frame.
A blocked outlet or worn seal can cause trouble even when the plastic itself is in good condition.
How long the frames can last
Well-made uPVC frames can remain in use for decades, but weather conditions, installation and upkeep all affect their lifespan.
Hardware and sealed glass units may need attention earlier than the frame.
Misting between the panes, for example, can indicate failure of the glass unit’s seal. Replacing that unit may be possible without replacing the surrounding frame.
A repair assessment should establish which component has failed before you commit to new windows throughout the house.
The limitations of uPVC
uPVC expands and contracts a little as its temperature changes, which is normal for the material.
Correct sizing, reinforcement and experienced installation allow for that movement, so a properly fitted window keeps opening and closing smoothly year after year.
Deep scratches and damage to welded corners can be harder to repair neatly than marks on timber. Against that, the frames stand up to the everyday knocks and weather that would have a painted frame needing attention within a few years.
A woodgrain finish gives the appearance of timber without the upkeep, though it won’t reproduce every detail of a traditional wooden frame.
It’s worth seeing a sample in person if that distinction matters to your home.
What uPVC gets right
uPVC doesn’t rot or swell with damp, and it never needs repainting.
A well-made frame keeps its shape for decades, and because the material is a poor conductor of heat, the frame itself adds very little to a window’s heat loss.
Against painted timber, uPVC is usually the lower-cost frame to buy and needs far less spending on it over its life.
The right dimensions, opening style and glass specification decide the rest of the value, and once it’s in, it’s a window you’ll spend very little time thinking about.
Recycling uPVC after replacement
Old uPVC can be collected, separated from glass and metal, and processed into material for new products. Recycled plastic can form part of a new window profile, so a frame doesn’t have to contain entirely new PVC.
The frames we fit at The Advanced Group are made from 80% recycled or renewable uPVC, and the old frames we take out go into our recycling programme instead of a skip.
Before work starts, ask any installer about their collection route for the removed frames and whether the replacement profiles contain recycled material. The ability to recycle a product doesn’t guarantee that every discarded frame reaches a recycling facility.
Manufacturing and transport still use resources, and uPVC does not biodegrade like untreated wood. Keeping serviceable frames in use through suitable repairs can avoid premature replacement.
Choosing uPVC for your home
A useful window quotation identifies the profile system, glazing and opening arrangement, with the energy performance stated for the specified product.
Ask about the locks and reinforcement too, especially where a large opening needs additional structural support.
The installation should suit the existing wall opening and provide effective sealing around the frame.
Gaps left at that junction can admit draughts even when the window itself has a good energy rating.
Check the written guarantee for the frame, glass, hardware and finish.
Different components can have different cover, and the maintenance conditions should be clear before you agree to the work.
See our uPVC window options in person
At The Advanced Group, we’ve supplied home improvement products in Scotland since 1988.
Our windows come with a 15-year guarantee, and you can view frame styles and finishes at our Glasgow showroom in East Kilbride.
If you’re choosing replacement windows, bring your questions about frame materials and glazing to a free home survey.
Request your survey or call 0131 370 0444 to discuss the options for your home.
