Choosing windows is two decisions that get discussed as one: what the frame is made of, and how the window opens. The material decides cost, sightline, maintenance and lifespan. The opening style decides ventilation, cleaning, escape and whether it suits the building. Getting them separate makes a showroom conversation much easier.
Frame materials from uPVC to composite windows, honestly compared
UPVC is the volume choice: cheapest, effectively maintenance free, thicker sections that eat glass area, and colour options that cost extra. Aluminium is stronger, so the frames are slimmer and you get more glass in the same hole, with a thermal break doing the insulating work; it costs more and suits modern elevations and large openings. Timber suits period and listed buildings, performs well and needs repainting. Composite puts a timber inner face with an aluminium outer, giving the look inside and the durability outside at the highest price.
How the window opens
A casement is hinged at the side or top and is the British default. A sash slides vertically and is what most Victorian and Georgian houses had. A tilt and turn does two things with one handle: tilt the top in for secure trickle ventilation, or turn the whole sash inward like a door for cleaning and escape. Windows that open inwards are common across Europe and less so here, and they need clear floor or sill space inside, which is the usual objection to them.
Flush casements and the detail people argue about
A flush casement sits level with the frame when closed, as a timber window does, rather than standing proud of it. It looks considerably better on a traditional house and is the reason many people pay more. The trade offs are a slightly narrower opening for the same hole, more exacting manufacturing tolerances, and a higher price than a standard stormproof casement. On a modern estate house the difference is mostly invisible and the money is better spent on the glass.
Fixed lights and large picture windows: price, UK sizes and where they suit
A fixed pane is cheaper per square metre, better sealed and better insulated than an opener, because there is no gasket line and no hardware. A picture window is simply a large fixed pane, and what moves its price is not the glass area alone but the weight that comes with it: past a certain size the unit needs thicker or laminated glass, a frame stiff enough to carry it without bowing, and enough people or a lifting machine to get it into the opening, which is a separate cost on an upper floor or through a narrow house. Practical size is set by what the glass processor's line can make and by what can physically be carried to the hole, rather than by any published maximum. The safety glazing rules apply where the glass sits low in the wall, and every room still needs its ventilation and, where required, an escape opening, so a wall of fixed glass needs at least one opener doing that work. Ask for the large pane priced as its own line, because it is the one item in a window schedule where two suppliers can be a long way apart.
Keeping what you have: secondary glazing cost and performance
Secondary glazing is an independent second window fitted inside the existing one. It is the standard answer where the original windows must stay, it outperforms most replacement glazing on noise because of the wide air gap, and it costs less than replacement. It is visible from inside and it is not as good thermally as good new windows. On a listed building or in a conservation area it is frequently the only option that will be permitted.
Questions people ask about window types UK
Aluminium vs uPVC windows: which should I choose?
UPVC for value and thermal performance at the price. Aluminium for slim sightlines, large openings and a modern look, at a higher cost. Both perform well when the whole window rating is good, so compare that rather than the material.
What is a tilt and turn window?
One that tilts inward at the top for ventilation or swings fully inward like a door on the same handle. It cleans easily from inside and makes a good escape opening, and it needs clear space in the room.
Are flush casements worth the extra?
On a period or traditionally detailed house they change the look considerably and are usually worth it. On a modern house the difference is slight.
Is secondary glazing a poor substitute?
Not for noise, where it often beats replacement glazing outright. It is weaker thermally than good new windows and it is frequently the only permitted option on a listed building.
How long do windows last?
Frames commonly last decades in any of the materials. The sealed units are the shorter lived component and can be replaced on their own while the frames continue.