Shedding some light

Martyn Haworth from Bison Frames answers your questions about the wide range of window and door options available to self-builders, while describing some of the benefits of different styles and materials, and what to watch out for.

Windows and doors clearly play a crucial part in the overall look of your self-build, so choosing the right products is key. But the vast choice of styles and materials can be pretty overwhelming ,and make it hard to know where to begin.

Which are the most popular types of windows and doors?

In terms of materials, most modern windows and doors are made from PVCu, aluminium or timber. There are other options available (such as steel or hybrid), but they’re not so common. Of the three, PVCu is still dominant, especially for windows. At the same time, timber continues to decline. It still has its niche, particularly in the high-end replacement market, but isn’t used so much on new build and self-build projects. In contrast, aluminium declined badly in the 1990s but is making a strong comeback.

Styles and designs seem to be changing; what’s available?

When it comes to window designs, casements sit in the number one spot, followed by more specialist styles such as sash windows. More traditional styles are seeing a big increase in demand, partly driven by improvements in the versatility of PVCu, allowing it to be used to create much more authentic looking windows. As a result sash windows have been growing in popularity for several years, and more recently traditional flush casements have burst onto the market.

For doors it’s a different story. Composite doors are by far the most popular choice for entrances – their range of styles, colours and designs means that they can cater for almost every taste, at a reasonable price. Around the back of the house bi-folding doors are popular on new builds and extensions, while French doors are often used on refurbishments where bigger doors are impractical. Patio doors, which almost died out completely in the 2000s, are on the rise again as well.

What are the relative merits of PVCu? 

The choice of material is governed by several things – not least personal taste. However, the two biggest considerations are generally style and budget.

PVCu is the market leader for a reason. It performs well in terms of insulation (both heat and sound) and security, it requires almost no maintenance and is generally the cheapest option. Its downfall used to be appearance – standard white PVCu was plain and bulky and in the early days earned a reputation for discolouring.

That has been resolved now though; modern PVCu can be made with a variety of woodgrain finishes and in a huge range of colours and shades. It performs better than ever before, the development of UV stabilisation means that it no longer discolours, and it’s fully recyclable up to 10 times, making it more environmentally responsible.

Also, more care now goes into the way it’s designed into windows, with developments such as PVCu sash windows and flush casements accurately mimicking the styles and designs of traditional windows. In short, PVCu has come a long way from the plain white frames of the 1980s and 90s.

What about aluminium?

The key benefit of aluminium – both in windows and doors – comes from its inherent strength. That means its profiles can be slimmer than other materials, maximising light and giving a clean, modern look. It’s ideal for high-end modern builds, where architects, builders and homeowners want unfussy, understated windows. The real driver behind its recent popularity though is doors – specifically bi-folding doors.

Aluminium’s strength makes it ideal for large aperture doors that help builders and architects blur the line between indoors and outdoors. Like PVCu, aluminium is also low maintenance, and especially long lasting. However, typically it’s expensive, and in its standard form it suffers from poor thermal efficiency (although there are now hybrid forms on the market such as WarmCore which include a PVCu core through the aluminium profile in order to dramatically improve insulation).

And what about timber?

Timber is the traditional option for windows and doors, and brings a soft, warm feel. It’s been used for hundreds of years, so it’s well established. It performs well across the board and looks good – especially on more traditional projects.

If chosen with care it can also be long- lasting and sustainable.

However timber is generally in decline as a choice for windows and doors, replaced by PVCu in the window market and composite doors for entranceways. There are two reasons for this: cost and maintenance. Timber windows and doors are usually expensive to buy, especially if you go for a long-lasting hardwood option. It’s also the option that requires the most maintenance – repainting or staining every five years or so to keep it protected and looking good. This can put people off.

Once I’ve selected my windows and doors, what else I should look out for?

Whichever option you go for, make sure you buy from an established manufacturer. Everything they make should be CE Marked, while information on U-values and energy ratings should be available and – if you’re taking any extra options such as enhanced security – a manufacturer’s PAS 24 or Secured by Design accreditations should be available to you too.

When installing your windows, be aware that they’re subject to building control, so they will be inspected. If you’re using an installer (rather than fitting them yourself or your builder

doing it), the installer should be part of an approved Certified Persons Scheme – FENSA is the most common – which negates the need for an inspection.

Finally, as a manufacturer my advice is to not order windows and doors off plan – wait until the apertures are in place and have them properly surveyed. And always allow a 10 mm fitting tolerance. I’ve seen too many projects go wrong when windows were ordered off plan, arrived and didn’t fit – the windows were the right size, but the holes they go into weren’t. It can be a costly mistake!

Martyn Haworth is director of Bison Frame – manufacturers of the Genesis Collection and WarmCore windows and doors