A supply-only glazing order gives you more control over the project, but it also places responsibility for surveying, specification and installation firmly with the buyer. Get those decisions right and you can receive a made-to-measure aluminium door, window or rooflight ready for a professional installer or competent trade team. Get them wrong and even a premium system can be delayed by an incorrect opening size, unsuitable glass unit or inaccessible delivery.
This is how to order supply only glazing with the detail that protects your budget, programme and finished result.
Start with the finished opening, not the brochure size
The most common mistake is ordering to the size of an existing frame or a rough opening measured before building work is complete. Your order dimensions must relate to the finished structural opening and the installation method. This is particularly important on extensions, where brickwork, steelwork, cavity closers, insulation, floor build-ups and plasterboard can all alter the available space.
Measure the width at the top, middle and bottom of the opening, then measure the height on both sides and through the centre. Use the smallest width and height as the basis for the order. Check that the opening is square by measuring both diagonals, and establish whether the cill, lintel and reveals are level, plumb and sound enough to accept the frame.
A frame should not be manufactured to fill every millimetre of the aperture. Your installer needs a practical fitting tolerance around it for packers, levelling, fixing and perimeter sealing. The required allowance depends on the system, opening condition and installation detail, so agree this before placing the order rather than guessing a deduction.
For doors, confirm the finished floor level at the threshold. A low threshold can create an excellent inside-outside transition, but it must work with the external patio level, drainage detail and any weathering requirements. Ordering before the floor construction is finalised is a costly risk.
Choose the right product before specifying the glass
Glazing is part of a complete system. The frame depth, sash weight limits, opening arrangement, drainage design and thermal break all affect what can be manufactured safely and perform as expected.
For a bifold project, decide early whether the priority is maximum opening, a daily access door, a particular fold direction or minimal frame lines when closed. Systems such as Smarts Visofold 1000 Bifold Doors, Schuco ASFD75 Bifold Doors, Cortizo Bifold Plus and Origin OB49 Bifold Doors each have different configuration options and visual characteristics. The panel layout needs to suit how the room will actually be used, not simply divide the opening into equal sections.
For wider uninterrupted views, a sliding system may be the better choice. Cortizo COR Vision Plus Sliding Doors and Schuco ASE80 Sliding Doors are commonly considered where slim sightlines and large glass areas are central to the design. Bear in mind that a sliding door retains fixed panels when open, whereas a bifold can open most of the aperture. Neither is automatically better – the right answer depends on furniture layout, access and the view.
Windows need the same discipline. Opening casements, fixed lights, trickle ventilation requirements, handle position and fire escape needs should all be resolved before a quotation becomes an order. A fixed Cortizo Hidden Sash Window may suit a contemporary elevation, while an opening Smarts Alitherm 400 Window may be more practical for ventilation and cleaning.
Specify glass for performance, safety and privacy
The glass unit is not an add-on. It determines much of the door or window’s thermal performance, solar control, acoustic comfort and safety rating.
For most external glazing, a high-performance double-glazed unit with low-emissivity glass, warm-edge spacer technology and argon gas filling offers strong everyday thermal efficiency. Aluminium frames with a thermal break combined with energy-efficient glazing are well suited to British weather, helping reduce heat loss without sacrificing the slim, modern look buyers expect from aluminium.
Triple glazing can improve thermal performance in some applications, but it is not an automatic upgrade. It adds weight and can affect maximum sash sizes, lead times, cost and solar gain. On a large south-facing elevation, solar-control glass may matter more than an incremental improvement in U-value. It can reduce overheating and glare, though it may also make the glass appear slightly tinted and reduce useful winter solar gain.
Safety glazing must be specified where required. Toughened or laminated safety glass is typically needed in critical locations, including low-level glazing and doors, with the exact requirement dependent on the installation. Laminated glass can also support improved security and acoustic performance. For overlooked boundaries or bathrooms, obscure glass should be selected by privacy level, rather than assuming all frosted finishes provide the same obscurity.
Ask for the performance of the complete product, not just the centre-pane value of the glass. A good glass specification cannot compensate for an unsuitable frame, poor installation or an uninsulated surrounding reveal.
Confirm compliance and the installation responsibility
Supply-only does not mean compliance-free. The person arranging the work must ensure the completed installation meets the applicable Building Regulations and planning conditions. On a straightforward replacement, your installer may manage the relevant certification route. On an extension, new build or structural alteration, the project will usually need to align with the wider building control process.
Thermal requirements, ventilation, safety glazing, means of escape and security can all influence the specification. For example, the need for background ventilation may affect window or door options, while certain projects may call for enhanced security performance. If the product sits beneath a new steel lintel, within a structural opening or forms part of a rooflight installation, clarify responsibilities between the builder, structural engineer, installer and supplier before manufacturing begins.
A specialist supplier can help ensure the product itself is correctly specified and manufactured from approved system components. However, the site survey, structural suitability, fixing method, weatherproofing and finished installation remain critical. If you are not using an experienced glazing installer, supply-and-install may offer better protection for a complex opening.
Put every visible choice on the order confirmation
A quotation can look clear until the product arrives in the wrong colour, with handles on the unexpected side or an opening configuration that does not match the drawings. Read the order confirmation line by line and check the elevations rather than relying on a verbal discussion.
Confirm the external and internal frame colour, including whether you want a single colour or a dual-colour finish. Check the handle finish, hinge colour, trickle vents, cill, threshold type, drainage arrangement and any glazing bars or integral blinds. For doors, establish from which side the product is viewed when describing left or right opening. Supplier drawings normally state this clearly, but it is worth checking against the site plan.
Also verify whether the frame is being delivered glazed or unglazed. Large glazed units are heavy and need careful handling, while some access restrictions mean frames and glass should be moved separately. This decision affects the delivery plan and installation sequence.
Plan delivery as carefully as the survey
A made-to-measure bifold or sliding door is not a parcel delivery. Before confirming the order, make sure there is suitable vehicle access, a safe unloading area and enough people or lifting equipment to move the units without damage. Check narrow gates, steps, side passages, overhead cables and soft ground. A large sliding glass panel may require specialist glass handling equipment, even if the frame itself can reach the opening easily.
Inspect the delivery promptly against the paperwork. Check sizes, colour, glass labels, hardware and visible condition before installation starts. Photograph any damage and report it immediately. Store units upright, dry and protected from impact, plaster contamination and building traffic.
Give manufacturing the right information first time
The strongest supply-only orders are based on a settled design, accurate finished-opening dimensions and a clear installation plan. That is the point at which transparent pricing becomes genuinely useful: you can compare systems, glass upgrades and configuration choices without comparing assumptions.
Bifolding Door Factory supports nationwide supply-only orders for homeowners, self-builders and trade buyers who want premium aluminium systems without compromising on specification. Bring measured openings, drawings and your intended installation detail to the quotation stage, and resolve uncertainties before the product enters manufacture.
A few extra checks before ordering are far cheaper than changing a made-to-measure frame afterwards. Treat the survey and order confirmation as part of the build, not paperwork at the end of it, and your glazing will arrive ready to do the job it was designed for.