The enduring popularity of bi-folding doors is reflected in the sheer number and diversity of products currently available. So what are the key points specifiers should consider when choosing an aluminium system?
Aluminium bi-folding doors can surpass both wood and uPVC in terms of performance and durability. The material’s inherent strength means that the frame profile can be slimmer and the glass panel wider. It also means that corner or bay bi-fold options are achievable. Furthermore, aluminium is easy to maintain and only needs periodic cleaning with a soapy non-abrasive cloth (solvent-based cleaning materials should not be used). Last but not least, aluminium bi-folds are aesthetically pleasing and can be powder-coated in a wide range of RAL colours.
Low or mid-quality bi-fold doors will only meet the weather standards set by the industry; high-quality doors will exceed them. Applications with more extreme weather conditions, such as coastal homes, are best suited to doors that exceed the standards. The weather and thermal performance of Origin’s aluminium bi-fold doors include air permeability of 600pa Class 4, watertightness of 600pa Class 9A, resistance-to-wind load of 1200pa Class A3, and U-values of 1.6 (double glazed) and 1.3 (triple glazed). The latter exceeds current building regulations requirements by 30 per cent.
Sightlines, dimensions and configurations
Aluminium provides some of the slimmest sightlines available. Manufacturers measure sightlines in different ways: some provide only the width of the profile without including the width of the glazing bead to give an accurate representation. Dimensions relate to the doors, including the overall size of the aperture and individual sizes of the panes. Configurations relate to how the doors open, for example, a six-door set could have the following configuration: 3+3 (three-doors folding in each direction). They also indicate if the doors fold left or right and open inwards or outwards.
Standard threshold with cill
When it comes to waterproofing bi-fold doors, thresholds are necessary. Origin provides two types of threshold: non-weathered (when the track is almost completely flush to the floor) and weathered (when there is a small lip on one edge of the track). The seal on the bottom of the bi-fold door compresses against the lip to create a weathertight seal. Weathered thresholds are designed to give greater protection against driving rain and draughts. Though rebated, the track can be sunk so that the upstand is just 14mm from outside to in. Non-weathered thresholds offer a completely flat transition between inside and out, and are particularly beneficial for toddlers and those with mobility issues. However, because the door seal doesn’t have a solid lip to compress against, optimal weather performance cannot be guaranteed. This type of track is ideal for internal use or a sheltered outside area.
Non-weathered threshold with cill on flush floor with deck
Non-weathered threshold without cill on flush floor with paving
Weathered threshold with cill
Channelling rainwater away from the threshold of external bi-fold doors and stopping it from pooling in the track are important design considerations. There are commonly two types of drainage used with weathered and non-weathered thresholds. The first is face drainage, where water enters the lower chamber of the track and exits via a capped hole in the outer face. The second is concealed drainage, where water exits the bottom track through a polyamide break barrier, before entering the top of the cill. From there it travels through the front section of the cill and out of the front edge underneath.
Locks, handles and hinges must conform to PAS 24 standards or beyond to ensure adequate security
The weak areas for all doors are the cylinder/locking barrel and handle. Part Q of the Building Regulations requires bi-fold door systems to conform to PAS 24 standards for new-build and extension projects. Origin Bi-fold Doors have a unique eight-point locking system featuring 20mm chamfered linear bolts and deep throw security hooks, ensuring PAS 24 compliance. However, to increase security, specifiers can request TS007 three-star security cylinders, which are proven to guard against snapping, picking, drilling and bumping. Hinge strength is another important security factor: zinc hinges with rivet nut and bolt screw arrangements ensure the requisite strength and security.
Quality and service
Origin is the sole manufacturer of its bi-fold door systems, ensuring complete control over every aspect of quality and supply chain. They are made from prime aluminium with an extrusion run quantity of two tonnes before the dye is cleaned and polished. This ensures imperfection-free surfaces for long-lasting powder-coated finishes. A 20-year guarantee covers all manufactured parts, and a ‘Your Lead Time, Not Ours’ promise means bespoke doors can be manufactured and delivered to site within 48 hours.
For more information visit the Origin website