Aluminium Bi-folding doors have been around for ages in Europe where cafe owners would use them to completely open the front of their shops. Back then the folding doors would not have even been thermally broken as this was not high on the agenda at the time. The modern folding glass doors must pass many more stringent performance criteria while still retaining the sleek beauty and effortless operability. Aluminum does not suffer the same expansion problems that can plague PVCu & Timber folding doors (Plastic expands 2.5 times more than Aluminum). It is also important that Aluminum doors are thermally broken as the cold and heat will easily penetrate into the home without the thermal break making the doors completely inefficient for climate control in the interior.
Explanation of the above chart
Slimmer Sightlines – Aluminum can have vent to vent sightlines as low as 122mm, this compared to PVCu of 170mm and Timber 169mm
PVCu Bi Folds Usually have the track, rollers and hinges face fixed and covered with plastic cappings. Whereas Aluminum Folding doors have integral tracks and rolling gear.
Expansion Issues – Of the 3 materials Aluminum has the smallest expansion factor. PVCu expands 2.5 times more than Aluminum!
Look closely at the main opening door on any Bi Fold Door and you will see that the measurement between the door operating perfectly and a door that is “sticking” is about 4mm! What do you think may happen in the height of summer?
Low Maintenance – Because Aluminum is more stable it is less likely to expand and cause moving parts to become stuck.
Also the method of fixing hinges and locks to the door material is much more mechanical in Movable Glass Walls Aluminium Bi Folds than in PVCu or Timber.
Aluminum Hinges can be clamped to the extrusion because of the inert strength of the material. Click here to watch a video. (Hinge detail is shown at 6 minutes 32 seconds if you want to go direct to hinge explanation)
Something that PVCu and Timber just cannot achieve.
As beautiful as Timber undoubtedly is, the downside is that it will require a fair bit of maintaining. A Timber Stained Door usually only carries a 3 year colour warranty.
Maximum Door Sizes – Aluminum again wins hands down here. Movable Glass Walls Inc. system officially has the largest permissible vent size of any Aluminum system at 1200mm wide by 3000mm high.
Not to mention the heaviest weight carrying capacity at 120kgs per leaf! Timber Bi Fold Door panels are limited to 1000mm x 2700mm
PVCu Bi Fold vents are usually limited to 900mm wide by 2400mm high and this reduces further still if you want a colour other than white. Maximum suggested weight capacity is about 80kgs per leaf.
Stability Of Hardware – PVCu hinges are fixed through the plastic skin in to steel sections with self tapping screws.
Timber Bi Fold hinges are generally fixed into the timber with woodscrews.
Aluminium uses machine screws. These can be tightened and untightened many times without the threat of stripping the thread (as shown in earlier video link) whereas PVCu hinges where the thread can easily become stripped. When this happens a fix known as a repair screw is used (basically a screw with a wide thread) which has definite sustainability issues. (see a typical Plastic Bi Fold Door detail here)
U Value – ability to accept Triple Glazing – With the increasing requirement of building products to lower heating bills it is becoming essential for glazing products to accept wide Triple Glazing that in turn help it achieve greater U values. Triple Glazing of 48mm Standard and 44mm in Slimline can give you an overall Bi Fold Door U Value of 1.2.
Timber and Plastic Bi Fold Doors are already compromised by size limitations due to their lack of strength. So when you add another pane of glass (double to triple glazed) to their limited weight carrying capacity the maximum sizes become even smaller!
Drainage – ability to contain water ingress – Timber being a porous material cannot match Aluminium or PVCu when it comes to holding water safely without causing damage to the material once it passes the gaskets and sits in the drainage area. No matter how tight the glazing gaskets may be, some water will inevitably pass between bead and gasket coming to rest within the drainage area of the system until it is displaced or evaporates.
Colour Finish Warranty – Dependent on where the powder coating is applied Aluminium offers colour fastness guarantees of between 10 and 25 years. Timber Paint finish usually has a 5 year warranty and Timber Stain Finish only 3 years! PVCu Bi Fold Doors are generally white in colour which is fairly stable. But when you require a colour option the maximum size limitations reduce the overall door size significantly.