Multi-leaf panoramic Bi Fold Doors
The way bi-fold doors open & “stack” fully to the sides is a unique feature which helps to create the widest clear opening of any type of patio door, allowing unrestricted views, superb ease of access to your garden and illuminate the inside of your room with natural light.
- Internally beaded glazed panels for extra security
- Toughened, double or triple glazed sealed panels (including laminated glass options)
- Stainless steel tracks & top guides with all round Multi-point locks
- Draught proof weather seals to ensure no leaks
- For energy efficiency there are options for gas filled glass panes
The door leaves (panels) slide easily on tracks that are fitted into the frames and can be folded (or “stacked” to left, right, inside or outside the room and even though they may look difficult to move the tracking system allows very easy sliding of the panels with very little effort.
With a large proportion of the door being glazed, it will be worthwhile considering energy efficient double or triple glazed gas filled glass panels for the door to manage heat loss (or build-up) – with low- emissivity (low-e) glass, there is a metal oxide coating on the surface of the units which reflects solar radiation and also helps to keep your heat inside the home. Look for the BFRC rating label (go here to learn more: BFRC)
Size of the door & number of panels
Bi fold doors are more likely suited for medium to large openings. Whilst you can get a 2 panel bi fold door, they really work well when you get up to 3 or 4 panels.
2 Panel design – Typically up to 2.5m (approx. 8 feet) with doors folding to left / right. Stack inside or out.
3 Panel design – Typically from 2.4m to 3.0m (approx. 7 to 10 feet) with doors folding to left / right. Stack inside or out. Can also be fitted “2+1” where 2 panels fold & one is independently hinged like a normal door. This feature is to allow entry or exit without having to slide all the panels.
4 Panel design – Typically from 3.0m to 4.0m (approx. 10 to 13 feet) with doors folding to left / right. Stack inside or out. Can also be fitted “3+1” where 3 panels fold & one is independently hinged like a normal door. This feature is to allow entry or exit without having to slide all the panels.
5 Panel design – Typically 4.0m & over (13 feet +) with 2 or 3 Panels that can open to the left, right or open from centre. Also can stack inside or outside the room.
6 Panel design – Typically over 4.0m (13 feet+). A set of bi fold doors this wide will be a specialised job. 16 feet or 5 metres is usually as big as a “standard set of doors would go. All panels can slide left, right or open from centre & stack inside or out. One panel can also be independently hinged like a normal door. This feature is to allow entry or exit without having to slide all the panels.
Hanging the doors
It is possible to decide to have the installation “top hung” or “bottom hung”. This is really about where the loading of the door is concentrated.
Top hung doors have the roller system built into the head of the opening and allow for low or no threshold options, but this may come at a price. Having a very low or “no” threshold can reduce or even remove the weather proofing (ingress of water, wind etc.). This can be accounted for by good installers who fit them with a Lip of around 15mm (outside is lower than inside). Make sure you have weatherproofing built into your doors if you are going for very low thresholds.
You also have to ensure that the existing overhead Lintel can take the weight.
Bottom hung doors have the rollers in a floor level track and as such they usually have a threshold that needs to be stepped over (like a regular door).
Some manufacturers and good quality installation companies have come up with low threshold options.
Poorly installed bottom hung doors can put a lot of pressure on the overhead guide tracks and if the rollers are not “captured” (enclosed in the guide track), the weight of the doors as they open can sometimes make the roller pop out of the overhead guide track.