Bifold doors are a brilliant way to open a room up to the garden, but not all of them are equal, and the best bi folding doors are the ones that get five key things right. Before you sign anything, run through this checklist. It will save you money, hassle and a few regrets down the line.
1. The frame material and thermal performance
Most quality bifolds are aluminium, and for good reason. Aluminium is strong enough to hold large panes of glass in slim frames, which is exactly what you want when the whole point is a wall of glass. uPVC bifolds exist and cost less, but the frames are chunkier and they do not span as wide.
The thing to check is the thermal break, a barrier inside the aluminium frame that stops cold transferring indoors. Together with good double glazing, argon fill and a low emissivity coating, it makes the difference between a warm room and a cold one. Ask for the U value and do not just take "energy efficient" at face value.
Our aluminium sliding and bi-fold doors are built around a proper thermal break for this reason.
2. The threshold: flush or rebated
The threshold is the track at the bottom, and it is a bigger decision than people expect.
- A flush, low threshold gives a near level step from inside to out. It looks fantastic, suits wheelchair and pushchair access, and feels seamless underfoot. The trade off is that it needs careful detailing to stay weathertight.
- A rebated, weathered threshold has a small upstand that keeps driving rain out more easily. It is a touch more practical for an exposed, garden facing wall, but you do step over a small lip.
Neither is wrong. It comes down to how exposed the opening is and whether level access matters to you. Talk it through before ordering, because it is not easily changed later.
3. Which way the doors fold and stack
Bifolds fold back on themselves and stack to one side, and where they stack matters. Think about: - Which side you want the doors to pile up, so they do not block a path, a patio set or a favourite view. - A traffic door, a single leaf that opens on its own like a normal door, so you are not folding the whole set back every time you nip out to the garden. - Inward or outward opening, which affects where the stack sits and how much internal space it uses.
Sketch your room and garden, and picture using the doors day to day, not just flung wide open on a sunny afternoon.
4. Security and glazing
A wall of glass needs to be a secure wall of glass. Look for: - Multi point locking on the main doors. - Internally beaded glazing, so the glass cannot be popped out from outside. - Toughened or laminated safety glass, which is standard for low level and door glazing. - Quality hinges and shootbolts that hold the leaves firmly shut.
Good bifolds are secure by design, but it is worth confirming the spec rather than assuming. If security is a priority elsewhere too, our composite doors are worth a look for the main entrance.
5. Who is fitting them and what is guaranteed
A bifold is only as good as its installation. A poorly fitted set will drop, stick and let in draughts no matter how good the product is. Check: - That the opening will be surveyed properly and any structural support, such as a lintel or steel, is accounted for. - The guarantee on both the product and the fitting, and what it actually covers. - That the work is done by people who fit bifolds regularly, not as an occasional extra.
Replacement doors that alter an opening may fall under Building Regulations, and the work often needs registering or signing off. Rules change, so check the current position with your local authority, and use an installer who handles the paperwork.
FAQs
What are the best bi folding doors made from?
The best bifolds are usually aluminium, because it is strong enough for slim frames and large panes of glass. Look for a proper thermal break and good double glazing for warmth. uPVC bifolds cost less but have chunkier frames and span smaller openings.
What is the best threshold for bifold doors?
It depends on the opening. A flush, low threshold gives level, seamless access and looks superb, but needs careful weatherproofing. A rebated threshold with a small upstand handles driving rain more easily on exposed walls. Choose based on exposure and whether level access matters.
How secure are bifold doors?
Good bifolds are very secure, with multi point locking, internally beaded glazing so the glass cannot be removed from outside, and toughened safety glass. Always confirm the security spec before buying rather than assuming.
Do bifold doors need building regulations approval?
Replacing or forming a large opening can fall under Building Regulations, and the work often needs registering or signing off. Rules change, so check the current position with your local authority and use an installer who manages the certification.
Should I get a traffic door in my bifold set?
If you will use the doors for everyday access to the garden, a traffic door, a single leaf that opens on its own, is well worth it. It saves folding the whole set back every time you step out.
Thinking about opening up to the garden? Download our latest brochure to see the styles and finishes, or request a free quote and we will come and take a look.