How to choose patio doors
There is such a huge choice of patio doors available, it can be hard to know which is right for your project — our guide takes you through the options
Natasha Brinsmead’s guide explains all before you buy
Patio doors come in many styles, materials and configurations. Some tend to be better suited to traditional homes, whilst others are the mainstay of more contemporary houses — and others span the bridge between the two. Then there is the matter of their performance, price and maintenance requirements to take into account. Here we outline the options along with their pros and cons.
Installation
It is always advisable to get your patio doors fitted by a professional — preferably the supplier. The mechanisms involved in their workings can be intricate and the most common reason why doors don’t operate or lock correctly is bad installation. If the supplier fits them, the responsibility will lie with them.
SLIDING DOORS
As the name suggests, sliding doors operate by sliding from one side of the frame to the other. Unlike bifolds, they don’t allow a 100% clear opening, although a pocket door (see overleaf) makes this a possibility. Usually they are configured to provide a half, two-third or three-quarter openings. Where sliding doors have the edge over bifolds is the unimpaired views they allow for — less frame means more glazing. They also require no stacking space inside or out.
CORNER DOORS
Glazed doors that are configured in a 90° corner system are perfect for opening up an entire room to the outside space.
Sometimes a supporting column is used in the centre of the two runs of doors, although it is also possible to include supports within the roof structure — a structural engineer or builder should be consulted.
POCKET DOORS
The frame for a pocket door is built into a wall, as is the track that it slides on. This allows the doors to disappear into the wall when open — removing any barrier between inside and out.the more panels that make up the door, the greater the depth of the pocket required. Each sliding pane requires its own track, which will usually be 60mm deep. This style of door is good for new buildings or extensions, as the construction of the wall can be planned out early on, ensuring it is deep enough to take the tracks and insulation. Check that the system you choose has a sealing method to prevent debris getting into the pocket. In the case of the doors on the left, cavity blocking caps on the end panel of the sliding glass close up the exposed cavity opening when the doors are slid shut.
With ‘open pocket’ doors, a single door slides over either the inside or the outside of a solid wall — a simpler, yet arguably less visually striking solution. Lift and slide doors offer another option, with a different method of operation.to open and close the doors, a handle turns 180° to lower or raise the doors out of or into a base track.
The cost of patio doors
It is impossible to give a firm price for patio doors as there are so many variables — material, opening and panel size, style of door and extras such as integrated blinds being just a few. And if you are having bespoke doors there is no general rule.
However, if buying ‘off-the-shelf’ you can assume that French doors and bifolds will usually be cheaper than sliding, with French starting from as little as £400 for a PVCU set and bifolds from around £450/m2. Sliding doors tend to start from around £550/m2.
PIVOT DOORS
Glazed pivot doors can make a real architectural statement when used as a patio door.they turn 90° on an asymmetrically located axis and can be designed for enormous openings and with minimal framing.they can also work well in combination with sliding doors.
They tend to be better for low traffic areas rather than as a main point of access and as they sit above the floor, as opposed to within a track in many cases, they are not always failsafe in areas of high exposure.
“Pivot openings are not as water and weathertight as casement-style doors or sliding doors,” explains Rebecca Clayton, director at IQ Glass. “That’s because the nature of a pivot opening is that the door or window sits snug within the outer frame. It does not overlap the frame at any edge. For this reason pivots are not recommended for highly exposed elevations of a building or projects with a very high wind load.
“If a pivot opening is being used you need to make sure that the system has a suitable drainage base and proper external drainage [see below].”
Can flush thresholds be watertight?
“To achieve a flush threshold the internal and external floor finishes need to be on the same level with a flat base frame to the doors. The easiest way to achieve this whilst maintaining high levels of weathertightness is with a sliding door,” explains Rebecca Clayton of IQ Glass. “The sliding leaf sits within a small recess in the base (12-13mm is optimum) which means there is a proper weather seal at the base.
“Bifolds, pivots and casement doors can also have flush thresholds but the opening leaf will sit above the base frame with a brush seal providing the weather seal at the base. This makes these openings unsuitable for flush thresholds in highly exposed areas or projects with high wind loads.”
In this case it is better to design a threshold with a very slight gradient — it will hardly be perceivable to the eye but will make all the difference to the performance of your doors.
“With any solution, you need to ensure that the door system has a built-in drainage base below the base frame and that proper drainage has been designed in,” explains Rebecca. “Many systems will offer a drainage system with their doors. Alternatively the builder can provide a French drain or similar.
“The drainage base below the door base frame means that any water that builds into the base track can drain onto the drainage base below which is designed to force water into the external drainage solution. The external drainage solution then carries the water away.”
FRENCH DOORS
French patio doors consist of two sets of hinged doors set within a frame, that lock together in the middle. These are perfect for smaller spaces and openings, with standard sizes of 1.2m, 1.5m and 1.8m.they give you maximum glass for the width — so a three door 1.8m bifold, for example, would give you less glazing than a 1.8m French set. Where they don’t do as well is in openings of more than 1.8m. Being limited to two doors means that going any wider than this leaves supporting the leaves tricky. Of course those after a wider glazed opening could always extend their French doors using sidelights (as above), but these will be fixed rather than opening.
BIFOLD DOORS
Bifold doors, also sometimes referred to folding sliding doors, consist of individual leaves (at least three) that fold and slide along a track and concertina together at the end of the frame. This action allows for much wider apertures to be opened up than with other styles of patio door — beyond 4.8m in some cases.while the size of the openings that can be created with bifolds is impressive, the frames that make up each leaf does mean the amount of glazing is less than with sliding doors.
What are thermally broken frames?
When it comes to aluminium patio doors, thermally broken frames are a must to avoid condensation. They have a piece of material that does not conduct heat sitting between the exterior and interior frames, separating the two.
“Back in the 1970s and 1980s, aluminium door and window frames were manufactured from single pieces of aluminium — but this caused issues with ‘coldbridging’,” explains David Clarke of Idsystems. “As the frame was a single piece of aluminium, if it was warm inside your home but freezing cold outside, both the inside and outside of the frame was cold, which used to cause significant condensation on the internal face of the doors and windows that would drip down the frames of the doors.
“Now we use two separate frames with, in our case, a high performance polyamide thermal break between the two.the outer and inner frames never touch each other so the coldbridging is no longer an issue. A thermal break is also key to the thermal performance (or U value) of a door or window system, because without it the aluminium would allow heat to escape easily. Generally, the deeper the thermal break, the better performing the doors.”
OVDEORORSSIZED DOORS
The trend for oversized patio doors continues, meaning so too does the development of bigger and better designs from window and door companies.
The minimal windows 4+ system from IQ Glass, shown here, allows for sliding doors of up to 4.5m high and 12m2 for each sliding panel — the perfect way to make a design statement.