August 14, 2017

Picking the Right Patio Door for Your Project

Written by Rebecca Clayton

Hermitage Lane Interior-3
two pane minimal window patio door minimal windows sliding doors to residential development by KEA

The old-fashioned phrase ‘Patio Door’ conjures an image of a chunky uPVC door set and having to step up and over a base frame onto your external patio.

This reality has long since passed with the advent of flush floor details, step-free access, modern framing design and the progression of slim framed door systems.

Bifold and large glass sliding doors are replacing old, outdated uPVC patio doors and are available to use on all ranges of projects, from complete remodels to a like for like replacement into existing openings.

aluminium patio doors to modern house Sieger 85 sliding doors from Hedgehog Aluminium to development in Bucks

When looking at selecting new patio doors for a design or development there are many options available for you to consider, from which ranges, your budget, to frame sizes and more.


Sliding Doors vs Bi Folding Doors

The first step to selecting your patio door is to decide whether you want sliding or bi folding doors to the rear.

Bi Fold Doors can be used to open up entire apertures of a building. This ability means that bifold doors are sometimes preferred by homeowners, with the draw of opening up a large expanse of your rear elevation in the few warm months we receive.

white framed bi folding doors to bedroom White framed bi folding doors to residential refurbishment in London

Multiple panes can be connected together within an opening to provide huge expanses of glass to the rear of a property. When these panels are open you will need to think about where they stack. Most bi-fold doors will be externally opening and fold to the outside. Therefore you need to make sure that you have the space outside to do that. If there is a steep slope or a wall directly outside the doors this may not be possible.

If creating a very slim framing design is the most pressing element of the design then sliding doors will be your best bet. Sliding patio doors can achieve a vertical sightline of as minimal as 21mm; compare that to a 120mm sightline of a bi folding door….

large frameless sliding doors Large sliding glass doors to RIBA award winning home in Swansea

Sliding door panes can be huge, up to 15m2 per sliding panel. This allows you to create entire walls of glass that can slide open. You have to consider where the sliding panes will sit when open. Unless you have the wall space available to create sliding pocket doors then you will always have an element of fixed glazing within the opening. This should be designed to sit in a less used corner of the patio door opening.




Aluminium Sliding Doors vs Bi Folding Doors - At a Glancesliding doors vs bi fold doors infographic

Modern Sliding Patio Doors

two pane minimal window to London town house minimal windows sliding doors to a luxury two unit development in London

There is a range of sliding door systems available that all range in terms of sightlines, frame materials and cost.

An aluminium framed sliding door will give you the slimmest sightline option. The minimal windows sliding glass door has a vertical sightline of 22mm and can be finished framelessly on all other edges. Preferred by architects and designers this sliding door starts at roughly £1000 per m2 and offers a premium finish to any patio door opening.

When you start looking at lower cost options the sightlines start to increase going on a sliding scale down from the Sieger slim sliding door system with a sightline of 30mm to the Schuco ASS 70 sliding door with a sightline of 105mm. Each step down the cost ladder increases the framing slightly on all sides of the opening.

5 track sliding door to a basement swimming pool When considering the threshold of the sliding doors keep in mind that every track you add to the installation will add depth to the overall frame. This project in Kent installed a 5 track minimal window to the basement swimming pool. Each track is 60mm deep resulting in a sliding door system 30cm deep from the inside to outside floor finishes.

Modern extension with sliding pocket doors Modern extension by Architecture WK which used slim framed sliding pocket doors to open the entire patio opening.

Sliding doors all offer a flush threshold across the base. As sliding doors actually sit into the floor track, rather than just sit on top of it, the weather seal you achieve is slightly better than a flush threshold bi folding door.

If you have the wall space available you could design the sliding patio doors as pocket doors. This means that you can slide the whole face of the door opening into a hidden pocket within the wall. This modern home extension by Architecture WK created a hidden pocket in the rear wall of the extension allowing all three sliding door panes to slide away. This creates a fully open doorway whilst still maintaining the benefit of the slim sliding door frames when the doors are closed.

Don’t want an aluminium frame?

Steel sliding doors are also making a comeback with the CWS-85 S from the Mondrian® Range now available. The frames have a full thermal break through their depth and can be made from Galvanised Steel, Stainless Steel, Corten Steel and Architectural Bronze as desired.


Bi Folding Doors as Patio Doors

Bifolding doors to Woodwind new build house. Aluminium bifold doors to a new build house in Berkshire.

BiFold Doors can be seen throughout every home magazine you pick up off the shelves these days. These modern patio doors are designed to fold open, creating a fully open aperture to a room. The bi folding panes can be up to 3m tall and are available up to 1.2m wide per unit. When coupled together, up to a maximum of 7 panes folding in one direction, you can create large doorways that can constitute for an entire wall.

When bifold door panes are closed you will create a thicker frame than what is available from a sliding door. The slimmest bifold door that is available has a vertical sightline of 120mm when the doors are closed together. This will create a more dissected view through the elevation of glass and may be a consideration when deciding between sliding and bifold doors.

At the moment aluminium is the best way to create a modern elevation of bifold doors although advances are currently being made in both timber and thermally broken steel framing design.

three pane bi folding door to rear extension A three-pane bifold door installation to a modern extension on Onslow Avenue

The main point of difference between bifold door designs will be sightline size and cost. Generally speaking the thicker the sightline the lower the cost. The Schuco ASS 70 FD bi folding door is one of the slimmest on the market with a vertical sightline of 120mm and starts from approximately £1400 per bifold pane. A lower cost option from the Sieger range will give you a sightline of 140mm and starts at £1100 per panel.

It is now possible to achieve a completely flat threshold from inside to outside with bi folding doors as long as adequate drainage is integrated. A flush threshold bifold door relies on brush seals to weather seal the base of the door when closed. For this reason, a completely flat threshold may not be suitable for coastal projects or areas with high wind loads and driving rain.

flat threshold to bi folding doors A flat threshold across the bi-fold door base @ Sky House Design Centre

A rebated track is a good alternative to a completely flush threshold. Here the internal finished floor level is slightly higher than the outside, giving the doors a small lip of frame to close against. The rebated track from Hedgehog Aluminium has an 8mm step, almost completely flat, but offers a substantial increase in water tightness and resistance to wind load.

Integrating a Traffic Door

One of the additional benefits of a bifolding door installation is a traffic door. This is a door that can be integrated into the bi folding door opening that acts independently from the stack. This allows you to nip in and out of the door without having to fold an entire section back.

Traffic doors are most easily integrated into a bi-fold door install with an uneven number of panes (3, 5 or 7 pane bifold doors). The door can then be clipped back to the panes to open the doorway fully.

If you are looking to install an even paned bifold door then you could still have a traffic door with careful consideration of the opening configuration. A bi parting opening of 3/5 panes sliding in each direction will create an opening French door that could be used as a traffic door at the centre for example.

four pane bi folding door with glazing bars The Quarrendon Street project included a four pane bi folding door. They integrated a traffic door by hanging one door leaf from the side frame which can act independently from the stack.

Something a Bit Different

Sliding and Bi-fold doors makeup approximately 80% of the modern patio door market and can be easily integrated into any development for enhanced design and kerb appeal. But some projects are looking for something different and looking to add that ‘wow’ factor to a rear patio opening.

Sink the Patio Doors into the Floor

Merge the two main ‘pros’ from a sliding door install and a bi-fold door into one with a descending window. These automated patio doors from HIRT can hold a fixed piece of glass or a door system. When a button is pressed the entire rear wall will sink below the floor leaving you with a flat threshold across the top to the outside.

[video width="640" height="360" mp4="wp-content/uploads/2017/08/HIRT-SF-XL-Wollerau-Schweiz-SD360.mp4"][/video]

Slide the Patio Doors Upwards

minimal guillotine window Counterweighted minimal Guillotine Windows on site @ Dormers

The minimal windows sliding door range has recently been engineered into a vertically sliding Guillotine window. The slim framed sliding door can be turned on its side allowing the sliding panes to slide upwards over the building face or fixed glazing above.

The system can be fully automated using motors or counterweighted as required.

If you want to see any of these modern patio door designs in person simply make an appointment to visit the Sky House Design Centre which houses the showroom for IQ Glass and associated companies.


Download the Guide

For those interested in sliding door solutions click here to download our FREE Guide to Sliding Door Specification which details many of the sliding door systems listed in this article.

For further information or a quotation please call the team on 01494 722 880 or email