How to choose between a Sliding Door and a Bifolding Door

The advantages of Sliding Doors

Sliding patio doors have been installed for over 40 years in UK properties. In the last 18 months there has been a resurgence in popularity for this type of door opening, often chosen in favour of the relative newcomer, Bifolding doors.

The two most popular material choices for sliding doors are uPVC and aluminium. We believe that the recent resurgence of patio doors is due to the flexibility that sliding doors offer over bifolds or French double doors, plus their very low maintenance features.


How wide is the average Sliding Door?

Sliding doors can carry a much larger and heavier glass unit, be it double or triple glazed. Therefore, sliding doors offer home owners much larger unobstructed area of glass than any other product. uPVC sliding patio doors can carry a 1.3 metre wide double glazed unit but aluminium sliders can carry a 3 metre wide unit. A six-metre wide expanse of glass interrupted by one vertical door mullion is very appealing.

Modern uPVC and Aluminium sliding patio doors feature enhanced security products; anti-lift blocks, multipoint locks and 3 Star security cylinders. Plus, all Kitemarked/PAS 24 certified patio doors must have a sheet of laminated glass as part of the sealed unit to deter even the most avid potential intruder.

KAT manufacture an extremely wide range of aluminium sliding patio doors, including mono rail/track, duo track and triple track. This allows KAT to offer door combinations from 2 doors up to 6 doors.

sliding patio doors






What are the differences between Inline or Lift & Slide Doors?

There are two different types of opening and sliding mechanisms.

In-line Slider Mechanism– this system is used on uPVC sliding doors and for smaller aluminium sliders. To open the door, you unlock the cylinder, flick a short lever to disengage the hookbolts and simply slide the doors open. KAT recommend a maximum sash width of circa 1500mm wide for in-line sliders, provided the doors are not taller than circa 2200mm.

Lift and Slide Mechanism – this system is ideally suited for large doors with wide expanses of glass. The German manufactured Lift and Slide gearing is mechanically fixed around the sash in a secure, dedicated aluminium channel, and when you turn the large lever handle through 180 degrees, the sliding door actually lifts off the outer-frame, allowing one to effortlessly glide the door open.

Image shows KAT Aluminium Inline Sliding Doors













Because sliding patio doors can carry huge pieces of glass, they offer exceptional Energy Ratings, also known as ‘U’ values. The ‘U’ value of a patio door will easily exceed that of a Bifolding door as Bifold sashes can only accommodate glass units at a maximum circa 1,100mm wide.

uPVC and Aluminium sliding patio doors all have slim vertical mullion sightlines. This is a major factor in the resurgence of this type of door as there is far less obstruction to impede the view. The standard door systems offered by KAT have an interlock sightline 94mm (approx.4 inches) which satisfies most market demands. There are aluminium sliding patio doors with a very slim 22mm vertical interlock sightline, but it is important to note that they are not PAS 24 certified. An excellent compromise is the premium KAT 4700 range of sliding door with a 47mm vertical sightline, at the meeting style interlock, which is PAS 24 certified. Contact KAT to find out more

What kind of door handles are fitted to Sliding Patio Doors?

KAT offer a range of handle finishes to complement both uPVC and aluminium sliding doors. In-line sliding doors are usually supplied with ‘D’ handles, made from durable steel. Lift and Slide patio doors have a long wand-like handle to allow the user to lift the opening door. All KAT ranges of sliding doors are available in many finishes. uPVC doors have a laminated foil bonded to the uPVC core material to offer colour options and aluminium doors feature a wide range of RAL, powder-coated finishes.


KAT's Lift and Slide handle

Aluminium sliding patio doors are usually the product of choice where very large expanses of glass are required. uPVC patio doors are a very cost-effective solution and they are well suited to installation in marine applications because there are no open joints for salt to attack. Contact KAT

The final justifications for choosing a sliding patio door over bifolds or French doors, is that patio doors slide within their own tracks. They don’t use up any internal or external space and do not prevent one from putting furniture right next to the doors, if required. Because the sliding sashes on sliding patio doors are effectively encapsulated within a fixed outer-frame, there are no single doors that can potentially flap around in high winds making them a much safer product for many sites. Telephone KAT on 01625 439666 to speak to a member of the Customer Services team or email

KAT manufactures a wide range of doors and windows in either uPVC or Aluminium.