Revolutionary slimline sliding door design: Cutting building costs and expanding design possibilities

The space-saving convenience of sliding doors is well appreciated by homeowners, but the problems of sticking , scraping and scratching can be frustrating. This issue occurs when the timber moves or warps and is particularly common where there is exposure to direct sunlight, uneven temperature and humidity either side of the door, such as between the garage and internal living spaces.  

Superior Doors addressed this issue over 15 years ago, when they were the first in the country to create steel-reinforced doors with a steel substrate, framed in timber, with an outer timber skin. The rigidity of this design prevents these issues and increases longevity. Now, their latest innovation, Slimline doors, uses the same technology but with a new, slimmer and stronger steel-reinforced substrate that offers greater design possibilities. We spoke to Superior Doors’ Nathan Davidson who shares how Slimline doors allow design flexibility and can cut costs. 

Slimline steel reinforced timber doors: how they work

“People have been asking us for a while for larger doors with 6mm skins that will still fit in a standard 90mm stud wall.  With the old design we needed to use thinner skins which have a greater risk of component show-through and a lesser paint finish,” says Nathan.

For situations where there is a dividing wall where there’s a distinct difference in temperature or moisture level difference between two spaces, such as a wall where there is an internal heated space on one side (for example, a room running a heat pump next to a garage) or a room with high moisture next to a dry room ( for example, a laundry room next to a living room) a steel-reinforced sliding door will ensure the conditions don’t affect the rigidity of the door and its ability to move in the cavity. However, the inability to use more rigid timber skins with the standard steel-reinforced design hasn’t allowed for larger doors or more premium surface options—until now.

In the new Slimline model, the thickness of the steel component has been reduced from 30mm to 25mm, but uses a significantly stronger profile of steel reinforcing and timber framing, which means it’s now possible to have the same rigidity but with the option of using premium 6mm timber skins. 

Collectively, these component innovations have significantly increased the door’s rigidity, reduced its thickness from 38 mm to 37 mm, and eliminated the need for oversized doors to be 42 mm thick, enabling the use of standard 90 mm cavities for oversized doors.

The benefits of the new slimline design

With the standard steel-reinforced door, it was only possible to use the 4mm timber skin (in a 90mm stud pocket), which was limiting for designers and specifiers—but the new slimline design means skins up to 6mm can be specified, giving designers greater flexibility and a better paint finish.

“A 3mm timber skin is very thin and imperfections show up fairly easily—whereas a 6mm skin can achieve a much better finish, which is ideal for projects with a premium aesthetic,” says Nathan. 

For oversized doors, which typically require a wider 140mm door cavity due to the increased width of the door to sustain rigidity, the Slimline design offers a whole new world of possibilities. 

Designers can specify larger doors without having to increase the wall stud to 140mm, and can choose from a wide range of premium timber skins. 

“This combination of increased strength and reduction in thickness has resulted in improved performance of the product and a reduced overall cost to the builder and end-customer,” says Nathan. “As well as the new design possibilities for the door, being able to use a standard wall stud can mean cost savings for homeowners as there are fewer overall materials required.”

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