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Flush Threshold Patio Doors with Minimal Windows

Flush threshold patio doors are becoming more and more important in modern architectural design. Modern glass extensions and new build homes alike all want that smooth and easy transition from inside to outside. A flush threshold to the patio doors is a key component of achieving this design. With a flush threshold, when the sliding patio doors are open the internal and external spaces are merged together into one, blurring the boundaries between inside and out. This visual design trick extends your interior space and forms the garden into part of the home.

This is merging if inside and out is only possible with a flush threshold to the patio doors. Premium sliding door systems like minimal windows will offer a flush threshold detail as standard. The minimal windows range of sliding glass doors include a variety of base options, but every one of them is flush in keeping with this modern architectural requirement.

So, if you’re looking to include a flush threshold patio door into your project what do you need to know?

What is a flush threshold patio door?

A flush threshold patio door is a sliding door system which offers a base detail with no step or level change. The base of the sliding patio door is exactly in line with the internal floor finish and the external floor finish. The aluminium framing of the patio door is built into the floor structure so that the top of the sliding rail and base frame sits flat and in line with the floor finishes inside and out.

How do you get a flush threshold to a patio door?

You can achieve a flush threshold detail for your sliding door by first of all specifying a sliding door system which has this detail as standard. You then need to ensure that your internal and external floor finishes have been designed to lay at the same level.

When the sliding door frame is integrated into your building structure you want the top of the aluminium frame base to sit in line with the internal and external floor. This detail is only possible through close collaboration of the architect builder and architectural glazier. You will need to ensure that there is enough space below the finished floor level for the aluminium base frame to be recessed allowing the top of that frame to be level with the floor finishes.

What is the difference between a low threshold and flush threshold patio door?

A flush threshold patio door is different to a low threshold patio door.

You will often see the term ‘low threshold’ being used to promote bi-folding or typical aluminium sliding systems. A low threshold door is not flush and does have a level change between inside and outside or across the frame. With these types of systems that offer a low threshold it is often required to achieve weather performance.

Premium sliding door systems like minimal windows don’t need this level change to achieve the high levels of weather resistance required. All base options for minimal windows have a fully flush threshold to the sliding doors for step free and flat transition from inside to outside.

What are the advantages of a flush threshold patio door?

There are various advantages to a flush threshold detail for a patio door. When looking purely in terms of design, the absence of frame or structure at the base of the glass doors allows the merging of inside and out to occur even when the glass doors are shut. In many projects it’s difficult to discern from images alone when the glass doors are open or closed. This continuation of building and living space from inside to out is a desirable trait for most modern home projects.

In terms of usability, a flush threshold creates an easier transition between the internal and external living spaces of a building. This can be showcased easily on swimming pool projects where the threshold of the sliding door is likely to be walked over in bare feet. You want this threshold to be flat and level with the floor finishes to ensure this is comfortable for the users.

Flush thresholds have an obvious use inaccessible or inclusive building designs. The minimum window sliding door thresholds have been tested and certified for barrier free access ability which showcases the benefits of its use in a wheelchair or accessible environment. These sliding patio doors have been designed with wheelchair users in mind. A flush threshold allows wheelchairs or other access ability devices to manoeuvre over the frame with no step level change or catches.

You can see this detail used to great effect on the accessible building design for Claywood House. All exterior doors used a flush threshold for wheelchair access within the minimal windows doorways. This allowed the architects to create an inclusive home design for the wheelchair user and their family.

How does a flush threshold patio door maintain weather resistance?

When specifying a flush threshold patio door you want to ensure it maintains its weather resistance even with this flat base design. Sliding door systems have the advantage over bifold doors in this area thanks to the recessed nature of the sliding door pane.

The sliding glass panels within the minimal windows sit recessed in the base frame of the glass doors. This overlapping of frame and glass create the robust weather resistance expected and required of high profile projects. This then allows systems like minimal windows to achieve high levels of water and wind resistance whilst maintaining a completely flat threshold detail. The minimum windows 4+ system for example uses a flush threshold detail and has been tested to hurricane levels of wind and water.

Do flush threshold patio doors include drainage?

One important consideration for flush threshold patio doors is ensuring that drainage is detailed and built into the base frame as standard. When your floor finishes are continuous from inside to outside you need to ensure that water run-off and surface water outside will be dealt with properly. Your slim sliding door system should have built in drainage both within the base frame itself and outside of the flush threshold. The nature of this external drainage will depend on your building project and other aspects of the build however various drainage options are available for the minimal window system that are designed to maintain this flush internal to external design.

Whether you opt for a hidden slot drain or a higher volume external drainage channel, the transition from inside to outside maintains the flush nature and allows for proper water drainage and high levels of rain resistance.

aluminium sliding doors by swimming pool

How do i include a flush threshold patio door on my project?

If you were looking to include a flush threshold patio door on your project you first want to make sure that the sliding door you’ve chosen has been designed to be used this way. Thankfully all minimal window sliding door systems and all the base options have been designed and tested with this flush threshold detail.

You need to ensure you plan the integration of your flush threshold patio door as early as possible. Your builder will need to see the base details of the sliding glass door system to ensure there is enough space below the finished floor level for the frame and drainage to go. By considering these interfaces as early in the project as possible you will achieve a flush and continuous finish from inside to out.

All the windows sliding door systems have been designed for flush threshold details. If you would like to include a flush threshold patio door on your project contact the team at minimal windows to find out how you can integrate a premium sliding door into your project.