Mastering flush tracks: A technical guide to achieving an effective weather seal

With UK searches for the term ‘indoor outdoor living’ increasing 51% year-on-year according to Google Trends, there is a growing demand for seamless transitions between indoor and outdoor living. IDSystems Technical Sales Manager Edward Stobart supported countless projects, including those where previous mistakes have had to be corrected.

• Flush tracks now account for more than 70% of total ID Systems installations - but they are still relatively rare for existing doors and older homes.
• As flush tracks require higher technical precision than traditional thresholds, without expert guidance, this can unfortunately lead to mistakes that are costly and time-consuming to correct.
• Having worked on over 40,000 projects at the forefront of mastering these complex installations since their inception.

Below, Stobart explains why installations still go wrong, and how mistakes can be avoided.#1 Not understanding which types of doors can achieve a completely flush track

Sliding doors and slide & turn doors can be designed to achieve a flush finish with a solid weather seal, but most other doors such as bifold and french doors need at least a low threshold to seal against.

Bifold and French doors close into the track or upstand. While it is possible to purchase completely flush track bifold and French doors with no upstand, in those instances, the only connection between the bottom of the panels and the track is brush pile, which is not an effective method of preventing drafts and rain.

Stobart advises against opting for bifold doors or French doors with no upstand, saying: "These were common-place when folding doors first became popular but with only brush-pile sealing the base of the panel to the track they are incredibly prone to drafts getting in and even water ingress. Completely flush bifold tracks should only ever be used for internal applications, for external doors you need an upstand against which the panels can close to create an effective seal. We get customers who have their hearts set on the completely flush appearance, but when we explain the risks and that the low-threshold track is only 14mm, they understand.”

This doesn’t mean you need to compromise on your flush track dreams. Bifold doors can be manufactured with tracks that are designed with a small 14mm upstand, against which the panels close. This upstand is barely noticeable, complies with Building Regulations Part M for wheelchair access, and still appears to be almost completely flush when viewed from inside and out.

[edit] #2 The flush track is too high

The most common mistake when trying to achieve a flush track finish is the track sticking out above the flooring. Unfortunately, this is also the issue that is usually the most difficult to fix. Stobart explains: “Typically, if the track is too high, it is because the base has been built up too much. To fix this issue, it would have to be lowered by digging out the base and reforming it to the correct height.

“Unfortunately, this is time-consuming and, more importantly, will have a knock-on impact throughout the rest of the ground floor of the finished floor height.”

“For a new-build, this may be possible, but for an extension where you are likely to be matching the floor height of the existing house, it is far more challenging. If it is not possible, the likely result would be the track sitting slightly above the level of the finished floor.”

[edit] #3 The flush track is too low

Stobart explains: “When the track is too low, we have the potential ability to pack underneath the frame to bring the height of the track up to match the finished floor level.”

“However, how much it can be raised is dependent on the size of the doors and the tolerance allowed for at the head of the system.”

If you want to raise the bottom track, the entire door panel has to raise with it. There is a certain amount of tolerance at the top of the door to allow for smooth operation and small changes in structural settling of the building over time. It’s not possible to raise the track beyond the tolerance of the system without changing the size of the opening.

[edit] How to ensure the perfect flush finish

For Stobart, successful flush track installations come down to one thing: precise measurement of the system, opening, and finished flooring: “The biggest bit of advice is to know the depth of the track for the system you are installing and to make sure that is accounted for when the size of the doors is ordered - especially if the systems are being manufactured based on planned sizes.

“Where the opening is being surveyed prior to manufacturing it is crucial that the finished floor level (including the chosen floor finishes) are communicated to the surveyor so they are incorporated within the calculations of the aperture sizes.

“Almost every manufacturer and every system has a different track depth and ensuring that the base is built to the correct height to accommodate your particular door is crucial to the end result.

While the technical requirements of a flush track are more demanding than a standard threshold, the aesthetic pay off is undeniable. Stobart notes that because these systems require such high levels of precision, some contractors or builders may be hesitant to install them: “I was on site recently and the builder had originally tried to talk the client out of having a flush track because it meant more work and detail for him – but the client stuck to their guns and in the end the project looks so much better for it.”

“Just make sure you do your homework on the technical details, and installing flush or low threshold tracks doesn’t have to be a headache, but showcasing your expertise can instead open the door for more luxury build work in the future.”

--Floor