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Interlocks: are they necessary?

A very popular and common question here at the support team at Seconline is regarding the necessity of interlocks or interlocking for security doors.

Before I answer the question let me first describe the reason that an interlock is installed to a sliding security screen door. A common or basic track system will consist of a bottom pip track that is designed to support the bottom roller and guide it along the track. The same should apply for a top track; however, it should also have a U-channel to add extra security for support so the door cannot be easily pulled off the track. A U-channel is desirable at the bottom as well so as to completely encompass the door into opposing U-channels, but this would obviously in most cases cause a bottom trip hazard. Also some top tracks will only have a U-channel and will not have the pip top track and this is acceptable but not ideal as the top track will allow the door to accurately negotiate the track from left to right and also to engage with the lock.

Again, it is usual to have a defined closing U-channel so the door will have protection both on the inside and the outside the entire length of the locking side. These can vary in width and depth but will need to be a minimum of 22mm wide as our doors and most doors in Australia are 20mm wide. Usually located on the fixed glass panel towards the back which is the glass side will be the receiving interlock. Again these can vary in depth and in the distance out from the fixed glass panel. Usually they will be around 20mm deep and 6mm to 10mm wide. These are designed by the manufacturers of  glass doors to allow the security door to interlock into as it engages into the fully lock position. This is done without anyone doing anything other than sliding the door closed into the position as per normal.

Not all sliding glass doors will have a provision for a receiving interlock, particularly the older ones. When I say older I'm talking pre-1990. Some extruders of glass sliding doors have  included the receiving channel as it is extruded as part of the extrusion from much earlier and they have always made their doors this way. The need for high security will vary in terms of Australian standards from state to state and not all doors will need to have high security. For example, doors on balconies of high-rise apartments will have little to no real need for security compared to the rear door or side door of a low-set three-bedroom brick home in the suburbs. This will depend also on the particular suburb. Areas of high security and high crime do vary and so will the need for security.

If, however, there is little need for high security then it is not necessary to have interlocks. The basic function is to lock the door of the non-closing side. In the case of fly doors or lightweight diamond doors then it could be argued that they would have little use and a far better option would be to select a side bug seal instead. At the factory we install the bug seal which will save additional installation time. In the case of interlocks they have to be installed on site.

Frame interlocks are a standard inclusion in our 316 stainless steel mesh security doors, perf mesh and low-vis mesh security doors. If a high level of security is not required or if there is no receiving interlock then this can be substituted for a side bug seal instead. Please note this on your order because as previously stated a frame interlock is standard.

In brief, a short answer to the question of whether interlocks are necessary is no; however, they do provide additional security if needed.

For Seconline Security Sliding Screen Doors Online look to Seconline!

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