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I am wanting to build a sliding gate for my driveway entrance. I have already built the wall and made the pedestrian gate. I thought I will make it a manual gate for now and adding the automatic motor can be the next project. The gate will be 3750 W x 1500 H.
Any suggestions on what to make the gate frame out of? I did want to do it in steel tube like I did for the pedestrian gate. But I made that out of 20 x 20 steel square tubing and I am pretty sure that won't be strong enough for a bigger driveway gate? It would need to be 50 I would think? I did think of the Fortress Gate kits? Can you make one in the size I need for a driveway gate?
I also thought of using Pine, maybe 70 x 35 H3 Structural Treated Pine? I was thinking this would be the easiest, quickest and cheapest option. Would this work?
Thanks!
Welcome to the Bunnings Workshop community @Conway. It's marvellous to have you join us, and many thanks for your question about sliding gates.
Before getting too deep into materials, it’s really important to step back and look at how sliding gates actually work, especially if your end goal is to automate it later.
The first thing to confirm is whether you physically have the space for a sliding gate of this size. A sliding gate does not just need the clear opening width of 3750 mm. It also needs enough run to slide fully clear of the opening. In practical terms, you generally needs the opening width, plus a bit extra so the gate does not run off the track. That means you are looking at roughly 3.7 metres of clear space beside the driveway to allow the gate to fully retract. If you do not have that space, a sliding gate is going to be problematic from the start, regardless of what you build it from.
The second major point is that it is not a great idea to build a manual sliding gate now and assume you can easily add a motor later. Most automatic sliding gate systems are designed first, and the gate is built specifically to suit the motor, track, rollers, and weight limits of that system. Retrofitting automation later often leads to compromises or complete rebuilds because the motor, rack, rollers, and guide posts all have very specific requirements. In short, the kit dictates the gate design, not the other way around.
In terms of materials, 20 x 20 steel tube is very light for a gate of this width. It could only work if heavily braced, and even then you would need to carefully manage flex over the span. Moving up to 50 mm steel tube would certainly be stronger, but that introduces another issue, which is weight. Many domestic gate motors are designed to move relatively lightweight gates. A heavy steel frame can quickly exceed what a standard motor can reliably operate, leading to slow movement, strain, or premature failure.
Fortress gate kits are generally not designed for wide driveway sliding gates. They are typically intended for smaller, hinged gates and lighter-duty applications, so they won't suit a 3750 mm wide sliding driveway gate.
Treated pine such as 70 x 35 H3 could be used structurally, but again weight becomes a concern. Sliding gates are usually designed to be as light as possible while remaining stiff. Timber can work, but it needs careful design to prevent sagging and twisting over time, and it still has to fall within the limits of any motor you plan to use later.
At this stage, the best approach is to decide on the automated gate system you ultimately want to use and work backwards from that. Look at something like a Richmond automatic sliding gate system and check the maximum gate width, weight, and construction recommendations. Once you know those parameters, you can design the frame, materials, and track layout to suit the system properly from the outset.
If you find you do not have enough space to retract a sliding gate fully, it may be worth reconsidering the design altogether and looking at automated swing gates instead. They often work better in tighter spaces and can be easier to retrofit if planned correctly from the start.
Please let me know if you have any questions.
Mitchell
