Measuring for a Steel Driveway Gate: Swing or Sliding
Two things decide whether a made to measure gate fits the opening it was ordered for: the type you choose, and the number you send the workshop. Choose the type first, because a swing gate and a sliding gate are measured differently and want completely different things from the ground around them.
Then measure the clear opening between the posts or piers, not the gate you picture hanging in it. A leaf is always narrower than the opening, because it has to give up a hinge gap on one side and a latch gap on the other. Order a 4 m gate for a 4 m opening and it will not fit, whoever built it.
Swing or sliding, decided before anything is measured
A swing gate is the simpler and cheaper answer. Nothing crosses the ground and the posts carry everything. What it needs is clear space to swing through. Its real enemy is a driveway that rises away from the road. A leaf hung to open inward over rising ground will bind long before it is fully open, and no amount of hinge adjustment fixes a gradient.
There are three honest fixes. Hang the gate to open outward, which is only acceptable where it cannot swing over a road, a footway or a shared access, and which several EU countries prohibit outright. Raise the bottom rail so the leaf clears the slope, accepting a larger gap under the closed gate. Or accept that the opening wants a sliding gate. In every case, a pair of leaves halves the swing radius of a single leaf, so an opening above roughly 3 m is usually built as a two leaf gate regardless.
A sliding gate costs more and needs a real foundation, but it asks nothing of the space in front of or behind the opening. It stays level as it travels, so a climbing driveway is simply not its problem. It also suits a short drive where a car has to wait close to the gate while it opens.
Sliding comes in two forms. A tracked gate runs on a rail set into the ground: less foundation work and lower cost, but the track collects grit, leaves and ice and has to be kept clear, which in a snowy climate means clearing it before every use. A cantilever gate carries the leaf on rollers mounted on a foundation to one side, with nothing crossing the driveway: no debris problem, but it needs a longer clear run and a substantial concrete foundation to hold the counterbalance.
Which leads to the rule that usually decides for you. A tracked sliding gate needs clear run back alongside the opening roughly equal to the opening width. A cantilever needs meaningfully more, because the counterbalance tail travels past the opening as well. If that side space is taken by a wall, a hedge, a bay window or a neighbour's boundary, the answer is a swing gate. Folding leaves remain an option for a tight drive, and they are more mechanism to buy, adjust and maintain.
| Criterion | Swing, two leaves | Sliding on a ground track | Cantilever sliding |
|---|---|---|---|
| Space it needs | Clear arc in front of or behind the opening, about half the opening width per leaf | Clear run back beside the opening, roughly the opening width | Clear run back beside the opening, meaningfully more than the opening width |
| Rising or sloping ground | Poor, the leaf binds on ground that rises through the arc | Good, the gate stays level as it travels | Good, and nothing crosses the driveway |
| Foundation | Post foundations only | Post foundations plus a rail bedded across the opening | A substantial concrete foundation on one side |
| Maintenance | Hinges and a latch | The track has to be kept clear of grit, leaves and ice | Rollers and the drive rack, nothing at ground level |
| Relative cost | Lowest | Middle | Highest |
| Suits | Level ground with room to swing | Side space and a surface that stays clean | Side space where the driveway must stay clear |
Measure the opening, at three heights
Measure the ground as it is today. If the drive will be resurfaced, say so and give the finished level, because 40 mm of new paving eats a gate's ground clearance.
- Clear opening width between the finished faces of the posts or piers, at the narrowest point. Take it at the bottom, at mid height and at the top, and give the fabricator the smallest of the three. Piers are rarely parallel, and brick or stone piers often lean out at the top.
- Height, measured from the ground at the opening, and state whether that figure includes any decorative top.
- Fall across the opening. Lay a long level or a laser across it and note the difference in millimetres from one side to the other. Ground that falls across the opening means the gate is either built as a parallelogram to follow it, or hung square with extra clearance at the low side. Say in writing which one you want, it cannot be inferred from a width.
- Ground clearance under the closed gate, enough to clear gravel, snow and any rise through the swing, small enough to satisfy whatever gap matters to you for dogs or children.
- What the posts are. New steel posts to be supplied, existing brick or stone piers, or concrete. Hanging a heavy leaf on an existing pier is a different job from setting a new post, and the pier has to be checked first: many are a thin skin of brick around a hollow core that will not hold a hinge under load.
- Pedestrian gate. Is there one alongside, and do the two have to match in rail heights, infill spacing and colour.
- Photographs from both sides of the opening and one from the road. Four photographs tell a fabricator more than a paragraph of description.
What drives cost, and what drives buildability
Wind load. A solid or closely boarded infill turns the gate into a sail, and that one choice travels through the whole structure: heavier posts, heavier hinges, deeper foundations and a stronger operator if automated. An open bar or slatted design lets the wind through and asks far less of everything holding it up. Wanting full privacy on a wide, exposed opening means specifying the frame and the foundations, not just the look.
Sag. A long single leaf wants to droop at the latch corner. The answer is a properly triangulated frame or a deeper top rail, not thicker steel everywhere, because thickness adds weight and weight is what makes it sag.
Automation. Decide before fabrication, never after. The actuator type dictates the hinge choice, where the hinges sit, how big the posts have to be and where cable ducts run. Retrofitting an operator to a gate designed without one usually means new posts. Ducting under a driveway is trivial before the surface is laid and expensive once it is, so run a spare duct even if automation comes later.
Posts and foundations. Post size and embedment follow the leaf weight, the leaf height and the wind load. Normal trade practice is to set gate posts in concrete to a depth that is a substantial fraction of the height standing above ground, and below the local frost line. Treat that as workshop practice rather than a code figure, and have the depth confirmed for your own ground.
Safety and sign off. A powered gate is a machine, covered across the EU by the national rules on power operated doors and gates and the harmonised standards behind them. In practice that means force limitation or safety edges and photocells, a documented handover, and installation by someone competent to certify the finished installation. Local building control governs what is allowed, and for a gate onto a public road the highway or planning authority does too, so confirm both before fabrication.
What to send with an enquiry
The smallest of the three widths, the height, the fall across the opening, the ground clearance, what the posts are or will be, whether it will be automated, and the photographs. With that, a workshop can build a gate that fits. You can see the range of made to measure steel gates and fencing, or how gate work sits alongside the heavier steel structures we fabricate.