Preparing posts and foundations for a made to measure steel gate

A made-to-measure gate is only as stable as its supports. A swing leaf acts as a long lever on its hinge post, a solid infill transfers wind to both posts, and a sliding gate depends on foundations that remain aligned along its travel. If a support moves after fabrication, the latch misses, the ground gap changes and an automated gate can develop unsafe movement. Prepare the supporting works before confirming an order from gates and fencing.

Freeze the gate concept before the foundations

Do not ask a groundworker to pour two generic blocks before the gate designer has defined the arrangement. Record:

• swing, tracked sliding or cantilever sliding operation;
• one or two leaves, manual or powered now or later;
• clear finished opening, leaf height and intended ground gap;
• open bars, perforated infill, close slats or solid sheet;
• hinge side, opening direction, stops, latch and drop-bolt positions;
• steel posts, masonry piers or an existing reinforced concrete support;
• exposure to wind, vehicle impact, slope, water and de-icing salt.

Those choices change the reactions at the posts. A tall solid gate is not just a heavier version of an open gate, it is a wind surface. Wind actions are assessed using EN 1991-1-4 with the relevant national rules. The designer needs the site location and exposure, not a guess based on the leaf weight.

Separate the responsibilities

The fabricator supplies leaf geometry, hinge or roller reactions and fixing interface. The structural engineer designs posts, reinforcement, concrete and the load path. The ground assessment checks soil, water and frost. The installer sets out and records the work.

EN 1997-1 covers geotechnical design and EN 1992-1-1 concrete structures. National annexes and local requirements apply. They do not provide a universal footing size: site and gate data govern it.

Investigate before excavation

1. Locate electricity, water, gas, drainage, communications and gate-automation ducts.
2. Identify made ground, soft spots, tree roots, groundwater and previous trenches.
3. Record nearby walls, retaining structures, kerbs and foundations that excavation could undermine.
4. Establish the final driveway build-up, including paving bed, asphalt, falls and drainage channels.
5. Set a datum that will survive the works and mark the finished ground level at each post.

A neat block of concrete cast into loose backfill can rotate with the post. A deep hole is not automatically a foundation if its sides collapse, it fills with water or it undermines a neighbouring wall. Where conditions are uncertain, stop and obtain the engineer's detail before digging further.

Choose the support arrangement

Steel post cast into concrete

The post and its embedded detail must be designed together. Coating at the concrete and air interface needs particular care because water collects there. Follow the drawing for sleeves, shear details, reinforcement and drain paths. Do not weld scrap bars to a finished post on site as a substitute for the designed embedment.

Steel post on a base plate

The plate must bear on structural concrete, not block paving, screed or asphalt. Concrete thickness, edges, reinforcement and anchor layout are verified before drilling. Fixings are designed to EN 1992-4 and selected through the current European Technical Assessment and manufacturer's instructions. Moving a hole because it meets reinforcement changes the connection and requires approval.

Masonry pier

A decorative brick or block shell is not necessarily a gate support. The engineer must know its core, reinforcement, ties, foundation and intended hinge connection. An expanding anchor in thin masonry or aerated block can split the unit. Do not assume a resin cartridge turns hollow or weak masonry into a structural pier.

Place reinforcement, ducts and templates before concrete

Use a setting-out drawing that relates post centres, finished faces, hinge axis and driveway datum. Secure the reinforcement and post or anchor template so they cannot float or twist during placing. Maintain the concrete cover and reinforcement geometry on the engineer's drawing. Do not push loose bars into wet concrete after the pour.

Install every required duct before concrete: power, controls, photocells, intercom, lighting, earthing and drainage where the project calls for them. Keep electrical and drainage details under their competent designers. Cap ducts during construction and record their routes. A forgotten motor cable commonly leads to drilling through a new foundation at the worst possible position.

Set the posts without building in an error

Check each post for plumb on two faces, check both top levels and confirm the distance between the defined finished faces at top, middle and bottom. Brace the posts until the concrete has achieved the strength required by the design. Do not pull a post into line with the gate leaf or hinges after the concrete has begun to harden.

Sliding gates need a foundation along the movement

A tracked gate needs its rail straight, level and supported along the run. A cantilever gate needs a designed base for the roller carriages and a clear run-back for the leaf and counterbalance tail. The motor, end stops, catcher and safety devices each need their own set-out point. A small change in level over the run can twist the leaf or alter the motor engagement.

Do not bridge a drain, soft verge or service trench with a rail and expect the gate to average out the movement. Coordinate the track or roller base with the driveway slab and drainage channel. Sliding and cantilever support frames belong to the wider field of steel structures.

Allow for water, frost and corrosion

Shape the finished paving so water does not pond around the post, base plate, track or motor foundation. Keep designed drains and hollow-section outlets open. Where de-icing salt can reach the steel, specify the exposure before the coating system is chosen. Site cuts, drilled holes and damaged coating must be restored with the specified compatible system.

Local frost conditions can move shallow isolated foundations and change the relationship between the two posts. The engineer sets founding depth and detail using the site and local rules. Do not copy a depth from another property or from a milder part of Europe.

Powered gates require early coordination

If automation is planned, declare the operator type before the gate and posts are finalised. Powered gates require a safety strategy, suitable hinge or roller geometry, force limitation or protective devices, safe gaps and reliable stops. EN 12453 addresses safety in use of power-operated doors and gates. The responsible gate and automation professionals must apply it with national requirements.

Final hold point before fabrication

Measure only after render, caps, paving and other finishes that define the opening are complete. Send the as-built record, photographs and final dimensions to the workshop, then check the fabrication drawing before approval. For other made-to-measure gate configurations within structures and gates, use the same hold point. Confirm commercial questions about supplied fixings or installation in the FAQ and order documents.