Fences

All you see of a fence is the infill; what works is underground. So the conversation is better started not with profiled sheet but with the soil: it decides whether the fence still stands straight after three winters.

A whole bay

A fence bay is two posts, two rails between them and the infill on the rails. A top rail runs along the top and a gap is left to the ground. Everything else is variations on those four parts.

A fence bay: two posts with concrete foundations in section, two rails on brackets, the left half clad in profiled sheet, a top rail, the gap to the ground, and dimensions for height, bay and depth — A bay with its foundations in section. There is more post underground than you would think: 1.2 m for a fence 1.8 m high.

That proportion is worth remembering: for a fence 1.8 m high, about 1.2 m of post sits in the ground. A third of the tube is never seen — and it is the part holding everything up.

What closes the bay

Six infills for the bay between posts: profiled sheet, a steel palisade, a 3D panel, a welded grille with spear tops, wrought iron and louvres — Six infills. Solid versus open is not a question of looks but of the load on the posts.

Infills fall into two groups, and not by price. Solid ones — profiled sheet, louvres, close ironwork — shut the yard off but catch the wind; their posts go closer together and deeper. Open ones — palisade, 3D panel, welded grille — let the wind through and allow a wider bay.

Profiled sheet — the cheapest way to close a plot completely, and it goes up in a day.
Steel palisade — dearer, but tidier to look at and no sail.
3D panel — a factory answer for long perimeters: quick, even, no welding on site.
Welded grille with spear tops — the classic in front of a house; made to the size of the bay.
Wrought iron — dearest of all and always to order.

Posts: six ways of setting them

Choosing the method is choosing for the soil, not for the budget. On firm clay everything works; on heaving ground with a high water table the concrete is pushed up along with the post, and by spring the fence stands in a wave.

Six ways of setting a fence post: concreting, driving in, a screw pile, gravel packing, a brick pillar with cast-in plates and fixing to an existing plinth — Six methods. Gravel packing and the screw pile win where concrete is pushed out: water is allowed to leave rather than held against the post.

Gravel packing is often underrated: the post is driven or set in a bore, and the annulus is filled with compacted gravel. Water drains away, there is nothing to freeze around the post, and it costs less than concrete. There is one catch — it will not do for the posts of a heavy gate.

Where to go next

A fence is almost never ordered separately from the gates and wickets: they share the infill, the colour and the logic of the posts — only the gate posts go deeper. If the perimeter also needs window grilles, see grilles, doors and hatches. Price and lead time are in how ordering works.

Frequently asked questions

What bay width should I use between posts?

2.5–3 m for a light infill, 2.0–2.5 m for solid profiled sheet. A solid fence works as a sail, and as the bay grows the load on the post rises faster than the saving on the number of posts.

How deep does a fence post go?

1.0–1.2 m when concreted — below the frost line. On heaving ground the concrete is pushed out along with the post, and there a screw pile or gravel packing wins: they let the water leave instead of holding it against the post.

Why leave a gap at the bottom?

So the lower edge does not stand in water and snow. The usual gap is 8–12 cm: enough to keep the fence from rotting from below and to let a mower under it, too little for a dog to get through.

How long does a profiled sheet fence last?

As long as its coating does. A polyester layer over zinc holds 10–15 years, provided the sheets are not cut with an angle grinder on site: an overheated edge rusts first. Posts and rails outlive the infill and are usually replaced once in the life of the fence.

Author: welder Updated: 20 August 2026