Add together the ground clearance, the height of the sign and the depth in the ground. Beside a public footway the bottom of the sign should be at least 2100mm above the ground and (depending on the sign size) at least 600mm of post should be in the ground, so a 750mm sign needs 2100 + 750 + 600 = 3450mm, which means a 3.6m post. Signs on private land and away from walkways can be mounted lower, so a shorter post will often do. For large signs, the wind-loading may need calculating to determine an appropriate post and foundation.

76mm is the standard post for a single road sign up to around 750mm and is the size most clips and fittings are made for. Step up to 89mm for larger signs, exposed or coastal sites, or two signs on one post, and to 114mm for big rectangular signs or very windy locations.

All our posts are hot-dip galvanised steel, which protects against rust for 25 years or more with no maintenance, so plain galvanised is the right choice for most highway, industrial and rural sites. Powder coating adds a tough colour finish on top of the galvanising: traffic grey blends into the street scene, and black suits conservation areas, town centres, car parks and private developments where looks matter. We can powder coat other colours to order, so get in touch if you need a particular RAL shade.

Straight posts are the standard choice and are set in a concrete foundation. Welded-base posts have a steel plate welded to the bottom so they bolt straight down onto existing concrete or tarmac where you can't dig but aren't stable for large signs. Wide-base posts flare out to a 140mm base with an access door for cabling, so they're the post for illuminated signs, LED school signs and anything else that needs power.

For a single sign on a 76mm post, plant at least 600mm of post in a concrete foundation around 450mm square, and go deeper and wider for bigger signs, taller posts or exposed sites. A handy rule of thumb is 200mm in the ground for every metre above it. On the public highway the council's own standard foundation drawing takes precedence, so check with them first.

On a public road the bottom edge of the sign normally sits 900mm to 1500mm above the carriageway, with speed limit and other safety-critical signs at 1500mm. Where the sign overhangs a footway it needs at least 2100mm of headroom, rising to 2300mm over a cycle track and 2700mm over a bridleway. On private land you can mount lower, as long as the sign stays visible and clear of head height.

Yes, a single-post sign is a straightforward job: dig the hole, set the post upright in concrete or post-mix, let it cure, then clip the sign on with a spanner. If you can't dig, a welded-base post bolts down onto existing concrete instead. Work on or next to the public highway needs the highway authority's permission, so check with them before you start.

Choose channel clips to match the outside diameter of your post, not the size of the sign; we stock 50mm to 140mm and 76mm is by far the most common. Each clip slides into the channel on the back of a post-mounted sign and bolts around the post with an M6 bolt, and most signs need two clips per post. For bigger jobs, boxes of 50 work out cheaper per clip.

Screwband clips fix a sign using a steel band that wraps around the post and tightens with a screw, so one clip fits a wide range of diameters. Use them on lamp columns, oversized or non-standard posts, or anywhere a fixed-size channel clip won't fit. The 24 inch band suits posts up to roughly 180mm across and the 36 inch band up to roughly 280mm.

A post cap closes the open top of the post so rain can't get inside and rust it from within, and it gives a neat finish, so we recommend one on every post; choose the size to match your post diameter. A base plate sits at the foot of the post inside the concrete foundation and stops the post twisting, so the sign can't be turned by wind or vandals. Both can be added with one click when you order a post.

Yes. A post will happily carry a sign on each side (back to back) or a supplementary plate under the main sign, and each sign just needs its own set of clips. For two large signs or a tall stack, step up to an 89mm or 114mm post so it can take the extra wind load.

Our warehouse holds a large stock of posts, clips and accessories, so most orders can be dispatched quickly. If you're working to a deadline or have particular delivery requirements, contact us before you order and we'll confirm what we can do.

Posts are long and heavy, so delivery is worked out at checkout from the size and weight of your whole order rather than a flat rate. Make sure the delivery address can take a post delivery, which usually means access for a larger vehicle and someone on hand to help unload. If that's awkward, you're welcome to collect from our warehouse instead.