Weather-resistant site signs: which materials last outdoors.

Start with how long it has to last

Two questions settle most of the choice. How long will the sign be up, and how exposed is the spot?

A board on a hoarding for the length of a project needs a different material from a notice that changes every few weeks. A banner on an open fence line takes far more wind than one fixed flat to a wall.

This guide is about materials. For which sign goes where, see our guide to what to order for each part of a site.

Rigid boards

We sell three rigid boards that work outdoors. All three are made to your own size, up to roughly 2.4m by 1.2m in one piece, and can be ordered with 5mm drilled holes, rounded corners, a shape cut or a hook-and-loop backing.

• Aluminium composite (often known by the brand name Dibond) is two aluminium sheets around a polyethylene core, 3mm thick. It is durable, weather-resistant and made for signs that stay up. Your design is printed on self-adhesive vinyl and applied to the face.
• Fluted board (Correx) is fluted polypropylene: think corrugated cardboard made in weatherproof plastic. It is light and rigid, and it is the economical choice for temporary signs. For a permanent sign, aluminium composite is the longer-lasting option.
• PVC foamboard (Foamex) is a solid, lightweight PVC board in 3mm or 5mm. It is suitable outdoors, but it can expand in heat and direct sunlight, by up to 5mm per linear metre. Fitted tightly inside a frame, it can warp.

Fluted board can also expand by up to 5mm per linear metre, so keep borders and important content a little in from the edge on both.

Banners: solid PVC or mesh

PVC is a flexible plastic, and banner PVC is sold by weight in grams per square metre (gsm). We print three weights.

• 440gsm PVC is the standard banner material. It is printed on one side with UV-based inks, works indoors and out, and is flame resistant to DIN4102.
• 500gsm PVC is a heavier, coated banner PVC, printed with fade-proof UV-based inks. It is M1/B1 fire-rated and suited to tension-frame systems.
• 740gsm block-out PVC has a light-stop lining through its core, so it can be printed on both sides without one face showing through the other.

A solid banner catches the wind like a sail. On a wall or a solid hoarding that rarely matters, because the wind cannot get behind it. On an open fence it matters a great deal.

That is what mesh is for. Our Heras fencing banners are printed on mesh that lets roughly a quarter of the wind pass through. They are sized to sit just inside a standard 3.5m by 2m panel, and they are M1/B1 fire rated. There are two mesh materials, and AirMesh Polyester is the PVC-free one.

How the materials compare

Posters, magnetic signs and bollard covers

Outdoor posters come on four materials. Blueback paper is water-resistant rather than fully waterproof, and is made for short campaigns of around 4 to 6 weeks. If a poster has to stay out longer, choose the 440gsm PVC or the 400gsm PVC-free option.

Magnetic vinyl signs hold to iron and steel and lift off without residue. They will not hold on aluminium, fibreglass or plastic. They are suitable for outdoor use for up to two years.

Printed bollard covers are cut from 4mm corrugated Correx. They are weather-resistant, lock together with tabs and come apart undamaged, so one set can be used again.

Fixing and placement

How a sign is fixed matters as much as what it is made of.

• Use every eyelet. A banner tied only at the corners flaps, and the movement strains the eyelets.
• Pull banners taut. Cable ties work well on fencing. A slack banner moves more in the wind.
• Put solid banners on solid backgrounds. Where the wind can get behind a banner, choose mesh.
• Fix boards at every corner. Order drilled holes so you are not drilling on site.
• Leave room for movement. Do not trap fluted board or foamboard tightly in a frame.

For safety signs, the material is the smaller part of the decision. Your site's own risk assessment and the law decide which signs are needed, and HSE publishes the guidance.