The Art of Shuttering: How to Set Up Shuttering Correctly for a Concrete Base

Shuttering (also called formwork) is the temporary frame that holds wet concrete in shape while it sets — and it defines everything about the finished base: its size, its edges and its level. Set the shuttering up square, level and firmly braced before you pour, and the slab looks after itself. Get it wrong, and the error is cast in concrete.

Start with the dimensions — and don't assume the base is simply the size of the building. Always follow the building manufacturer's guidelines, because they often specify a base larger than the building itself, both to spread the load properly and to allow for measurement tolerances. Think about overhangs too: guttering and fascia boards project beyond the walls, so check the finished building won't overhang a boundary before you fix the base position.

Next, choose your shuttering material. Plywood, timber and metal are the common options — which is right depends on the load the shuttering must hold and whether you want to reuse it afterwards. Timber suits most one-off domestic bases; metal formwork earns its keep on heavier or repeated work.

Finally, kit yourself out properly before you start: gloves, safety goggles, boots, a high-visibility jacket and a hard hat. Wet concrete and swinging hammers deserve respect.

• Measuring tape • Hammer and nails, or screws • Spirit level • String line or marking paint • Saw • Shuttering boards • Release agent • Corner braces • Supporting stakes or props

1. Prepare the site — clear away debris so you're working on clean, firm ground.

2. Mark out the area with string line or paint. Take your time getting the lines straight and the corners at true right angles — everything that follows builds on these marks.

3. Cut the shuttering boards to length and assemble them along the marked lines.

4. Check the levels. Work around the frame with a spirit level until every board sits true — the top of the shuttering is what you'll strike the concrete off against.

5. Secure the corners with braces so the frame can't be pushed out of square.

6. Add external support — stakes or props driven in against the outside of the boards. Wet concrete is heavy, and unsupported shuttering will bow or burst under the pressure.

7. Apply a release agent to the inside faces so the boards strip away cleanly once the concrete has set.

8. Make your final checks — measurements, diagonals, levels and bracing — before a single drop of concrete is poured. This is the last moment a mistake is free to fix.

• Use screws rather than nails if you want to reuse the shuttering — the boards come apart cleanly instead of splitting. • For projects carrying heavy loads, consider metal formwork over timber. • For anything complex or structural, get a structural engineer's input before you build the formwork. Advice is cheap; demolition isn't.