- Risers may be made from cut down slabs or contrasting materials such as stone walling or bricks. The first riser is laid on a concrete bed, while the rest of the risers are bedded directly onto the step tread below. The tread lengths are all the same, but the excavation for the first step is longer than the others.
- Mark out the site with builder’s line and pegs. Fix two parallel lines down the length of the slope to mark the outer edge of the steps, and two more to mark the top and bottom. Check corners for a right angle with a builder’s square.
- Calculate how many steps are required by first measuring the vertical height of and horizontal distance of the flight of steps. Knock in a peg to mark the back of the highest tread, then hold one end of a long spirit level (or a level and straightedge) at the top of the peg.
- Divide the vertical height by your riser height to calculate how many tread s are required.
- Strip away any turf in the marked out area.
- Use lines to mark the back of the treads – allow an extra 50mm depth at the back of the tread, to allow enough room to work. Roughly shape the steps with a spade. Leave enough depth beneath the stone step treads for 100mm of hardcore.
- Dig a trench about 125mm deep for the footing for the first riser. Drive in pegs levelled with a spirit level to mark the surface of the footing before you pour in the concrete. If you are going to have a paved surface leading to the steps, then dig a deeper footing and lay one or two courses of engineering bricks on top of it, below ground level. You will then be able to lay your paving right up to the first riser.
- Concrete the footing, making sure the surface is level with your pegs. Leave it to dry for 24 hours before you build on it.
- Build the first riser on the concrete footing.
- Fill behind the riser with hardcore – it should extend beyond the back of the slab when you lay it. After this, then compact the hardcore with an earth rammer. The hardcore should rise slightly towards the back of the step. You can do this by using a spirit level and laying 10mm of shim across the front of the step.
- Lay a continuous bed of mortar on the riser and hardcore, and position the slab for the first tread on top of it. The slab should overhang the riser at the front and sides by about 40mm. Place the spirit level along the front edge to check the step is in line. If you are laying two slabs side by side, make a pointing mortar with three parts sharp sand to one part cement, and spread it on the edge of the first slab before you lay the second. This will make it easier to fill the joints.
- Use a spirit level and 10mm shim to check the treads have a slight fall towards their front edge. Then fill all the joints with mortar.
- Next, build the next riser on the first tread. Check its depth is the same as the first, and make any adjustments to the horizontal joints.
- Carry on building the steps, checking the tread lengths are right. Then place a long spirit level or straightedge on the front edge of the treads to check they are in line.
