Stone is the most durable material for steps, as well as looking attractive and less obtrusive than wooden steps on upland sites. On some upland sites, suitable stone is naturally available close to paths, but on others, stone must be transported onto the site. The tendency in several areas is for wooden steps to be replaced with stone steps as decisions are made to invest in more durable solutions to path management. There are many ways in which stones can be used for steps, but they fall into two general types.
Firstly, there are simple steps made by using very large stones placed at intervals up a slope, with the treads formed by the natural substrate, or by stone aggregate brought onto the site.
Secondly, there are steps built as an integral part of the path surface. Smaller stones can be used, that rely for their stability on being wedged firmly together to form riser and tread. In principle this is similar to stone pitching. Pitching tends to be used on slopes up to about 20 degrees, the slope being gained by each stone being placed slightly above the preceding one. On slopes steeper than about 20 degrees, the construction of definite steps becomes necessary.
Whatever type of stone steps are built, it is very important that they are positioned and finished in such a way that walkers are not tempted to go round them. Stone steps are generally used on slopes with thin soils that rapidly erode, and control of erosion is the main aim. Placing of boulders or rough stone barriers may be needed to encourage walkers to keep to the steps.
Simple stone steps
The general rule for using stone for simple step construction is that if one person can safely move the stone, then it’s not big enough and will not be stable. The work of building stone steps in this way requires skill and practice in moving and positioning large stones, as well as good judgement in designing the route so that the steps are used. The treads, or the sloping path between intermittent steps need to be stable enough that they will not erode, or the stone step will become loose, or the riser face too high to be usable.
Select as large stones as possible, up to about the dimensions shown. These will normally need to be winched into position. Set the stone in at least 30% of its depth, with the smoothest face for the tread. The tread length should be at least equal to its depth. Dig the trench carefully so that the stone rests securely without rocking. It will probably be necessary to excavate a trench larger than the stone, to allow for levering it with a crowbar, and wedging underneath with smaller stones as necessary. Wedge stones firmly behind and in front of the step to finish.
Stone block risers
Where fairly regular ‘block’ shaped stone is available or can be supplied on site, smaller stone can be used which will fit together to make a stable structure. The Cleveland Way Project specify the following design for steps with aggregate treads (Cleveland Way Project, unpublished notes). The stones are set in a minimum of 30% of their height, carefully bedded in and any gaps filled with compacted stones or soil, topped with seed and fertiliser. The treads are made of excavated soil compacted down, and then topped with 75-125mm depth of stone aggregate. On steeper slopes, stone drains are constructed to take water off the treads about every ten steps.
Mortared steps
Where visually acceptable, for example on popular paths near to carparks, and where access for materials is easy, stone steps can be mortared for extra stability. The design shown below is used on the steps to the viewpoint of Mam Tor, in the Peak District. Where care is used in choosing the colour of the sand for the mortar, and the surface of the mortar is brushed before it sets, the mortar blends fairly unobtrusively. If the steps are stable and followed by walkers, vegetation grows up along the bottom of the riser and at the edges to disguise the construction.
Stone block stepped path
This design is used by the Cleveland Way Project, using sandstone blocks supplied to the site. Curving routes are chosen with step widths varying between 1.2 and 1.4m to avoid a formal staircase effect. The riser blocks are set in to about 50% of their height, leaving a rise of between 150 and 200mm. The stones are set so the tread has a downhill gradient and crossfall of between 2 and 5 degrees. Larger stones are chosen for the edges of the steps.
Every ten steps or so the tread is set about 50mm below the top of the riser, draining to a stone drain which takes the water away from the steps. This prevents a waterfall effect down long flights.
Pitched steps
This method has been used in the Yorkshire Dales National Park. Stones of about 1m x 500mm x 200mm are used for the steps, spaced a minimum of 400mm apart on steep slopes, with a longer spacing on gentler slopes. The gap is then pitched with smaller stone, packed tightly. A team of four people can work on a section, with two people working ahead to place the steps, and two following on with the pitching. A length of about 5m can be built in one day. For further details on pitching, see Chapter 9 – Steps.
Stone slab steps
This method is used by the Cleveland Way Project, on slopes of about 15 degrees. The blocks are set in as described above to form the risers, and stone slabs used for the treads, laid to a 2-5 degree downhill gradient. Any gaps are packed with compacted small stones and soil, topped with seed and fertilizer. All excavated turf and soil is carefully bedded in at the sides and on eroded areas.
Capping stone steps
This style of step requires a supply of fairly flat stones, with enough large capping stones to hold the smaller stones in position. They can only be built in a ‘staircase’, but are suitable for short steep sections where no other route can be taken, for example between outcrops of bedrock.
Sawn stone steps
The steep cliff path down to Man O’War Cove in Dorset is used by 0.75 million people each year, and timber steps have proved not sufficiently robust. It was decided to invest in purchasing sawn stone steps of local Purbeck limestone, which were set in a double flight of about 100 steps. The high initial cost (£15.50 per stone) was felt to be justified by the site, and by the fact that once purchased, the stone would last forever, and the steps could be repositioned as necessary if further erosion occurred.
The steps were supplied with grooves cut as shown to accept 16mm x 750mm steel bars, used to anchor the steps. The riser face of the stone was rough cut, and when viewed from a distance the finished steps blend well into the cliff.
The work was done in August 1994 by two consecutive volunteer projects, and had to be completed while the path was busy with holidaymakers. The first group built one flight to get people safely up and down. The second group followed on fitting the second matching flight, butted up to the first. Access was from the cliff-top, so work proceeded from the top downwards. The second group split into teams of two or three, working on different sections of the flight, as the location of each step was set by the first flight.
Various methods were used to carry the stones. A wooden cradle, designed to carry two at a time, was found to be too heavy. The best method was to use a rope sling tied through the grooves, carried by two people.
The stones were set with the top slanting slightly back to allow for settling. The tops were levelled with a spirit level. The cliff is mainly clay, and there was no problem knocking in the steel bars. The treads were surfaced with crushed limestone.
