Step By Step Stairs – The Base


A flight of sawn Yorkstone treads & risers

Yorkstone Steps – Supplied & Fitted By English City Stone

“Before anything else, preparation is the key to success.” – Alexander Graham Bell

If you are thinking about installing new stone steps at your property it is worth thinking long and hard about the base they will sit on. Although our Victorian and Edwardian ancestors would often construct stone steps without a base we no longer consider stone to be load bearing for the vast majority of step projects. Picking the right materials for your base and working out the correct dimensions will improve both the durability and visual aesthetic of the finished flight.

Our Step By Step guide is just that – if in doubt ask the experts.


  1. Work out the total fall on the steps, this is the measurement from ground level at the foot of the steps to the highest level of the top step. This can be done using a spirit level and tape, but it is a lot easier and more accurate with a laser level. In our example, below, the total fall is 800mm (from A to B).

    Section drawing showing steps and base

    An example flight of steps with their base. Stone measurements are give on the top & left with base measurements on the bottom & right – click to enlarge

  2. Calculate the height (rise) for each step. If there is an existing flight of steps then it is usually best to keep the same number of steps. Where possible, the steps should be of equal height and each should be no more than 225mm (approx. 9″). In our example there are four steps, so each step height is 800/4 = 200mm.
  3. Now work out the ‘true going’ on each step tread. This is the foot-fall or depth of the step not including any overhang that the final stone tread will include. The final ‘going’ measurement for the stone tread will the the true going + width of a riser + the overhang. In our example the three lower steps have a true going of 250mm and the larger top landing step has a true going of 700mm. The stone is 50mm thick, as is the the overhang (for aesthetic purposes), so the final going measurements are 350mm for the treads and 800mm for the landing.
  4. Next, we calculate the dimensions of the base that will be required to support the new stone steps. To do this, subtract from the finishing levels the thickness of the tread and mortar substrate. If your stone is 50mm thick, subtract at least 70mm from the finishing height of the steps to find the finishing height of the base. If in doubt, subtract more; you an always build up the level with mortar. You’ll notice that the bottom step of the base is less than all the others. This is correct; if it was the same height as the others then when you add the stone the result will be a bottom step that is taller than those above it. In our example we are using 50mm stone and have allowed for 30mm of mortar. At it’s tallest point the base is 80mm lower than the total fall (A to B) i.e. 800-80 = 720mm. Working downwards we see that each step of the base is 200mm until we reach the bottom step, which will be 80mm shorter than the others i.e. 120mm.
  5. The materials you use to build the base will depend on the location of the steps. If they are entrance steps with a usable space beneath consider pre-stressed concrete lintels. If there is no space beneath then concrete blocks or shuttered concrete may suffice. For garden steps it may simply be a case of shaping the earth into a base.


Good luck with your build!


Mark Bowler
English City Stone

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