Stone Steps – Slab Stone vs. Tread & Riser

Tread and Riser – Shepherd Stoneworks

Tread/riser stone stairs

Stone stairs can basically be built one of two ways:

either by using solid stone slabs stacked one after the next or by assembling some combination of treads & risers.

There are a number of variations within these categories, of course. The tread & riser style, for instance, can be done completely without mortar, but they are often done by pouring a concrete structure and using thin stone veneer as the riser face.

The design of your landscape and home will generally determine the right type of stairs to install, as will the given purpose for steps. Are you building a front stoop with several steps? Is it a couple of rises needed in a sidewalk that leads uphill? Or maybe it’s a series of wide low steps that also serve as seating or a place for large potted plants? I wanted to take a moment to consider the two approaches of slab stone vs. tread/riser and their optimal uses.

solid-slab steps, set in crushed rock (before wall installation)

Stone Slab Steps

Using large and very heavy, flat slabs of stone, stairs are constructed by moving the pieces (with some kind of machinery) into place. The bottom step is laid first in a deep bed of crushed rock and made to sit level (with a slight forward slope for drainage). The pieces must be deep enough front-to-back to be able to overlap by at least 4” and still allow for the correct rise and run of your stair.

The slabs that are available range from rough/random-shaped chunks to machine-split rectangles to sawn/flame-finished slabs (shown in second photo).  Many of these are kept in stock at the stone yard (Marenakos, Rock Mountain, Terrazzo) but in some cases the pieces have to be special-ordered for fabrication.

In addition to being very impressive and visually stunning, slab steps can be put in for less cost than our other alternative. While the material cost of the slabs can be quite high and their installation requires machinery and manpower to put in, they can usually go in a day or so compared to the tread/riser stair which takes several days to complete normally.

Tread & Riser Steps

Wall stone is fit together to form risers for each step, leaving the top 2” to be capped with slab stone treads. If the steps are to be done entirely without mortar, it is necessary to have deep treads that can be embedded under the next step in order to best utilize the gravity holding it together. I often will mortar on the treads instead without extending them into the next riser – the way I see it, tread stones can easily get damaged or oil-stained over the years, and if one ever needs replacing this makes it a lot easier to do so.

Tread & riser does tend to have a more formal look which is usually more suitable in an urban surrounding. Additionally, this type of construction is often the only option on worksites that can’t be accessed with the large machinery (because of extreme grade change, stairs, no alley entrance, etc.) needed to set slab steps.

Hopefully this has been helpful!

by Mark Shepherd

(206) 618-0558

Bringing the finest in Stone Masonry to the Greater Seattle Area.

Natural stone walls, patios, steps and rockery of all sizes.

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