Natural Stone Steps and Porches
Natural stone steps are the most durable option for stairs and porches: stone withstands constant foot traffic, frost and rain and needs no regular repairs. For outdoor porches granite and basalt are chosen most often; for indoor stairs, marble, travertine and dense limestone are also used.
The key selection criterion is safety and durability: a dense rock with low water absorption, a non-slip finish on the tread and sufficient thickness for the span and load.
Stone steps are chosen by private homeowners for porches and terraces, and by developers and architects for the entrances of residential complexes and public buildings. Other rocks and their properties are covered in the section Natural stone for facades and interiors.
Choosing the Rock
The rock determines how the steps will perform after years of use.
| Rock | Outdoors | Indoors | Features |
|---|---|---|---|
| Granite | excellent | excellent | the most wear-resistant, many colours, withstands frost and de-icers |
| Basalt | excellent | excellent | dark, dense, does not show dirt |
| Quartz sandstone | good | good | naturally non-slip, warm tones |
| Dense dolomite | good, with impregnation | good | light, easy to work |
| Marble | limited | excellent | wears faster than granite, loses its polish outdoors |
| Travertine, limestone | limited | good | outdoors, only dense grades and warm climates |
Granite steps are the standard choice for an outdoor porch in central Russia: the stone withstands freeze-thaw cycles, salts and mechanical loads better than other rocks. The characteristics of the specific batch are checked against the test report.
Indoors the rock is chosen primarily by style, but for high-traffic stairs (public buildings, lobbies) granite or hard grades of marble are preferable.
Slip Resistance
Slip resistance is the main safety issue for stone stairs, especially outdoors.
• Tread finish. Outdoors: flamed, bush-hammered, sandblasted or natural split. A polished surface is unacceptable outdoors: when wet or frozen it becomes dangerous.
• Anti-slip grooves: cuts or strips of rough finish along the tread nosing. Strips in a contrasting tone also mark the edge of the step, which matters for people with limited mobility.
• Inserts: rubber, metal or abrasive strips set in a groove near the nosing.
• Tread fall of 1–2% outwards, so that water does not stand and turn to ice.
• A canopy over the porch reduces the amount of snow and ice on the steps.
For indoor stairs honed and polished surfaces are acceptable, but at entrances and where moisture is possible (from footwear, by a pool) it is better to use matt finishes or anti-slip strips.
Thickness
Step thickness depends on the construction.
| Element | Approximate thickness |
|---|---|
| Tread on a concrete base (outdoors) | 30–50 mm |
| Tread on a concrete base (indoors) | 20–30 mm |
| Riser | 20–30 mm |
| Cantilevered step or step on stringers | from 40–60 mm, by calculation |
| Solid block step | equal to step height, 150–180 mm |
| Porch landing | 30–50 mm on a concrete slab |
The values are approximate. For cantilevered and self-supporting steps, thickness is determined by calculation based on the flexural strength of the stone, span and load. Flaming or bush-hammering removes a few millimetres of the surface, so the initial thickness is taken with a margin.
The overhang of the tread over the riser (nosing) is usually kept small, 20–30 mm; a large overhang on a thin slab can break off on impact.
Installation
Stone porch cladding is carried out on a concrete base.
1. Base. A concrete porch on its own foundation, separated from the house foundation by a movement joint; otherwise differential settlement will cause cracks. Beneath the base, a non-frost-susceptible bed and drainage.
2. Waterproofing of the base and drainage away from the building.
3. Layout. The stone is cut to measurements: treads, risers, landing, side cladding (strings) and the porch plinth. Measurements are taken after concreting to account for the actual geometry.
4. Installation on frost-resistant natural stone adhesive or on mortar with full bedding: voids under a slab lead to cracks. Risers first, then treads, from the bottom up.
5. Joints are filled with frost-resistant grout or flexible sealant; movement joints are retained.
6. Protection: water-repellent treatment for carbonate rocks and sandstone.
Installation at sub-zero temperatures without special measures is undesirable. TECHNOFORMA takes measurements with its own surveyors and provides layout and installation of natural stone; the cost is determined after a site inspection.
Care
Caring for stone steps:
• regularly sweep away sand and small stones, which act as an abrasive and scratch the surface;
• wash with water and pH-neutral stone cleaners; no acidic cleaners for marble, travertine and limestone;
• in winter, use plastic shovels and sand or granite chippings; salt de-icers destroy joints and carbonate stone and leave stains;
• renew the water-repellent impregnation on porous rocks as it loses effect;
• repair joints promptly: through a failed joint water gets under the slab and lifts it when it freezes;
• for indoor stairs, periodically restore the shine by honing and polishing.
It is worth inspecting the porch once a season: check for cracks, chipped nosings, voids under slabs (found by tapping) and failed sections of joints. A local repair, such as replacing one slab or regrouting a joint, costs far less than relaying the whole porch after several winters with water under the cladding.
If the steps have become slippery over time because the finish has worn, the surface can be renewed by re-flaming or bush-hammering on site, or anti-slip grooves can be cut.
Examples from TECHNOFORMA Projects
TECHNOFORMA carries out facade works with natural stone, glass fibre reinforced concrete (GFRC) and porcelain stoneware; the TECHNOFORMA projects section contains no separate case studies on porch cladding. Granite on a company project was used on the facade of the Dinastia club house in Kislovodsk: 700 m² together with porcelain stoneware and 6,000 m² of GFRC, with design and installation by the company. Stone for steps (granite, basalt, sandstone, dolomite, marble) is supplied from stock or to order.
If you also need stone inside the house, read the article “Natural stone in interiors”.
FAQ
Which stone is best for porch cladding?
Granite or basalt with a non-slip finish: they withstand frost, de-icers and constant foot traffic.
How thick should outdoor granite steps be?
A tread on a concrete base is usually 30–50 mm, a riser 20–30 mm. For cantilevered steps the thickness is determined by calculation.
Which finish should be chosen for granite steps?
Outdoors, flamed, bush-hammered or sandblasted; polished surfaces are used only indoors.
Can outdoor steps be made of marble?
In a warm climate and under a canopy, yes, but marble wears faster than granite and loses its polish outdoors.
Why do stone steps crack?
Most often because of voids under the slab, no movement joint between the porch and the house, frost penetrating the base, or water getting under the cladding through failed joints.