Sandstone for Facades and Plinths

Facade sandstone is a natural cladding stone made of cemented sand grains, most often quartz. It copes well with outdoor conditions, has a pleasant matt texture and a warm palette, from grey and greenish to yellow, red and brown.

The key criterion when choosing sandstone is the type of cement binding the grains: siliceous sandstone is dense and frost-resistant, while clayey and calcareous types are softer and absorb more water. This determines whether the stone is suitable for a plinth or only for walls above splash level.

Sandstone is chosen for cladding private houses, plinths, fences and landscaping, as well as for facades of public buildings where a natural material of moderate weight is needed. Other rocks are described in the section Natural stone for facades and interiors.

Sandstone is classified by several features, and all of them matter for facade cladding.

By grain composition:

• quartz sandstone: more than 90% quartz, the strongest and most wear-resistant;

• arkose: containing feldspars, often in pinkish tones;

• greywacke: with fragments of other rocks, dark, grey-green.

By cement: siliceous (the densest), ferruginous (red-brown, strong), calcareous (reacts with acids), clayey (soft, sensitive to water). Siliceous and ferruginous varieties are suitable for facade and especially plinth cladding.

By product form:

• sawn tiles of calibrated thickness, for even sandstone cladding with thin joints;

• tumbled tiles with rounded edges;

• rock-faced (split) stone with a textured surface;

• flagstone: natural irregular slabs, mostly for plinths, fences and paths.

Dagestan sandstone for facade cladding is a common option in southern Russia: yellow and beige tones and good workability. As with any stone, batch characteristics should be checked against the test report.

Typical sandstone characteristics are given below. The ranges are wide, depending on the deposit and cement type; exact values are stated in the product data sheet or test report.

Sandstone does not burn, is vapour-permeable, UV-resistant and does not fade. Quartz varieties hardly react with acids, which sets them apart favourably from limestone and marble. The rough surface is not slippery even when wet, so sandstone is suitable for steps and paths.

Weaknesses: porous grades absorb water and dirt, develop efflorescence and biological growth, and with poor cement the surface may flake.

On a facade sandstone is used in several zones:

• Walls. Full cladding or accent areas: corners, piers, bay windows. Small and medium-format slabs on adhesive or large slabs on a rainscreen system.

• Plinth. One of the main applications thanks to its resistance to abrasion and splashes. Dense grades with low water absorption are used for plinths.

• Surrounds. Reveals, window sills, string courses, cornices.

• Fences and pillars. Flagstone or sawn stone on a brick or concrete base.

• Landscaping. Paths, steps, retaining walls, kerbs.

Indoors sandstone is used for lobby walls, fireplaces and staircases. For cladding a small house, adhesive-fixed tiles are usually chosen; multi-storey buildings and large slabs require a ventilated rainscreen system with calculated fixings.

Sandstone combines well with wood, render, glass fibre reinforced concrete (GFRC) decoration and metal: its matt surface is neutral and does not compete with other materials.

The sandstone installation method depends on the building height and stone format.

Adhesive fixing is used for tiles up to 30–40 mm on brick, concrete and rendered substrates:

1. substrate preparation: strength, flatness, priming;

2. laying out the stone on site, matching by tone and texture;

3. installation from bottom to top on frost-resistant natural stone adhesive with full back coverage;

4. for large formats, additional mechanical fixing;

5. pointing the joints with vapour-permeable grout;

6. cleaning and water-repellent treatment.

A ventilated rainscreen facade is used at height, on insulated walls and for large slabs. The stone is fixed to a metal substructure with clips or concealed anchors; slab thickness, bracket spacing and fixings are selected by calculation for wind load and cladding weight. A ventilated gap between the stone and the insulation carries moisture out of the wall.

TECHNOFORMA carries out both systems: design, insulation, installation of ventilated rainscreen facade substructures and natural stone cladding by its own installation team of more than 100 specialists. The cost is determined after a site inspection.

Even dense sandstone benefits from protection:

• Water-repellent treatment with penetrating siloxane products reduces water absorption, soiling and the risk of efflorescence while keeping vapour permeability. Treatment is repeated as the water-repellent effect wears off.

• Biocidal treatments are applied on north-facing walls and in shade, where moss and algae appear.

• A waterproofing barrier between the foundation and the plinth cladding prevents the stone from absorbing ground moisture.

• Sills and an apron sloping away from the wall protect the bottom course from run-off and splashes.

Film-forming varnishes are undesirable on facade sandstone: they impair vapour permeability and peel over time. For cleaning, low-pressure water and neutral products are used; abrasive high-pressure washing damages the surface of soft grades.

Sandstone is part of the TECHNOFORMA natural stone range. The company’s equipment processes soft rocks, including sandstone, and hard rocks such as granite and basalt, so slabs can be made to the layout of a specific facade. The stone is held in stock in the Moscow region, and supply to order is also possible.

An example of a facade where natural stone is combined with other materials is the Dinastia club house in Kislovodsk: 700 m² of granite, 700 m² of porcelain stoneware and 6,000 m² of GFRC, with design and installation by the company. Other work is in the TECHNOFORMA projects section. If you are considering a more striking but more demanding rock, read “Marble on the facade: where it fits and how it behaves”.