Subframe for natural stone

Subframe for natural stone

Natural stone is the heaviest cladding in the catalogue and the most prestigious. Granite, marble, limestone and travertine are chosen for banks, ministries, hotels and landmark residential buildings. The subframe must carry loads of up to around 100 kg/m2, and be designed so that a failure of one anchor never results in a fallen slab.

System

Stone slabs, commonly 20 to 30 mm thick, are fixed with stainless steel anchors set into edge kerfs or undercut holes, or with clips. The anchors engage aluminium rails or horizontal profiles, which are carried by heavy brackets at close spacing. Each slab usually has four supports, with two taking the weight and two restraining movement.

Stone choice

Check strength, water absorption, frost resistance and flexural strength in tests. Some stones, such as certain marbles, stain or weaken outdoors, so choose according to the climate: Batumi's humidity and Tbilisi's heat need different consideration. Low-absorption granites and dense limestones perform most reliably.

Design points

• Natural stone is often used on plinths and lower floors, with lighter imitations or panels above, which reduces load and cost.
• Anchors, brackets and rails are calculated for dead load, wind and seismic action. Tbilisi lies in a seismic region, so a fallen-stone risk is evaluated carefully.
• Allow the stone to move with joints sized for the slab length.
• Keep stainless fixings away from aluminium contact with isolation.
• Adopt tolerances for stone cutting and plan each slab on a drawing.
• Stone is non-combustible, but above 12 m the facade as a whole is reviewed under Chapter 14 of the Building Safety Rules in Georgia.

Pricing is on request. Send us your elevations and we will prepare a stone layout and a subframe calculation.

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