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June 1, 2017

Everything You Need to Know About Stone Anchoring for Your Building

Stone anchoring gives buildings a unique and contemporary look. But what is the science behind the aesthetics?

From office blocks to domestic homes, stone cladding is an increasingly popular way of finishing off the building to create an attractive and modern design that stands out from the crowd.

The choice of stone, and the way that it is anchored to the overall construction, will have a major impact on more than just the appearance, however. It will affect the overall performance of the building envelope and, of course, the costs in both construction and ongoing maintenance.

Here we take a look at some of the main considerations that need to be taken into account at the design and planning stage.

Type and size of stone

The basics of anchorage are equally applicable to both natural and cut stone. What makes a real difference, however, is the size of stone you are considering.

Smaller stones, such as those used on a domestic premises, are typically secured in place using simple veneer-type mortar bedded anchors. However, these are insufficient for the much larger stones that are used in major commercial builds, such as modern offices and public buildings.

For these, a system of anchor straps needs to be put in place at specific points, to handle the enormous load weight and stresses that are involved. The straps are manufactured from stainless steel, and four or more might be required for each stone.

In general, they will need a solid masonry system behind them to ensure they remain secure for years to come. Attaching to a stud frame might be possible under some circumstances, but is unlikely to be sufficiently robust, and can lead to problems in the medium to long term.

Designing the system

When working out the anchorage system, it is essential to distribute the load as evenly as possible. When stones are of a reasonable size and a uniform geometry, this is not too complex a matter, and four anchors are typically sufficient. Where you have larger stones, or those of unusual dimensions, it can be a worthwhile investment to conduct finite element analysis to understand the load distribution across each stone.

This gives a far more accurate picture of the physics involved in terms of the internal stresses. It is worth bearing in mind that just adding an extra anchor will not necessarily relieve the stress on the others, and could, in fact, lead to increased pressure points and exacerbate a point of weakness.

Types of anchor

The stainless steel anchors that are typically available are usually of 1/8” or 3/16” thickness and widths starting from 1”, all depending on the size of stone to be anchored. The most common design is to have a “split-tail” system, with tabs pointing up and down at each end to affix stones on either side of the joint. Alternative methods are to use dowel pins that hook into pre-drilled holes in the stone.

Built to last

Cladding provides an attractive look as well as an additional level of protection to any building. But make sure the science behind the anchoring is given the attention it deserves from the word go, for a finish that will stand the test of time and save you trouble and money in the long term.

To find out more about stone anchoring, talk to the experts here.