Selecting the correct stone

Stone Federation explores a range of points including the latest CE Marking legislation that affords architects with the information they need to ensure that the right material is chosen for the right application

The process of selecting the correct stone starts before you even begin to look at samples. The first, and perhaps most crucial step is to get the natural stone professional involved in the process at the earliest opportunity. By involving them from the design stages, you will avoid wasting time by selecting the wrong stone for the desired application. Websites list natural stone professionals, all of whom are vetted and approved Stone Federation members, and are therefore the ideal place to start.

Once the natural stone professional is involved you can begin to look at the samples. The first step is to ensure that your samples are up to the task in hand – namely giving you a true representation of what the final product will look like. One key factor in this is looking at range/control samples. These will show the range of geological characteristics typically found within the bed of stone as opposed to the small snapshot you would find in a single indicative sample piece. This helps avoid any confusion as to what the end product will look like. However, it is worth bearing in mind that this is a natural product, and therefore each stone will have its own unique features.

Step two is tied into the first, and this is to visit the quarry or mine itself. Stone Federation strongly advises that a visit is made so that the stone proposed for the project can be carefully inspected. This is also the ideal stage to involve an independent stone consultant to come and provide you with an expert opinion. Many of our quarrying members host quarry open days where architects can see not just the stone samples, but also get a look inside the process of quarrying itself; these always prove to be both informative and highly enjoyable occasions. The visits provide an opportunity to examine the stone faces and the stock, and to familiarise yourself with the geological variations between the different beds or types of stone.

The third and final step is the technical assessment of the stone. All natural stones will weather, but it important to make an initial assessment of the stone’s technical properties before it is added to the project short list. There are various tests that help build a picture of stone’s potential suitability for a particular application and whilst past projects are a good indicator, recent test data should be examined.

A relatively recent piece of government legislation has gone a long way to making this stage of stone selection even clearer. The 2013 CE Marking legislation requires each stone to be labelled in accordance with BS EN 12400 Natural Stone – Denomination Criteria, meaning each stone should have the traditional name, quarry location, country of origin and petrological family declared, together with a sample reference number. All stones should also have, available to view at the sample stage, a Declaration of Performance (DoP) and CE Certificate that will help you ascertain which stones are fit for the desired application.

To summarise, when looking to select natural stone for a project there are four key considerations you should make. Firstly, ensure that you involve your natural stone professional at the earliest opportunity, next make sure you know what to look for in a sample, thirdly, try and arrange a visit to the quarry or mine and finally ensure that the stone’s technical assessments are in order and comply with the latest CE Marking legislation.

By following these simple steps, you help make the process from design through to project completion a much smoother journey.