What You Should Know When Specifying Natural Stone;
Understand what the stone will look like.
Understand the appearance of a stone before specifying. Look at large samples, such as full size tiles, and ask about the potential variation. Select your slabs by going to the warehouse or at least ask for photographs.
Make sure the stone is suitable for your application.
Discuss your intended use with your Stone representative to confirm that you are specifying the right material for the application.
Consider budgeting constraints.
If the budget is a concern, understand the cost of the stone before specifying. If you need to reduce costs, tell us, and we will suggest less expensive alternatives.
Specify a maintenance program.
Since long term satisfaction of a stone floor is centered around maintenance, write a specification for floor maintenance. See our web site article regarding Stain Protection which describes our recommended maintenance chemicals.
Consider the issue of slip resistance.
This is a complex issue since the tests for slip resistance are unreliable, including the most popular test, ASTM C1028. In addition, in our opinion, natural stone cannot be accurately measured for slip resistance because there are hard spots and soft spots on each piece. Our best suggestion is that you consider the motto "a wet floor is a slippery floor".
Check the availability of the stone before specifying.
It is important to be aware of when the stone is going to be installed to make sure that what you are specifying will be available when needed. If the project is fast track and stone will be required within several weeks or sooner, check with us to confirm that the material is in stock or due to arrive within the required time. Then contact the owner or contractor, or whomever is buying the material, and encourage them to get an order placed within the necessary time frame.
For large projects or cut-to-size factory orders, check availability to determine when the stone must be ordered to arrive on schedule.
There can be a very large time difference, depending on several factors, so do not assume that you know the answer. Factors such as: time of year (most European factories are closed for the month of August), the factory's backlog, transit time and availability of good stone. Steamship sailing time to the east coast of the US is approximately two weeks from England and France, and around five weeks from China and India.
Be aware of elevation issues and how to solve them.
Interior projects, particularly alterations, often have issues that will restrict the thickness of the stone flooring. In these cases, you need to know the maximum thickness of the stone you can specify. If the existing floor is relatively flat and you can accept a thin-set installation, you can assume around a 1/4" thick adhesive bed, plus the thickness of the stone. Stone tiles will usually be between 3/8" and 5/8" thick, depending on the stone, finish and size.
While most 12"x12" tiles are 3/8", 16"x16" and 18"x18" will typically range from 3/8" to 5/8" in thickness. Larger tiles, from 24"x24" and up, are usually 3/4" thick and require a mud set installation with a bed of at least 3/4" of mortar. An exception to this is 24" x 24" Burlington Stone, which can be produced in 1/2" thickness. These tiles can be thin-set, bringing the elevation of the floor down as much as 1/2" to 5/8".
Basic Types of Stone
Textured Stone: Textured stone such as limestone or slate, tend to be hard and very durable which do not show foot abrasion in high traffic areas. They are also more water absorbent which also means that they stain more readily. Food and oil spills will leave a permanent stain! This type of stone also has a more uneven surface that allows dirt to stick, making cleanup and maintenance more difficult. In the case of textured stone the concern is not in protecting a polished surface but to protect against the infiltration of water, dirt, and stains. Once you have properly cleaned and achieved protection, maintenance is a breeze!
Polished Stone: Polished stone like marble, granite and limestone is so smooth and shiny that it is highly light reflective. Over time, these types of stone will show signs of abrasive wear from foot traffic. These wear patterns are very noticeable due to the loss of gloss units (luster) or the improper bonding of a protective coating. Tap water which contains chlorine, fluorine, purifiers and other minerals and salts will penetrate natural stone. Tap water and common cleaners are too harsh, they can discolor stone, grout and destroy the natural polish.