Tech Q&A

Q: Why are the 6mm brass strips turning darker in colour a short time after the completion of the final grinding of the terrazzo floor?

A: It is a well known fact in our industry that when brass strips are used and water is introduced in the grinding process a reaction takes place. Brass contains a high amount of copper. This metal is attracted to moisture and a chemical reaction takes place between the disbursement of the by-products of the matrix, aggregate, water and brass. This is only a temporary superficial condition. Given a bit of time for the trapped moisture to dissipate, this discolouration can be removed by the maintenance crew with their normal maintenance equipment.

Q: The owner of a commercial mall recently renovated a floor with a new 300mm x 300mm x 10mm tile inquired "if there is a tolerance for lippage" as a standard?

A: Lippage is a condition where edges of the tile are not at the same plane with each other. Over the years the Terrazzo, Tile and Marble Association of Canada has received many inquiries from architects, interior designers, engineers, owners, contractors and suppliers requesting information on what are acceptable industry standards. This resulted in many conflicts, because what may have been acceptable to the installer was not acceptable to the owner resulting in litigation or withholding payment to the sub-contractor. Consult the latest edition of the TTMAC Specification Guide 09300 Tile Installation Manual for clarification of the standard for lippage.

Lippage should not exceed 1 mm when setting square edge tile with narrow joints(3 mm or less). More lippage can be tolerated when wider grout joints are used or the tile doesn't have a square edge, but lippage should not exceed 1mm per 3 mm joint width.

Q: I am looking to redo the entrance and hallway of my home and would like to use marble. I am not sure as to which marble I should pick. I have been to many different stores and cannot differentiate between the qualities of the marbles. I see names like Bianco Carrara and Nero Assoluto but have no idea what the lettering following the name means. How do I know that I am getting the best material?

A: Unless you are a qualified expert in natural stone, one would not know if he/she are purchasing the best material suited for their intended purpose, therefore a reputable and knowledgeable supplier with a few years under his belt would be instrumental in advising the purchaser on the different types and qualities of marble. One of the most important criteria one should know and ask for would be the Abrasion Resistance or in other words the hardness of the stone which is an important factor for wearing qualities subject to foot traffic. The harder the stone, the more abuse it will take. So when purchasing marble for your entrance hallway and any other area of your house do not forget to ask the salesperson if the marble has a hardness of HA10 or more.

Q: We are in the middle of renovating my condominium and would like to tile the kitchen and hallway floors. I have been advised by the property manager that if I choose a hard surface type floor that I need to ensure that there is adequate sound proofing. I understand what sound-proofing is, but how do I make sure that I am using the proper material before I have tile installed?

A: There are a number of products on the market that are promoted and used to alleviate and control sound transmission in floors especially in high rise residential buildings where structural concrete slabs between floors are 1500 mm+ in thickness and sound can be transmitted through to the floor below. Materials such as cork, fibre matting or rubber matting are being used as a sound control underlayment to which hard surface materials such as tile, marble, granite, slate and limestone could be installed. However, some of these materials are limited in their contribution to the total sound rating to which it should be achieved and therefore those systems should be evaluated and examined on their merits. In addition to the sound performance of these products, one should also be aware of their support stability since cork and fibre mats are somewhat compressible and may not sustain the required support. Manufacturers recommendations must be followed. If cork is to be used for sound control the Tile Council of North American (TCNA) Handbook for Ceramic Tile Installation 41st Edition, Detail F 135-03 calls for 13mm thick cork underlayment sheets, having a density of between 11.8 and 13.6 lbs per cubic foot. Regardless of which product or installation system used, a sound rating of 50 STC (Sound Transmission Class) and 50 IIC (Impact Insulation Class) is the minimum rating required.

Q: An automotive parts client of mine is considering a number of options with regards to floor finishes in the lunchroom cafeteria area. I would prefer to use tile over other products because of its durability. However, I am concerned that oil and grease will be tracked into this area from the plant. What type of tile would give me the slip resistance to deal with the grease and oil and at the same time not absorb anything that is being tracked in?

A: If tile is the preferred choice for your automotive business I would suggest using a high quality tile with a textured surface as this will increase the coefficient of friction (Slip Resistance) above the 0.5 requirements for a safe walking floor. In addition, it will also greatly increase the stain resistance due to the body density, imperviousness and the vitrification of the tile, in other words use a porcelain tile. Low porosity unglazed porcelain tile is the material with the best characteristics with regards to the ease of cleaning and maintenance. Porcelain tile has a smooth, compact impermeable, chemically inert surface that can take aggressive cleaning if required. Since your main concerns are with staining and slip resistance, I would suggest to use an epoxy grout in lieu of cementitious based grouts, in addition a silicone based penetrating sealer can be applied to the tile for added protection, ease of maintenance and increased slip resistance capabilities. As ease maintenance, hygienic conditions and the abrasion resistance are in general better due to the greater compactness and impermeability of the surface, it can only be fair to say that porcelain is the tile that will have the best performance for your needs.
Q: Why do I need to pay particular attention when installing green marbles? Are there any other stones that react in a similar way?

A: Certain marbles, such as Ross Levanto, green marbles, some green slate and agglomerate are notorious for warping and curling when installed with bond coats that contain water. These materials generally have to be installed with solid epoxy mortar or at the very least with a rapid set latex based bond coat. The reason why these stones warp is somewhat of a puzzle. It is believed that water fills the pores of the stone and when it evaporates the orientation of the stone crystal changes and cause it to warp. Regardless of the true reason, one this is certain green marble can warp when installed with bond coats that contain water.

Q: Is it recommended that I seal my floor and are there any downsides by doing this?

A: Sealing depends on the location of the installation and the type of tile. If the installation is exterior and subjected to seasonal conditions it is not a good idea to seal the tile as any topical sealer that is applied whether it is a solvent base or rater base, will only last for a very short time due to adverse weather conditions. Impregnators and penetrating sealers are more appropriate for exterior use as they do not require constant attention to maintain the quality of the finish and are unaffected by outside elements. The sealing of interior tile installations is the choice of the owners. If a high gloss appearance is desired, a topical sealer can be applied followed by an application of polymer floor wax and then buffed. The application of sealer should only be applied to unglazed ceramic and absorptive tile. Sealers, unless recommended by the tile manufacturer are generally not used on non-absorptive surfaces such as porcelain or glazed tile but may be used to protect the grout joints from staining. The downside to sealing is the decrease in the coefficient of friction/slip resistance (COF) of the floor and an increase in the cost of maintenance due to stripping and reapplication of sealers.

Q: We have just had a granite kitchen counter-top installed in our home. There seems to be some conflicting opinions as to whether or not this should be sealed. One of the concerns that we have is that if we use a sealer, can this contaminate our food?

A: Granite is a natural stone and therefore does not have the ability to absorb. The type of granite you have selected will determine the natural rate of absorption. It is highly recommended that you seal the granite to help prevent staining that can occur in a kitchen. Beet juice, mustard and cooking oils can have a very detrimental effect on the countertop. Sealing of the granite however, does not preclude you from cleaning up the spills that contribute to staining. The sealer simply acts as a barrier to reduce the ability of the stain to penetrate the stone. With regards to the possibility of the sealer contaminating your food, this is highly unlikely. In selecting the appropriate sealer for the application you should insist on a penetrating sealer. Penetrating sealers work in the pores of the stone and not directly at the surface and therefore do not come in direct contact with the food itself. I am sure that much time and consideration was taken in selecting the type of granite that you have had installed on your countertop and I am quite confident that you would like the materials appearance to look as good in 10 years as it did the day it was installed. Therefore, seal the stone and enjoy the beauty and durability of a granite countertop.

Q: We are in the process of specifying slate for a commercial building lobby and a facing at the exterior entry. We have reviewed quite a number of materials and although we are really drawn to some colours we are concerned with the apparent "shaling" of some of the samples.

A: Slate can be a very tricky material for exterior applications. There has been an onslaught of slates entering the market; some perform well in exterior applications and others do not. Depending on the height of the exterior installation, the use of mechanical anchors may be required by the local building code. Always consult the supplier of the potential stone and procure test data that itemizes the materials water absorption, flexural strength, etc. This data will greatly assist you in making a better decision. A common rule of thumb however is to take a look at the side of the material and check for voids in the lines of separation. If there are voids, moisture can enter and fill these pockets and later freeze causing the material to flake and fall right off the wall. If you are not sure about the material and the data you have received, contact the TTMAC office and we will provide you with technical assistance.