Marble slabs are used for flooring, stairs, facing, table tops, etc. and marble tiles are used in floors, dados and skirtings, etc. Marble blocks are either used for monuments or for further converting to slabs or tiles. In this article we will discuss Installation procedure for Marble stone.
STEP ONE: PREPARING THE SUBFLOOR
- Marble Tile
- Cement Board
- 1 1/4” cement board screws
- Line Chalk
- Notched Trowel
- Tape Measure
- T Square
- Tile Spacers
- 2X4 Wood
- Rubber Mallet
- Marble Sealer
- Grout Float
- Foam Brush
- Work Gloves
- Wet Saw (Or custom cut pieces)
You want to make sure that the subfloor is completely flat and free of divots, defects, or bumps. Raised areas may need to be sanded down and dips may need to be repaired with filler. Getting the subfloor perfectly smooth is vital to the integrity of the entire floor installation, because any gap between surfaces will be a weak point that can lead to damage. Before you can lay marble tile, you need to install cement board. Thin set mortar can be spread directly on a plywood subfloor with a notched trowel. The cement board sheets are placed one at a time, and are fastened using 1 1/4” screws.
STEP TWO: DRAW THE REFERENCE LINE
You want the marble tiles that you install to radiate outwards from the centre of the room, rather than starting abruptly from one of the walls. In order to achieve this effect you need to draw a reference line on the surface of the underlayment. Find the centre of two opposing walls and use a line chalk to draw a path in between them. Then measure to the centre of that line, and use a T square to make an intersecting chalk path to the other two opposite walls. This gives you the centre of the room while also dividing it into 4 neat quadrants.
STEP THREE: MIX AND SPREAD THE MORTAR
Mix thin set mortar according to the manufacturers instructions. Only mix a little bit at a time, and make more when necessary. Using a notched trowel, begin to spread the adhesive onto the floor, starting at one of the corners where your reference lines intersect in the centre of the room. As you work, use the notched edge of the trowel to create grooves in the mortar. This will increase the adhesive strength of the bond with the bottom of the marble. On marble tiles that are 12” square in size or smaller a 1/4” notched trowel will create large enough grooves. However if you have much larger tiles, or if you are using irregular tumbled or natural cleft materials, then you will want to use a 1/2” notched trowel to create larger , deeper grooves in the adhesive.
STEP FOUR: SETTING THE MARBLE TILES
Spread enough mortar to easily cover the bottom of a single tile, and make sure that its entire surface is notched. Then take the first tile and gently press it into place, being careful to line its corner up with the point where the two chalk lines intersect. As you press it down, twist the tile slightly in order to ensure that it properly sets in the mortar bed below.
STEP FIVE: THE RUBBER MALLET
A rubber mallet is a large hammer that is made with a soft rubber head. This can be used to lightly tap the surface of the marble tile, in order to press it more firmly into the mortar. However you want to be careful not to tap too hard, as marble is a relatively soft material, and it can crack rather easily. You also want to avoid moving the tile as you are setting it.
STEP SIX: MARBLE TILE SPACERS
Continue to work, spreading enough mortar for one tile, then placing it, before moving on to the next one. Follow the reference line towards the wall, using it as a guide to keep your placement straight. The use of tile spacers between each piece will help you to keep grout lines sharp and consistent as well. Once you reach the wall take note of any gaps that may require custom cut pieces. Then move back to the reference line, and continue to place tiles adjacent to the first row. Take a moment after every few tiles to ensure that all of your lines meet up, and the entire floor looks sharp and consistent. As you work be aware that it is inadvisable to step on a marble floor tile for at least 48 hours after installation. Because of this you have to be careful not to tile yourself into a corner that you can not escape from. Work on the quadrant that has the door last, and as you set tiles make sure that you leave rows open for yourself to escape through.
STEP SEVEN: CONSISTENT FLOOR TILE HEIGHT
Once you get three or more tiles in place next to one another, you can use a 2×4 to ensure that they all have an even height set into the mortar. Place the wood on the floor, stretching across the tiles. If the marble is polished you may want to cover the front of the wood with a piece of carpet to prevent scratches. Just ensure that the surface remains flat and consistent. Then, lightly tap the middle of the wooden plank with a rubber mallet. As it goes down both sides will also go down, ensuring that all of the tiles have a consistent level. This can be done across multiple rows as you work.
STEP EIGHT: CUSTOM CUTTING TILE PIECES
In most marble flooring installations you will need custom cut pieces in order to stretch the floor out to meet the walls. You will also need to fit tiles around architectural features in the room, as well as permanent appliances and equipment. The way to do this is with the use of a wet saw. A small wet saw will cost around $100 dollars, and will be able to handle basic straight cuts on 12” tiles or smaller. Larger commercial saws are also available which can cut much larger, thicker materials. In some cases you may be able to rent a wet saw for the day from a local hardware store. A wet saw works by spraying water on the material, as you run it through a spinning table saw blade. The water helps to keep the blade cool and the cuts smooth as it moves through the marble. With a basic wet saw you will only be able to make straight cuts, slicing tiles into smaller squares or rectangles. There are also pieces available that can assist in the cutting of diagonal triangle shaped pieces. Marble is a very delicate material and you have to move very slowly as you cut each piece. It is very easy to end up cracking, damaging, or completely shattering a tile that you are trying to make a tiny cut on. For this reason some people prefer to measure the floor and purchase materials already cut up by the supplier. This is especially true if you need round or angled pieces cut into the material.
STEP NINE: REMOVE EXCESS MORTAR
You want to use enough mortar so that you can create notches in it with the trowel, without seeing bare cement board. You then want to set the tile with enough force that it collapses those gaps, but not so much that it forces the mortar up through the grout lines. If excess adhesive does spew up through the cracks it needs to be removed using a paint stick or a utility knife. You need to wait for the mortar to dry completely before moving on. Follow the manufacturer’s recommendations on this, although the process can sometimes take as long as 48 hours. During that time nobody should be allowed to walk on the floor, or you will risk moving or depressing a tile.
STEP TEN: SEALING THE MARBLE
Marble may seem like it is a very hard, solid material. It is rock after all. But in actuality marble is a very delicate flooring material that needs to be taken care of. Not only is it prone to cracking and chipping, but it is also very porous, and many materials can penetrate the surface of the stone causing permanent stains. That is why the next step you take has to be properly sealing the surface of the floor with a high quality marble surface sealing agent. It is important to do this before you grout the floor, because the grout mix will slop around the grooves to some extent, and can end up causing stains in the marble. That is why you want to ensure that the material is protected before moving on, despite the fact that you will have to seal the grout lines as well at a later time.
STEP ELEVEN: GROUTING A MARBLE FLOOR
When mixing grout make sure that you follow all of the manufacturer’s recommendations. As with the mortar you only want to mix enough for about 15-20 minutes worth of work, as any longer and the mix will start to dry out and harden. The grout can be applied to the joints using a grout float. Try to direct as much of the mix into the grooves as possible, and wipe up any excess that gets on the tiles.
STEP TWELVE: WIPING THE TILES CLEAN
Use a large sponge that is slightly damp to gently wipe the surface of the marble tiles clean of any excess grout. As you work be careful not to allow any moisture to seep down into the grout lines, as this can cause the mix to become muddy and washed out. You also do not want to inadvertently swipe some of the grout mix out as you work with the sponge. Allow the grout to dry for at least 4 hours.
STEP THIRTEEN: SEALING MARBLE GROUT LINES
Once the grout feels completely dry to the touch you want to seal the entire floor again. Even though you already sealed the tiles, the grout lines are also susceptible to stains and moisture penetration, and so they need a protective surface coat as well. It is also a good idea to seal a marble floor several times after installation, waiting for each successive coat to dry before applying a new one. This will create a strong protective layer over the surface of the material. If you have polished marble then you want to use a very thin coat of seal, applied with a foam brush. Smooth away any puddles or tiny bubbles that appear in the surface, as they can dry into permanent features. The surface of tumbled and honed marble will be more forgiving, but the same rules apply there as well. You will need to reapply this sealant to the marble every 6-12 months depending on how much traffic the room gets.