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How to Lay Limestone on Porch Steps

Tim Daniel

Limestone, a sedimentary rock formed by prehistoric geological pressure, consists of a mixture of minerals fossils compressed and joined in a multi-million-year natural phenomenon. The use of limestone dates back thousands of years.

The Great Pyramid of Giza, Egypt, was constructed entirely of limetone.

The ancient Egyptians, for example, constructed the Great Pyramid of Giza entirely of limestone. Todays do-it-yourselfer may not be able to match the Egyptian efforts of centuries past, but the variety of beautiful materials available today still gives the homeowner the opportunity to build something amazing.

Starting out, installing the Treads

  1. Consult a professional for advice on material selection. Limestone may be slippery in wet exterior situations. Visit a local building supply center or tile supplier to determine the applicable size, surface finish, and color of limestone for the project. Limestone comes in a variety of shapes and sizes, so select a material that best conforms to your steps. For example, select a 12-inch limestone if the tread (or horizontal surface) of the steps is 12 inches wide or less. Making a selection that closely matches the dimensions of the steps avoids excess cutting and elbow grease.

  2. Clean the steps thoroughly. Use a hammer and cold chisel to remove any high spots of concrete. Sweep the steps, apply a sponge with clean water to stubborn dirt and grime areas. Use a pressure washer to wash away the most stubborn sediment. Allow the area to dry completely before proceeding.

  3. Measure the steps, starting at the middle step. Find the middle of the middle step, and mark it with a construction pencil. Measure the "riser" or vertical piece above the "tread" or horizontal step piece, and mark the center. Measure and mark the center for the the steps farthest from the center, both top and bottom, and connect the points by snapping a chalk line. Use a pencil to connect the center lines, and start installation at the center line of the center step.

  4. Measure the limestone tread step piece that needs to be cut. Mark with a construction pencil in a straight line, and verify that the tread piece has enough 'overhang" or space to allow for the limestone riser piece. Cut the piece with a wet tile saw and "dry-fit," testing the piece for correct sizing. Continue cutting the tread pieces for the middle step area. Proceed to the remaining steps, and follow the same steps until you have cut every necessary tread piece.

  5. Install the tread pieces. Start at either the top or bottom to avoid being worked into a corner. Start at the center line. Mix acrylic-modified thin-set in a bucket to a medium consistency, following manufacturer directions. Use a notched trowel to apply the thin-set to the first piece, and a thin coating to the immediate installation area. Avoid applying too much. Level the first piece, tap in with a rubber mallet,and allow enough overhang for the riser piece. Continue the same process to finish the first step, and then proceed to the next steps. Use an applicable tile spacer to separate the pieces, allowing for a grout joint. Verify that the height between the first course of steps and the second course is within the code restrictions of your area. Allow 24 hours for the treads to dry before proceeding to the riser pieces.

Installing the Risers, Finishing up

  1. Start at any of the step center points, measure your first riser piece to cut and mark a straight line with a construction pencil. Cut with a wet tile saw and dry-fit to ensure correct sizing. Measure the front or "face" of the riser piece to the front edge of the tread piece. Use this measurement as a measuring guide and stick to this number as you proceed.

  2. Mix acrylic-modified thin-set in a bucket to a fairly stiff consistency, apply the thin-set to the back of the piece with a notched trowel, and apply a thin coating to the immediate installation area. Line up the riser pieces with the tread pieces, and continue installing until the riser pieces are finished. Wait 24 hours before proceeding to the final steps.

  3. Clean the limestone of any excess thin-set or sediment, remove tile spacers and sweep the area clean. Mix a matching grout color in a bucket to a medium consistency, following manufacturer directions. Apply the grout with a grout float to the grout joint only. Avoid applying excess grout to the surface of the limestone. Allow time for the grout to dry before cleaning with a clean sponge and water. Rinse the sponge of grout, and use clean water to provide a final wash. Use a clean, dry rag to clean grout "haze" or dust from the surface when the grout has completely dried. Wait 24 hours before proceeding to the final step.

  4. Verify that the limestone steps are free of sediment, dust and dirt. Clean the surface a final time, if necessary. Use a clean rag or dry sponge to apply a tile/stone sealant. Allow the sealer to penetrate the surface of the stone and the grout, and allow time to dry. Repeat the application of sealer until the limestone stops absorbing it.

  5. Warning

    In order to pass building code, limestone steps may not exceed a certain variation in height and length between the steps. Check resources below for the local building code in your area.