How to Add Stone to a Foundation Wall

A foundation wall is usually made from solid concrete or concrete blocks. The concrete enhances rigidity and helps maintain a solid foundation that can withstand the test of time. However, both solid concrete and concrete blocks are usually bland and unappealing in appearance. To make the foundation wall aesthetically attractive, adding decorative stones can do the trick.

Tools and Materials Needed:

  • Scrub brush
  • Muriatic acid
  • Brick sand
  • Type S mortar
  • Wheelbarrow
  • Mason’s trowel
  • Grout bag or pointing trowel
  • Hand gloves
  • Stone veneer or decorative stones 
  • Wire brush

Step 1 – Prepare the Foundation Wall

Clean the foundation wall by using muriatic acid and a scrub brush. The muriatic acid will both clean and purify the surface of the foundation wall. This will enable the stones and mortar mix to firmly stick to the surface of the wall. Using the scrub brush will tend to leave small etch marks on the surface, which will further help the mortar to bond with the surface of the wall. In the case of painted walls, it would be best to remove the paint first by using a pressurized washer or commercially available paint stripper. After all the paint has been removed, use muriatic acid and a scrub brush to take off further residue.

Step 2 – Prepare the Mortar Mixture

Mix Type S mortar with brick sand and water in the wheelbarrow. Thoroughly mix the mortar until a toothpaste consistency is achieved. Remember to keep the consistency of the mixture balanced; a mixture that is too thin might slide off the wall upon application. A mixture that is too thick, on the other hand, might fall off the wall. The consistency can be kept balanced by adding more mortar or water as needed.

Step 3 – Prepare the Stones

Put an adequate amount of mortar mix at the back of each stone. A mason’s trowel can be used to do this. The stones may be of different sizes, but they will mostly be flat. Once all stones have been applied with mortar, press them firmly one by one on the foundation wall, starting at the bottom portion. It is during this process that the artistic side of your personality will come into play. The stones will resemble a puzzle with 1/8-inch spaces or joints in between them. Do not worry about the spaces. Just try to cover the wall with the stones as much as possible. Leave the stones for at least 24 hours to allow them to set.

Step 4 – Fill the Joints with Mortar

Fill each of the spaces or joints with mortar. Mix about half a bag of type S mortar with eight to ten shovels of sand and 2 ½ to 3 gallons of water. The consistency of the mortar mix needs to be a bit sandy for easy application. When deciding to use a grout bag, fill the bag with the mortar mix and use this to fill the joints in the wall. You may also use a pointing trowel to push the mixture between the joints. Let the mortar set for 20 to 30 minutes before using a wire brush to remove excess mortar between the joints. You may also clean the stones by using a damp sponge.

Let the foundation wall set for at least 24 hours for maximum adhesion. You may then clean the wall with detergent and water after it has fully cured. The entire process of adding stone to the foundation wall may take at least two or three days to complete, but it is relatively easy even for an average DIY person.