How To Grout Your Cast Stone Mantel and Range Hood
This grouting video can be used by homeowners, masons and other installers.
Please review our installation video before getting started.
Normally the only stones needing a bed of grout are the hearth stones. Any regular grout mix can be used since it is not visible. Once the hearth is level, set and dry, the entire mantel can be laid up dry, on 1/4″ spacers, anchoring each stone to a stud as you go up. L-brackets or brick ties can be used for anchoring. L-brackets are preferred since they are more rigid. It is also recommended that the mantel be set 1/4″ off the wall and a grout joint be placed between the mantel and the wall. This is good masonry practice and helps compensate for any variances in the wall.
Included with your mantel is a bag of sand which is color-matched to the stone. This is for mixing the finish out grout only. You may use either white Portland cement (never use gray cement) or white sandless mortar mix. The ratio should be the standard 3 parts sand to 1 part cement or mortar mix. If using white Portland cement, a little lime added will increase the adhesion and plasticity of the mortar.
A grout bag may be used as a method of injecting the grout into the joints. If using our “Buff” sand, you should sift the larger aggregate out to prevent plugging the tip on the grout bag. Once dry, the joints will appear slightly lighter than the stone. After acid-washing the entire mantel the color will mellow. Be careful to keep excess grout off the surface of the stones since that can leach into the stone causing a permanent white discoloration. That is why we strongly recommend taping the edges of the joints with blue masking tape before handling or grouting. This also helps prevent damage to the edge of the stones during handling or setting.
Alternate grouting method using water
As an alternative to taping of the grout joints, you may use a 5-gallon garden sprayer to saturate the stones. You can not wet the stone too much. The stone will soak up the water like a sponge. Once the water begins to roll down the surface of the stone proceed to other surface areas until the entire stone is saturated. Once this has been done, go back over the entire surface area to ensure the stone has completely soaked up as much moisture as possible.
As long as the stones are completely saturated no taping is required. It is not possible for the mortar to discolor the joints as long as the surface of the stones are saturated.
You must continue the grouting process immediately. You can not saturate the stone and then come back later to complete the grouting process. Then as you grout, it is important that you have a couple of clean sponges to keep the surface of the stone clean from all grout.
Continue to dip the sponges in a bucket of water to keep the sponges clean. It is important to continually empty the bucket and replace with clean water throughout this process.