How to Mortar Re-Point
Brick is one of the most commonly used façade materials for homes because of its ease of maintenance and timeless beauty. Bricks are durable, but a brick façade does have one weakness: the mortar that holds the bricks together. The only thing you really have to do for brick façades to maintain them and that is to repair cracked or eroded mortar. If you don't repair cracked mortar, your walls could fall apart due to water damage. Repairing mortar, also called re-pointing mortar, doesn't take a lot of skill, but does take a lot of work and patience, so you can do it yourself. Keep your brick sharp by following these step-by-step instructions on how to repair damaged mortar:
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Step #1: Break out the old mortar.
Start by breaking out the old mortar with a hammer and cold chisel. Remove the mortar until you reach solid base for bonding the new mortar. If you encounter mortar that is so soft the bricks are loose, you may have to remove and reset the bricks.
If the cracked mortar is hard to chisel out, use an angle grinder with a diamond blade to make a relief cut down the center of the mortar then use the chisel and gently chip out the mortar in contact with the brick. Only use an angle grinder to make relief cuts in the mortar as it will also cut through brick if you get too close. Always cut the vertical joints first then the horizontal joints.
Once the cracked mortar is removed, clean and dust out the joints. Wet the joints lightly to prepare them to receive the new mortar.
Step #2: Mix the new mortar.
Follow the manufacturers instructions for mixing your new mortar, but when it is finished it should be a paste about the consistency of peanut butter that will stick to an over-turned trowel, but not crumble. Give the mortar ten minutes to rest and absorb the water before you start using it. If a mix doesn't turn out right, don't try to add water to make it usable, simply mix a fresh batch instead.
Step #3: Fill the joints.
If the weather is hot, work in shaded areas first and mix small batches of mortar so it doesn't become unusable by drying to quickly in the heat. Don't try to re-point mortar when the temperature is below 40 degrees F. Use the mortar you have mixed and re-pointing tools to pack the joints tightly. You don't want any air bubbles or voids when the mortar dries or you'll be doing the same thing again soon. If you are resetting brick, lay a mortar bed own first, then pack the vertical joints. If the joint is greater than _ inch deep, fill them in two layers allowing the first layer to partially dry before you add the second layer.
Step #4: Joint matching.
The last step is to use a mortar finishing tool to match your new mortar joints to your old joints. Allow the mortar to cure enough that you barely leave a thumbprint when you press the mortar before you finish the joints. There are four common joint profiles so be sure to get the tool that fits your old joint profile before you re-point your mortar. The common joint profiles are raked (mortar is removed ¼ inch deep with a raking block), V-joint (formed by the pointed end of a brick jointer, looks like a concave V), flush joint (formed by cutting off the edge of your mortar with a trowel so it is flush with your wall), and concave joint (formed with the curved end of a brick jointer, most common joint).
