Introduction on How to Tuckpoint Mortar Joints

Introduction Fortunately the need to repair a mortar joint is more common than having to replace a brick.
The mortar joint plays a significant role in the structure and structural integrity of the wall. It holds the bricks together, it bears the compressive weight of the wall just as the bricks, and it keeps water out of the wall. It is also the weak link in the brick wall system because if water is allowed to get past the mortar and into the wall, brick failure may occur such as cracking or popping (spalling).
The process of repairing a mortar joint is called tuckpointing. 
This term is derived because you are tucking mortar into the
damaged mortar joint with the point of a trowel called a "pointing trowel" (original isn't it?). This repair isn't too difficult but takes a little patience and finesse. Often one of the biggest challenges with this repair is getting the repaired mortar joint to blend in with the surrounding mortar. Let's see how this repair is performed:
Difficulty Level
Average

Needed Tools and Materials
Cold Chisel Heavy Hammer Stiff Bristled Brush Mortar Hawk (or overturned brick trowel or flat 8"x12" plywood with a 6" long 2x2 fastened perpendicular to its underside as a gripping handle) Joint Strike Mortar Mix and Pigment (if needed to match existing mortar) Eye Protection Leather Work Gloves

The first step in repairing the mortar joint is to clean out all loose and adjacent mortar in the area to be repaired. There are a couple of ways to prepare the mortar joints. You can chisel the joint clean or use a power drill and masonry cutting wheel to cut into the mortar joint.

 If using a cold chisel, clean the joint of loose mortar and chisel out the adjacent mortar in the repair area to a depth of 3/4" to 1". Place the chisel at the edge of the brick and chisel toward the center of the mortar joint. Do not drive the chisel toward the brick or you may crack off a piece of the brick face.

If using a cutting wheel, cut the mortar joint along its centerline. As in the above step, place the chisel at the edge of the brick and chisel toward the center of the mortar joint being careful not to crack the brick. Once the mortar is cleaned out from the joint to a depth of 3/4" to 1" you can proceed with the next step.
Mixing mortar consists of mixing sand and masonry cement. The various ratios of each component affect the strength and hardness of the mortar. One issue that comes up in tuckpointing brick in older homes is that today's redi-mix mortar (just add water) is mixed to be stronger and harder than the brick used on older homes and that can cause a problem and brick damage. Older homes usually had a lower percentage of cement. For smaller tuckpointing repairs this is less of an issue, but if you have a larger multiple brick repair on an old home, you may want to consult a masonry supply house for a proper mortar mixture.

Mix a small amount of mortar at one time using clean drinkable water. Mix with a liquid latex binder to improve adhesion and reduce cracking and shrinking.

Mix the mortar to a consistency like pudding, where you can slice a piece off with your trowel.

The next step is to place the mortar into the joints and tool the mortar joint to blend in with surrounding construction.

Take the Mortar Hawk (or overturned brick trowel or flat 8"x12" plywood with a 6" long 2x2 fastened perpendicular to its underside as a gripping handle) and load with fresh mortar.

Holding the hawk against the brick and just under the joint to be filled, pack mortar into the open joint with the tip of a pointing trowel.

With masonry work it is important to keep the mortar off the face of the brick so take care in that regard.

Pack the open joint with mortar then scrape any extra mortar so the mortar in the joint is flush with the brick.

Vertical joints are a little tricky. Take a smaller amount of mortar on the tip of the pointing trowel and scoop and pack the mortar into the open joint. As with the horizontal joints, scrape any extra mortar so the mortar in the joint is flush with the brick.

As the mortar begins to stiffen, strike the joints with a joint strike tool. Tool the vertical joints first, then the horizontal joints.

This last step is very important. Keeping the tuckpoint repair damp allows the mortar to cure properly.

Spray the new repair lightly with water to aid in proper curing of the mortar.
Keep the area misted with water for 3 days.

Cover the area with a plastic sheet if desired to help retain moisture.

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