Restoration, Cleaning & Maintenance
Tuckpointing, repointing depth, expansion joints, sealants, backer rods, masonry cleaning, and sealers.
- Explain tuckpointing and repointing procedures including proper removal depth
- Describe expansion joint design, sealant types, and backer rod selection
- Identify safe masonry cleaning methods and acid safety precautions
- Describe cold weather and hot weather masonry construction practices
- Identify essential bricklayer tools and scaffold safety requirements
Lesson 1
Tuckpointing & Repointing Techniques
Why Mortar Joints Deteriorate
Mortar joints are the most vulnerable part of a masonry wall. Over time, exposure to rain, freeze-thaw cycles, and atmospheric pollution causes mortar to crack, crumble, and erode. When mortar deterioration reaches a certain depth, water infiltration increases dramatically, accelerating further damage. Repointing (also called tuckpointing) is the process of removing deteriorated mortar and replacing it with fresh mortar.
Mortar Removal Depth
The single most important factor in a successful repointing job is the depth of mortar removal. The old mortar must be removed to a minimum depth of twice the joint width - for a standard 3/8-inch joint, that means removing at least 3/4 inch of old mortar. Shallow removal does not provide enough surface area for the new mortar to bond, and the repair will fail prematurely.
Mortar Matching
The replacement mortar must be compatible with the existing masonry. Using mortar that is too hard (such as Type M on soft historic brick) will cause the brick to crack and spall because the mortar does not flex with the wall. Always match or use a softer mortar than the original.
Removal Tools
- Hand tools - plugging chisel and hammer for small areas and delicate historic work
- Grinder with diamond blade - faster but requires skill to avoid cutting into the brick face
- Raking tools - specialized mortar rakes that ride along the brick face to control depth
Packing New Mortar
Apply new mortar in thin layers (not all at once) to avoid shrinkage cracking. Pack each layer firmly with a tuck pointer or slicker. Allow each layer to firm up before applying the next. The final layer is tooled to match the existing joint profile (concave, flush, raked, etc.).
Remove old mortar to a minimum depth of twice the joint width (3/4 inch for a 3/8-inch joint). The replacement mortar must be compatible with the existing masonry - never harder than the brick. Apply new mortar in thin layers and tool to match the original joint profile.