Tuckpointing
Also called: repointing, pointing, tuck pointing, mortar joint repair, brick repointing, chimney repointing, regrouting brick
Grinding or chiseling deteriorated mortar out of brick joints to a depth of 3/4 inch or more and packing in new mortar, tooled to match. Strictly the decorative two-color version of repointing, but in the U.S. the words are interchangeable. $500–$2,500 for a chimney stack.
Mortar is designed to be the weak link in a brick wall: softer than the brick, it takes the movement and the weather so the brick doesn’t, and it’s meant to be replaced every 25–50 years. On a chimney, exposed on all sides and wet from above when the crown fails, the joints go first — they crack, powder, and open until water runs through them and freezes. Repointing is that replacement: the failed mortar is cut out to a depth of two to two-and-a-half times the joint width (3/4 inch is the usual minimum), the joint is cleaned and dampened, and new mortar is pushed in with a narrow tuck pointer in compacted layers, then tooled to the original profile when it’s thumbprint-hard.
Two things separate good repointing from the kind that fails in a few winters. Depth: a skim of mortar smeared over the surface of an old joint bonds to nothing and falls out; the grind has to reach sound mortar. The mortar itself: modern Type S is stronger than most brick made before the 1950s, and a hard mortar on a soft brick moves the weak link into the brick, which spalls. Type N is the default for exterior brick above grade; older or softer brick wants a lime-rich mix, and matching the color and joint profile is what makes a repair invisible.
The word: tuckpointing originally meant a British decorative technique — a mortar tinted to match the brick, with a thin line of contrasting putty “tucked” into it to imitate fine joints — and repointing is the structural repair. American masons and homeowners say tuckpointing for both. On a chimney it’s the middle tier of the cost page and the DIY job the guide is built around; on a retaining wall it’s rarely needed, because segmental block has no mortar.