Tuckpointing & Mortar Joint Repair

Mortar is softer than brick by design, so it wears out first. When the joints recede, crack, or wash out, water pours in and freeze-thaw takes over. Tuckpointing removes the failed mortar and repacks the joints so the chimney sheds water again.

Signs you may need tuckpointing & mortar joint repair

• Joints look recessed, cracked, or hollow
• You can scrape mortar out with a screwdriver
• Sand or mortar bits collect at the base of the chimney
• Water stains are appearing where joints have failed
• The chimney looks weathered and 'gap-toothed' up close

What we check first

Good work starts with looking. Before we recommend anything, here is what we examine:

• Depth and extent of mortar loss
• Whether brick around the joints is still sound
• Existing mortar color and joint profile for matching
• Signs that failed joints have already let water in
• Areas most exposed to weather and runoff

How the work goes

What can change the scope

How much of the stack needs repointing and how bad the joints are drive the work. Matching mortar strength matters too — too-hard mortar next to old brick can actually cause damage, so we match it to the masonry rather than just grabbing the strongest bag.

Missouri considerations

In Missouri, joints on the weather side of a chimney fail first. Wind-driven rain soaks the mortar, then a freeze expands it, crumbling the joint over a few seasons. Repointing before brick starts spalling is the cheaper stop.

Repair or replace?

If joints have failed but brick is sound, tuckpointing is the fix. If the brick faces are already spalling, you're into masonry repair as well. Catching it at the joint stage saves the brick.

Keeping it in good shape

Once repointed, waterproofing the sound masonry adds another layer of protection. Keep an eye on the weather-facing joints, since they'll always be the first to show wear again.

Why water is the problem behind most chimney repairs

Almost every masonry chimney repair traces back to the same culprit: water. A chimney sheds rain through a layered system — the crown throws water off the top, the cap covers the flue opening, the flashing seals the roof joint, and sound mortar joints keep the brick from soaking it up. When any one of those fails, water gets in, and Missouri's freeze-thaw winters do the rest, expanding inside cracks and joints until a hairline gap becomes spalled brick or a leak on your ceiling.

That's why the honest first step is finding where the water actually enters, not sealing the nearest stain. A leak that only shows in wind-driven rain points to flashing; one that appears after any rain often points to the crown or brick. Repairs that last address the entry point and match materials to the existing masonry — mortar matched in strength and color, brick matched in size and profile. Once the water path is closed, breathable waterproofing on sound masonry buys years of protection, but it is never a substitute for a real repair.

Frequently Asked Questions

Related reading from our blog

• Chimney Crown Repair vs. Rebuild in Missouri
  Learn how crown condition, drainage, construction, and surrounding masonry help determine whether a Missouri chimney crown can be repaired or should be rebuilt.
• Tuckpointing an Older St. Louis Chimney
  Learn why mortar compatibility, joint preparation, curing, and moisture diagnosis matter when tuckpointing an older St. Louis chimney.
• Common Chimney Repair Estimate Questions
  Ask better questions about scope, materials, access, hidden conditions, cleanup, and documentation before chimney work.