Repointing & Tuckpointing

Professional Reference

Sourced exclusively from the National Park Service, Brick Industry Association, ASTM International, the IRC, and NFPA 211.

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Section 01

Why This Matters

Mortar joints are designed to be sacrificial. They absorb stress, accommodate thermal movement, and channel moisture — all so the masonry units are protected. When the wrong mortar is used, the brick becomes the sacrificial element.

Section 02

Repointing vs. Tuckpointing

REPOINTING

Removal of deteriorated mortar and replacement with new mortar. Single application, matched to original. This is what 95% of the trade calls "tuckpointing."

TUCKPOINTING (Traditional)

Decorative two-mortar technique from 18th-century England. Base mortar flush and color-matched, plus a thin raised line of contrasting lime putty along the joint center.

Section 03

Mortar Type Selection

ASTM C270 classifies types M, S, N, O, K (from MASON WORK). Replacement mortar must always be equal to or softer than the original, and softer than the masonry units.

Type	PSI	Application
M	2,500	Foundation, below-grade, retaining walls. Highest compressive strength for structural load paths in direct ground contact.
S	1,800	Below-grade, structural load-bearing, high wind/seismic zones. Superior water impermeability for CMU and below-grade chimney foundations.
N	750	General above-grade exterior. The standard for most chimney exterior repointing on post-1930 construction.
O	350	Interior, non-load-bearing, and soft/historic brick. Required for pre-1900 masonry and limestone to prevent spalling.
K	75	Historic preservation only. Highest lime content. For extremely soft historic brick where even Type O is too rigid.

Section 04

Safe Material Removal

Removing too little mortar prevents bond. Removing too much compromises the wall. Minimum depth: 2-2.5x joint width. Maximum: half the masonry unit depth.

Section 05

Repointing Step by Step

This sequence is from NPS Brief 2, BIA Technical Note 46, and ASTM E2260. Shortcuts at any stage compromise the entire job.

1 Document & Assess

Photograph all elevations. Map deterioration patterns. Identify moisture sources — repointing over active water intrusion is wasted effort. Per NPS Brief 2, all drainage problems must be resolved first.

2 Mortar Analysis

Sample existing mortar from multiple locations. Determine original composition. Specify repointing mortar that matches or is softer in compressive strength. Per ASTM C1713 for historic masonry.

3 Joint Preparation

Remove deteriorated mortar to a minimum depth of 2 to 2.5 times the joint width. Never exceed half the masonry unit depth. Hand tools preferred — grinders only on horizontal joints, never on vertical joints.

4 Pre-hydrate Mortar

Mix dry ingredients. Add only enough water to form a damp ball. Let stand 1 to 1.5 hours. Then add water to working consistency — significantly drier than laying mortar. Reduces shrinkage per BIA 8B.

5 Dampen Joints

Mist the prepared joints several hours before pointing. Damp but no standing water — saturated surface prevents bond; dry surface pulls water too fast.

6 Pack in Lifts

Apply mortar in layers no thicker than 1/4 in. Each lift must be thumbprint-firm before the next. Deep joints may require 3 to 4 lifts. Rushing lifts causes voids and debonding.

7 Tool the Joint

When mortar is thumbprint-hard, tool to match the original profile. Tooling compresses the surface. Concave joint has best weather performance; raked joint has worst.

8 Cure & Protect

Mist-cure for a minimum of 3 days. Protect from freezing for 72 hours. Final color cannot be evaluated until full cure — 72 hours minimum.

Repointing Toolkit

Plugging Chisel (Cape Chisel): The primary hand tool for mortar removal. Angled 45-degree tip pushes mortar out of the joint as you work. 10-inch length with a narrow blade matched to joint width. Use with a hand-weight hammer — light controlled strikes, not heavy blows. Required for all vertical (head) joints where grinders cannot be used safely.
Tuckpointing Grinder with Diamond Blade: Dedicated grinder with adjustable depth stop and dust shroud. Diamond tuckpointing blades (typically 4-4.5 inch) cut mortar without contacting brick. Use only on horizontal (bed) joints — never vertical joints per NPS guidance. Always run a test area first. Pair with a HEPA vacuum for silica dust control (OSHA Table 1 compliance).
Raker Bar / Joint Raker: Forged steel bar with a curved, sharpened tip at each end. The traditional mortar removal tool before grinders. Roll-type joint rakers with depth-adjustable nails work fast on soft lime mortar. Still essential for spot repairs and areas where grinders risk brick damage.
Hawk Board (Magnesium or Aluminum): Flat plate with a handle underneath — holds mortar at the wall face while you work. Hold the hawk edge flush against the joint and press mortar off the hawk into the joint with the tuckpointing trowel. Magnesium hawks are lighter for overhead work.
Tuckpointing Trowel (Caulking Trowel): Narrow, flexible, one-piece forged carbon steel blade in widths from 3/16 inch to 1 inch. Matched to joint width. The flex allows you to press mortar deep into the joint. Use to pack each 1/4-inch lift. This is the tool that makes or breaks the job — cheap trowels bend and skip.
Jointers / Slickers: Profiling tools that compress and shape the final mortar surface. Concave jointers (most common) create the best-performing weather joint. V-jointers, flat slickers, grapevine jointers, and convex jointers each produce a different profile.
Stiff Fiber Brush: Used to clean joint cavities after mortar removal and to brush excess mortar from brick faces after the mortar has stiffened. Natural or synthetic bristle — never wire brush on soft or historic brick (damages the fired face).
Spray Bottle / Garden Sprayer: For misting joints before mortar application and for mist-curing fresh work. A pump-action garden sprayer covers more area. The goal is damp surfaces with no standing water — never soak the wall.

Section 06

Chimney Mortar Zones

A chimney contains distinct thermal and exposure zones, each requiring specific mortar. A mason who uses one mortar for an entire chimney does not understand chimney construction.

Zone	Area	Mortar	Reason
1	Crown / Wash	Type N or S	Exposed to maximum weathering. Must resist freeze-thaw and water pooling.
2	Exterior Shell (above roof)	Type N	Standard above-grade exposure. Must be softer than the brick to remain sacrificial.
3	Smoke Chamber	Refractory (ASTM C 199)	Direct flue gas contact at 400-1,000+ degrees F. Portland cement breaks down at ~600 degrees F.
4	Firebox	Refractory (ASTM C 199)	Direct flame contact. Joints must not exceed 1/4 in per IRC and NFPA 211.
5	Flue Liner Joints	Refractory (ASTM C 199)	Continuous flue gas exposure. Must seal liner against CO migration.
6	Exterior Shell (below roof)	Type N or S	Subject to moisture migration from the roof intersection.
7	Foundation / Footing	Type S or M	Below-grade, ground-contact structural application.

Section 07

Chimney Flashing

The roof-to-chimney intersection is the most common point of water intrusion. IRC R1003.20 requires a cricket on any chimney wider than 30 inches on the upslope side.

1 Roof Deck

Structural substrate — plywood or OSB sheathing. Must be sound and properly fastened before any flashing layers are applied.

2 Ice & Water Shield

Self-adhering membrane. Extends minimum 24 inches up the chimney face and minimum 24 inches onto the roof deck on all sides. This is the primary waterproofing layer.

3 Step Flashing

Individual L-shaped pieces woven into each shingle course. Minimum 2 inch overlap between pieces. Each piece extends up the chimney wall and under the next shingle course above it.

4 Counterflashing

Set into a reglet (saw-cut groove) in the mortar joint, minimum 1 inch deep. Laps over the top of the step flashing to shed water away from the joint. Reglet sealed with urethane or polyether sealant.

5 Cricket / Saddle

Required by IRC R1003.20 when chimney width exceeds 30 inches on the upslope side. Diverts water around the chimney instead of letting it pool. Constructed of metal or framed and covered with roofing membrane.

6 Crown / Cap

Minimum 2 inches thick concrete or mortar wash. Must have a bond break (caulk or membrane) between crown and flue liner to prevent differential thermal expansion cracking. Overhangs the chimney face by minimum 1 inch with a drip edge kerf.

Flashing Toolkit

Aviation Snips (Left, Right, Straight): For cutting step flashing, counterflashing, and drip edges from sheet metal. Left-cut and right-cut snips for curves and tight corners. Straight snips for long cuts. Use on aluminum, copper, and galvanized steel up to 24 gauge.
Reglet Grinder / Masonry Saw: A 4-inch grinder with a diamond blade cuts the reglet (groove) into the mortar joint for counterflashing. Set depth to minimum 1 inch. Cut along the mortar joint only — never cut into the brick face.
Hand Seamer / Brake: Bends sheet metal to precise angles for step flashing L-shapes and counterflashing profiles.
Caulk Gun (High-Ratio): For applying urethane or polyether sealant into the reglet after counterflashing is set. High-ratio (26:1) guns provide the smooth, controlled bead needed for sealant work.
Flat Pry Bar: For carefully lifting existing shingle courses to weave step flashing underneath without damaging the roofing.
Roofing Hammer / Roofing Nailer: For securing step flashing to the roof deck and re-nailing shingle courses. Stainless steel or hot-dipped galvanized roofing nails — never electro-galvanized, which corrodes under flashing.

Section 08

Brick Replacement & Spalling Repair

When brick faces pop off a chimney — spalling — the unit has failed. Per NFPA 211, masonry chimneys must be structurally sound and free from defects. Spalling that reduces wall thickness below IRC R1003 minimums, exposes flue tiles, or compromises the mortar bond system makes the chimney code-deficient and requires repair.

Why Chimney Brick Spalls

1. Freeze-thaw cycling. Water saturates the brick, freezes, expands ~9%, and pops the face off. This is the primary cause on chimneys because they are exposed on all four sides with no shelter from the roof overhang.

2. Wrong brick grade. Per BIA Technical Note 19B and ASTM C216, chimney brick must be Grade SW (Severe Weathering). Grade MW brick on a chimney will spall.

3. Bricks not spanning through coring holes. Modern brick often has core holes. If laid with cores facing the exposed face, water pools in the cores, freezes, and blows the face off.

4. Failed crown or flashing. Water intrusion from above saturates the entire chimney stack. Per BIA Technical Note 46 Table 3, missing or damaged flashing is a primary contributor.

5. Too-hard mortar. Repointing with mortar stronger than the brick reverses the sacrificial relationship.

1 Assess the Damage

Inspect all elevations. Map every spalled, cracked, loose, and delaminated unit. Per BIA Technical Note 46, conditions warranting brick replacement include spalling, loose units, and cracks through multiple units. If spalling is widespread, a structural engineer should evaluate whether the chimney needs partial or full rebuild.

2 Remove the Damaged Brick

Break the damaged brick from the center outward using a cold chisel and hammer. Work from the middle toward the edges to avoid transmitting impact force into adjacent brick. Do not pry against adjacent units.

3 Clean the Cavity

Remove all remaining mortar from the top, bottom, and sides of the cavity using a chisel. Per BIA Technical Note 46, thin slivers of mortar remaining on the brick must be removed. Brush out dust and debris. Rinse with water or blow out with oil-free compressed air.

4 Match the Replacement Brick

The new brick must match existing in color, texture, and size. Per BIA Technical Note 46, use a mock-up or sample panel. For chimneys, replacement must be ASTM C216 Grade SW. Ensure coring holes are oriented correctly — cores must run vertically.

5 Butter & Set the New Brick

Dampen cavity surfaces. Apply mortar to top, bottom, and both ends of new brick AND cavity surfaces. Mortar must be same type and strength as original — Type N generally for chimneys; Type O for older or softer brick.

6 Point the Joints

Fill and tool all four joints around the unit to match original profile. Pack in 1/4 inch lifts, tool when thumbprint-hard. Mist-cure minimum 3 days.

CORE HOLE ORIENTATION

Cored brick must be laid with the cores running vertically (top to bottom). If cores face the exposed surface horizontally, water enters the cores, cannot drain, freezes, and blows the face shell off. This is one of the most common causes of chimney brick spalling.

Brick Replacement Toolkit

Cold Chisel Set (3/4 in, 1 in, 1-1/4 in): The primary tools for breaking out damaged brick and removing remaining mortar from the cavity. Start with the narrower chisel at the center and work outward.
Hand Drilling Hammer (2-3 lb): Paired with cold chisels for brick removal. Controlled hits, not sledge force.
Plugging Chisel: Angled tip cleans mortar slivers from cavity walls after the damaged brick is removed.
Margin Trowel (5 in x 2 in): The workhorse for buttering mortar onto the new brick and cavity surfaces.
Brick Set (Bolster Chisel): Wide-blade chisel for scoring and cutting replacement brick to size.
4-Foot Level and String Line: For verifying the replacement brick is flush, level, and plumb with the surrounding coursing.

Refacing a Spalled Brick with Mortar

When a brick face has popped off but the back is still sound — and replacement brick cannot be sourced — the face can be rebuilt with a cementitious composite patch.

1 Cut Back to Sound Brick

Remove all loose, delaminated, and spalled material back to solid, sound brick. Use a chisel or grinder to create a relatively flat substrate. The remaining surface should be a minimum of 1/2 inch recessed from the finished face to provide adequate patch depth. If the remaining substrate is less than 1/2 inch deep, the patch will not hold — the brick needs full replacement, not refacing.

2 Create Mechanical Key

Score the substrate with a chisel, grinder, or masonry bit to create a rough, textured surface for the patch to grip. An intentionally rough or multiplanar surface provides mechanical interlock for the new material. Without a key, the patch relies only on adhesive bond and is far more likely to delaminate. Drill shallow holes or crosshatch score lines at approximately 1 inch spacing.

3 Dampen & Apply Bonding Layer

Dampen the substrate thoroughly — damp, not dripping. If using a proprietary repair mortar, follow manufacturer instructions for bonding agent or slurry coat. For site-mixed patches, brush a thin slurry of portland cement and water onto the damp substrate immediately before applying the first lift. This slurry coat must not be allowed to dry before the patch mortar goes on.

4 Build the Patch in Lifts

Apply the repair mortar in compacted lifts no thicker than 1/4 inch at a time. Each lift must reach thumbprint firmness before the next is applied. For a typical spall repair, 2 to 4 lifts will bring the patch flush. Do not apply the full depth in one pass — it will shrink, crack, and debond. The patch mortar should be no stronger than the surrounding brick.

5 Texture & Color Match

Before the final lift hardens fully, shape and texture the surface to match the surrounding brick faces. Use a trowel, sponge, or brush to replicate the texture. Color matching can be achieved by adding synthetic mineral oxide pigments to the mix (same NPS limits: 10 percent max, 2 percent carbon black max), or by applying a masonry-compatible stain after cure.

6 Cure & Protect

Mist-cure for a minimum of 3 days. Protect from freezing for 72 hours. The patch is more vulnerable than fired brick to freeze-thaw damage during its initial cure period. In cold weather, cover with insulating blankets. Do not apply sealers or coatings until the patch has fully cured — typically 28 days for full strength development.

Section 09

Laying Brick

Bricklaying is deceptively simple in concept and unforgiving in execution. Practices from BIA 7B, TMS 602, and IMI.

MATERIAL PREP

Brick with IRA over 30 g/min/30 sq in must be pre-wetted. Saturated but surface-dry. Blending: mix straps from different cubes to prevent color banding.

MORTAR & TIMING

Mortar = ~20% of wall face. Mix with max workable water. 1-minute rule: lay brick within 1 minute of spreading bed mortar.

1 Measure & Dry Lay

Measure foundation, snap chalk lines, dry-lay to verify fit, check bond pattern, locate cuts, confirm spacing.

2 Set the First Course

First course bed joint: 1/4 in min to 3/4 in max (TMS 602). Compensates for foundation irregularities. Use string line and 4-foot level.

3 Butter & Place

Full bed mortar — no deep furrowing (TMS 602 prohibits voids). Butter head of each brick. Press with enough force to extrude mortar from all sides.

4 Fill All Joints

Unfilled head joints are the #1 source of water penetration (BIA 7B, IMI). Both bed and head joints must be fully filled.

5 Consistent Joint Thickness

Standard: 3/8 in. TMS 602 tolerances: bed +/- 1/8 in, head -1/4 to +3/8 in. Use story pole — 3 courses = 8 in module.

6 Level, Plumb & Course Height

TMS 602: plumb +/- 1/4 in per 10 ft, 3/8 in per 20 ft, 1/2 in max. Check every 3-4 courses.

7 Tool Joints

Thumbprint-hard = ready. Concave and V-joints have best weather performance. Tool heads first, then beds.

8 Clean as You Go

Scrape excess immediately. Never wet-wipe porous brick — forces mortar into pores.

9 Rack, Don't Tooth

Rack back (stair-step) when stopping. Toothed profiles produce poor bond on resume (BIA 7B).

10 Cover Unfinished Walls

Cover with weighted tarps every night and during rain. Uncovered walls = efflorescence, freeze damage (BIA 7B).

Bricklaying Toolkit

Brick Trowel (10-12 in, London or Philadelphia pattern): The primary laying tool. Scoops mortar from the board, spreads bed joints, and butters head joints. London pattern has a narrower, more pointed blade for precision. Philadelphia pattern is wider for spreading more mortar per stroke.
Brick Hammer (Mason's Hammer): Combination striking face and chisel blade. The striking face sets brick into the mortar bed. The chisel blade rough-cuts brick on site. Weight range: 16-24 oz — heavier is not better; control matters more.
4-Foot Level (Box Beam or I-Beam): Checked against every corner and every 3-4 courses for level and plumb. Keep vials clean and verify accuracy regularly — a bent level ruins a wall.
Story Pole / Course Rod: A straight pole marked with course heights (every 8 inches for standard modular 3-course module). Catches creeping joints before they become visible errors. Make one for every job.
Mason's Line and Line Blocks: String line stretched between corner leads to guide each course for straightness. The line must be tight with no sag — even 1/8 inch of sag creates a visible wave in the finished wall.
Joint Raker / Sled Runner: Runs along the mortar joint after it has stiffened to rake out a consistent depth for tooling. Used primarily for raked joints.
Jointers (Concave, V-Joint, Flat Slicker): Concave jointer is the default for exterior work — best weather performance. V-jointer for decorative work. Flat slicker for flush joints. Tool head joints first, then bed joints.

Site Tolerances (TMS 602)

Measurement	Tolerance
Plumb	+/- 1/4 in/10 ft, 3/8 in/20 ft, 1/2 in max
Level	+/- 1/4 in/10 ft, 1/2 in max
Bed joint	+/- 1/8 in from 3/8 in
Head joint	-1/4 to +3/8 in
First course	1/4 in min to 3/4 in max

Section 10

Bond Patterns

Structural bonding: overlapping units, metal ties, or grout adhesion. The metal tie method is recommended for exterior walls — allows differential movement.

Running Bond: All stretchers, offset 1/2. The standard default.
Common (American): Running bond + header course every 5th-7th course.
English Bond: Alternating all-header and all-stretcher courses.
Flemish Bond: Alternating headers/stretchers every course. Decorative + structural.
Stack Bond: No offset — decorative only. Requires reinforcement for structural use.

Section 11

Mortar Color Matching

Color matching is where craftsmanship meets chemistry. Mismatched mortar is the most visible sign of amateur work.

1 Sample Extraction

Remove mortar samples from at least 3 unexposed locations. Clean samples of paint, soot, and biological growth before analysis.

2 Sand Matching

Sand contributes 70-80% of the final mortar color. Match the sand source, grain size, and color distribution.

3 Binder Adjustment

For 1890-1930 buildings, a half-gray / half-white portland cement blend often works. Pre-1890 buildings require natural hydraulic lime or lime putty.

4 Pigment Limits

NPS limits pigments to 10% max of cement weight, carbon black to 2% max. Synthetic mineral oxide pigments only. Integral pigments only.

5 Test Panels & Evaluation

Build a minimum 3 ft x 3 ft test panel. Wait 72 hours minimum before evaluating — wet mortar is always darker.

COMMON MISTAKES

Matching weathered color — Sample from protected spots

Evaluating while wet — 72hr cure minimum

Natural pigments — Synthetic mineral oxides only

Ignoring sand — Sand = 70-80% of color

Exceeding limits — 10% max, 2% carbon black

Surface colorant — Integral pigment only

Section 12

Authoritative Sources

Every claim traces to one or more of these. No trade blogs, no marketing, no forums.

National Park Service

Preservation Brief 2: Repointing Mortar Joints

ASTM International

E2260-21, C270, C1713, C199, C216

Brick Industry Association

Technical Notes 1, 7B, 8B, 18A, 30, 46

ICC

2021 IRC Section R1003

NFPA

NFPA 211: Chimneys, Fireplaces, Vents

The Masonry Society

TMS 402/602

International Masonry Institute

Brick New Construction Best Practices

IIBEC / SMACNA

Flashing Best Practices / Sheet Metal Manual

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