What to Grout Brick With: Mortar vs Grout Guide
Learn what to grout brick with and when to use cementitious mortar, cementitious grout, or epoxy grout. Practical guidance for homeowners and DIYers from Grout Maintenance.
When you ask what to grout brick with, traditional masonry practices rely on mortar, not grout, for brick joints. Grout is typically used for tile joints; if you’re tiling over brick, you’ll grout the tile joints with cementitious or epoxy grout. For historical or exterior brick, repoint with mortar that matches the original mix. According to Grout Maintenance, understanding the distinction helps prevent cracks and failures.
Understanding Brick Joints and the Difference Between Mortar and Grout
Brick joints are traditionally filled with mortar, a cement-based binding material that seals and anchors bricks in place. Grout, by contrast, is designed for tile joints and is formulated to fill gaps between tile pieces. If you’re wondering what to grout brick with, the correct answer in most masonry projects is: you generally wouldn’t grout brick joints with standard grout. The Grout Maintenance team emphasizes that for structural or historic brickwork, mortar remains the appropriate filling material. If you’re placing tile over a brick surface, you’ll grout the tile joints with cementitious or epoxy grout instead. This distinction matters because mortar and grout have different movement tolerances, bonding properties, and weather resistance. A mismatched choice can lead to cracking, moisture intrusion, or failures in outdoor walls. Grout is less flexible than mortar and can crumble under repeated brick movement, so use it only where tile joints exist.
In this section you’ll learn why mortar is the default for brick masonry, how grout fits into tile-over-brick scenarios, and where modern alternatives come into play. The guidance here aligns with best practices from Grout Maintenance and is suitable for homeowners tackling repointing, tile installations on brick, or decorative brick features. A quick takeaway: mortar = structural filler; grout = tile joint filler. This foundational idea dictates material selection for most brick projects.
Grout vs mortar also affects color, texture, and weather resistance. Mortar can be tinted to blend with brick and is typically more forgiving for exterior exposure. Cementitious grout, when used in tile joints, can be sanded for strong gaps, but epoxy grout offers superior stain resistance and chemical durability in damp spaces. The Grout Maintenance team notes that exterior brick projects may benefit from traditional mortar to maintain breathability and moisture handling, while interior tiled brick walls can accept cementitious or epoxy grout depending on location and use.
Tools & Materials
- Grout float (rubber)(For pressing grout into tile joints if tiling over brick)
- Masonry trowel or pointing trowel(Essential for applying mortar to brick joints)
- Mixing bucket and drill with paddle attachment(Needed for consistent mortar or grout mixing)
- Grout sponge and clean water(For cleaning surfaces during grouting (tile joints))
- Polymer-modified cementitious grout(Use only if grouting tile joints; otherwise skip)
- Epoxy grout kit(Optional for moisture-prone interiors; follow manufacturer directions)
- Mortar mix (Type N or S as appropriate)(Exterior or historic brick joints usually require mortar)
- Mortar mixer or paddle(Ensure a smooth, lump-free mix)
- Sealant or penetrating sealer(Apply to cementitious grout after curing in wet areas)
- Safety gear (gloves, eye protection, mask)(Protect from dust and splashes)
Steps
Estimated time: 2-6 hours
- 1
Assess the project and choose the correct material
Inspect joints and determine if you’re repointing brick with mortar or grouting tile joints on brick. For traditional brickwork, select a mortar mix that matches the original, such as Type N or S in exterior applications. If you’re tiling over brick, decide between cementitious grout and epoxy grout based on moisture exposure and cleaning needs.
Tip: When in doubt, test a small area first and compare mortar color to brick for a seamless look. - 2
Prepare the surface and mix the material
Dampen the brick joint surface as needed to prevent suction, then mix mortar or grout following product guidelines. Achieve a consistency like thick peanut butter—neither too dry nor too runny. Proper mixing reduces gaps and improves bond.
Tip: Avoid over-watering mortar; too-wet mixes weaken joints and can cause efflorescence later. - 3
Apply mortar or grout to the joints
Using a pointing trowel, press mortar into vertical joints and strike off excess along the face of the bricks. For tile joints on brick, spread grout with a grout float at a 45-degree angle, ensuring full joint contact and removing excess material promptly.
Tip: Work in small sections to prevent mortar from drying before tooling. - 4
Tool and finish the joints
Finish mortar joints with a jointing tool for a consistent profile. For tile grout, use a damp sponge to wipe excess grout from brick faces after the initial set. Allow cementitious grout to cure according to manufacturer guidelines.
Tip: Avoid metal tools that can scratch brick surfaces; use plastic or wooden tools instead. - 5
Cure and seal as needed
Cure times vary by material; protect from rain and direct sun during curing. Seal cementitious grout only if recommended, especially in wet areas. Epoxy grout requires a different curing regime and is less permeable.
Tip: Keep moisture away during curing to prevent cracking. - 6
Assess results and perform touch-ups
Inspect joints for uniform depth and fill. Remove any haze or residue from brick faces. If any joints show gaps, re-work them promptly. For exterior brick, monitor for cracks and repoint as needed.
Tip: Document changes with photos for future maintenance.
Got Questions?
Can you grout brick joints with regular grout?
Not usually. Brick joints are typically filled with mortar. Grout is meant for tile joints. If you’re working with brick that will be tiled, grout the tile joints instead of brick joints.
Brick joints are usually mortared; grout belongs to tile joints. If you’re tiling over brick, grout the tile joints, not the brick joints.
Is epoxy grout good for brick projects?
Epoxy grout provides excellent stain resistance and durability in wet areas, making it suitable for interior brick walls that are tiled or exposed to moisture. For bare brick or exterior brick, mortar remains preferred.
Epoxy grout is great for moisture-prone interiors with tile, but for plain brick, mortar is usually better.
When should I seal grout on brick projects?
Seal cementitious grout after it fully cures when it's recommended by the manufacturer, especially in showers or exterior installations. Do not seal epoxy grout unless the product specifies it.
Seal cementitious grout after it cures if the project calls for it; epoxy grout typically doesn’t require sealing.
What about repointing old brick with mortar?
Repointing uses mortar to restore joints in historic or damaged brickwork. Do not attempt to repoint with grout. Match the lime or cement-based mortar to the original composition for best results.
Repointing uses mortar, not grout. Match the original mortar mix for best results.
What causes efflorescence after grouting brick?
Efflorescence occurs when soluble salts migrate to the surface from cementitious materials. Proper sealing, ventilation, and avoiding overly wet mixes help prevent it.
Efflorescence is salts coming to the surface; use proper sealing and avoid excessive moisture to prevent it.
Do I need to hire a pro for brick grouting projects?
For exterior brickwork or historic brick repointing, a professional mason is often best to ensure correct mortar matching and long-term durability. Tile-over-brick projects with grout can be DIY-friendly with careful preparation.
Consider a pro for exterior or historic brick repointing; tile-over-brick projects can be DIY with care.
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The Essentials
- Mortar, not grout, is the standard for brick joints.
- Tile-over-brick requires grout in the tile joints, with cementitious or epoxy options.
- Choose mortar for exterior or historic brickwork to preserve breathability.
- Seal cementitious grout only if recommended and only after full cure.
- Plan, test, and patch as needed for durable results.
