Grout vs caulk

Grout vs caulk: An overview

Whether you use grout or caulk depends on what project and which part of the house you are focusing on. Grout is commonly used between tiles, providing stability and a clean finish. Caulk is best for sealing gaps where movement or moisture is a concern.

Understanding the differences between the two will help you choose the right material for your home project. In this article, we will walk you through everything you need to know about grout and caulk. 

What is the difference between grout and caulk?

The primary difference between grout and caulk is their composition, purpose, and application. 

• Composition: Grout is a mixture of cement, sand, water, and sometimes additives like polymers for improved strength and flexibility. Caulk is a flexible sealant made from silicone, latex, or polyurethane.
• Purpose: Grout is used to fill the gaps between tiles on walls, floors, and backsplashes, especially in areas where no movement is expected. Caulk is used to seal joints or gaps where materials meet and where movement is likely to occur.
• Application: Grout is typically used in static areas where no significant movement is expected, such as between tiles on walls, floors, and backsplashes. It is applied with a spatula or grout float, pressed into the joints between tiles, and then wiped off the tile surface before it hardens. Caulk is used in dynamic areas, such as corners, edges, and where two materials meet (e.g., tiles to a bathtub or countertop). It is applied using a caulk gun and can be smoothed into place with a finger or caulk tool.
• Flexibility: Grout is rigid once it hardens, which makes it prone to cracking if applied in areas that experience movement or expansion. Caulk is flexible and remains pliable even after it cures.
• Water resistance: Grout is water-resistant but can absorb water if not properly sealed. This is why grout in areas exposed to constant moisture, like showers, may require sealing to prevent water from seeping into the joints, leading to mold or mildew growth. In contrast, caulk, especially silicone caulk, is completely waterproof and forms a tight seal that prevents water from entering joints

What is grout?

Grout is a thick, paste-like material used to fill the gaps and cracks between tiles and other masonry surfaces. It’s commonly sold in powdered form, which is mixed with water to become a rock-hard adhesive when cured. However, there are also pre-mixed paste options that are ready to use right out of the container.

Grout's primary function is to provide a durable, long-lasting seal between tiles and prevent dirt, moisture, and debris from entering the spaces between them. 

Depending on the type, grout is made from cement, sand, water, and sometimes additional additives, such as polymers for flexibility or epoxy resins for chemical resistance. The most common types used in home projects are unsanded, sanded, and epoxy grout. 

However, specialized grouts such as single-component grout, high-performance polymer cement grout, furan resin grout, and pre-mixed polymer resin grout exist for specific applications.

Unsanded grout

Unsanded grout is made from a mixture of cement, water, polymers, water retention agents (like cellulose), and plasticizers. This combination gives it a smooth texture, making it ideal for narrow grout joints (typically less than 1/8 inch wide) and delicate tiles like marble, glass, or polished ceramics, as it won’t scratch the surface. 

Unsanded grout’s moisture resistance and ability to inhibit mold growth make it a great choice for wet areas like bathrooms, kitchens, and showers. 

However, it’s not as strong as sanded grout, so it can shrink, crack, and crumble if used in wider joints. It’s also less durable for high-traffic areas, making it better suited for smaller, low-traffic spaces like bathroom walls, kitchen backsplashes, and shower walls.

Sanded grout

Sanded grout is made from cement, water, and sand particles. The sand acts as a filler, reducing the overall amount of water needed in the mix. This, in turn, minimizes the grout’s tendency to shrink during the curing process and makes it best for wider grout joints (typically 1/8 inch to 1/2 inch or wider). 

However, if used for narrow grout seams, the sand particles mixed with the grout can put too much pressure on the surrounding tiles and weaken the tile structure.

In addition, sanded grout is best for high-traffic areas like floors, kitchens, and entryways because of the increased structural strength and resistance to cracking under pressure or movement.

Epoxy grout

Epoxy grout is made from a mixture of resins and hardeners, which, when combined, create a strong, durable grout that doesn’t rely on water to set. This makes it waterproof and resistant to stains, mold, and mildew, making it ideal for wet areas like bathrooms, kitchens, and commercial spaces. 

However, it’s more challenging to work with because it sets quickly, requires precise mixing of the two components, and can be difficult to clean during installation. It’s also more expensive than standard grouts, so it’s typically used for areas where durability and resistance to chemicals or moisture are crucial.

Single-component grout 

Single-component grout is a modern grout option that comes pre-mixed (ready to use from the container) and combines the best qualities of cement-based and epoxy grouts. It contains polymer additives that make it more flexible, durable, and resistant to cracking or shrinkage while providing excellent adhesion. 

However, it tends to be more expensive than regular cement grouts, and it may not offer the same level of chemical resistance as epoxy grout, making it less suitable for environments with heavy chemical exposure.

High-performance polymer cement grout 

High-performance polymer cement grout combines cement with latex polymer to make it stronger, more flexible, and more durable than regular cement grout. This makes it a great option for high-traffic areas or places where temperature and humidity fluctuate, like commercial kitchens, installing a backsplash, bathroom floor tile renovations, or outdoor spaces like patios and balconies.

Furan resin grout 

Furan resin grout is a highly specialized grout made from synthetic resins, hardeners, and polymers of furfuryl alcohol. This makes it withstand exposure to harsh chemicals, acids, or high temperatures (up to 350°F) and is used in industrial or commercial settings, like factories, food processing plants, or laboratories.

However, it’s difficult to work with due to its complex mixing process and strict application requirements. It’s also one of the most expensive grout types, so it’s generally reserved for situations where other types of grout would fail under harsh conditions.

Pre-mixed polymer resin grout 

Pre-mixed polymer resin grout is ready for use right out of the container. It combines the strength of cement with the durability and flexibility of urethane polymers, fine fillers, and water.

The polymer resin’s water-resistant property makes this type of grout a great option for wet areas like bathrooms, kitchens, and outdoor spaces. However, since it’s a relatively new grout type, it’s not as widely available, and each supplier makes a slight variation in their properties.

What is caulk?

Caulk is a flexible, paste-like material used around stationary surfaces like kitchen backsplashes, sinks, tub surrounds, and toilet bases to prevent water, air, or dirt from entering the gaps, cracks, and joints.  

Caulk comes in several types, each formulated for specific applications. Knowing the differences can help you make the best choice for your project.

Latex caulk

Latex caulk is water-based and made from acrylic resins. It is easy to apply, dries quickly, and can be cleaned up with water. Latex caulk is ideal for interior use, such as sealing around windows, doors, baseboards, and crown molding. 

Latex caulk is not suitable for high-moisture areas like bathrooms or kitchens.

Adhesive caulk

Adhesive caulk combines sealing and adhesive properties, making it great for bonding surfaces. Not ideal for wet areas, instead adhesive caulk is commonly used for sealing HVAC ducts and bonding tiles, trims, and moldings. 

Silicone caulk

Silicone caulk is highly flexible, durable, and resistant to water, extreme temperatures, and UV exposure.  It is made from silicone polymers, a non-water-based material which allows it to resist mold and mildew. Silicone caulk is best used in bathrooms, kitchens, and other wet areas like around sinks, bathtubs, and showers. It cannot be painted and is tricky to clean up and apply.

Fireproof caulk

Fireproof caulk is made from fire-resistant materials such as intumescent compounds or mineral-based resins. It is formulated to expand when exposed to heat. It is essential for fireproofing around electrical outlets, pipes, ducts, and fire-rated walls or ceilings.

Butyl-rubber caulk

Butyl-rubber caulk is made from synthetic rubber compounds. Used outdoors, it is very flexible, waterproof, and weather-resistant. Butyl-rubber caulk is perfect for sealing around windows, gutters, roofing, and even in automotive or marine environments. While it bonds well to move surfaces and can withstand UV exposure, this type of caulk is not paintable and can be messy to apply.

Foam caulk

Made from expanding foam, this type of caulk expands significantly when applied to provide excellent insulation and a strong seal. It is best for sealing large gaps or cracks around windows, doors, plumbing, and attic areas. Foam caulk will expand too much if not applied carefully and doesn’t create as smooth a finish as other types of caulk. 

Polyurethane caulk

Polyurethane caulk is made from synthetic polymers. Ideal for outdoor seals, this extremely durable caulk is flexible, and resistant to weathering and UV rays. While polyurethane caulk adheres well to wood, metal, and masonry, it does require solvent cleanup (e.g., mineral spirits) and can be more difficult to apply neatly.

Solvent-based caulk

Designed to provide a strong seal and excellent adhesion, this caulk is made with solvents like acetone or mineral spirits. Solvent-based caulk is often used in industrial or commercial applications, such as sealing HVAC ducts, joints, and roofing. Unfortunately, it has a strong odor, requires solvent-based cleanup, and can be tricky to apply neatly.

Hybrid Caulk

Hybrid caulks are usually a blend of silicone and polyurethane or acrylic materials. Ideal for both interior and exterior projects, hybrid caulk offers the flexibility and water resistance of silicone, with the added benefit of being paintable and having better adhesion.

Caulk vs grout for tiles

Grout is best for tile-to-tile joints on floors and walls. It's typically used when there are consistent gaps between tiles (usually 1/16" to 1/2" wide). On the other hand, caulk is ideal for edges, corners, and where tiles meet other materials (e.g, between the tub or sink and the tiled wall).

Grout vs caulk in a shower

Grout is used in static shower areas (e.g., between wall and floor tiles). Once it hardens, it’s rigid and very durable. However, it’s not as water-resistant. On the other hand, caulk is used where tiles meet the bathtub or at the shower enclosure edge. It’s flexible and waterproof but not as durable as grout.

Caulk vs grout around a bathtub

Grout can be used between tiles on the walls around the bathtub but not where the tiles meet the tub because the area experiences expansion and contraction. Instead, caulk, particularly silicone caulk, is the preferred material for sealing gaps between the bathtub and surrounding tiles.

Grout vs caulk: What to know

Caulk and grout have their place in the home. Knowing the differences and their proper applications is key to understanding which to use for your tile project.

Both grouting and caulking are tasks that many DIYers can handle with a little practice. The decision to tackle them yourself or hire a professional depends on your confidence, skill level, and the project's complexity.

If you're dealing with a more complex project (e.g., one that involves waterproofing or an intricate tile pattern), hiring a professional will ensure the grout and caulk are applied evenly and without risk of water damage.

We recommend checking out Angi for home projects pros. You can expect to hire fully equipped, background-checked professionals, read detailed reviews, and see their hourly rates upfront.