Differences between Sanded Grout and Unsanded Grout

Sanded versus Unsanded Grout

Grout is a cementitious mixture used to fill the spaces between tiles, securing them and preventing moisture from reaching the substrate. The two primary types of cement-based grout are sanded and unsanded. The fundamental difference between them is the inclusion of fine sand in the mixture of sanded grout. This sand acts as a bulking agent and provides strength, making each type suitable for different applications.

The selection between sanded and unsanded grout primarily depends on the width of the tile joints and the type of tile being installed. Sanded grout is generally used for wider joints, while unsanded grout is used for narrower spaces and with tiles that are prone to scratching.

Comparison Table

Category	Sanded Grout	Unsanded Grout
Composition	Portland cement, pigments, and fine silica sand.	Portland cement, pigments, and polymer additives; contains no sand.
Recommended Joint Width	1/8 inch to 1/2 inch (3mm to 13mm).	Under 1/8 inch (3mm).
Texture	Gritty and coarse.	Smooth paste-like consistency.
Durability & Shrinkage	More durable, resistant to cracking and shrinkage due to sand content.	Less durable in wide joints, more prone to shrinkage and cracking.
Common Applications	Floors, high-traffic areas, and wide-joint installations.	Vertical surfaces (walls, backsplashes), narrow joints, and delicate tiles.
Risk of Scratching	Can scratch polished stone, glass, and other delicate tile surfaces.	Will not scratch delicate surfaces.
Cost	Generally less expensive.	More expensive due to the cost of polymer additives.

Venn diagram comparing Differences between Sanded Grout and Unsanded Grout

Applications and Considerations

The width of the space between tiles is the most critical factor in choosing a grout type. Sanded grout is recommended for joints that are 1/8 inch or wider. The sand particles provide bulk, which prevents the grout from shrinking and cracking as it cures in these larger gaps. For joints narrower than 1/8 inch, unsanded grout is preferred because its finer consistency allows it to be easily worked into the tight spaces. Using sanded grout in narrow joints can result in a poor fill and voids, as the sand particles can bridge the gap.

The type of tile material also influences the choice. The abrasive texture of sanded grout can scratch delicate surfaces such as polished marble, limestone, glass, or some metal tiles. For these materials, unsanded grout is the safer option to avoid damage during application.

For flooring applications that experience heavy foot traffic, sanded grout is typically the better choice due to its superior durability and resistance to wear. Unsanded grout is often preferred for vertical surfaces like shower walls and kitchen backsplashes. Its stickier consistency, resulting from a higher concentration of polymers, helps it adhere to vertical surfaces with less sagging compared to the heavier sanded variety.

Composition and Properties

Sanded grout is a mixture of Portland cement, colored pigments, and fine silica sand. The sand strengthens the grout, making it less prone to shrinkage and cracking, which is especially important in wide joints. Unsanded grout is composed of Portland cement and powdered pigments but lacks sand. To compensate for the absence of sand, it contains polymer additives that improve its workability and adhesion, particularly for vertical applications.

Due to its porous nature, cementitious sanded grout typically needs to be sealed after it cures to protect it from stains and moisture. Some modern unsanded grouts with high polymer content may not require sealing.