Is S1 or S2 tile adhesive better?

Many tile adhesives have an S1 or S2 rating, but what’s the difference? Summary: Flexibility, water resistance, bond strength, uses cases, and cost.

Flexibility

 S1: S1 adhesives are more flexible and are suitable for tiling applications that may experience some movement, such as underfloor heating systems or substrates with slight expansion and contraction.

 S2: S2 adhesives are even more flexible and are more suited to applications that have more movement and / or vibration for example, floating floors or tiling on to tongue and groove floorboards.

Water Resistance

 S1: S1 adhesives offer good water resistance and can be used in wet areas like bathrooms and kitchens.

 S2: S2 adhesives provide higher water resistance and are ideal for submerged or permanently wet areas, such as swimming pools. Also can help with frost resistance

Bond Strength

S1: S1 adhesives offer a strong bond and are suitable for most standard tiling applications.

S2: S2 adhesives provide an exceptionally strong bond and are often used for heavy or large format tiles.

Use Cases

S1: S1 adhesives are versatile and can be used in various tiling projects, including wall and floor tiling, indoors and outdoors.

S2: S2 adhesives are typically reserved for more demanding applications, such as commercial projects or areas with extreme conditions.

Cost

S1: S1 adhesives are generally more cost-effective and suitable for most residential tiling projects.

S2: S2 adhesives are usually more expensive due to their specialised properties, making them a choice for specific, high-performance applications.

Some of the most popular S2 tile adhesives include:

S1 tile adhesives include: