Which adhesive is best for porcelain tiles?

Porcelain tiles have a very low absorption rate, so you must use a high-quality polymer-modified powder adhesive (usually C2 rated). Ready-mixed adhesives are generally not suitable for porcelain or large format tiles as they rely on evaporation to set, which is blocked by the non-porous tile.

Do I need flexible grout?

If you are tiling onto a surface that may experience slight movement—such as plywood or chipboard floors, or walls with underfloor heating—you should always use a 'flexible' or 'S1/S2 rated' grout and adhesive to prevent cracking.

How long does tile adhesive take to dry?

Standard set powder adhesive usually takes 12-24 hours to cure before you can grout. Rapid-set adhesives can often be grouted in as little as 3 hours, which is ideal for floor projects where you need to get back into the room quickly.

What trowel size should I use?

For standard wall tiles, a 6mm square-notched trowel is common. For larger floor tiles (300mm+), an 8mm or 10mm trowel is recommended to ensure a deeper bed and better coverage. Large format tiles (600mm+) may require a 12mm trowel and back-buttering.

Which adhesive is best for porcelain tiles?

Porcelain tiles have a very low absorption rate, so you must use a high-quality polymer-modified powder adhesive (usually C2 rated). Ready-mixed adhesives are generally not suitable for porcelain or large format tiles as they rely on evaporation to set, which is blocked by the non-porous tile.

Do I need flexible grout?

If you are tiling onto a surface that may experience slight movement—such as plywood or chipboard floors, or walls with underfloor heating—you should always use a 'flexible' or 'S1/S2 rated' grout and adhesive to prevent cracking.

How long does tile adhesive take to dry?

Standard set powder adhesive usually takes 12-24 hours to cure before you can grout. Rapid-set adhesives can often be grouted in as little as 3 hours, which is ideal for floor projects where you need to get back into the room quickly.

What trowel size should I use?

For standard wall tiles, a 6mm square-notched trowel is common. For larger floor tiles (300mm+), an 8mm or 10mm trowel is recommended to ensure a deeper bed and better coverage. Large format tiles (600mm+) may require a 12mm trowel and back-buttering.

Grout & Adhesive Calculator

Calculate precise material requirements for professional tiling.

Tiling Area (m²)

Tile Size (mm)

Thickness (mm)

Joint Width (mm)

Adhesive Bed (mm)

Material Weights

Pro Tip: When using large format tiles (over 600mm), we recommend **back-buttering** each tile with a thin layer of adhesive in addition to the trowelled bed on the wall or floor. This ensures 100% coverage and prevents hollow spots that can lead to cracking.

The Perfect Bond: UK Tiling Science

Powder vs Ready-Mixed

Choosing the right adhesive is just as important as the tiles themselves. While ready-mixed tubs are convenient for small ceramic wall tiles, almost all modern professional tiling (especially floors and porcelain) requires powder-based adhesives mixed on-site.

Our **grout and adhesive calculator** helps you avoid the common mistake of underestimating material weight, which can lead to multiple expensive trips to the trade counter mid-job.

Typical Coverage Rates

6mm Trowel (Wall)~2.5kg per m²

10mm Trowel (Floor)~4.5kg per m²

Joint Grout (3mm)~0.5kg per m²

Joint Width & Aesthetics

Joint width isn't just about looks; it's a technical requirement. Grout joints allow for slight thermal expansion of the tiles. In the UK, the minimum recommended joint for walls is **2mm** and for floors is **3mm**.

Wider joints (5mm+) are often used with traditional 'quarry' tiles or rustic slate to hide variations in tile size, but they will significantly increase the amount of grout required.

Bag Logic

Adhesive is typically sold in **20kg bags**. Grout is usually sold in smaller **2.5kg, 5kg, or 10kg bags**. Our calculator rounds up to the nearest bag size to ensure you have enough to complete the job including a small amount of waste.

Tanking Wet Rooms

In showers and wet rooms, grout is **not waterproof**. You must install a waterproof 'tanking' membrane behind the tiles to prevent moisture from seeping into the walls and causing structural rot or mould.

Pro Tip: Mixing Small Batches

Always add powder to water, not water to powder. This prevents dry clumps at the bottom of the bucket. Only mix as much as you can use in 30-45 minutes (the 'pot life') to avoid the adhesive setting in the bucket before it's on the wall.

Tiling Material FAQ

Project Disclaimer

Material coverage varies between brands and depends heavily on the flatness of the substrate. This calculator provides an estimate based on standard industry averages. Always refer to the manufacturer's specific instructions on the bag for precise coverage data.