Frequently asked questions about the Joint mixtures category
What is the main difference between cement-based and epoxy grout?
Cement-based: Affordable, easy to apply, and porous. Ideal for most dry living areas but requires sealing in wet zones.
Epoxy Grout: A two-part resin-based grout that is virtually waterproof and stain-proof. It doesn't require sealing and is perfect for showers, kitchen splashbacks, and heavy-traffic floors.
How do I choose the right grout colour?
Matching: Creates a seamless look that makes a room feel larger.
Contrasting: Highlights the layout and shape of the tiles (e.g., black grout with white subway tiles).
Practicality: Mid-to-dark greys are the best for floors as they hide everyday dirt and foot traffic best.
How do I calculate how much grout I need?
The consumption depends on the tile dimensions ($A$ and $B$), thickness ($H$), and the width of the joint ($S$). The general formula for $kg/m^2$ is:
$$\text{Consumption} = \frac{A + B}{A \times B} \times H \times S \times 1.6$$
Where 1.6 is the average density coefficient. It’s always safer to use our online calculator on the product page.
Is standard grout suitable for underfloor heating?
Not all. For underfloor heating, you must use a flexible grout (often marked "flex"). These are polymer-modified to handle the thermal expansion and contraction without cracking.
Do I need to seal my grout lines?
If you use cement-based grout in a bathroom or kitchen, yes. Applying a grout protector (sealer) creates a barrier against moisture and mould. Epoxy grout is non-porous and does not require sealing.
How long should I wait after tiling before I start grouting?
You should typically wait 24 to 48 hours to ensure the tile adhesive has fully cured. Grouting too early can trap moisture, leading to discolouration or a weak bond.
What is the ideal grout joint width?
Standard wall tiles: 2–3 mm.
Large-format porcelain: 1.5–2 mm.
Rustic or quarry tiles: 5–10 mm.
What should I do if my grout has turned black or mouldy?
For cement grout, try a specialized acidic cleaner or a grout refresh pen to restore the colour. If the mould is deep-seated, the old grout may need to be raked out and replaced with a formula containing anti-mould additives.
Can I use grout in the corners instead of silicone?
It is not recommended. Internal corners and joints between walls and floors (or baths) should be filled with sanitary silicone. Silicone is flexible and allows for the minor movement of the building, whereas grout will crack.
Why does my grout look lighter than the sample on the bag?
This usually happens if too much water was used during the mixing or cleaning process, which "washes out" the pigment. Slow drying times or highly porous tile edges can also affect the final shade.