Grout might seem like a minor detail, but choosing the wrong type can lead to staining, cracking, or even water damage behind your tiles. Whether you're retiling a bathroom, kitchen splashback, or outdoor area, understanding the difference between epoxy grout and cement grout will help you get a result that lasts. Here's a straightforward guide tailored for New Zealand conditions.
What Is Cement Grout?
Cement grout (also called cementitious grout) is the traditional, most widely used type. It's made from a blend of Portland cement, sand (for wider joints), and sometimes pigments. It comes as a powder that you mix with water, or as a pre-mixed paste.
Cement grout is available in two main forms:
- Unsanded grout – used for narrow joints (generally under about 3 mm). Smooth texture, ideal for polished or delicate tiles.
- Sanded grout – contains fine sand for wider joints (generally 3 mm and above). More resistant to shrinkage and cracking.
You'll find cement grout from brands like Ardex and Mapei at most NZ tile and building suppliers.
What Is Epoxy Grout?
Epoxy grout is a two- or three-part system made from epoxy resins and a hardener (and sometimes a filler powder). When mixed together, a chemical reaction occurs that creates an extremely hard, dense, and non-porous material. Unlike cement grout, it contains no Portland cement.
Because epoxy grout is non-porous, it is:
- Highly resistant to stains, chemicals, and moisture
- Much less likely to harbour mould or bacteria
- Extremely durable and long-lasting
Epoxy grouts are also available from suppliers like Mapei and Sika, and are stocked at trade and tile specialty stores.
Key Differences at a Glance
| Feature | Cement Grout | Epoxy Grout |
|---|---|---|
| Composition | Portland cement + sand | Epoxy resin + hardener |
| Porosity | Porous (absorbs moisture & stains) | Non-porous |
| Durability | Good | Excellent |
| Stain resistance | Low–moderate (needs sealing) | Very high |
| Chemical resistance | Low | High |
| Ease of application | Easy – beginner friendly | Tricky – sets fast, sticky |
| Cost (as a guide) | Lower cost | Noticeably higher cost |
| Colour consistency | Can fade or stain over time | Holds colour very well |
| Best for | Most general tiling jobs | Wet areas, commercial, food prep |
When to Choose Cement Grout
Cement grout is perfectly suitable for the majority of residential tiling jobs in New Zealand. It's a good choice for:
- Dry areas such as living rooms, hallways, and bedrooms
- Wall tiles in lower-moisture areas
- Budget-conscious projects where cost is a priority
- DIY projects where ease of application matters
One important note: cement grout must be sealed after installation and periodically thereafter to protect it from moisture and staining. This is especially important in NZ's humid climates — think Auckland summers or Northland coastal homes.
When to Choose Epoxy Grout
Epoxy grout is worth the extra investment in situations where performance really matters:
- Showers, wet rooms, and bathrooms – NZ Building Code clause E3 (Internal Moisture) requires wet area construction to prevent moisture penetration. Epoxy grout's non-porous nature is a significant advantage here.
- Kitchen splashbacks and benchtops – resists cooking oils, food acids, and cleaning chemicals
- Outdoor tiling – handles NZ's UV exposure and temperature swings better
- Swimming pools or water features
- Commercial kitchens or food preparation areas where hygiene is critical
- Light-coloured grout joints where staining would be very visible
BRANZ research consistently highlights moisture management as one of the most critical factors in NZ building performance — epoxy grout supports this in wet areas.
Application: What You Need to Know
Cement Grout Application
Cement grout is forgiving and DIY-friendly. Mix to a smooth, lump-free consistency, apply with a rubber float, work it into the joints at an angle, and clean off the excess with a damp sponge before it fully sets. Allow adequate curing time before sealing.
Epoxy Grout Application
Epoxy grout is significantly more challenging to work with:
- It has a limited working time (pot life) — once mixed, you must work quickly
- It is sticky and difficult to clean off tile surfaces, especially textured or porous tiles
- Cleanup requires specific solvents rather than just water
- Temperature affects working time — on a hot NZ summer day, it sets even faster
For epoxy grout, many homeowners find it worthwhile to hire an experienced tiler, particularly for large areas. A qualified tiler will also ensure the installation meets the requirements of NZS 3604 and relevant building code clauses.
Do You Need to Seal Epoxy Grout?
No — one of epoxy grout's biggest advantages is that it does not require sealing. Cement grout, on the other hand, should always be sealed, especially in wet areas. Factor the ongoing cost of grout sealer into your decision when comparing the two options.
When to Call a Professional
While grouting itself is not legally restricted work in New Zealand, the broader tiling job in a wet area often connects to work that is. Waterproofing membranes in showers and wet rooms must comply with NZ Building Code clause E3, and if the work is part of a larger renovation involving plumbing, that work must be carried out by a registered tradesperson licensed by the Plumbers, Gasfitters and Drainlayers Board.
For best results — especially with epoxy grout, large format tiles, or complex wet area installations — it's well worth engaging a qualified tiler. You can find experienced local tilers on tradedirectory.co.nz.