FAQs Answered by our Tile Layers

Tiling experts

Tiling FAQs

How much wastage should be allowed when ordering tiles?

If the area is fairly regular in terms of overall dimensions, 10% extra should be enough. However, if the tile in question is an unusual shape, or the area to be tiled is a complex shape then 15% is probably a better figure. Having a few spares is a good idea, because if you need more of the same shade (batch number) it may not be available.

What are tiles made of?

Tiles consist of mineral raw materials, primarily silicon and aluminium. Plastic raw materials are clays and kaolin; hard materials are feldspar, quartz, chalk and dolomite. As a result of the firing process the tiles no longer contain any organic compounds, which mean that they do not represent a health risk (the ideal covering for people who suffer from allergies). For more info visit https://www.regaltiling.nz/2018/05/24/how-are-tiles-made/

What is the difference between Ceramic and Porcelain Tile?

In short – Porcelain Tile is impervious and has a water absorption rate of less than 0.5%. Ceramic Tile is anything with a higher absorption rate.

What are rectified tiles?

When tiles are being kiln dried there can be differential shrinkage. To “rectify” the size variations between tiles, they are cut or grinded, processes which produce tiles with very precise dimensions and permit installation using narrow grout joints.

What is a Full bodied tile?

A Full bodied tile is when the surface colour of the tile goes through the entire body of the tile, meaning when you look at the back of the tile it will be the same colour as the face of it. Therefore the edges of the tile can be polished and provide a great looking finish. Full bodied tiles are very hard wearing, also should your tile chip it will be less obvious than a ceramic or standard porcelain tile.

How much do tiles weigh?

These weights are only intended for a guide; to get an exact weight the particular tile must be weighed

Tile thickness and type Weight per m²(approx)without adhesive
6mm Ceramic 14.5 kg
8mm Ceramic 18 kg
10mm Ceramic 21 kg
12mm Ceramic 24 kg
8mm Porcelain 20 kg
10mm Porcelain 24 kg
12mm Porcelain 28 kg
10mm Natural stone 31 kg
12mm Natural stone 36.5 kg
20mm Natural stone 58 kg

Where can your tiles be used and what is a PEI rating?

PEI classes range from 0 to 5. The Porcelain Enamel Institute rating scale is not a measurement of quality. It is a scale that clearly indicates the areas of use each manufacturer recommends and has designed their tile to fit.

For example a PEI 2 tile has been designed for areas where very low traffic and soiling is anticipated. In most cases the aesthetic detailing of these tiles is of prime consideration. You will often find high gloss levels, vibrant colorations and metallic elements in this group of tile. Conversely, a PEI 5 tile has been designed for abusive extra heavy foot traffic.

The technical aspects such as surface abrasion resistance will be considered and must be achieved first before aesthetic effects are incorporated.

A detailed guide on the ratings

Group 0 or PEI 0 – No Foot Traffic: Wall tile only and should not be used on floors.

Group 1 or PEI 1 – Very light traffic: Very low foot traffic, bare or stocking feet only. (Master bath, spa bathroom).

Group 2 or PEI 2 – Light Traffic: Slipper or soft-soled shoes. Second level main bathroom areas, bedrooms.

Group 3 or PEI 3 – Light to Moderate Traffic: Any residential area with the possible exception of some entries and kitchens if extremely heavy or abrasive traffic is anticipated.

Group 4 or PEI 4 – Moderate to Heavy Traffic: High foot traffic, areas where abrasive or outside dirt could be tracked. Residential entry, kitchen, balcony, and benches.

Group 5 or PEI 5– Heavy Traffic: Ceramic tile suggested for residential, commercial and institutional floor subjected to heavy traffic.

Please note this is for glazed tiles or tiles with a coating only. A full bodied porcelain has no glaze and is very durable.

Which substrates can be tiled over?

Practically every possible background – including concrete render, timber, plasterboard and metal – can be tiled over. Our leading adhesive manufacturers produce a wide range of adhesives for use in virtually every environment, including fully immersed conditions (e.g. swimming pools).

Can I tile over existing tiles?

Yes, it is possible but there are a number of things to consider.

1.The existing tiles must be firmly bonded to the existing background.

2.When tilíng walls, substrate weight limits should not be exceeded.

3.Clean existing tiles thoroughly and de-grease them.

4.Apply a suitable primer, in conjunction with suitable adhesive – contact Regal Tiling Ltd.

How wide should grout joints be?

Many manufacturers of tile recommend narrow tile joints to reinforce the appearance of natural stone which is often laid with 1mm to 2mm grout joints.

Much depends on the flatness of the floor (substrate), if the floor is flat and smooth narrow grout joints can be used.

The recommended grout joint for ceramic floor tiles is 3mm. If the tiles are irregular in size the joint width can be increased to 6, 8 or even 12mm. Special grouts are available for wide grout joints.

Wall tile joint spacing is usually 2mm. Spacer pegs can be used but they should not be left in the joints.

Exterior tiles should have a minimum joint width of 3mm to reduce the tensile stresses induced by any movement of layers under the tile.

How long will tiles last?

The requirements of the New Zealand building code, with normal maintenance, specified to be a minimum of:

  • not less than 5 years for the tiled finish(except where installed behind plumbing fixtures-for this instance a minimum of 15 years durability is required.
  • not less than 15 years for substrate materials generally
  • not less than 15 years for tile waterproofing systems
  • Installed correctly you can expect tile to last 20 years

How can I remove stains from tile?

Whatever method is chosen, remember the three golden rules of cleaning:

Rule 1: Try a small inconspicuous area first

Rule 2: Rinse off well with clean water afterwards

Rule 3: Avoid high concentration of cleaners for prolonged periods of time.

Disclaimer: Regal Tiling Ltd does not accept any responsibility or liability for any damage caused by the following cleaning products. Always follow manufacturer’s instructions!


Type of Stain Compound Detergent
Tomato, Fruit, Chocolate, Sauce Ammonia, Hydrochloric Acid (HCI) 10% Alkaline detergent
Oil, grease, beer, wine, coffee, linseed oil, ice cream HCI 10%, Pottasium Alkaline detergent
Blood Hypochloride, eythlene Alkaline detergent
Rubber sole, tyre Nitric solvent, trichloroethylene, ammonia(HCI)10% Organic solvent
Pencil, shoe polish Trichloroethylene, acetone Organic solvent
Resin, laquer Aqua regia, trichloroethylene, nitric solvent, acetone Organic solvent
Ink Diluted sodium hypochlorite, sulphuric or nitric acid Acid detergent
Cement lumps, efflorescence HCI 10% Acid detergent
Rust HCI, sulphuric acid Acid detergent
Nicotine Citric acid Acid detergent

Will electric undertile heating also heat my room?

This will depend on the U Value of your room. U Value is an industry term for the total measure of resistance of each component that makes up the fabric of the building.

Simply put, this means that old buildings will lose heat faster than modern buildings where the latest materials are incorporated. Under floor heating insulation will go a long way towards offsetting these drawbacks, helping to retain the heat within the room. Underfloor heating acts like a large, low level radiator gently heating the room from the feet up, this requires approximately 15% less energy to feel the same level of comfort experienced using convection heating.

For any other questions, please contact us

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