When restoring concrete roof tiles the age and condition of the tiles is important. The most common types of roof tiles are listed below.

4.1 OLD TILES, HAND AND MACHINE MADE, POOR CEMENT COMPACTION

Due to loose compaction and poor original coating thickness and quality, these tiles absorb large amounts of water and will break easily. Re-roofing may be required if the tiles are not restored at some stage.

The tiles are very rough and definitely require sealing prior to coating. Two top coats alone may not provide a consistent glossy finish.

Seal these tiles with GP Primer or Master Sealer, and top coat with a minimum of two coats of Colourfast, Nuflex, Tileflex 2000.

4.2 OLD TILES, MACHINE MADE, WELL COMPACTED CEMENT SURFACE

Due to the solid construction of these tiles they are generally quite strong, and are very suitable for restoration. Examples of these tiles include headlocks and some bungalows.

These tiles are usually very rough after cleaning and will require sealing and at least two coats to achieve an even glossy finish.

Seal these tiles with GP Primer or Master Sealer, and top coat with a minimum of two coats of Colourfast, Nuflex, Tileflex 2000.

4.3 MACHINE MADE, WELL COMPACTED, WITH A POWDERY OXIDISED SURFACE

These tiles are generally very strong and the concrete base will last a lifetime. They are the most common types of tiles, but they are difficult to repair because they have a very unstable powdery oxidised surface.

These tiles MUST be primed with a penetrating coating which is saturation applied to bind the powdery surface to the tile and prevent coating delamination. It is very important to apply a thick coating to guarantee adhesion and ensure a durable finish.

In hot weather it is recommended that the tiles be sprayed with cold water just before priming to cool the surface and assist the primer to penetrate into the tile surface. Mist spraying a primer, in particular on a hot day, may result in coating failure.

Prime these tiles with one saturation coat of NuPrime, and then apply of two coats of Colourfast, Nuflex, Tileflex 2000.

4.4 NEW TILES UP TO FIVE YEARS OLD - SEALED GLOSSY SURFACE

These tiles have a smooth stable surface and often still have the original glossy factory applied coating. Due to the glossy surface, coating adhesion can be difficult to achieve.

Nutech has developed an adhesion promoted primer for these tiles called GP Primer.
It is recommended that these tiles are primed with GP Primer and subsequently top-coated with two coats of Colourfast, Nuflex, Tileflex 2000.

4.5 METAL SHEET ROOFING

After cleaning, replace badly rusting sheeting, carefully checking overlaps and joints. Remove scale from the surface rust areas using a wire brush or corrugated wire broom. Work Rust Converter thoroughly into any patches of rust to neutralise it, whereupon it should go black. Thoroughly rinse with clean water, no longer than 3 hours after application.

WARNING: Rust Converter is a mild acid and should be handled carefully avoiding contact with skin or clothes.

Do not apply any coatings on a hot surface. A surface temperature in excess of 30 Degrees Celsius may damage the coating and affect surface adhesion.

Apply one coat of Anti-Corrosive Metal Primer followed by two coats of Colourfast, NuFlex, TileFlex 2000.

4.6 ASBESTOS AND CEMENT SHEET ROOFING

To remove moss, lichen, and mould apply one saturation coat of Hypo using a watering can or backpack sprayer. Saturate the surface and leave for a minimum of one hour. Do not apply in direct sunlight.
Disconnect all downpipes from the guttering system. If possible leave for 24 hours before cleaning the surface using low pressure water pressure and a soft broom. It is illegal to high pressure clean an asbestos sheet roof.
Cement sheeting may be cleaned with a high pressure water blaster.

WARNING: Hypo is a strong alkaline chlorine solution. Avoid contact with skin and clothing and avoid breathing vapours. Hypo can also make the surface slippery so care should be taken when walking on the roof.

Unstable fibrous asbestos surfaces require priming with one coat of Asbestos Sealer, which is formulated to penetrate into the asbestos and "lock" it down. On surfaces in particularly poor condition it is recommended to apply a build coat of either Waterproof Membrane, NuBond, or GP Primer as the next coat; followed by one coat of Colourfast, Nuflex, Tileflex 2000. More stable surfaces may just be over-coated with two coats of Colourfast, Nuflex, Tileflex 2000.

On stable cement sheet surfaces apply one saturation coat of NuPrime, and then two coats of Colourfast, Nuflex, Tileflex 2000.

4.7 TERRACOTTA TILES

To remove moss, lichen, and mould apply one saturation coat of Hypo using a watering can or backpack sprayer. Saturate the surface and leave for a minimum of one hour. DO NOT apply in direct sunlight. If possible leave for 24 hours before cleaning the surface using low pressure water pressure and a soft broom.

To obtain a high gloss finish, apply two coats of TerraGlaze on unglazed or semi-glazed terracotta tiles.
Coating of glazed and highly vitrified non-porous surfaces with TerrGlaze is NOT recommended.

WARNING: Care should be taken when determining the level of glaze on a tile as the definition of 'semi-glaze' is a grey area. Also, highly vitrified surfaces can appear porous and easily glazable, where in actual fact adhesion to them can be difficult.

To waterproof all types of terracotta, including unglazed tiles, without changing the appearance (ie glaze finish), apply two to three saturation coats of Silicon Sealer.

4.8 EXISTING PAINTED SURFACES

If the existing coating is stable and has good adhesion, apply two coats of Colourfast, Nuflex, Tileflex 2000.

If the coating is flaking or stability is uncertain, remove all loose coating under high pressure water cleaning, before applying one coat of Waterproof Membrane followed by two coats of Colourfast, Nuflex, Tileflex 2000.

WARNING: It is important to remember that adhesion of the original coating cannot be guaranteed in all circumstances.