Why use Slate and Tile Roofing for your Concrete Tile Roof?

Our concrete tile roof installations are second to none but we go one step further than the rest.

  • Each and every time you get a roof underlay of the highest quality available. You will find many contractors not using any roof underlay as building code says it is not required above 25 degrees!!! In our opinion the roof underlay is a secondary barrier and should always be installed.
  • On replacement roofs old battens are removed and new battens installed, again many of the cheaper prices will be because old battens are not removed.
  • If you have valley trays on your roof are they getting replaced? Our price includes this.
  • What finish do you expect? Again we do believe we deliver a finish that is not surpassed by any other contractor. We use all the best materials with the best installation techniques.

These are just a few points to consider if you are looking for a roof replacement or new roof installation.

Concrete Tile Roofing

Concrete Tiles are a man made substitute for slate and was formed as a cheaper alternative to using slate for our roofs. There is a wide range of concrete tiles and fittings available. There are interlocking and double lap tile available from several suppliers and cost vary from tile to tile. These tiles are mainly machine made and Concrete tile technology has developed different colours and finishes which replicate the appearance of slate and other traditional roof cover as well as many different colours.

Concrete Tile Roofing Craftsman

On appearance the installation of concrete tile roofs is seemingly easy and a ‘weekend warrior’ may be tempted to have a go themselves because looking from below it just looks like playing with lego on a roof. However with all things that initially look easy it can quite easily become a major disaster and emergency help is required.
I will also say I have seen many concrete tile roofs installed by ‘professional’ tradesman and in all honesty I would not let them tile a dog kennel the work quality is that bad.
With most roof installs you are also looking at flashings being installed and this really does show if a tradesman knows their trade or if they should just get on their horse and ride out of town. Flashings are a major part of any roof as they are at intersections of where roof faces meet and these areas obviously get water channeled to them so they need to be watertight and not reliant on any mastic. As a personal preference I am of the opinion you should always choose a lead flashing as this will simply last the longest of any other flashing material and is never reliant on a mastic for waterproofing. Please view my gallery for examples of lead welded flashings.
Choose your Concrete Tile Roofing contractor carefully because if done right the roof will be correct in installation and watertight for many years.

You may also wish to look at my recent blog regarding Concrete Roof Tiles here

Maintenance of Concrete tile roofs

Mosses and Lichens on Concrete Tiled Roofs

The principal cause of the growth of mosses and lichens on tiled roofs is due to their rough surface that filters dirt out of rainwater. Decaying matter in the form of dead leaves which fall on to the roof, also tend to lodge on the surface. Spores and seeds of mosses and lichens are also blown on to the roof, or get carried there by the feet of birds, and sooner or later take root in the dirt and begin to grow. Inevitably, the surface of some concrete tiles that have a sanded or granule facing, are the first to attract moss growth.

Moss tends to flourish on roofs where trees are nearby and where there are shady, damp conditions. Steeper pitched roofs are less likely to support moss and lichen growth as they shed water more quickly than low-pitched roofs.

The primary effect of moss on a roof is that it holds water. Thus, the flow of water into gutters is slowed down and the water is held on the roof in contact with the tiling for a longer time.

If the mosses and lichens affect the drainage of water down valleys, abutment gutters and the interlocking drainage channels of the roof tiles, they should be carefully removed.

In normal circumstances, the growths are not deleterious to concrete and in some circumstances can impart a mellow and pleasing appearance. In circumstances where they are considered undesirable, there are several methods of removal.

Methods of Removal

Spraying with a Toxic Wash

This is perhaps the least expensive, but very great care has to be taken. Any spray that is toxic to moss can also be dangerous to garden plants in the vicinity of the roof and perhaps to the plants in adjoining gardens. There is also the possibility of ill effects to animals and birds.

Toxic washes take a few days to be fully effective and should preferably be applied during a spell of dry weather, since rain may wash them off before they have had time to act. The action is hastened if thick growths are removed and the wash is well brushed in. Normally, one treatment is sufficient to kill the growths but sometimes repeat applications are necessary. The dead growths will eventually weather off and disappear.

If rapid removal of the dead growths is required this can be achieved by a low pressure jet of water, taking care not to spray against the tile laps. This is a job best suited to experienced and qualified labour using a proprietary toxic chemical. On no account should a high pressure water jet be used to clean off moss and lichen growths from concrete tiles. This will result in erosion of the surface thereby reducing the potential lifespan of the roof tile.

Some toxic washes leave a residue that discourages subsequent growth, but even under favourable circumstances the residual effect is unlikely to last for more than two or three years.

A wide range of toxic washes is available, but care must be taken with regard to Health & Safety and Environmental Regulations.

Copper Wire

A more permanent answer to the problem of maintaining a clear roof can be obtained by trailing copper wires across the roof surface. These can be fixed at intervals up the roof slope, directly below the front edge of the tiles, so that with every shower of rain, the copper slowly oxidises in the atmosphere and provides the roof with a wash of copper salts which prevents renewed growth.


This is not recommended as it can result in broken or damaged tiles and unsightly scrape marks on the surface of the tiles, however carefully the work is carried out. Inevitably the process will have to be repeated in the future as the mosses and lichens return. Generally, moss and lichen growths are not unsightly, and sometimes give a weathered appearance to the roof, but they should be removed if they affect the discharge of rainwater from the roof.


Efflorescence is a general term used in the construction industry, to describe the white deposits found on building materials such as concrete roof tiles, paving blocks, clay bricks, calcium silicate bricks, mortar, concrete etc.

The term efflorescence covers a number of different phenomena and different forms of efflorescence can occur on concrete products as a result. With concrete roof tiles, subtly different reaction mechanisms at various stages of the production process and lifespan of the products can give rise to the formation of calcium carbonate, which appears on the surface of the tiles as a white bloom.

Efflorescence as found on concrete roof tiles is often categorised as lime bloom, which is a deposit apparent either in the form of white patches or as a more general lightening in colour. When the latter effect is seen, it is often misinterpreted as a fading or washing out of the colour of the concrete.

Efflorescence forms more readily when the concrete tile becomes wet and dries slowly and therefore there are more occurrences during the winter. It is also generally only likely to occur in the early life of concrete roof tiles and materials installed for a year or more without experiencing lime bloom, are unlikely to be affected in the future.

Perhaps the most important factor for the specifier, builder and property owner is that the natural weathering process gradually removes efflorescence on concrete tiles. This natural removal restores the original colour of the product and in no way affects the products impermeability, or continuing strength growth with age.

Efflorescence may sound like a complicated chemical phenomenon, but in reality, it is merely a superficial characteristic feature of quality concrete roofing products.

Maintenance Check-list For Concrete Tile Roofs

  • Look for signs of any cracked or broken tiles caused by possible impact or wind damage. Check the security of all vertically tiled surfaces, particularly beneath window openings, where ladders may have damaged flashings and tiles
  • Inspect inside the loft space for signs of dampness, which may be caused by a cracked or broken tile or defective valley gutter. Check the roof underlay for any holes which might allow moisture to penetrate to the roof structure and ceiling. Check for moisture on the back surface of the underlay that may be due to condensation
  • Inspect valleys for deterioration and any damage to raking cut tiles and bedding mortar.
  • Examine top edge and abutment metal flashings for damage and re-fix /re-dress or replace as appropriate
  • Check all vent pipes and other protrusions through the tiled roof covering to ensure that lead collars and flashings are correctly fitted and sealed.
  • Check bedding mortar for cracks caused by roof settlement or shrinkage. Re-bed or replace ridge or hip fittings and mechanically fix if required.
  • Clear all eaves / back gutters of leaves and other debris and check free flow of water to rainwater outlets.
  • Cut back overhanging trees or foliage that may impair roof drainage or cause damage to the roof covering during a storm. Check the security of all aerials and roof accessories.
  • Clear all ventilation grilles and terminals of dust and debris that may block the ventilation path.
  • Clear mosses and lichens that affect the free flow of water from the roof.