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ROOF COVERINGThe choice of covering material for your roof will often be determined by the shape of the roof: pointed, flat or even rounded. Unfortunately, this choice does not always lie with us …

At present, architects are happy to use flat roofs, because they allow more possibilities in terms of creativity and layout of sub-ridge pieces. In Flanders, where the trend in the building sector is dominated by small farms, open flat roofs are particularly popular.

The architect and the owner can not always do what they want. Indeed, in the centers of villages and cities, as in housing estates, they must respect certain urbanistic prescriptions. These also concern the shape, the height, and even the covering material. The state wants to avoid that the urban image becomes too chaotic.

A flat-roofed house in a row with only sloped roofs, or the opposite, is all but happy. A house with a roof covered with tiles located between several houses with slate roofs is not much better. In some Walloon municipalities, obtaining a permit for a flat roof is almost a miracle!

In the case of flat roofs, the material must be waterproof; the choice of materials is therefore limited. By cons for sloping roofs, the choice is much larger. The aesthetic aspect does not come into play for flat roofing because the covering is rarely visible from the ground floor or from the inhabited part of the house.

Unlike tiles, for example, roof waterproofing materials do not exist in many colors and designs. Update on the main roofing materials:

Sloped Roofs


Tile manufacturers spontaneously grant a thirty-year guarantee on natural qualities. In case of renovation, it is not even necessary to recover the old tiles weakened. There are new, high-quality tiles on the market that have been specially treated to look aged. In recent years, more and more tiles have been used to dress vertical facades.

In a humid and wooded environment, an enameled tile is preferably used. Thanks to this layer of enamel, tiles are less sensitive to the formation of mosses, algae, and molds. An enameled tile dries more slowly than an ordinary tile. Inquire during the purchase as to its frost resistance (warranty).

Other surface treatment: engage. In this case, the dry tile, not yet fired, is sprayed with a suspension based on clay, to which was added coloring oxides. During cooking, this layer of engobe grés in the surface of the tile, which gives it a matt or satin appearance.

Both for the ridge and the side panels, there are many accessories such as connection modules for ridge, triangular roof panels and others. The higher the number of accessories, the more the final score will be affected.

Concrete Tiles

Concrete tiles are not fired. The mixture of clay, cement, and sand hardens like concrete. These tiles are available in large sizes and are therefore a little cheaper. Because of their weight, however, they require a stronger frame. They are not suitable for roofs with complex shapes and are generally more sensitive to foaming.

Natural slates

Natural slates are among the most durable and expensive roofing roofs. But a beautiful slate roof can defy the centuries. As is the case with any natural product, the quality of the slates is not always equal. The presence of quartz crystals on the surface and the calcium carbonate content play a role.

Artificial slates

Artificial slates consist of a mixture of cement, reinforcing fibers and minerals. The surface layer has anti-foaming properties and on the back, an acrylic resin is applied. In addition to the classic shades of natural slates, artificial slates are also available in green, pink, dark blue and mauve shades.

Most manufacturers grant a thirty-year warranty on natural properties and fifteen years on color. There are artificial slates on the market that have uneven surfaces and fluted edges. They are hardly distinguishable from natural slates, but they are deformable. Despite the improvement of the product, artificial slates are still subject to the formation of foams.

Thatched roof

A thatched roof has advantages and disadvantages. Thanks to a whole series of tips and products, the fire safety of a thatched roof have been significantly enhanced. Thatch has excellent insulating properties but is more expensive than tiles. There is no gutter, however, and the house is surrounded by a ring of moisture, usually pebbles with a drainage system from below, to prevent the formation of muddy puddles. Stagnant water is the sworn enemy of stubble. It is for this reason that strawberries prefer a steeply pitched roof.

Thatched roofs are not suitable for houses that are constantly in the shade, given the risk of algae formation. If you choose stubble, be patient. Specialized professional enterprises are hardly numerous. The thatched roofs are out of date and the straw roof is gone.


Zinc is a growing success, especially with architects, because it lends itself better to rounded shapes than any other material. A zinc roof is relatively light and therefore does not represent a heavy load for the roof structure.

Caution: Gutters and downspouts must be run in the same materials as this may create electrochemical reactions.


Steel tiles exist in classic formats. But we usually use large  plates whose relief mimics the real tiles. These plates can be, in principle, canary yellow or sky blue. In practice, we find mostly the same colors as tiles or slates.

Large plates are easy to process and inexpensive, but sophisticated shapes are excluded. This material is perfect for a renovation. The existing roof can remain as it is and the steel roof is placed over it. The steel is galvanized and coated with a coat of paint and stone aggregates.

Other materials

Roofs can be covered with other materials, but their use is still limited in our region: copper (instead of zinc), aluminum (instead of steel). In Canada, wood shingles (sheets of covering material) rarely meet but are safe values in North America.

There is still corrugated sheets of original cement fiber but only on garden huts old as the world. The current ranges are much more elegant thanks to their acrylic coating and anti-foam treatment. It is a relatively inexpensive material, but it is less suitable for sophisticated roof shapes. The advantageous price is especially important for supermarkets.

For tight budgets, there are asphalt shingles. These are cheap except that their lifetime is well below that of other materials.

Flat Roofs

The ‘Roofing’

Most roof waterproofing layers consist of bituminous products, commonly referred to as “roofing”. Both bitumen and additives to enhance the elasticity and strength of the material are made from crude oil. The roofing rollers consist of bitumen reinforced with a layer of aluminum, polyester or a glass membrane and a rough finish layer based on sand, slate scales or even chippings. The rolls can be laid in one or more layers. The bitumen layers can be glued or welded to each other.

Bitumens are often referred to as ‘plastomers’ or ‘elastomers’. A plastomer bitumen never resumes its original shape. An elastomeric bitumen, on the other hand, moves. It is more resistant to cold but less well UV.

Synthetic membrane

For the waterproofing of the roof, various synthetic products have been developed. Of these, PVC, EPDM and TPO. Synthetic roof sealing rollers are available with or without reinforcement and are installed in a single layer. To fix them, we proceed by welding, vulcanization or gluing.

EPDM is a synthetic rubber. It offers good resistance to UV rays as well as to mechanical loads caused by frequent passages. If it is made to measure and delivered in one piece, it will be very sensitive to dilation. It is then necessary to provide seals around the periphery to absorb this expansion. During the 1980s, PVC experienced a remarkable growth thanks to its strength and its laying in a single layer.

The use of TPO (thermoplastic polyolefin membranes) has been growing in popularity recently. It has the same strength, durability, and possibility of thermal welding as PVC, without the environmental disadvantages of the latter (chlorinated particles and plasticizers).

Recently, a polyester coating, which is in the form of a liquid, has been developed. It is particularly suitable for surfaces with many notches such as terraces, but also balconies.

The vegetation

Some plant species suitable for green roofs are available as precultivated vegetation mats. Extensive roofing is a combination of sedums (succulents), herbs and flowers. This formula requires little maintenance. As for the ‘intensive’ green roof, it is a real roof garden with trees and lawn to mow regularly. This type of green roof requires a heavier building. Extensive roofs cannot be trampled. They are the most common because they are much cheaper.

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