Method of forming a painted, fibre reinforced bituminous roof coating and roof coating material for use in connection with said method

Description

[0001] The invention relates to a method of forming a painted, fibre reinforced bituminous roof coating on a roof surface comprising bonding to the roof surface a fibre reinforced bituminous sheet material having incorporated therein a first fibre reinforcing layer and applying to the top surface of said sheet material a coat of paint.

[0002] It is well known to produce a roof coating by bonding to the roof surface partly overlapping sheets of a fibre reinforced bituminous material, the fibre reinforcement being incorporated in a bitumen layer.

[0003] The fibre reinforcement may e.g. consist of a glass fibre fleece, polyester fleece, glass tissue, jute tissue or a polyester netting.

[0004] The surface of a coating thus produced is typically covered with a stone granulate consisting of granules of a size of 1-3 mm, the granules being partly embedded in the surface of the coating or with a layer of loose stones of a size of 10-20 mm of a thickness of 2-5 mm. The purpose of the stone layer is i.a. to give the surface a desired appearance and to protect the asphalt underneath against the effect of the light.

[0005] Likewise, it is well known to cover the surface of the bituminous layer with a coat of paint which is applied by spraying after the fibre reinforced bituminous sheet material has been rolled out.

[0006] The coat of paint preferably contains white pigments or aluminum pigments which reflect the sunlight. Such a reflection of the sunlight is important as it contributes considerably to keeping the temperature under the roof at a level which is considerably lower than the temperature under a bituminous roof coating with a black or a dark gray surface. The decrease of the temperature thus obtained plays an important part in case of roofs under which there are rooms which are air conditioned as the said temperature reduction results in substantial energy savings in connection with the air conditioning. Furthermore, the coat of paint provides protection against UV-deterioration of the asphalt layer underneath.

[0007] The application of a coat of paint to a known roof coating of the above mentioned type normally cannot be effected until the top surface of the coating is completely dry and after it has been cleaned as it will usually be coated with sand or powdered with talc to prevent the rolls from sticking together. Furthermore, a coat of paint which is directly applied to the surface of the bitumen layer has a tendency to crack during drying, especially if the desired thickness is to be obtained with as few layers as possible.

[0008] Attempts have been made to overcome this drawback by initially applying a coat of paint, then a layer of fibres and finally another coat of paint. This is a very arduous and costly method which has to be carried out by craftsmen at the building site, and the adherence of the applied coats to the sheet material is still problematic and completely depends on the workmanship including the care shown in connection with the cleaning of the sheet material prior to the application of the paint coats.

[0009] The method of the invention comprises using a fibre reinforced bituminous sheet material having its surface covered with a second fibre reinforcing layer and applying a coat of paint to the second fibre reinforcing layer.

[0010] The invention is based on the discovery that the coat of paint applied to the second fibre reinforcing layer is more resistant to cracking than a coat of paint which has been directly applied to the surface of the asphalt layer.

[0011] Furthermore, when a second fibre reinforcing layer of the above mentioned type is used, there will normally be no need for cleaning the surface of the sheet material prior to the application of the coat of paint.

[0012] The bonding of the second fibre reinforcing layer to the surface of the sheet material is preferably obtained by applying the reinforcing layer while the surface of the bituminous sheet material is hot and sticky during the manufacture in the factory. The result is that the bitumen layer only partly permeates the reinforcing layer and that the non-permeated part of the latter becomes active for maintaining and reinforcing the coat of paint.

[0013] Such an application of the surface reinforcement is easily accomplished in connection with the prodution of the fibre reinforced bituminous sheet material and the sheet material formed is thus ready for use when it arrives at the building site.

[0014] As mentioned, the surface reinforcement serves primarily to improve the adherence of the coat of paint and to reinforce it. However, at the same time it contributes to increasing the strength of the sheet material.

[0015] The surface reinforcement preferably consists of a glass fibre fleece of a weight of about 50-100 g/m² or a polyester fleece of a weight of 50-200 g_/m².

[0016] The invention will now be further described with reference to the following example:

EXAMPLE

[0017] A glass fibre web of a weight of 200 g/m is impregnated with oxidized asphalt of the type 95/30, and a 2 mm thick layer of bitumen containing a filler is applied to the one side of the material thus formed. The surface of the bitumen layer containing the filler is then coated with sand. On the opposite side a 1 mm thick layer of bitumen without filler is applied. After proper cooling, a fibre reinforcement of a glass fiber fleece of a weight of about 50 g/m² is applied to the 1 mm thick bitumen layer. The material is then rolled up in such a way that the glass fiber fleece turns upwards when the material is rolled out on a roof.

[0018] The application of the sheet material to the roof surface is effected by a proper pre-treating (priming) of the roof surface with an asphalt solution in mineral turpentine and by applying about 1.5 kg oxidized asphalt per m² heated to a temperature of about 200°C onto the roof immediately before the above mentioned sheet material is rolled out on the roof.

[0019] The application of the sheet material to the roof surface may also be effected by another known method, e.g. by using viscous asphalt solutions in mineral turpentine containing about 65% asphalt, about 10% fibres and about 25% mineral turpentine or by activating an asphalt layer on the back side of the fibre reinforced sheet material by heating with a gas burner. In addition to adhesion or bonding, the application of the sheet material may be effected by mechanical securing means consisting of a proper number of screws and fixing disks. The joints between the sheets are made water proof by molten bitumen or by another known method.

[0020] Immediately after the application of the sheet material, the top surface thereof may be sprayed with a coat of acrylic resin paint in an amount of about 300 g/m². After the paint has dried, a film will appear without the cracks which normally appear in connection with spraying said amount of paint in one step on a non-reinforced sheet surface.

[0021] However, painting of the second fibre reinforcement preferably takes place after the sheet material has been rolled out onto the roof surface but may optionally also be effected wholly or partially in the factory so that the sheet material can be delivered to the building site in painted or primed condition, thus allowing one or more coats of paint to the applied to the sheet material after the application to the roof surface.

Claims

1. A method of forming a painted, fibre reinforced bituminous roof coating on a roof surface comprising applying to the roof surface a fibre reinforced bituminous sheet material having incorporated therein a first fibre reinforcing layer and applying to the top surface of said sheet material a coat of paint, characteri- - z e d in using a fibre reinforced bituminous sheet material having its top surface covered with a second fibre reinforcing layer and applying a coat of paint to the second fibre reinforcing layer.

2. A method according to claim 1, characterized in that the second fibre reinforcing layer is partly embedded in the surface of the fibre reinforced bituminous sheet material.

3. A method according to claim 1 or 2, characterized in that the application of paint to the second fibre reinforcing layer is effected after the sheet material has been rolled out onto the roof surface.

4. A roof coating material for use in connection with the method according to any of the previous claims and comprising a fibre reinforced bituminous sheet material having incorporated therein a first fibre reinforcing layer, characterized in that a surface thereof is covered with a second fibre reinforcing layer.

5. A roof coating material according to claim 4, c h a - racterized in that the second fibre reinforcing layer has been primed or provided with a paint coat.