Over the past twenty years, the choices offered have become much more diverse in terms of roof coverings. To find your bearings, first of all, there are two categories: roofing for sloped roofs and flat roofs. We have already discussed previously the essential role played by the roof.
Conventionally, for roofs with a steep slope, there is a cover asphalt shingle or sheet steel (Canadian roof). On the other hand, roofs with a slight slope are often covered with an asphalt and gravel membrane.
In general, large buildings (concrete or steel) such as condominium buildings or commercial and industrial buildings have flat roofs with asphalt and gravel surfaces or, for some, an inverted membrane such as Hydrotech membrane. The inverted roof designates the flat roof whose sealing is placed on the support and whose insulation is placed on the waterproofing. We also find the EPDM and TPO membrane.
Asphalt and gravel or elastomer coating
Very popular for a long time, the membrane asphalt and gravel still has a significant disadvantage, namely a relatively short life in case of lack of regular maintenance on an annual basis. In fact, in recent years, the life of this type of membrane has decreased significantly, in some cases, because of poorer asphalt quality.
For many years now, elastomeric roofing (modified bitumen) has been replacing, more and more, asphalt and gravel roofing, because the elastomeric membrane has a longer life than the latter. In addition, this elastomeric membrane requires little maintenance work.
For this reason, the elastomeric membrane has become a preferred choice for condominium buildings and commercial buildings with flat roofs. It is the same for small wooden buildings and houses.
Installation methods (elastomeric membrane)
There are two methods of installation for the elastomeric membrane, either the conventional way or the installation of an inverted membrane.
- Conventional roofing: this type of durable and aesthetic coating consists of two layers, a bitumen base and a topcoat (with granules) that protects against the sun's rays. In a conventional roof covering, the insulating material is located below the sealing layer.
- Inverted roof: the waterproofing membrane is completely protected by insulation and gravel. Thus, the insulation is installed over the elastomeric membrane and adds the geotextile membrane which is then covered with a ballast (gravel).
Case Study (Montreal Realization)
We undertook a comprehensive study of a residential building of several condominiums struggling with water infiltration issues. The flat roof consisted of a concrete slab and the roof had reached the end of its useful life. As part of this project, we conducted a budget study. In discussing with the syndicate of co-owners all the possibilities, it has therefore fixed its choice on an inverted elastomeric membrane. SOPREMA's products have been selected to produce this elastomeric membrane.
The steps of our roof study:
- Analysis relating to recurrent problems ofwater infiltration, to top-floor units, from the roof - We conducted our verification, using an infrared camera, to capture thermal images to locate moisture in the roof;
- Breakthrough exploratory holes about parapets in several locations - These exploratory sections demonstrated that the structure of the parapet had undergone significant deterioration, either inside the steel sheets. In addition, the installation of this parapet had not been made according to the rules of art. This defect in the installation of the parapet caused more water infiltration to the units on the top floor;
- Breakthrough exploratory holes in the membrane existing roof in many places that could be constantly wet - This allowed us to see that the slope of the slab was incorrect and unacceptable in some places, because there was standing water on the slab. Thus, a correction of the slope of the slab was essential at the places in question to ensure adequate drainage of the roof;
- Holding a explanatory meeting with the condominium syndicate to explain the condition of the roof and parapet and associated problems - The union later opted for the replacement of the existing membrane and the repair of the parapet;
- Achieving a roof lift in order to locate all the devices overlooking it - This is to make an exact plan to calculate the area and quantities of materials needed to remake the roof and parapet.
- Production by thebuilding engineer de plans and technical specifications required to complete the study of the replacement of the existing roof with an elastomeric membrane - The technical specifications included, among others:
at. The scope of work;
b. Existing deficiencies (at the time) in the concrete slab supporting the roof;
c. Deficiencies in the parapet;
d. Corrective plans for the slope and parapet;
e. Descriptions of the materials of the elastomeric membrane;
f. Execution of works with details;
g. Inspection during roof replacement work;
h. Final inspection after completion of the work.
- Preparation of tender documents (submission) by inviting several contractors considered qualified to perform this type of installation;
- Choosing a contractor according to several criteria and coordination meeting with the engineer and the on-site contractor;
- Work supervision during the execution of the elastomeric membrane work - The engineer must make numerous visits at all the essential stages of the installation.
The engineer referred in his plans and specifications to the documents of theAMCQ (which is the Association of Master Roofers of Quebec) and the directives of the manufacturer of the membrane SOPREMA.