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L'auteur étudie les toits à pente forte et à pente faible, les toits inondés et les toits-terrasses. On ne peut pas normalement construire un toit parfaitement plat; les fléchissements de la charpente entraînent inévitablement des pentes. Il est préférable de prévoir des pentes en vue de l'évacuation de l'eau. L'inclinaison minimale pour les parties principales du toit serait d'environ un quart de pouce à choque pied, mais une pente plus grande est préférable. Lorsque le mode de drainage est du genre tôle pliée, il importe de placer des dossiers à la jonction des surfaces plus grandes afin de détourner les eaux vers les drains. Lorsqu'un toit exige un drainage réglé ou un refroidissement par évaporation, une couverture inclinée présente moins de risques qu'un toit-terrasse. Dans les toits à membrane protégée, la membrane principale sur le plancher sous l'isolant et les matériaux d'aménagement devrait être à un angle, continue et scellée à la jonction de toutes les pénétrations.

In the last 20 years several new types of roofing material have been introduced to the construction industry, including various inorganic and organic materials and their combination, generally prefabricated. This paper deals only with single-ply membranes made from such materials as flexible polyvinyl chloride (PVC), elastomers, that is polyisobutylene (PIB), ethylene propylene diene monomer ( EPDM), hypalon (CSPE), and other rubber and rubber-like materials and reinforced modified bitumens. As there is need for criteria to facilitate appropriate selection and for specifications to ensure proper application, several test methods have been evaluated that assess physical, mechanical, and weathering properties of single-ply membranes. Some have been incorporated in the Standards of the Canadian General Standards Board (CGSB). Some of the more important tests include those for lap-joint performance, dimensional stability, water absorption, stress- strain properties, low-temperature flexibility, static and dynamic puncturing, load-twist, and the so called wheelbarrow test., Symposium on Single-Ply Roofing Technology: 24 June 1981, Detroit, MI, USA

Worldwide, there are more than 40 tests to assess the properties of nearly 400 conventional and new roofing products that exhibit wide ranges in a given property. New roofing materials can be divided into six distinctly different groups: 1. Hot applied rubberized asphalts; 2. Cold applied liquid membranes; 3. Prefabricated elastomeric sheeting; 4. Flexible polyvinyl chloride (PVC) membranes; 5. Prefabricated, reinforced, modified bituminous membranes; 6. Sprayed polyurethane with weather-resistant top coats. Each of these groups has its own specific characteristic properties that must be taken into consideration at the design stage. Test procedures were selected or, where necessary, developed to quantify properties before and after subjecting the materials to accelerated exposure conditions. This paper highlights the state of evaluating new roofing materials and describes test methods for this task. The concept and rationale of selecting tests for the different types of membranes and the tentative limits for various properties are discussed., Proceedings of Second International Symposium on Roofs and Roofing: 1981

On étudie d'abord différents genres de toits. Il importe de noter que la fiabilité d'un toit à membrane protégée est liée à une seule membrane qui empêche le passage de la vapeur d' eau aussi bien que de l'eau. Cette membrane doit être continue et imperméable à l'eau dès la mise en place et tout au cours de sa durée de service. Elle se trouve dans un milieu favorable quant à la température et au climat et dure ordinairement plus longtemps que l'isolant, qui peut se détériorer considérablement avant que la membrane soit atteinte. On peut prolonger la durée de l'isolant par des mesures de drainage et d'évaporation de l'humidité quelle qu' en soit la source.

Steeply sloped roofs, low sloped roofs, flooded roofs and roof terraces discussed. A perfectly flat roof cannot be achieved in normal construction and slopes will inevitably develop owing to structural deflections. It is better to build in slopes to control water on a roof. The practicable minimum for main roof areas is about 1/4 inch per foot, and greater slope is desirable. Where drainage is achieved by a folded plate type of arrangement, crickets should be placed at the intersection of the larger slopes to direct water to the drains. When controlled flow drainage or evaporative cooling are required on roofs, a sloping roof produces a less hazardous condition than a flat roof. For protected membrane type roofs, the principal membrane at the deck below insulation and landscaping should be sloped, continuous and sealed round all penetrations.

Different roofing systems discussed in the opening paragraphs. It must be realized that the performance of a protected membrane system is related to a single membrane that serves as both air vapour barrier and water barrier. It must be continuous and waterproof from installation throughout its service life. It is in a favourable environment in relation to temperature and weather and will usually outlast the insulation, which can largely deteriorate before the membrane will be affected. The life of insulation can be extended by designs that allow for drainage and evaporation of moisture from all sources.