In the world of co-ownership, managing and maintaining common portions represent a constant challenge for boards of directors. Among the most critical and costly elements is the rehabilitation of flat roofs. Choosing the right contractor for these works is a crucial decision that can heavily impact the co-ownership’s budget. Boards of directors often struggle to evaluate the skills and reliability of potential candidates. A poor selection can lead to additional costs and delays, exacerbating the initial problems and ultimately compromising the quality and longevity of the repairs.
The durability of a flat roof largely depends on two factors: adequate ventilation and proper maintenance of the drains. Insufficient ventilation can lead to major issues such as moisture buildup and mold formation, while stagnant water on a flat roof can cause leaks and structural damage.
Adequate ventilation is fundamental. Without proper ventilation, heat and humidity can cause problems. Excessive heat can dry out the frame and cause cracks, while too much humidity can lead to condensation and frost formation in cold weather, rust nails, and darken the sheathing. It is essential to install insulation properly to meet energy efficiency standards, and excessive humidity can promote mold growth.
As shown in this photo, inadequate ventilation can lead to major issues on the roof sheathing, notably mold formation. When ventilation is insufficient, humidity accumulates, creating an environment conducive to mold growth. These molds can weaken the wooden structure, cause health problems for occupants, and reduce the durability of the roof. Ensuring adequate ventilation is essential to evacuate moisture and maintain a dry and healthy environment above the roof sheathing.
Stagnant water on a flat roof can cause numerous serious problems. It increases the risk of leaks and infiltrations, potentially damaging the roof structure and causing mold. Stagnant water also puts additional pressure on the membrane, reducing its durability and increasing maintenance costs. Additionally, stagnant water promotes the growth of undesirable vegetation, which can clog drains and worsen drainage issues. To avoid these consequences, it is essential to ensure a proper slope and good drain maintenance. Regular inspections are also recommended to quickly detect and correct any water accumulation problems. By taking these measures, the roof’s lifespan can be extended, and the building's integrity protected.
When rehabilitating a ventilated flat roof, several aspects must be considered to ensure its durability and watertightness.
Choice of insulation
There are several types of roof membranes, each with its advantages and disadvantages. Here are the main options and factors that can affect their lifespan.
Roof rehabilitation entails significant costs. The involvement of an architect is essential to ensure the quality of the work, the materials used, and to obtain a realistic cost assessment. The architect prepares the plans and specifications to ensure that contractors bid on the same basis, and supervises the progress of the works to guarantee compliance and respect for costs. They issue the completion certificate after a final inspection and ensure that the contractor provides the necessary warranties.
The contractor must possess the necessary technical skills, be knowledgeable about industry standards and regulations, and hold the required certifications and liability insurance.
While flat roofs offer advantages in terms of cost and space utilization, they require particular attention to water management, ventilation, and insulation to prevent infiltration problems and ensure their durability. Additionally, flat roof rehabilitation is complex and demands careful attention to many details to ensure longevity. Collaboration with an architect facilitates the progress of the works and ensures their quality. Rigorous annual maintenance is also essential to prolong the roof’s lifespan.
For any additional information, please do not hesitate to contact us.
Georges Fallah, Architect
Member of the Quebec Order of Architects (MOAQ)
President of G.A.P.Immeubles inc
Tél. : (514) 946 8807
Fax : (450) 478-4932
Courriel : [email protected]
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