Why, despite the knowledge, decades of experience in the design and construction of flat roofs and the use of increasingly sophisticated materials, do flat roofs still bring doubts and worries to many property owner’s minds? The answer to this question lies in these three factors: Design, Construction and Operation. Very common flat roof problems stem from poor maintenance or a complete lack thereof. Regular maintenance requires flat roofs to be periodically inspected for damage, repaired, cleaned and checked for the functionality of its insulation and waterproofing properties
Design Errors – The cycling through hot and cold seasons deteriorates flat roofs across the Greater Toronto Area year after year. On the surface of a roof temperatures can range from -30 to +80 ° C. They are also exposed to UV (ultraviolet) radiation and several cycles of freezing and thawing. Therefore, the nature and properties of the materials from which the flat roof will be made and insulated with should ensure functionality under these conditions for at least 15-20 years.
Leaks, roof moisture and fungus are the most visible consequences of improper maintenance. Poor insulation promotes heat from escaping through the layers of roofs leading to leaks and flooding from melting ice and snow. This process becomes detrimental to the flat roof and leads to the deterioration and destruction of the membrane, flashings, gutters, downsputs, and melting or falling icicles that add danger your workplace.
Each type of roof should have carried out calculations of temperature and moisture. The aim is to not only select the correct thickness of thermal insulation, but also eliminate the possibility of condensation between the layers of the roof and eliminate conditions conducive to the growth of mold on the ceiling and walls on the inside. These calculations take into account the space around windows, skylights, roof hatchways, etc. These are the places where freezing frequently occurs and are favorable conditions for mold growth. With inadequate ventilation, steam and moisture within the layers cause separation and can be seen visually on the ceiling and wall in the form of streaks and peeling paint coating, which are tell all signs of weakness in the roof’s waterproof seal.
This layer on every flat roof, regardless of its function is crucial. The most common cause of leaks is due to errors by the contractors: lack of knowledge of the technologies used and the lack of a qualified team of employees.
Approaching the problem from the exterior (the “positive side”) seems to make the most sense to many people. It takes a considerable amount of labor to dig down to the base of your foundation wall. Once excavated, any areas in the roof decking or concrete foundation or walls that have been compromised can be repaired with a new waterproofing membrane.
Substitution of Materials
A common mistake is to use “just as good but cheaper” alternatives or materials other than those provided by the manufacturer or chosen and described in the project documentation. The resulting “savings” for the difference in price of material is usually superficial and disproportionate to the cost of any subsequent repairs.
Proper execution of waterproofing usually depends on the use of special equipment. The waterproofing layers can can be mechanically fastened and connected to factories, glued or welded with hot air, fumes, flame or heat-sealed and require the use of different types of equipment. Overheating of the burner flame can cause weight loss in the asphalt’s insulating properties and can be made “stale”. This risk is virtually removed with the use of insulating materials welded by hot gases or hot air. Welding temperatures in this case are too low to permanently damaged the roof waterproofing material.
Some property owners believe that the purpose of the roof, due to the fact that it is flat can be freely changed. Ventilation, HVAC units, television antennas and other rooftop equipment are connected via an internal installation carried out through the ceiling or attic, through which the lead wires are often randomly located. Each of these elements can have a negative impact on the stability of the roof, insulation and can increase the load.
Green Roof Problems
Roofs with a layer of grass need an appropriate thickness of the substrate (at least 20cm). The growing grass requires regular mowing and watering daily. Roofs with vegetation (shrubs and low trees) need to be cautious – it is unacceptable to hammer into a roof (such as wood or metal supports for trees) without the knowledge and consent of the manufacturer or professional contractor. Waterproofing layers can easily be damaged by this process leading to a re-roof or replacement, and this is an expensive venture.