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Re-Roofing with Hot Asphalt

Successful re-roofing projects for flat roofs can improve energy efficiency and contribute to the long term comfort, health, and safety of those who live and work in the building. Flat roof construction and repair has seen significant improvements in materials available to roofing contractors, but the key to a long-lasting, efficient and effective roof is quality installation.


What Factors Impact the Longevity and Functioning of a Flat Roof?

Flat roofs are covered with layers of roofing materials, some for insulation, some for waterproofing or strength, and these layers, or plies, are melted together to form a strong, cohesive whole. The most cost-efficient and effective method of melting the various layers together to form an strong structural roof is by using hot asphalt between the layers. This system gives a roof structure with backup if a single layer fails from a puncture, from weather or sun damage, or from deterioration with age.

Your Dan Tennis roofing contractor can recommend which of the many new materials available as insulation, vapor barriers, waterproofing, reflective mineral cap sheets, and other layers will work best for your particular roof. The decisions take into account weather, height, location, budget, and other environmental impacts on the building.

A building's owners may have specific needs for insulation and energy conservation, foot traffic and strength of the roof, or solar, salt, wind and weather protection. Building codes may reflect new standards, and insurance adjusters may have input in re-roofing materials and processes. Plans to use the roof for solar panels, rooftop gardens, and water catchment systems will impact how the re-roofing is done.

Some roofing materials, those that have particular structural qualities of mineral content, insulation, or other needed structural qualities, can be premade in factories and the layers or plies joined with heat, asphalt, or glues. These premade sheets containing several layers are then used in the re-roofing. The location, expected environmental exposures, the quality and condition of the old roof, and budget can impact the decision regarding materials used.

While many new materials are providing excellent insulation and water and vapor barriers, older, low-tech roofs, made with asphalt, layers of roofing felt, and gravel are also long lasting, efficient, and provide a sturdy, cost-effective roof. Many times, a mix of the old techniques with new materials will give owners an efficient, cost-effective and long-lasting roof.

The key to successful re-roofing is both the materials chosen and the experience and quality of the installation. Traditional methods of hot mopping asphalt to seal and protect a flat roof are skills that come from experience and careful craftsmanship.

How Does a Re-Roofing Project Proceed?

Careful inspection of the existing roof is followed by consultation with the owners regarding needs and budget. The roofing contractor will bring information regarding building codes, how much of the old roof can be salvaged, and give recommendations for materials based on priorities from the owners. A good roofing contractor is knowledgeable about the local environmental impacts on roofs, as well as community standards and the availability of materials and craftsmen to do the work.

Materials are ordered and the re-roofing is scheduled; the exterior of the building may be draped or tarps or other barriers put down on the landscaping to protect it. The old layers of the roof that need to be replaced are removed and disposed of, and the under roofing structures inspected for water incursion or other damage.

The new barriers or layers are brought to the roof, as well as the asphalt, the fire and safety equipment, and the roofers. The layers or plies are put down in order- waterproofing, vapor barrier, insulation- and between the plies, they are sealed with layers of hot asphalt. This asphalt is heated until it is pour-able, then is put down with a technique called hot mopping. Hot mopping uses a tool that looks very much like an old fashioned mop- though larger, stronger, and quite a bit heavier. After the layer of asphalt, the next ply or layer is placed on top, and the process repeats itself.

Care is taken to seal edges, seams, flashing, and other places prone to water incursion or failure.

There are safety standards for the craftsmen who install a new asphalt flat roof, as well as those living or working in the building. Both respiratory protection for those working with hot asphalt, and fire protection for the materials, is provided by the contractor, who follows governmental safety standards for protection of the workforce. All environmental standards for cleanup and disposal of materials are scrupulously followed.

What New Materials are Standard for a Re-Roofing?

While many traditional materials and processes for replacing a flat roof are very effective, several new standards in materials are improving the energy efficiency of flat roofs ad roof repairs, and impacting issues such as the urban heat island effect. In cities with more buildings than trees, solar energy tends to be absorbed by the materials of buildings, like brick and stone. With many buildings together in small spaces, the heat doesn't dissipate the way it would with more room between buildings. So heat tends to concentrate in cities, and the energy costs to keep people comfortable are sky-high.

To tackle the problem and reduce energy costs, many municipalities have changed building codes and standards to requiring the use of various mineral cap sheets or other surface cap sheets that are white. These final layers of a flat roof reflect the sunlight and do not absorb solar energy as much as dark roofs. They keep the building cooler, energy costs down, and multiplied by many buildings across a city, can impact the urban heat island effect.

These mineral surface cap sheets are applied like the other layers of a hot asphalt re-roofing, with the asphalt causing the layers to adhere together into a sturdy solid.

Traditional fiberglass insulation is still used in flat roofing projects, but new forms of rigid insulation and sheets of flexible insulation materials are bringing improved energy efficiency. With these more efficient rigid insulation panels, care is taken to protect them from the vapor and condensation that happens in humid climates during changes in temperature between day and night, and additional care is taken to keep their seams sealed. These new vapor barriers and methods of securing seams against water incursion are important for the long-life and functioning of the new roof.

Dan Tennis Roofing specializes in complex commercial roof repairs, but our craftsmen bring their high level of skill and care to residential re-roofing projects as well. We would love the opportunity to work with you. Please get in touch!