Activity 3.1.4 Commercial Roof Systems

1.    Why are flat roofs common on larger commercial buildings?

Flat roofs are the most economical choice of roof types.  Also, infrastructure may be added on top of the roof.  Solar panels or other green architecture may be adde on top of the roof, and pieces of equipment that would otherwise take up wanted space may be placed on top of the roof.

2.    Why are the standard pitched roof treatments not acceptable for a low-slope roof?

Low-slope roofs must be very watertight, so many pitched roof treatments that are acceptable due to the relatively high slope would be prone to leaking in a low-slope roof.  Things like overlapping shingles are not acceptable on a low-slope roof, becuase the lower water draining capabilities would lead to more leaking.

3.    Why are the typical low-slope roof surfaces not appropriate when public access is planned?

Tar covered with gravel is a common surface for flat roofs.  This is not advantegous to public access because the tar can be sticky, and the gravel is meant to protect the tar.  When the gravel is moved, the tar may become exposed and may lead to leaking.  Also, the gravel is meant to protect the tar from UV rays, so it could possibly increase the risk of cancer and eye disorders.  Flat roofs tend to be sensitive to human traffic. Anything which produces a crack or puncture in the waterproofing membrane can quite readily lead to leaks

4.     What factors are important to consider when designing a green roof?

The mass of weight on top of the roof must be considered, as too much vegeation may add excessive stress to the roof framing.  You have to consider how the greenhouse will function, and how it may affect your building and the surrounding environment.  The overall design style of the building should also be taken into consideration when adding a green roof, as well as the type of plants you wish to add, and the maintenance that will be required.

5.    What advantages do green roofs provide over standard low-slope roof treatments?

The soil barrier between the roofing and the sun allows for extra UV ray protection.  Also, the plants and soil act as a thermal buffer for the building, trapping heat from entering the building during the day, and releasing heat during the colder night time.  The green roofs may also be considered to be have a ghreater aesthetic appeal.   Green roofs also filter out pollutant like carbon dioxide to make clean oxygen.