Flat roofs are commonly used in commercial buildings and are also used in some residential buildings. It may appear flat but actually have a slope of about ¼ -1/2” for drainage. Flat roofs were extensively used in the Bauhaus movement founded by Architect Walter Gropius. Cubic form with flat sides and roofs were the main features in buildings under the Bauhaus movement.
Flat roofs have been in vogue thousands of years ago. In the Minoan period, around 2000 B.C., small stone structures where covered with thatching or wooden sticks and were braced with large timbers. Flat roof were also used in adobe houses found in the American Southwest and Mexico and in the arid climates of the Middle East. Traditionally, flat roofs were made up of corrugated iron, turf and straight run bitumen. In the 1970’s, Europeans developed modified bitumen where plasticizers were replaced by modifiers such as APP (attactic polypropylene) and SBS (styrene-butadiene-styrene).
At present, flat roofs are more widely used in commercial and in many residential buildings as well. The reason is the availability of the reliable materials. Kraton polymer, when applied, maintains the flat roof’s performance for a longer period. Insulation systems were also developed to withstand snow and other extreme weather. Available drainage systems such as suction floor can be installed between roof depression and the edge of the roof which have suction tubes to accumulate water. Any building material can have different percentage of heat absorption depending on what kind of material it is made of and even the color of the material. The roof is one of the building areas which accumulate much heat. The green roofs or commonly known as roof gardens, inherently cool roofs or light colored materials, and the coat roof are three main strategies used to achieve a cool roof.
Proper maintenance of flat roofs can make it last longer. An average life cycle of 10 years can be achieved if proper maintenance is done to flat roofs but this can still depend on the type of flat roof used. Flat roofs can be maintained by getting rid of pounding water accumulated within 48 hours. Scuppers and automatic siphons for ponds can be installed to get rid of the pounding. Application of roof coating is also necessary to protect the roof from ultra-violet radiation from the sun and also to fix leaks. Modern techniques and methods are also available such as the infrared thermography which takes pictures of the roof during nighttime in order to find wet spots or trouble spots that are not visible to the naked eye. The infrared can locate heat from these spots where sections of wet insulation may occur.