A Flat roof is what its name suggests, however, it does have a slight pitch to allow of water runoff. Generally used on commercial and industrial buidings, but it can be used for residential houses as well. This style can be also used for extra living space for a patio or garden. Heating and cooling units can also be placed on a Flat roof to keep them out of sight. This type of roof is not recommended for high rainfall or snowfall areas.