Flat Roofs

Flat roofs are found on garage roofs as well as homes and other structures. They are a popular choice for properties with a contemporary architectural design. Innovations in new roofing materials have made flat roofs increasingly popular and effective.

About Flat Roofs

Unlike sloped roofs, a flat roof's surface is almost level. Some flat roofs do have a slight slope or pitch. Although they are found throughout the world, they are often used in arid climates. Traditional flat roofs used on UK homes were often made with sheets or rolls of material that was glued together to create a watertight surface. Two or more built up layers of bituminous felt were generally laid on the roof. Alternatively, a felt layer was covered by a coat of bitumen (asphalt or tar) and gravel to help cool the roof. Other bituminous materials have felt and gravel embedded.

Types of Flat Roofs

A popular material for modern flat roofing is fiberglass or glass reinforced plastic (GRP), which are also known as liquid applied roofing systems. Single ply membranes are also used, especially for larger roofs. Alternatives to GRP include aluminium and copper that are laid in a single ply with felt and liquid membranes to create a waterproof layer. Bitumen continues to be used for flat roofs but is now made from higher quality materials known as reinforced bitumen membranes (RBM). Another material used for flat roofs is mastic asphalt and are often used with stronger roofs due to its weight.

Waterproofing in flat roofs is supported by a structural roof deck. This typically involves installing timber boarding that is supported on joists. The timber deck is placed over the ceiling. A flat roof may be insulated, with insulation placed somewhere between the deck and the ceiling. Insulation is required if the flat roof is over a habitable part of a property. Flat roofs on garages are generally not insulated. In some cases, insulation may be placed above the waterproofing layer. This is especially true when RBM is used, although this design is more common in commercial and industrial buildings.

The manner in which the roof deck and ceiling are built effects how waterproofing works on the top layer. There are two main types of waterproofing designs - a warm roof and a cold roof. Warm roofs have insulation above the roof deck to keep it warm. With this design, ventilation is typically not needed. In cold roof designs, the waterproofing is laid directly onto the deck and insulation is found above the ceiling. This design makes the roof vulnerable to condensation, which can lead to decay and warping. As a result, ventilation is needed. The NFRC recommends warm roof designs for UK homes, and cold roof designs are not recommended under the Scottish Building Standards Regulations.

Choosing a Flat Roof Contractor

Whenever having work done on flat roofs, look for contractors that are certified as a Competent Roofer with the National Federation of Roofing Contractors (NFRC). This is the main competent person scheme for roofing tradespeople recognised by the UK government. The NFRC represents more than half of the roofing industry. Its members follow a code of conduct to ensure high standards of workmanship, business practices and customer service. Roofers may also be members of the Institute of Roofing (IoR) and the Confederation of Roofing Contractors (CRC). Flat roofing specialists and suppliers might also be part of the Liquid Roofing and Waterproofing Association (LRWA) and the Single Ply Roofing Association (SPRA).

In addition to checking if the roofer is a member of a trade association, ask for proof of potential contractors' certifications and qualifications. You should also ask for proof of insurance to ensure work carried out by the contractor is adequately covered. To help you make a decision and assess the quality of their work, check references and look at online reviews written by previous customers. You should also obtain at least three different quotes from roofing contractors to determine a fair price. Always make sure that the contractor has extensive experience working on installing, maintaining and repairing flat roofs.