If you are experiencing a water leak or damp problem as a result of damage to a flat roof on your garage or home extension, there are lots of products and suppliers to choose from. This articles seeks to identify the range of options available and discusses the benefits and advantages of each.

It is important to first point out that significant strides have been made in flat roof technology over the last twenty years. Whereas old asphalt roofs may have lasted 10-15 years, new multiple ply membrane flat roofs will be guaranteed for 30 years. Despite these advantages, because asphalt roofs remain the cheapest option, they still remain popular but customers should insure that when they invite suppliers to quote, that they are clear on what you getting for your money.

There are five main types of flat roofs, including roll asphalt, single-ply, multiple ply, modified bitumen and flat-seamed metal.

Roll Asphalt
The vast majority of flat garage or extensions roofs built before the 1970’s will be roll asphalt, which consists of layers of asphalt-coated fibreglass felt, tar and water resistant materials, kept in place by nails or cement. Gravel or crushed stone will typically lay on top of the roof to provide protection against wear and tear from the elements. Whilst being the cheapest option, it generally won’t last more than 10 years.

Single Ply
Essentially single play flat roofs are single layer membranes, manufactured from a combination of man-made synthetic materials that provide waterproofing cover to a flat roof. Whilst they were established many years ago in Garmany, they have really only started to emerge as the preferred choice in the UK in recent years. Many single ply roofing manufacturers have emerged, with leading players including Sarnafil, Cefil, Alwitra & Protan. If you choose a single ply membrane, ideally choose a manufacturer whose roofs have been independently approved by the BBA, in addition to providing a product guarantee of at least fifteen years. Most single play roofs are mold resistant and maintenance free.

Multiple Ply
Multiple Ply flat roofs or Multi-Ply flat roofs, consist of multiple layers of fibreglass felt packed between layers of asphalt to provide a watertight barrier. Due to the reinforced multi-layers, multi-ply roofs are extremely durable because even if the top layer is damaged, back up layers stop water from penetrating the roof. Consequently, a multi-ply roof can last between 10 and 30 years.

Modified Bitumen
Modified Bitumen is used in some multiple ply roofs, and is made from asphalt and a variety of polymers, solvents and modifiers connected together. It has two key advantages, the flexibility of polymers and the water resistant qualities of asphalt. The top layer tends to be coated with a weather resistant and reflective material such as gravel and will typically last between 10 and 20 years.

Flat-Seamed Metal Roofs
Whilst more expensive than all the other options, metal roofs, usually made of copper and stainless steel can often last between 20 and 50 years.