Flat Roofs — Definition and Types, with insurance case studies (Ireland)

A pitched roof is defined by having a roof pitch above 1.5 degrees or above Fall of 1 in 40. Construction materials will differ depending on the pitch of the roof. – Standing seam roofs such as copper or zinc can be used over 1.5 degrees in pitch – Traditional tile/slate roofs pitches start at 22 degrees but some manufacturers can reduce this to 12.5- 15 degrees. Types of Flat Roofs • • • • Bitumen Roofing Liquid Membrane Single Ply Roofing Green Roofs Bitumen Roofing Common Trade Names • Built up Roofing • Bitumen Membranes • Material Felt • Mastic Asphalt Typical Construction • • • Waterproofing Layers (1-2 layers depending on system) Insulation with Vapour Barrier (this Barrier stops condensation). The insulation location can vary depending on the system. The Roof Structure can be either timber or concrete and should be designed to accommodate the loading required by the roof type and its usage (i.e. Balcony/Sundeck) Costs excluding structure €62-72 per m² Guarantees and Certification All new flat roof materials should have certificate by supplier and the roof material should have a IAB(Irish Agrement Board) or BBA (British Board of Agrement). This should guarantee the roof material for over 15-20 years and workmanship to 15 years. Types of Flat Roofs • • • • Bitumen Roofing Liquid Membance Single Ply Roofing Green Roofs Liquid Membrane Common Trade Names • EPDM Liquid Roofing • Rubber Membrane • Cold Applied Roof Typical Construction • • • Waterproofing Layers (1-2 layers depending on system) Insulation with Vapour Barrier (this Barrier stops condensation). The insulation location can vary depending on the system. The Roof Structure can be either timber/concrete or steel structural deck and should be designed to accommodate the loading required by the roof type and its usage (i.e. Balcony/Sundeck) Costs excluding structure €105-120 per m² Guarantees and Certification All new flat roofs should have certificate by supplier and the roof material should have a IAB(Irish Agrement Board) or BBA (British Board of Agrement). This should guarantee the roof material between 10-20 years. Types of Flat Roofs • • • • Bitumen Roofing Liquid Membance Single Ply Roofing Green Roofs Single Ply Roofing Common Trade Names • PVC Roofing • TPO Roofing • EPDM Roofing • Neoprene Roofing Typical Construction Single ply membranes are strong, flexible sheets composed predominately of synthetic polymer. Thickness is in the range 1.1mm to 2mm. Some products are homogeneous, others reinforced with glass fibre or polyester, depending upon the application. Costs excluding structure €48-55 per m² Guarantees and Certification All new flat roofs should have certificate by supplier and the roof material should have a IAB(Irish Agrement Board) or BBA (British Board of Agrement). This should guarantee the roof material for 10-15 years. Types of Flat Roofs • • • • Bitumen Roofing Liquid Membance Single Ply Roofing Green Roofs Green Roofs Common Trade Names • Green Roof • Living Roof • Sedum Roof • Intensive Living Roof • Bio-Diverse Roof Typical Construction The basic build up of a green roof is three layered: drainage, filter and vegetation layer. The waterproofing can be from the three previous roofing materials. Costs excluding structure €120-200 per m² depending on range of planting Guarantees and Certification All new flat roofs should have certificate by supplier and the roof material should have a IAB(Irish Agrement Board) or BBA (British Board of Agrement). This should guarantee the roof material for over 15 years. Advantages and Disadvantages of Flat Roofs Advantages • Cost One of the most significant benefits of a flat roof is that it is less expensive to install than a pitched roof. Rafters and engineered trusses must be installed to support a pitched roof, while a flat roof usually requires only basic support beams. As a result, less labour and materials are necessary, so you can save considerable money. • More Usable Space While a pitched roof can provide attic space that a flat roof cannot, the area is not usually suitable for use as a room. With a flat roof, you may opt to have your interior ceiling extended to the point where the roof begins, creating additional usable space in your home. In addition, you may have extra support added to the flat roof so it can house a deck or patio, creating additional space for outdoor entertaining. Disadvantages • High Maintenance The major drawback to a flat roof is that it typically requires more maintenance than a pitched roof. Because it is not sloped, the roof does not drain naturally so water can easily accumulate. If water puddles on the surface, it can soak into the roof through its seams and cause structural damage. You must check your roof on a regular basis to ensure that it is free of water and clean up any debris that has settled on the roof as well so the drainage system does not become clogged. • Shorter Lifespan A flat roof typically does not last as long as a pitched roof.