Roofing Information

Featured Roofing Companies (3 of 36)

Click here to show all companies

Roofs Explained

The basic roof structure has been progressively refined over the past decades with advances in material technology and composite materials. Some of the largest advances have been made in commercial and industrial roofing systems, however standard roof building practices have also evolved within the domestic sector.

Whether a timber framed build or conventional solid brick build is being constructed consideration will have to be given to roofing materials and roofing systems. Domestic roof structures were originally constructed from heavy duty solid wood roof timbers. High timber prices and the necessity to produce increasingly complex roofing structures to incorporate loft spaces and attic rooms have driven the widespread usage of timber roof trusses. Timber roof truss systems have a number of advantages over conventional roof timbers. The main advantages are that timber roof trusses are comparatively light weight making for easier erection and fitting on site and can be manufactured to suit many different roof designs cost effectively from shorter sections of timber. Roof truss types may include fink, mono pitch and cantilever trussed rafter configurations. A relatively new format of roof truss construction is the metal web system comprising metal web joists. The metal web system, sometimes referred to as easi-joists or eco-joists, utilises a timber carcase internally braced with 'V - shaped' metal 'webs' to create the structural strength of the truss. The metal web system reduces timber requirements and can be used effectively over large spans for the construction of flat roofs. Metal web systems are particularly popular where large amounts of services have to be routed, as there is generally no need for extensive truss alteration. Additional roofing timbers for longitudinal bracing, such as rafters and chevron bracing are also necessary to maintain roof truss support.

In response to rising timber prices and sustainability issues a variety of structural engineered timber products have been developed for roof construction. Engineered timber products are generally manufactured from reconstituted wood chips or timber laminations bonded together with an adhesive to create a single product. Key examples include glued laminated timber (GLT) beams, often referred to as glulam beams, which provide a pleasing natural wood finish along with improved structural performance. They are manufactured under strict quality controls within a factory environment and can be purchased in many bespoke styles including cranked beams or curved beams. Another example is laminated veneer lumber (LVL) which is similar to glued laminated timber but is finished with a veneer to replicate solid timber beams at a greatly reduced cost. Laminated veneer lumber is often used to create a pleasing visual appearance where exposed beams form an integral part of the building design.

Other material saving and cost effective timber products on the market include I joists often referred to as I beams. I joists are structural load bearing beams with a high strength to weight ratio, usually used to construct floors. They are lighter than conventional solid timber beams, can be used for large spans and are not as susceptible to warping or twisting. There manufacturing tolerances also help reduce floor board noise and they fall under the category of engineered floor joists.

Once completed it is essential that the roof structure is adequately water proofed. Where a roof is to be clad with roof tiles, slates or thatched a roofing underlay, often referred to as a roofing membrane, should be used to cover the roof prior to cladding. Roof membranes are breathable to reduce the risk of condensation build up internally within the roof space. They are important of help reduce wind drafts and retain building heat. Many companies offer different grades and thicknesses in various specifications with some roofing underlays incorporating foil to provide thermal insulation and further reduce building heat loss. Some roofing membranes also provide vapour protection. Roofing felt was traditionally used as roofing underlay until recently. Roofing batterns will need to be nailed over the roof membrane to hold it in place and allow attachment of the roof slates and tiles.

Roof insulation, often generically referred to as loft insulation, is also considered a key component of any modern development to reduce energy loss and energy consumption. Thermal insulation is available in many formats, including rolls, slabs and strips, to suit many specific applications. Acoustic insulation, often referred to as sound deadening material, should also be considered particularly where adjoining houses are being constructed.

A vast selection of roof cladding, coverings and protection measures are available on the market. Roof tiles can be purchased produced from a range of materials and in many different colours and forms. Traditionally roof slates were used to clad roofs, however due to the labour costs associated with slate production concrete based roofing tiles are now the standard roof cladding. Concrete roof tiles are produced in finishes and colours to replicate that of natural slate. Other more recent roofing tile materials include rubberised plastics, steel tiles and composites often used to create striking standout visual effects. Out buildings such as garages and garden sheds may be clad with bitumen based felt roofs. Items such as guttering and lead flashing along with ridge and soffit ventilation will be required to complement the appearance of the finished roof.

Over the years complex roofing systems have been developed to satisfy the needs of the commercial building market. One example is structural decking, often known as roof decking. Structural decking is produced from corrugated steel with integral strengthening bracing which enables long clear spans to be constructed without the need for high densities of horizontal bracing and vertical supports. Structural decking can also be purchased incorporating sandwiched thermal insulation and acoustic insulation into its structure. A range of factory finishes can be specified to eliminate the need for on site finishing and to save labour costs. Glazed roof systems are also increasingly popular to provide natural light to commercial buildings, whilst residential applications include various forms of skylights and rooflights.

Recent years have seen a rapid expansion within the area of Green roofs, although the base idea has been around for hundreds of years, typically on flat roofed Mediterranean properties. Green roof systems, often termed 'living roofs' have been developed to enhance the ecological value of urban environments and help maintain ecological diversity within rural areas. Green roofs can also be designed to maximise rainwater attenuation as part of a sustainable urban drainage system. Green roof systems vary from manufacturer to manufacturer however the basic configuration includes a vapour and water proof membrane laid directly on to the roof structure followed by a root barrier. A drainage media, usually comprising a layer of aggregates or corrugated plastic, is then laid over the membrane and a substrate comprising soil with vegetation and nutrients is laid on top to finish. Pre-grown vegetation on plastic mesh tiles can be used to cover sloping and inclined roofs. Green roofs are also referred to as Sedum roofs where they support water storing sedum plant species.