Pitched roofs have been a feature of our built environment since man first started building shelters to live in. In the British Isles, which has high levels of precipitation, it was common sense to build a roof structure which would quickly shed the water and snow and not allow the building to become waterlogged. Traditionally pitched roofs were covered with materials found in the local environment like stone, slate and clay. Before the days of industrialisation local areas would have local traditions according to the materials available locally and the needs of the local people. Many of these traditions survive to this day and are often called for on heritage projects and work on listed buildings
Traditional roofing products, whilst generally long lasting and durable, are also expensive to manufacturer and so technology and an ever-smaller world has seen the arrival of lower cost man made products.
All roof slates and tiles need to be fixed and some materials cannot be used at all in some locations. The exact fixing requirements for all slates and tiles will depend on the design of the roof, its locality and exposure. We are happy to provide guidance to our clients and advise on best practice for pitched commercial roofing.
Natural slating is an extremely long-lasting roofing system and in many cases a well laid slate roof can significantly outlive its occupants. Slating is durable and can withstand freezing temperatures as well as strong weather. Each slate is fixed with two nails using a ‘double overlap’ system. Whilst this ensure the reliability of the material it also means a relatively large number of slates are used compared to some other materials and it increases labour costs as well.
Traditionally slates used in the UK were mainly Welsh, but Cornish and Westmoreland were also widespread, often used on more prestige buildings. These slates are generally accepted as being the best products available for roofing but they are now very expensive and usually only specified on very highly specified projects such as listed buildings.
The local supply of these traditional materials has been supplemented by imports from many other countries. The most common source is Spain.
Imported slates come in a wide variety of qualities and price and great care must be taken when selecting them. Unfortunately, the criteria used to grade slates does not include all the features which are necessary to consider to achieve a high quality roof and it is tempting to be seduced by an attractive price. But all that glitters is not gold and so we are happy to advise our Clients on how to select the most suitable products and explain the differences.
Natural slates however can be both heavy and pricey and a lighter more economical alternative is man-made slates. Whilst these are significantly lower in price, they also have a lower life span. The most commonly used artificial slates are made from a fibre-cement mix. Other manufacturers use a more durable mixture of resin and reconstituted slate dust.
Tiles come in a variety of styles, shapes colours and materials. Below is a quick synopsis of the most commonly used but for a more in-depth appreciation please contact us and we will be happy to discuss your project or even provide a CPD seminar.
Tiles are traditionally manufactured from clay but for the last 100 years concrete has also been used. Concrete tiles have become more and more sophisticated and these days it is sometimes difficult to tell them apart.
Plain tiles and Peg tiles
‘Plain tiles’ are a very common style traditionally measuring 10 ½ “ x 6 ½” but with only one third of that surface area visible because the tiles overlap the two tiles in the courses below them. Approximately 20% of plain tiles are also mechanically fixed with nails.
Peg tiles are only produced in clay and rely on a wooden peg to hook them over battens, whereas plain tiles are secured by integral ‘nibs’ which are hooked over battens.
Interlocking tiles are a more efficient method of covering a roof than plain tiles or slates. While the former have a ‘double overlap’ (meaning they overlap the tiles or slates in the two course below them) interlocking tiles only have a single lap (meaning they only overlap the directly tile below them and they are connected to the tiles on either side with interlocking channels). Because of this far fewer tiles are required and roofing is far quicker and cheaper.
An additional benefit of interlocking tiles is that they can be used on lower roof pitches.
As with all roofs, when the coverings are replaced the new roof must comply with Building Regulations and this usually means that additional insulation has to be provided to meet the current requirement. This usually takes the form of insulation quilt but where there is no loft and ceilings are fixed directly to the underside of the rafters, more efficient rigid insulation boards are required to meet the required standard.
To prevent condensation the roof void has to be ventilated. In roofs where there is a loft area this is relatively easy to achieve but where ceilings are fixed directly to the underside of rafters, such as in Churches or vaulted ceilings, ventilation can become more complicated.
Lightweight metal roof tiles can be made from a variety of different metals. Sheet metal is pressed into a pattersn to mimic a single tile or a strip or sheet of tiles. The surface is then treated with a smooth or textured coating to protect the metal and provide a more pleasing aesthetic finish.
They offer a cost-effective solution, because they can be Installed quickly. Thicker tiles are particularly robust and ideal for areas where physical damage or vandalism or theft could be an issue. Schools and sports pavilions often choose them. They can also be sued on very low roof pitches and unlike most tiles, access for maintenance to retrieve balls or leaves will not result in breakages.
Their lightweight means that transporting them, both on site and to site, is much more efficient, saving money and the environment. Metal roof tiles are significantly less susceptible to cracking and very unlikely to split, therefore providing property managers with a very low maintenance roof.
Traditional construction would make the conversion of a flat roof into a pitched roof an expensive and time consuming operation. The additional load on the existing structure would often be prohibitive and the cost would not justify the long-term savings. However, a flat roof can quite easily be transformed into a pitched roof by forming a lightweight metal structure fixed directly over the existing slab. The new structure can be over roofed with lightweight, pressed metal roof tiles. The new lightweight roof is both aesthetically pleasing and will almost certainly reduce the cost of re-roofing over the life of the building.
Similar systems can be used to convert roofs into accommodation and office space. Creating a pitched roof also allows you to increase the insulation provision and reduce heating bills. Finally, a further environmental benefit is that the whole system is recyclable at the end of its life.