Which roof covering

Which roof covering

The roof will be one of the most dominant features of your new home, accounting for 20-30 per cent of the exterior visible area of your house. Its covering therefore needs careful consideration at the planning stage.

Factors dictating the roof covering include the style of your house, your architect and even your local planners, as choosing something in the vernacular may well get your plans rubber stamped. Slate, clay and concrete tiles are the main tile choices in the UK, with slate holding sway in areas where there is a local supply. But these days there is a lot of choice out there, with everything from handmade clay tiles to mass-produced concrete and imported slate.

Among the considerations that help you choose will be the unit cost, the coverage of the tiles, the green credentials involved in producing and shipping your material and, for renovation projects or builds in areas of outstanding beauty, historical integrity. For hands-on self-builders, the level of expertise needed to lay the material may also be a factor.

Typically the roof structure should cost around 10 per cent of your entire build cost (depending on complexity) and its covering about five per cent, although this will vary depending on the materials.

Interlocking tiles

Using interlocking tiles reduces the necessity for overlapping needed by some traditional tiles, in particular slate. It reduces the number of tiles needed per square metre and brings down the weight of the roof, although some interlocking tiles are heavier than their traditional counterparts.

Interlocking systems are weathertight and easy to lay, and many modern tiles emulate the look of traditional slate, with two interlocking edges on show and two riven edges.

Your choice of tiles will also be affected by the pitch and roof structure, so ensure that the roof can take the weight of your tiles – your architect or a structural engineer can work this out, or speak to your tile company. Of course, the roof must also comply with Building Regulations. The pitch of the roof and type of tile used will also affect how many and in what configuration the tiles must be nailed. A steep pitch or detail like a catslide will be on show, so it’s worth investing in quality tiles.

Great for curves and intricate details, clay tiles come in a range of colours and shapes, with special tiles for valleys, ridges and gulleys. Period builds or renovations can take advantage of impressive detailing such as dramatic ridge tiles/finials, while tile shapes, such as fish tail and bull nose, are used to create patterns.

Clay tiles have a long lifespan – a recent refurbishment of Boston Guild Hall in Lincolnshire found some of the tiles dated back to the 14th century. However, the weather in the UK can take a heavy toll on clay tiles, as our winters involve constant wet, freezing and thawing cycles. Tiles sold here, especially imported ones, have to meet the UK’s frost requirements.

Clay tiles also have a good second-hand market, making them fairly sustainable. Most clay tiles are machine-made, but hand-made and hand-finished options are also available. Keymer, Aldershaw and MST Roofing all produce handmade tiles, although not all are made in the UK – check with individual companies if this is important for you.

Traditionally, many manufacturers made tiles with local clay, and this gave rise to local colourways and sizes. Niche-market producers often reproduce these special or imperial tiles, which are ideal for conservation areas or for repairs to period homes. Babylon Tile Works, for example, produces Kent Pegs.

Stone is quite an expensive material to roof your house with, and it will probably only be worth while in areas where the stone is in the vernacular, such as the Pennines or Cotswolds.

Sedimentary stone splits naturally, like slate, into thin sheets that make good roofing material, with the thicker tiles making a heavier, stronger structure. They need a steeper pitch, usually a minimum of 45 degrees, and possibly a specialist fitter. Stone is laid in diminishing courses, with larger tiles at the bottom and smaller ones at the top. As with slate, curves are hard to achieve, and ridge tiles can be made of clay, metal or stone. UK-produced or salvaged stone tiles can be expensive, but may be specified by planning or preferred on certain high-spec builds.

Stone varies in thickness around the country, from the relatively thin Yorkshire stone, pictured left, to the thicker and less uniform stone slates traditionally used in the Cotswolds.

A major player in roofing materials, the advantage of concrete tiles is the vast range available – many of which interlock, offering improved waterproofing, secure fixing and shallower roof pitches – and good prices. A wide range of colours, textures and finishes is available, from the thick double-roman tile that dominates new-build estates to all sorts of heritage-look tiles matching traditional tiles at a smaller cost. The disadvantage of these tiles is that they don’t always weather in the same way as the original items do, and can have a shorter life-expectancy, depending on the product. However, the wide range of styles means that concrete tiles are fairly adaptable in achieving more difficult shapes and special tiles are easily available for ridges and gulleys as well as for curves.

A plentiful supply of this easily splittable stone in the UK ensured its dominance, especially in Wales, the north of England and Cornwall. Slates need significant overlapping on several sides to ensure water-tightness, and the tiles must be laid on battens over an underlay. A slate roof requires a pitch of 30 degrees, and must be finished with clay or metal at the ridges and junctions. Curves are harder to achieve with slate, and are costly as well – simple roof shapes are usually the most economical.

Slate provides a smart and yet traditional roofing material, usually grey, but is also available in colours, from purple to green. Imported tiles come from Canada, China and Spain, and modern versions are available, including composite look-alike versions  and recycled slate, such as Sandtoft’s BritSlate range, which comprises 80 per cent slate, crushed and reformed. Composite and concrete versions are often interlocking, reducing the need for overlapping.

Which roof covering

The best of the rest

You may think of metal roofing is something modern, but copper has been the roofing material of choice for centuries on domes and complicated features, while the Elizabethan gentry was well-used to taking the air on flat roofs covered in lead. These days there are many more metals available, and options include aluminium and zinc, which can be laid on relatively shallow pitches, usually on boards or rigid insulation. The fixing and seams vary according to the metal and fixing-system used.

Metal roofing is long-lasting and very adaptable for curves and complex shapes, but they do have drawbacks: environmental concerns in mining (for copper) and general production; prohibitive costs of many metals; and their appeal to thieves. Run-off from copper and lead run-off can also be a cause for concern.

A modern range of lightweight steel tiles, pressed to look like traditional tiles, is available, but more commonly in Europe. The advantage of these systems is that they are lightweight and can be laid on low pitches. Roofing membranes can also be coloured too look like metal, for a hi-tech take on a traditional look.

Thatch gives a wonderful organic shape which is perfect for curves, and insulates well. It’s a traditional and sustainable material that should be encouraged, and fire concerns – which have prevented it appearing on many new builds – are quite easy to overcome.

Thatch has a definite life-span, typically lasting between 15-25 years, with checks and possible maintenance needed every few years. The drier the climate the longer lasting the thatch.

In the UK thatch tends to be made of either long straw or the less common, but longer lasting, water reed, though there is currently a shortage of good thatching material, as well as thatchers.

It requires a steep pitch and has a deep overhang, rarely requiring a gutter.

shingles, and the more rustic-looking shakes, are a sustainable as well as long-lasting roofing material, with Western Red Cedar a typical wood.

They can be left untreated to weather to a beautiful silver, or, alternatively, they can be treated for longer life and to preserve some of the original colour. If you want to get the longest life out of your choice, opt for premium shingles.


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