In the latest of our market overviews, Caleb Mudzudzu of Gardiner & Theobald examines current issues in the roof coverings sector, including design and costs – plus a Q&A with a top-five specialist firm

This standing seam roof is a prominent feature of the Scottish Exhibition and Conference Centre in Glasgow, designed by Foster and Partners

Market overview

There is a wide spectrum of roof covering materials, which are used for different structural, aesthetic, economic, and performance reasons. Roof designs have developed from just being a weather performance element to an architectural trademark that can be environment-friendly, structurally sound, reasonably priced and aesthetically attractive.Gardiner & Theobald’s research has shown that the UK roofing market continues to grow, with estimated annual turnover of £1.8bn for 2005, up 15% from 2000 figures.

The increase in regeneration schemes throughout the country has contributed to the higher demand for roofing products, particularly steel roofs. Mixed-use developments have overtaken pure housebuilding, and the trend is to bring visual coherence to the different elements of a scheme by roofing them in matching materials.

According to figures supplied by Market & Business Development, steel roofs have had a greater increase in market share than any other roofing material over the past five years. In 2004, 48.8 million m2 of steel roofing was installed, compared with 34.1 million m2 in 2000, which is a 43% increase. Metal roofing as a whole has increased its share of the market from 34% in 2000 to 49% in 2004, primarily because of a huge increase in demand for standing-seam roofs.

The increased use of daylighting in buildings has resulted in roof glazing taking up a small portion of the market share.

When it comes to procurement, most roof covering contracts are let to domestic subcontractors, mainly because there is no design element involved in this package. All the same, specialist roofing contractors contribute valuable knowledge and expertise to achieve the required roof specification and produce the desired functional and visual effect in the finished building.

Factors affecting the UK market Legislation has been the most serious setback to the effective growth of the market. New legislation, or revisions to old legislation, is increasingly making it difficult for small and medium-sized contractors to stay in business. This trend is likely to continue with the upgrading of Building Regulations Part B, which increases fire precautions, and Part L, which increased thermal and energy efficiency (see “Hot topics”, right).Because of its dangerous nature, roofing work may be adversely affected during extended periods of bad weather. The increasingly turbulent storms and unsettled weather conditions of recent years have had a negative impact on the roofing market as a whole.

Shorter or wetter summers will affect the growth of the roof refurbishment market.

According to research conducted by MSI Marketing Research for Industry, other factors have a significant impact on demand for roofing materials in the UK. They include the overall UK economy, demand within the construction industry, the shortage of skilled labour and changing design considerations.

Architectural trends are of considerable importance to the level of demand for roofing materials in the UK. It is widely believed that over the past five years, architects have largely developed a preference for the use of more traditional materials such as slates and clay tiles because of the environmental and aesthetic advantages that they bring. The market for copper roofing has also benefited from a growing appreciation of its appearance and lengthy life expectancy.

Roof waterproofing, usually an impervious membrane, is now required on all types of roof, even in traditional domestic tiled and slated roofs, in the revised Part C4 of the Building Regulation, which deals with resistance to moisture. Accordingly, research by MSI shows that the UK market for roof waterproofing increased some 10% between 2000 and 2004 and a further 3% in 2004 alone.

Market forecast
According to the latest survey from Market & Business Development, the total market turnover for the roofing industry is anticipated to increase steadily between 4% and 5% a year between 2005 and 2007 before slowing down to 3% a year between 2008 and 2009. Translated to monetary values, the market will increase from £1.8bn in 2005 to £2.1bn in 2009, based on 2004 retail sales prices.

Hot topics

  • Bid rigging is rampant in the roofing sector and more cartels will be exposed soon, according to the Office of Fair Trading. Ten flat roofing contractors from Scotland and the North-east were fined a total of £500,000 for colluding to fix tender prices between 2000 and 2002.
  • Steel-based roofing materials have enjoyed increased use in the past five years but prices have gone up between 20% and 30%. Whether this growth will continue in spite of the price increase, only time will tell.
  • Labour rates have jumped recently as part of the Construction Industry Joint Council working rule agreement. On 27 June 2005, labour rates came into force giving a 10.1% increase to craft operatives with at least NVQ Level 2 and a 5.9% increase to adult general operatives and semi-skilled workers. It is too early to assess the impact on tender prices.
  • With the 2012 Olympics promising increased workload and tight timescales, labour shortages are likely to increase the roofing markets lead-in times. The demand for roofing materials suitable for stadiums and sports facilities is also likely to rise.
  • The ever-increasing use of bespoke designs are making it hard for small and medium-sized contractors to compete with large roofing contractors. There have also been reports of roof failures caused by problems of designing and installing roofs to these unique structures.
  • Roofing contractors are caught in a clash of Building Regulations. The requirements of Part L covering thermal efficiency are widely perceived to conflict with Part E’s acoustic robust details. The problem occurs in warm uninsulated roofs, where fitting the minimum 100 mm of mineral wool insulation to meet Part E falls short of satisfying Part L. Knauf Insulation’s solution is glass mineral wool with a thermal conductivity of 0.032 W/m2K. Installing a 185 mm thick layer between the rafters at 600 mm centres meets Part L’s 0.20 W/m2K target and also satisfies Part E.
  • Part L is to be further upgraded soon, and this is likely to push roofing material suppliers into investing more in machinery or raw materials.

  • Roofing specialist Q&A

    With an annual turnover of more than £30m and 200 staff, Prater is one of the UK’s top five roofing contractors – and Building’s Roofing Contractor of the Year for 2003. It started trading in the 1950s, and now provides complete building envelopes and installs all types of roof covering, with the exception of traditional slates and tiles; it operates across England and occasionally abroad. Here director Andy Newman give his insights into the British roofing scene.

    What is happening to tender prices?
    They are staying fairly stable. It is difficult for subcontractors such as us to raise prices, because main contractors take on lump-sum contracts fixed for 12 to 18 months and they are looking for the cheapest prices from subcontractors.

    Won’t recently increased labour rates push up tender prices?
    Not dramatically because the agreement only applies to PAYE operatives. We minimise our risk by subcontracting out 70-75% of our work.

    What are the current trends in materials?
    There’s a vogue for standing-seam metal roofing, such as Kalzip, as architects think it helps them win awards. Green roofs are also coming to the fore, and we have just completed one on the Wellcome Trust’s new Genome Campus outside Cambridge.

    Is health and safety growing in importance for roofing contractors?
    We regard safety as paramount, and we have a full-time safety officer as well as employing a safety consultant. Safety measures include erecting safety nets underneath entire roofs with open structures.

    What impact will the changes to Part L of the Building Regulations have?
    Some are already making allowance for the next revision, with U-values of as little as 0.16W/m2K and insulation up to 180 mm thick. It takes two people to handle them on site.

    What do you see as the next challenge for the industry?
    The biggest challenges to us will be other companies moving into the market – and keeping up with new regulations and standards.

    How do you see the future?
    The 2012 Olympics will bring in a lot of work, not just in sports facilities but in the whole regeneration of Stratford that will spin off it. The key challenge will be how to deliver all this in five to seven years, even if there isn’t a recession.

    Design and specification

    Because of performance requirements and legislation, roofs are now required to meet standards ranging from heat absorption and emission to solar glare, from weatherproofing to aesthetics. The selection of roof coverings is also subject to changing fashions. For example the use of steel roofs has spread from mostly industrial buildings in the past to include residential and commercial buildings today.

    All types of roof coverings provide the following basic functions:

  • They must provide adequate weather exclusion, have reasonable durability and be aesthetically acceptable
  • To resist overstressing by supporting its own self-weight, wind loads and imposed loads such as snow
  • To prevent excessive heat loss, at least to the standard set out in Part L of the Building Regulations
  • To prevent the spread of fire, as in Part B of the Building Regulations
  • To provide the required degree of sound insulation.

    According to BPTW Architects, the choice of a particular roof covering depends on a number of factors. The covering must be durable, has to be supplied with supporting warranties and British Board of Agrément certificate and should be easy to maintain, leading to lower lifecycle costs. The cost of the roof covering should also be reasonable. For example, there is a general assertion that when dealing with a simple roof, polymeric applied membranes are cheaper than turned sheet metal roof coverings. Buildability and installation time for roof structure and covering are also used to determine the pros and cons of each option.

    Solar gain is important factor when considering roof design and materials, as solar energy is absorbed more by horizontal or pitched roofs than by vertical walls or windows. One of the simplest way to keep solar heat out of buildings is to use reflective roofing materials.

    To play their part in reducing reduce global warming, designers should also consider the embodied energy of the desired roof covering materials along with the whole roof structure.

    Though relatively untried, green roofs offer several topical benefits (see below). By protecting the roof membrane, they increase life expectancy. They provide an amenity bonus in the form of a garden that does not eat into the footprint of a building. By improving thermal insulation, they reduce the running costs of the building’s heating and air-conditioning. And by absorbing up to 90% of rainwater, they reduce the need for stormwater drainage.

  • Roof types

    Pitched roof coverings
    A pitched roof is generally defined as a roof with a pitch exceeding 10°. Traditional pitched roof coverings consist of overlapping tiles of slate, clay or concrete, which are durable, aesthetically pleasing, low-maintenance and possess an inherently good fire rating because of the incombustible nature of the material.

  • Tiles Tiles in clay and concrete can be either double or single lap. Double-lap tiles, often called plain tiles, are laid over the whole roof in at least two overlapping layers, usually with every fourth course nailed. Single-lap tiles are manufactured either in clay or concrete and interlock by means of tongue-and-groove joints, which provide weathertightness.
  • Slates Roofing slates can be either natural or artificial and are normally used for roof pitches of more than 25°. Natural slate, being durable and attractive, is enjoying a renaissance as a roofing material and for floor and other surfaces. Artificial slates, made from fibre-reinforced cement, combine the attractive appearance of natural slate with the quality control and economics of a manufactured product.

    Flat roof coverings
    A flat roof is generally defined as having a pitch of 10° or less.

  • Built-up roofing Built-up roofing consists of multiple layers of bitumen and ply sheets laid on top of a flat or shallow-sloping roof deck, along with a vapour retarder, insulation, membrane and final surfacing material. It is traditionally used to roof commercial, industrial and institutional buildings.
  • Modified bitumen-felt membrane assembly An assembly is made up of continuous reinforcing membranes of saturated felts, coated felts, fabrics or mats alternating with layers of bitumen and topped by a surface finish. Factory-applied surfacing includes mineral granules, slag, aluminium or copper.
  • Single-ply membranes Based on thermoplastic polymers such as PVC to give flexibility, single-ply membranes include a reinforcement layer, usually polyester or fibreglass, to increase strength and dimensional stability. The membranes are tailored on site to the roof shape by means of heat or chemical-welded seams.
  • Preformed roof membranes These membranes consist of flexible sheets of compounded synthetic materials, which are preformed in the factory for strength, flexibility and durability. They have wide range of applications, as they have consistent product quality and versatility in their installation methods.

  • Metal sheet roof claddings
    Sheet roofing products have traditionally consisted mainly of lead, steel or aluminium, although copper and zinc are becoming more prominent. Generally formed from prefabricated sheets or panels, they can be laid with minimal slope without compromising weather protection. All five metals oxidise when exposed to air over long periods, and this forms a long-lasting, protective top coating to sheet roof coverings.

  • Lead sheet A heavy, malleable metal, lead is used in comparatively thick sheets of 1.8-3.55 mm as a roof covering. It is used for flat roofs and in historic restorations; lead has a useful life of 100 years or more, and zero maintenance is required for up to 60 years.
  • Copper sheet A strong, heavy, malleable metal, copper is used in quite thin sheets that can readily be beaten and bent to accommodate quite complicated roof shapes. A copper roof covering has a useful life as long as that of lead, and has the advantage of turning an attractive pale green colour upon oxidisation.n Zinc sheet A light metal that is strong but relatively brittle, zinc is prone to corrosion right through its thickness when exposed to air. This means that it has a useful life of only 20 to 40 years. Even so, zinc sheet is often used as a roof covering because of its low cost.
  • Aluminium sheet A light metal, aluminium is malleable and weather-resistant but only moderately strong. It has a useful life as a roof covering somewhere between zinc and lead.
  • Standing-seam metal roofing Standing-seam metal roofing is mainly intended for commercial and industrial buildings, where a highly durable attractive roof covering is required, especially for low pitches down to 1.5°. Stiff lengths of metal profiles or trays in either aluminium, copper, stainless steel, zinc or coated steels can span wide gaps between supports.

    Composite panels
    Sophisticated composite panel systems made by modern industrial methods offer much higher reliability than site-assembled cladding on roofs down as shallow as 1.5° in pitch. Panels incorporate mineral fibre to provide thermal insulation and eliminate interstitial condensation and cold bridging. They offer rigid and lightweight construction, with no vapour or breather membranes required, and being a single unit, significantly reduce installation time.Composite panels are suitable for use on all building types in the commercial, retail and industrial sectors, providing flexibility for change of future use. They can also be installed over existing sheet-covered roofs to improve thermal insulation and weather protection.

    Green roofsGreen roofs are becoming ever more popular and are increasingly demanded by local biodiversity action plans. Intensive green roofs are effectively roof gardens intended for recreational use. Extensive roofs are lightweight and contain only wind, frost and drought resistant plants such as sedums. Biodiverse green roofs, once known as brown roofs, are designed to replicate natural habitat lost through building development.

  • Costs

    The roofing market remains competitive, with only small inflationary increases being passed onto the consumer. The Gardiner & Theobald tender price indices report low price rises of between 3% and 5% a year in the past two years, despite steel prices rising between 20% and 30%. This can be attributed to the influx of labour from Eastern Europe, which has eased the labour shortage in the construction industry.

    Oil price increases have resulted in the higher transportation costs for the industry in general, and most of these increases have been passed on to the consumer. The liquid roofing sector has been most hit by oil price increases as they use oil-based materials such as asphalt and bitumen. The cost of liquid roofing is generally considered likely to follow fluctuations in oil prices for the foreseeable future.

    The price of steel-based roof coverings continues to rise, conforming with the general trend of steel prices over the past two years. The price of copper roof coverings has been reported to be rising weekly.

    The table below shows some current roof covering tender prices.

    A simple comparison of flat roof to pitched roof shows that a pitched roof takes about 10% more roof coverings than a flat roof, depending on the pitch. This extra cost needs to be weighed against the roof structure costs and the associated sundry fittings and rainwater disposal costs before a conclusion is reached as to which option is cheaper. Rainwater disposal methods, such as fulbore outlets cast into concrete flat roofs, tend to be more complex and hence more expensive than eaves gutters in pitched roofs.

    The preliminaries costs for roof coverings vary between 12% and 20% of the total roofing costs. The choice of covering and type of roof structure play an important part in determining the amount of preliminaries. For example, a concrete framed building with built-up roofing felt finish requires less scaffolding, craneage and working platforms because the finished roof frame can be used as both storage and working platform for the application of the roof finish. A similar building with a steel or timber roof structure will require more craneage and hoisting equipment to lift the roof trusses to the top of the building and will also require scaffolding and working platforms to install the roof coverings. It should be noted that preliminaries are driven by a number of factors such as location of the project, the complexity of the design, programme and the available working space among others. Tendering procedures also contribute to preliminary costs in that fixed price tenders attract a risk premium like any other construction tender.


    The roofing industry has been developing Sir John Egan’s proposals for single-point responsibility as highlighted in his report Rethinking Construction.

    Up until now, the norm is for a specifier or designer to specify a certain roof, usually with a name of the supplier given. The supplier will in turn have commercial arrangements with a few ancillary suppliers and approved contractors. This leaves the tendering installer with no choice as to the products he is committed to install. The maker usually guarantees the product, provided it has been installed properly, and the installer provides a separate warranty covering workmanship.

    But in recent years, progress has been made to concentrate responsibility for both the installation warranty and product guarantee into a single point. Vision 25, an independent insurance scheme from Alliance Warranty Management, offers building owners and developers a 25-year latent defects warranty covering both materials and labour. It requires audited accreditation of the roof installer and has the advantage of offering policyholders protection against installers going bust and being unable to honour warranty payments.

    Market players

    Principal roofing material suppliers

    Handmade clay tiles:
    Keymer Tiles

    Machine-pressed tiles:
    Lafarge Roofing (formally Redland)

    Natural slates from Spain and Argentina:
    SSQ Group

    Artificial slates:
    Eternit Slates

    Standing-seam roofing:
    Corus Kalzip

    Broderick Structures

    Alumasc Roofing systems

    Composite panels:

  • For a full list of suppliers, visit

    Principal roofing contractors

    Prater Roofing

    Knight Asphalte

    Marshott Non-Ferrous Roofing

    Briggs Roofing & Cladding

    Richardson Roofing

    For full lists of contractors, contact the trade bodies:

    National Federation of Roofing Contractors
    Confederation of Roofing Contractors
    European Liquid Roofing Association
    Metal Roof Contractors Association

  • The UK Market For Roofing Materials is available from MSI Marketing Research for Industry for £685. For further details, including a table of contents and sample pages, please call 0800-195 6756.

    This datafile was compiled by Caleb Mudzudzu, a project quantity surveyor at cost consultant Gardiner & Theobald. For further information email