Lead times are staying level in most sectors, but there is still a lot of worry over steel demand, according to Mace's Rob Darrow. Over the page, Gavin Murgatroyd of Gardiner & Theobald shines the spotlight on roofing
lead times have reduced in four sectors, with only three areas showing increases in the last quarter.

Piling → lead times remain at six weeks overall, following the small increase last month. Companies noted that several recent enquiries were for commercial office buildings, dormant for so many previous months. Reinforcement prices continue to affect the piling sector. Precast piles continue to require a four-week lead in.

The lead time for concrete works ↓ fell one week to five weeks overall. The volatility of reinforcement prices means that suppliers are unwilling at present to fix the reinforcement element of tender prices.

The average lead time for structural steelwork → remained at 11 weeks. Designers and CAD operators are difficult to recruit and this could affect shop drawing production times if demand increases unexpectedly. Rising steel prices are affecting all suppliers and those with a close business relationship with the main producer should be able to manage supply issues more effectively.

Curtain walling → was unchanged again at 19 weeks and this has been a consistent lead time for the past two years. All suppliers reported steady workloads that they did not expect to change for the next six months.

Atrium roofing → specialists report no change overall with a lead time of 28 weeks. Increased worldwide demand for steel is affecting tender prices, although the supply is not affecting lead times at present.

The membrane roofing → sector maintained lead times at eight weeks. Insulation products continue to require longer lead periods than required in the past.

Profiled roofing ↑ lead times increased two weeks to 14 weeks overall, following the reduction in the last quarter. Procurement of raw materials, with the rise in global steel demand, has led to the increase.

The lead time for metal windows ↓ fell one week to 16 weeks overall, the first fluctuation since the beginning of 2002. Suppliers note that new orders have been slower than anticipated. This has created spare capacity in the design offices.

Brickwork ↓ lead times fell to four weeks, a drop of one week. Generally brick and block layers are in good supply.

The lead time for demountable partitions ↓ fell by two weeks to nine weeks. Suppliers note that raw materials are readily available at short lead times and capacity exists in order books.

General joinery → suppliers continue to report a lead time of 12 weeks, which is unchanged in the last period. This lead time is not expected to change in the next period.

Suspended ceilings → are unchanged at 16 weeks, with new enquiries at a stable level. Suppliers say that lead times may extend in the next period due to the current steel shortages.

Decorating ↑ suppliers have extended lead times to five weeks on average. The one-week increase is due to increased order books, which is to be expected in the summer months.

Furniture ↑ manufacturers report current lead times of 14 weeks, an increase of two weeks. All suppliers are very busy, which has been reflected in the increased manufacturing period.

Ductwork → lead times were maintained at 12 weeks overall. Suppliers are quieter than six months ago, although are maintaining lead times to offset the continuing steel shortages and the commencement of major projects, such as Wembley Stadium and Heathrow Terminal 5.

Lead times for sprinkler installations → remain at eight weeks. Suppliers are concerned about the availability of piping during the latter half of 2004 and are reluctant to decrease lead times, despite fewer enquiries than six months ago.

Continued concern over increased steel demand is the common theme for many of the sectors for the second time in 2004. Although many suppliers are not citing the demand for steel as a reason to increase lead times, several have decided not to decrease lead times despite order book capacity, as they expect problems with steel supply for the remainder of 2004.

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    Spotlight on roofing
    Material selection
    The roof of a building must work in harmony with the insulation and ventilation to keep the building free of moisture and create a pleasant environment. The choice of materials as a covering has grown with the development of material technology, both in terms of weatherproofing and also more innovative considerations such as photovoltaic coverings to produce electricity and reflective coatings to prevent excessive heat gain.

    Roof designs and the materials used differ for residential and commercial buildings, with commercial buildings typically using low-slope or flat roofs and residential roofs usually being pitched. With each roof type comes different concerns regarding moisture, standing water, durability and appearance, and this is reflected in the options available for roof coverings.

    Roof design can impact on a building's thermal performance. For example, in metal-framed buildings the eaves can act as a thermal fin, moving heat out of the building and thus reducing the heat-load demands on the air-conditioning systems.

    Revisions to Part L of the Building Regulations have made thermal performance paramount in the thoughts of designers and clients. Roof materials have been developed to provide thermal properties as well as weather protection. Materials with good U-values, such as prefabricated metal sandwich panels with integral insulation, are therefore gaining market advantage.

    The types of roofing that achieve this can be categorised into the following three groups: Metal roofing
    Most metal roofing products have historically consisted of steel or aluminium, although copper and zinc are becoming more prominent. Metal roofs are generally formed from prefabricated sheets or panels, rather than blocks or built-up members. They are mainly laid with minimal slope and provide weather protection as effectively as any other roofing material.

    The lightweight nature, ease of fixing and commensurate capital cost savings of metal roofing have made the material more popular in recent years.

    Flat roof coverings
    Flat or low-sloped roofs on commercial, industrial and institutional buildings traditionally use built-up roofing. This consists of layers of asphalt laid on a roof deck, in conjunction with a vapour retarder, final surfacing material and insulation membrane. A bitumen-felt membrane assembly consists of alternate layers of felt and bitumen, with a reflective surface finish. Single-ply thermoplastic membranes, the most common being PVC, are based on plastic polymers, which provide strength, flexibility and durability.

    The advantages of prefabricated sheets over built-up roofing are the consistency of the product quality, the versatility of their attachment methods and, therefore, their broader applications.

    Pitched roof coverings
    Pitched roofs are traditionally covered with small tiles of slate, clay or concrete that are durable, aesthetically pleasing, low in maintenance and have inherent fire rating due to the non-combustible nature of the material. Most roof tile makers offer warranties of up to 50 years, or for the lifetime of the structure. At the end of the roof's life, these naturally occurring materials can be easily recycled.

    Due to the thermal capacity of tiles and the ventilated air space that the pitch creates, a tiled roof can reduce air-conditioning costs in hotter climates and produce more constant temperatures in colder regions.

    In recent years, manufacturers have developed water-shedding techniques, as well as adhesives and mechanical fasteners for high-wind situations. Because the ultimate longevity of a tiled roof also depends on the quality of the subroof membrane and structure, roof tile makers are working to improve flashings and other aspects of the underlay system.

    Tender prices
    The Gardiner & Theobald LLP tender price indicator for the first quarter of 2004 is forecasting a modest increase in roofing tender prices over 2005 and 2006. The increase in raw materials prices, for steel and aluminium, has affected the metal roofing market and are being passed on in higher tender prices. However, the materials price increases of 10-15% for aluminium and 30% for steel have translated into only a 2-3% overall increase in tender prices.

    Asphalt roofing, on the other hand, has declined in tender pricing during the first quarter of 2004. This is expected to continue during the year, ending 4% down on 2003 levels. Respondents to the G&T tender price survey suggest that 2005 will be flat with a modest 1% or 2% increase in 2006, but oil price inflation may yet change this outcome. These figures reflect competition and trends in the selection and use of different material types in the UK market.

    Of the contractors surveyed, all were concerned by the lack of major new-build contract awards, which has meant trimming margins and reducing overheads. Contractors are seeking more PFI-procured work where the life-cycle performance and maintenance cost of the roof is a significant factor when deciding on specification and use. The cost of bidding in PFI markets is high, with a limited success rate unless the firm is named in the initial specification. The larger roofing contractors are seeking a market advantage through assisting the designers at an early stage and developing the detail of their design and specification to suit their products. This ensures they are chosen for the work, reduces the cost of installation and facilitates the provision of a performance guarantee which is still an important issue for building owners.

    Market conditions
    The roofing materials market has grown over the past five years with overall output in the industrial and commercial sectors increasing by more than 21%. The major share of the market is for repairs and replacement of roofs rather than new build.

    According to the latest survey from Market & Business Development (MBD) the majority of roofs in the UK (in terms of area) are clad with lightweight steel, accounting for some 41% of the market coverage. This is an increase in its market share of more than 50% since 1999 and reflects the trends in architectural design for lightweight, lower cost roofing solutions.

    Aluminium has seen a similar percentage growth in market share but represents only 1% of the total comparable coverage of steel. Metal roofs account for the greatest share of new build work in the UK, being used on 54% of industrial and commercial buildings.

    Residential pitched roofs have maintained a consistent market share and, despite anecdotal evidence that more homes are being built every year, the roofing market figures do not reflect this.

    Other materials have maintained a consistent market share with the exception of concrete tiles, which has declined, and single-ply PVC, which has increased.

    The improved performance of plastic coupled with generous guarantees from manufacturers has led to the increased use of single-ply PVC. Architectural designers benefit from the manufacturers' design services and can incorporate standard detailing at inception stage. Coupled with the physical flexibility of the material, this gives the roof designer more confidence in performance.

    Forecasts for the market from MBD indicate a very stable period with overall output maintained at a level marginally higher than that for 2003. Little change is anticipated in each type of roofing sector year on year, with the exception of a modest increase in total coverage output in 2006 and 2007, reflecting the predicted upturn in overall construction market output.

    Future developments
    The roofing industry is developing products that reuse waste from other industries. For instance, recycled car hoses, tyres and other rubber products are now being utilised in a lightweight rubber "slate" tile. This is under trial in the USA at present but could be exported to the UK shortly.

    The reuse of concrete and slate tiles has been occurring for centuries during roofing repairs and maintenance, making roofers, masons and joiners, unwittingly perhaps, some of the first green contractors.

    Photovoltaics are forecast to continue as a roofing material, but need to develop as an integral stand-alone weatherproofing system rather than an additional layer on top of the weatherproofing defence.

    Roofing will be affected by the requirements of the forthcoming revisions to Part L which introduce more onerous conditions of thermal performance. This should lead to roofs being used even more creatively to generate value from passive solar-shading overhangs. The impact of roofs on the skyline of our cities will continue to raise the profile of this element.

    Going up

    ↑ Profiled roofing
    ↑ Decorating
    ↑ Furniture

    Staying level

    → Piling
    → Structural steelwork
    → Curtain walling
    → Atrium roofing
    → Membrane roofing
    → General joinery
    → Suspended ceilings
    → Ductwork
    → Sprinkler installations

    Going down

    ↓ Metal windows
    ↓ Brickwork
    ↓ Demountable partitions
    ↓ Concrete works
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