Summary
• Engineered joists offer timber and labour savings.
• Design software can remove costs and speed up installation.
• Engineered joists enable long spans and deep structural sections to be constructed.
• System suppliers will be able to take on more project management functions.

I-joists and metal web joists have been one of the success stories of the past decade, winning the hearts and minds of the construction industry and bringing engineered wood products (EWP) into the mainstream.

They have become the automatic choice for sub-floor systems and today the ‘battle’ is more about I-joist versus metal web than engineered versus solid joist – manufacturers of the former argue they have a cost advantage over metal web, while metal web manufacturers claim their products provide better service access. Manufacturers of both are keen to point out, however, that there’s room for all timber flooring solutions and that concrete and steel systems are the real ‘enemy’.

Reliable statistics for market share are hard to come by and largely exist on anecdotal evidence and ‘guestimates’ of competitors’ sales figures. For example, one set of figures for 2007 shows that solid timber accounted for about 30% of the joist market at nine million linear metres, I-joists accounted for around 55% (16 million linear metres) and metal web joists came in at 15% (four million linear metres). Other sources suggest I-joists account for around 70% of the market and that metal webs are more in the region of 5%. Either way, the NHBC predicts that the latter will be the fastest growing sector of the EWP market.

Labour savings

I-joists and metal web joists have endeared themselves to the construction sector for similar reasons – ease of installation and time and labour savings. “In a typical family home the cost of an EWP floor would not be dissimilar to that of an old style carcassing floor, yet construction takes less than half the time, the material involved weighs about half as much, the product is stable, strong and true and services are easy to install,” said Simon Jones, business development director of Boise Cascade, manufacturer of the BCI-joist.

An added bonus, as Masonite Beams sales manager Neil Lewis pointed out, is that they can be supplied as full floor kits. “And,” he said, “they are better for separating floors because they can be supplied in optimum depths – for example Masonite I-beams can be manufactured in depths up to 600mm. Compared to solid joists they allow greater depths of insulation and reduce cold bridging due to their narrower cross-section.”

Software developed by manufacturers in tandem with their engineered joists also takes the stress out of floor design and are, according to Mr Lewis, “a prerequisite”.

“A correctly designed floor not only performs for the housebuilder, but a clever design can also remove cost and speed up installation,” said Kevin Riley, director of building solutions at Finnforest, which manufactures the Finnjoist.

“Full layout drawings undertaken by competent design staff ensure that the kit is fit for purpose and site waste is non-existent, thereby continuing to reduce costs for the builder,” agreed Mr Jones, with the caveat “software aids expertise, it doesn’t replace it”.

Longer spans

Longer spans are achievable with engineered joists, meaning that load-bearing walls can often be removed, opening up all kinds of design potential, and their inherent stability results in flat, squeak-free floors, raising the expectations of homeowners and housebuilders alike.

Therein could lie the rub – housebuilding has nose-dived and demand for joists of any description has declined: “The market [for engineered joists] has halved this year and is only around 12 million linear metres at present,” said Andy Moore, managing director of Steico, manufacturer of the Steico-joist.

However, as he points out, although most engineered joists are used in new house build, they are increasingly being used in commercial projects, if not in floors, then in flat or lightly pitched roofs.

Apartment block slowdown

The collapse of the buy-to-let market and the subsequent slowdown in the building of apartment blocks has also not hit as hard as might be expected. “The majority of apartments are concrete floored, so this is not such a negative,” said Mr Moore. “If the fashion is back to ‘proper’ houses, then that’s good for us.”

And Paul Baron of Gang-Nail Systems, which manufactures the metal web Ecojoist, believes that timber frame apartment blocks (around 20% of the multi-storey residential market, according to the NHBC) will continue to be built. “Engineered timber floors have been used primarily in timber frame apartment blocks as the Robust Detail is only valid for timber frame construction, which we think will continue,” he said. “We think the net effect to our business will be a positive one.”

Indeed, gains have been made within the sector despite the economic meltdown in 2008, if not in volumes, then in custom. “Volumes have decreased from previous years as a direct result of the reduction in house starts, but we have added new customers to our existing Ecojoist manufacturing base,” said Mr Baron.

Boise also has “more customers using [its] products at the end of 2008 than at the beginning,” according to Simon Jones, and it’s a similar story at Wolf Systems, which manufactures the metal web easi-joist. “We’ve increased sales by around 35% this year,” said sales and marketing director Karl Foster. “This is due in part to existing manufacturers [of the system] growing their engineered floor business and also new manufacturers recognising the benefits easi-joist can bring.”

Ready for upturn

Opportunities certainly still exist for engineered joists and manufacturers are readying themselves for the day when the economy improves. “It’s clear for all to see that new builds have been affected by the current economic climate,” said Kevin Riley. “What is crucial is that, as a business, we are positioned to make the most of the upturn when it finally does arrive.”

“Investment in new technologies, systems and solutions is crucial to the longer-term sustainability of our building solutions business. The downturn has resulted in an acceleration of these new systems and solutions,” he added.

Meanwhile, Masonite Beams’ business strategy includes optimising other market opportunities – such as wall and roof systems – and pulling flooring I-joist sales through as a consequence. “Jointly with Exel Industries we are heavily promoting the TRADIS closed panel wall and roof system which incorporates Masonite I-joists and I-Studs,” said Neil Lewis. “When we’re selling the TRADIS system it results in stud sales and increased I-joist sales through additional floors.

Gang-Nail’s Paul Baron is looking forward to 2010 when level 3 of the Code for Sustainable Homes kicks in as a requirement. “Ecojoists will be able to provide the access through the floor zone that many builders will require in order to use mechanical ventilation and heat recovery (MVHR) systems,” he said.

Energy efficiencies

Wolf’s Karl Foster agrees that the government’s drive towards more energy-efficient homes will play into the hands of engineered joist manufacturers: “We expect to see more metal web floor joists used in non-traditional applications, particularly as the need for increased insulation requirements affects the design and manufacture of more traditional methods of construction,” he said.

“The ability of I-joists to provide deep structural sections very competitively for use in floors – as well as roofs and walls – and provide space for insulation, ventilation and other services will position them as the material of choice in the structural envelope of tomorrow,” agreed Simon Jones.

“The opportunity for the timber engineering industry to come out of this difficult period and provide a clear, sustainable construction strategy and solution is huge,” he said, adding that reduced employee numbers among builders will provide more opportunities for those kit suppliers able to take on more of the project management functions.

“Suppliers who can take developers’ pain away, providing housing system solutions that tick all the boxes will be well placed to ride the next boom,” he said.