What do Milan’s Metro system, the film industry, wood-turning, the Body Shop and Ford’s testing centre all share?

Not an easy one, granted. But they all represent applications of an engineered wood product which has perhaps not been in the limelight as much as glulam and LVL – Parallam. And according to its makers, iLevel Trus Joist, we could start seeing a lot more of it, as people switch onto its potential use in structural, and increasingly in decorative, applications.

Like many engineered wood products, Parallam, or parallel strand lumber (PSL) to give it its technical name, is not a new product. It was developed in Canada during the 1970s by MacMillan Bloedel, during a time of concern about timber scarcity, especially long length, solid clear Douglas fir, cedar and hemlock.

PSL basically consists of clips of wood stacked vertically on each other, then glued and pressed, before curing using microwave technology. The beams are capable of high strengths and long lengths.

James Sweet, iLevel Trus Joist’s European operations director, said until now the company has focused more on the TJI-joist as its star rather than PSL or its other rectangular beam sections. But this is being addressed in 2006, with new staff spreading the message and developing new markets for the product.

“Parallam, like glulam, like LVL and TimberStrand [laminated strand lumber], are finding an increasing market share, largely because there are a number of projects which in the past would have been built in concrete and are now being built in timber frame,” he said. ”Effectively, steel beams are going out and more robust timber/composite sections are coming in.

“We really feel it’s our responsibility to bring Parallam to the specifiers’ attention. The cost of steel is still escalating and on a building site people generally prefer a timber-to-timber option where possible.”

Hidden structures

Perhaps a reason for PSL’s lack of market prominence is because it is often hidden away in building structures, typically as primary members in residential structural floors. Its use as a rim beam in timber frame structures resolves particular design issues such as disproportionate collapse in multi-storey apartments. Columns and ridge purlins are also made from the material.

“It’s really that problem-solving beam,” said Philip Carney, iLevel Trus Joist’s European product development manager. “But people have started to move on to the fact that it’s also an aesthetic product. There are a number of large houses built where people have exposed Parallam.” Examples include roof design, with exposed purlins becoming a feature in bedrooms.

This trend for Parallam as a decorative feature was shown at the recent Interbuild show, where panels made from PSL on the company’s stand attracted interest from shopfitters. “It is quite a headturner, even people who know about timber do a double take. It has warmth, tactility and this very unusual figure,” said Mr Sweet.

You can even make bowls and vases out of the stuff – just visit www.outofcontrol-woodturning.com.

“The general public is warming to the idea of wood as a visible feature of the house. Wood is coming into its own, not only as a structural member, but as a feature structural member,” said Mr Sweet.

Applications

An example of this dual structural/decorative use is the Henry Doubleday Research Association’s organic research centre at Ryton near Coventry. To keep member sizes to a minimum, Parallam was used for the post and beam structure, with the material being left exposed in many areas.

A recent purely decorative application was a library in Folkestone, where PSL was cut into vertical panels.

Other interesting uses include Ford’s Dagenham testing centre. Scientists needed a stable material to use in their wind tunnel for testing cars in different climatic conditions.

Parallam is also being tested underground as railway ties on Milan’s Metro system and, in the film-making world, PSL beams support camera platforms.

iLevel Trus Joist believes the environmental credentials of its product have also helped it win blue chip contracts from the likes of the Body Shop in the US and Top Shop in the UK.

Inevitably, PSL will sometimes find itself competing with glulam for a contract. “If it’s in an exposed environment, the specifier will choose what he likes the look of. Glulam has a lovely clear blond finish, while PSL has more of a rugged depth to it. Beauty is in the eye of the beholder,“ said Mr Sweet.