Joists span ever wider choice

Summary
• Through MBM’s distributorship, LP’s I-joists are now available at merchants.
• Sales of Wolf’s easi-joist are up 50% this year.
• Steico has secured 90% of Masonite Beams’ former business.
• Boise Cascade’s Versa-Bloc provides fire resistance at floor level in timber frame party walls.

The engineered wood market is now a mature sector within the UK construction products sector and most builders wouldn’t bat an eyelid at the sight of an I-joist or a glulam beam.

Their eyes may well be opened, however, by a new development from Louisiana-Pacific (LP), the 225x63mm I-joist, which the company is launching into the UK merchanting and small/medium sized builder market.

LP already serves the national housebuilder/timber frame sectors through its partner Wyder Engineered Timber Systems.

But LP’s “simply better” business model, through the distributorship of MBM Forest Products, sees small builders opened up to the possibilities and benefits of I-joists, enabling them to pick up as little as one I-joist off-the-shelf from a merchant.

UK market

The 225i I-joist, a direct replacement for the 8x2in and 9x2 solid timber joists, is part of LP’s SolidStart engineered wood products range and was designed and sized to fit with traditional UK brick and block coursing and to match EU standard glulam depths.

LP has also developed two new laminated strand lumber (LSL) rim board products to fit the loft conversion and timber frame markets.

LP said the new 35x225mm 1.35E LP SolidStart LSL eliminates the need for complicated designs and expensive reinforcement end details for loft cuts.

In timber frame, LP has determined that its 29mm-thick LSL rim board is the best solution, regarding 32mm, 38mm and 45mm rim as over-specified.

Meanwhile, rival engineered wood brand Steico is changing its range of I-joists. Instead of the top and bottom flanges being made of solid wood, they will now be LVL. Steico says the change to Steicoultralam LVL will give a stronger all-round performance as well as combine well with its ultralam LVL rimboards. They are now the only fibreboard/LVL I-joist product in the UK.

It says the new combination offered the ability of wider spans for better living space and a more consistent volume production quality compared to solid softwood

Insulation is another focus area for Steico. “We believe this core element [I-joist] should not just be the physical load-bearer and control for the shape of the building but an integral part of the insulation envelope,” said Adrian Judd, Steico UK sales manager.

Reduced thermal bridging

Steico argues that the I-section profile of Steicojoists and Steicowall, with their reduced cross-section of an 8mm or 6mm web, reduces the capacity for thermal bridging, while insulation depths can be cut through the pre-insulation of the wall studs – usually via the space between the web and the flange filled with wood fibre insulation.

Fire performance testing of fire retardant treated products in the Steico range is ongoing.

Steico has been busy since it secured the majority of Masonite Beams’ UK business after the latter announced it was closing its UK operation. Steico has agreed terms with seven Masonite dealers representing about 90% of Masonite’s UK volume – around 1.5 million linear metres. Steico estimates the new business gives it approximately 28% of the UK I-joist market.

Fire protection

Intelligent Wood Systems (IWS), which produces a finger-jointed, super-dried building system where the main component is solid timber, is putting much focus on the fire protection issue. In the face of several high-profile construction site fires affecting the timber frame industry, IWS has developed IWS-FR in partnership with a number of partners including Arch Timber Protection, which adds fire retardant treatment to the system.

IWS says its interim report and testing on the system shows it can minimise concerns regarding timber frame during construction as it reduces ignitability, fire propagation and spread of flame. Tests show it can reduce generated heat in excess of 70 times and provide extra time to both escape the site and for fire crews to tackle situations.

IWS is about to relocate from Glenrothes to Perth to achieve efficiency savings and cost benefits. It will soon launch several new products and systems including a commercially attractive rim offer and a panellised roof system that will improve production and installation times. The facility at Glenrothes will be maintained to trial and showcase these new developments.

Open metal web

Karl Foster, sales and marketing director of Wolf Systems, said sales of the company’s easi-joist open metal web/timber flange joist are up over 50% this year compared with a year ago, with more products being used in different applications rather than just floors.

Wolf is working towards a new Robust Detail for separating floors in apartment buildings. Using a recycled product called Iso-rubber, the new floor construction detail is designed to offer quicker installation, reduced labour costs and more flexibility as the overall floor depth is significantly reduced due to the elimination of acoustic battens.

Wolf said initial tests show a significant reduction in sound transfer between dwellings, giving extra Code for Sustainable Homes credits.

Meanwhile, a six-month test programme into the use of easi-joist as extra-wide timber frame studs for wall construction has concluded. Wolf has previously supplied easi-joist for several projects, but the testing results will lead to a standard specification for manufacturers and designers.

Structural and thermal test performance data of easi-joist studs with a variety of insulants will be included in a forthcoming technical guide.

Services

The ability of I-joists to accommodate services such as plumbing is being promoted by Boise Cascade and the company has contacted 10,500 industry contacts about its pre-stamped knock-out hole I-joists.

The move comes amid increasing demand by housebuilders, main contractors and developers for larger holes to accommodate mechanical ventilation and heat recovery systems.

Boise has also developed its Versa-Bloc detail as a low-cost way to ensure fire resistance at floor level in timber frame party walls.

Versa-Bloc provides a sacrificial shield to Boise’s Versa-Lam (LVL) or Versa-Strand OSB rim board, ensuring sufficient structural columns remain at the end of the 60-minute fire resistance period required by Part B of the Building Regulations.

Versa-Bloc is fixed along the rim construction at centres of at least 600mm and allows the rim board to be reduced to a single ply on the party wall.

“Close working relationships with our customers allowed us to observe and challenge accepted practice,” said Simon Jones, Boise’s UK business development director.

Glulam contracts

Engineered timber construction systems specialist B&K Structures, which uses glulam, cross-laminated timber and structural insulated panels, as well as other materials in its projects, has secured five new primary school schemes since last September.

Other projects include the recently-opened Brockholes Wetland Centre for the Lancashire Wildlife Trust and M&S Cheshire Oaks, where the frame is almost complete.

The Brockholes project, designed by Adam Khan Architects, is a floating concrete pontoon with a glulam frame on top, clad with SIPs and oak shingles on the exterior. Mansell is the contractor while engineering is by Price & Myers.

Another recent B&K project – a 60,000ft² Tesco store in Barnstaple – used timber roof cassette technology to eliminate the time-consuming process of building purlins. The 12x2.4m self-spanning cassettes sit on the glulam frame and were installed in just three weeks.

B&K is also in the running for a prestigious project to build a series of new London fire stations. Its hybrid timber/steel solution is currently up against a concrete bid for the job, with a decision expected soon.