Summary
• iFrame claims a U-value as low as 0.13W/m²K.
• Timber frame company Code 4 has built 12 houses using iFrame.
• I-joist webs run in the same plane as the run of wall elevation.
• Components are assembled on site.

Masonite Beams is certainly pulling out all the stops to develop a full suite of timber build systems.

Its I-joists have long been used in the TRADIS breathing wall assembly, which also features specialist woodfibre boards and Warmcell recycled newspaper insulation.

The joists are also used in more standard timber frame panels in place of solid timber studs, as well as in a system still under development – the Masonite Flexible Building System.

Now a new option from the company, iFrame, developed with Worcester timber frame builder Code 4, uses engineered components but is assembled on site.

Neil Lewis, sales director of Masonite Beams parent company Byggma UK Ltd, said standard off-site timber frame fabrication was reasonably reliable but “panel creep” was sometimes an issue on site, while transport of prefabricated panels and the need to hire a crane could create cost and access pressures.

He said Code 4 Timber Frame originally developed a flexible wall system using solid timber and Masonite Beams realised it had potential. The two companies developed the product further over the past 18 months, replacing the solid timber with Masonite Beams I-joists, to create the iFrame system.

Off-the-shelf components

The result, Mr Lewis said, is an on-site build system using “off-the-shelf” standardised, engineered components.

The venture was an opportunity to see increased Masonite Beams production, with the goal being distributors moving into supplying the iFrame timber frame kit.

So far 12 houses and a couple of small apartment blocks have been built by Code 4 using iFrame, which also has two projects on the go at the moment. An 80-house site in Worcester is also on the cards.

Mr Lewis said the iFrame was designed to be a more cost-effective means of timber frame construction as an alternative to brick and block.

“The plan is to franchise the system across a network of distributors in the UK,” said Mr Lewis. “We have spoken to major distributors about the system and they were all very enthusiastic about getting involved. Our plan is to get these 80 houses started and then to start rolling it out across the distribution network.”

Specification

So how does it work?

A major feature is the Masonite Beams I-joist studs which are assembled/arranged and spaced with their web members in the same plane as the run of the wall elevation (opposite to normal use of I-joists in walls), thereby forming the desired wall elevation in situ.

Masonite Beams i-studs are converted into storey height panels with rebates cut into their upper and lower stud regions, allowing web members to be fixed to the edge of sole and head plates.

Secondary vertical/horizontal service panels overlap the insulated spaces between each storey height panel to provide an adjustable wall assembly and, it is claimed, improved racking performance (iFrame claims two to three times better than timber frame); isolation of services in relation to the vapour control layer; and superior fixing grounds and service routes.

Masonite Beams says this gives greater design flexibility because gaps for windows and doors can be repositioned during the build process.

Multiple leaf wall assembly includes layers of identical depth insulation in sets of standard widths and depths. The reversal of one leaf profile in relation to its adjacent leaf is a key feature and is designed to reduce tolerances in the fitting of insulation.

Mr Lewis said off-the-shelf components meant a kit could be ordered and delivered very quickly, with iFrame components for a large house able to be fitted onto one lorry.

Delivery and build benefits

Components can be unloaded by fork lift and then handled by one person, with the construction process sufficiently simple and deskilled for a bricklayer to complete. Build speed is billed to be as quick as standard timber frame.

Mr Lewis said a disadvantage with prefabricated timber frame was that open panels filled up a delivery vehicle quickly, requiring multiple deliveries.

iFrame’s claims are big – U-values from 0.23W/m²K down to 0.13W/m²K, with the double leaf construction said to be capable of achieving U-values to level 5 of the Code for Sustainable Homes. Masonite Beams says this is the result of tighter and more accurate fit on insulation, giving greater airtightness.

It is being targeted for housing, extensions, garages, garden structures, commercial buildings and other applications where traditional timber frame is used.

Testing has been done in conjunction with TRADA and BBA, with patents pending on the adjustable panelised wall elevations and multi-functional wall assembly process, including single multiple leafs of 70-100mm depth I-joist wall panels and their connecting components, used in external and internal walls.

“We hope to have distributors in place by the middle of this year,” said Mr Lewis. “We are going to use the first six months of 2010 to complete junction details and standard detailing.”

Masonite Beams sees a 50/50 business split between its supply of engineered floors and building systems (I-joist studs, Tradis breathing wall, Masonite Flexible Building System and iFrame).