Stuart Devoil of Smartply explains how the humble sheet of OSB has become a design solution as engineered timber panels are being used across the building sector, from the construction of energy efficient and low carbon homes to site hoardings and everything in between.
People often misunderstand engineered boards such as OSB (Oriented Strand Board), and don’t really see where the ‘engineering’ part fits in. A big hint is in the first part of the name: ‘oriented.’
Unlike plywood which is built up from thin layers of wood veneer, OSB consists of individual strands and flakes of wood. These are bonded and deliberately arranged in a three-tier structure, with the strands in the outer layers oriented in the same direction as the panel length, and those in the core layer at right angles to it.
The result is a solid panel with no core gaps that will not delaminate under normal use. This structure gives OSB a great deal of strength, which means it can be used in a broad range of applications, everything from the manufacture of furniture to high performance technical solutions for construction. The flakes are specifically positioned or ‘oriented’ in terms of where they lie within the board, therefore the board is engineered. However, not all engineered boards are the same.
Not only must any construction board or panel be strong and fit for purpose, but it must also be manufactured from legal, sustainable raw materials. The environmental body Greenpeace has advised as follows: “Demand for tropical hardwood plywood in the UK and internationally is one of the main causes of illegal and destructive logging in the rainforests of countries such as Brazil and Indonesia. This deforestation is causing the loss of biodiversity, displacing local communities and contributing to climate change.
“The construction industry is the biggest consumer of timber in the country which is why it is vital for contractors, architects and builders to source timber from environmentally and socially responsible sources such as those certified by the Forest Stewardship Council (FSC)”.
With this in mind, it is essential to ensure that any timber panel product, be it plywood, OSB, MDF or any other timber based board is sourced, from sustainable, credible, compliant, certificated sources. In the UK, Forest Stewardship Council (FSC) certified products are guaranteed to give you this peace of mind, however just because a product is manufactured from the right material, it doesn’t mean it is fit for your specification.
There was a time when OSB was used purely for boarding up broken windows, or constructing shed roofs and floors. However, recent advances in manufacturing technologies and processes now mean that OSB is the perfect answer to numerous design challenges.
Old ‘Daylight Press’ technology led to OSB often being out of tolerance, out of square and out of consideration for high quality specified applications. But modern, ‘Conti-Roll’ manufacture ensures products are flatter, straighter and within stricter tolerances than ever before. And the benefits don’t stop there; the continuous conveyer method and updated controls mean that OSB is now available in a broader range of thicknesses, widths and lengths than physically possible with the ‘Daylight Press’ technique.
This means OSB can now reach much wider spans, making it ideal for use in timber joist, roof or structural applications where there is no longer a restriction on length. Teamed with the strength of OSB, and technical variants including flame retardant and moisture resistant panels, these extended sizes allow a huge amount of design flexibility.
Where do we go from here?
With fully certified raw material, new manufacturing methods and a whole host of new opportunities, what is next for OSB? Some would say ‘the sky’s the limit’, with longer and wider structural panels allowing the construction of larger, taller, more complex buildings. But sky may not be the next new arena for OSB – air may be.
With the growing trend towards low energy or Passivhaus constructions, OSB must look to the future and innovate to stay relevant. For many years, people have assumed that OSB is airtight, however, contrary to popular belief, standard OSB (or any standard wood panel) is not suitable for use as an air and vapour tight layer. This issue has been the subject of much scientific research in order to evaluate the air permeability of OSB panels and to provide limits to manufacturers and end users.
Further to the results of this research and a great deal of development, specialist OSB panels are now available that are not only structural but airtight and vapour tight too, perfect for use in Passivhaus or Low Energy construction. The smooth finish provided by the ‘Conti-Roll’ manufacture even assists here, where the smooth surface provides ever improved adherence for jointing and sealing tapes.
OSB has moved a long way from its old roots as an emergency hoarding panel and now sits at the top table with the most sustainable, innovative and flexible products on the planet, and they don’t cost the earth either.
Stuart Devoil is head of marketing and brand at Smartply.