Timber is a fundamentally important material to offsite construction and one of the leading mainstream, renewable, low-carbon building materials. Structural timber has developed in recent years to become a popular way to build all types of building. Timber can be used in several slightly different build systems including solid wood, engineered solutions such as cross laminated timber (CLT) and glulam, as well as timber frame, SIPS and associated open and closed panel systems. Timber has impressive thermal and acoustic performance levels as well as huge aesthetic appeal.
Cross Laminated Timber (CLT)
Increasingly popular as part of hybrid builds and multi-storey timber structures, CLT panels are precision-manufactured to any dimension and shape from single-layer timber boards then glued together at right angles to form large solid timber panels for walls, floors and roofing. CLT panels have huge structural potential and are suitable for most building types.
Attractive with design appeal, glulam beams provide large-span structures without supporting columns, with lots of natural light. Glulam is a strong and sustainable alternative to concrete or steel beams. Made from layers of parallel timber laminates glued together, glulam sections are now frequently used in the construction of all types of building including supermarkets and swimming pools.
Timber frame building can consist of wall panels, alongside floor and roof panels – often referred to as cassettes. These can also be open panel or closed panel. Open panels are timber frame wall panels, comprising studs, rails and sheathing on one face and a breather membrane. Closed panels also include linings on the faces of the panel, a vapour barrier and breather membrane. Closed panels may also include fitted windows, openings for doors and service routes. Manufactured in factory conditions, these cassettes and panels are brought to site and fixed together to form a rigid load-bearing superstructure. These consist of timber studs and beams, stiffened on one side with oriented strand board (OSB) and plasterboard.
Structural Insulated Panels (SIPS)
SIPS are primarily a timber-based panel that consists of two parallel faces – usually oriented strand board (OSB) or cement-bonded particleboard – with a rigid core of polyurethane (PU) foam or expanded polystyrene (EPS) inside, SIPS are a cost-effective and energy-efficient solution to a wide range of building types and can provide airtight walls and roofs. SIPS panels also offer high levels of insulation due to the use of the in-filled material. Properly used, SIPS needs no other structural frame supporting them.