Glued laminated timber, glue laminated timber.
Glulam, short for glued laminated timber, is an engineered wood product. Large glulam members are produced from smaller pieces of stress graded and seasoned timber, known as laminates.
Glulam originated in Germany around 1900 but didn't make its way to Australia until the 1950s. It is now used for both structural and decorative applications.
The manufacturing process produces large and long length glulam members, which also results in increased strength when compared to that of the individual member. This also means that much larger pieces of timber can be produced than would otherwise be possible with traditional solid sawn timber. Glulam is consistently stronger than solid timber, in part due to the reduction in size and occurrence of natural defects.
Timber laminates used in the production of glulam are typically finger-jointed into continuous lengths and available in a range of both softwood and hardwood species. The thickness of the laminates will depend on the application and species used. Prior to gluing, the laminations are accurately dressed to exact and uniform thickness. The laminates will also be clamped together under constant pressure until the glue has cured. Once glued, members are planed, cut to exact size and may be coated with a water repellent sealant.
Many manufacturers are able to produce a variety of shapes and sizes at the designer's request. The length and shape of glulam sections is limited only by manufacturing, transport and handling capabilities.
Australian manufacturers generally produce deep sections with the laminates horizontal. In Europe, glulam has been used with face and edge lamination to produce deep sections with vertical laminations; this technique may also be used by some Australian producers.
It is possible to manufacture a glulam beam with higher strength laminates in areas of high stress - such as in the top or bottom laminates of beams - and lower strength laminates in the areas of low stress. Steel and fibre reinforcement can also be incorporated in areas of high tensile stress and may be positioned either parallel or perpendicular to the laminate direction.
Suitability for structural applications
Glulam offers many benefits when it comes to structural applications:
- Large section sizes and long lengths - glulam can be manufactured curved or straight and is often used as structural beams. Finger jointing allows for long lengths.
- Increased strength due to the laminating process - glulam is stronger than solid timber as it has fewer natural defects and a wider distribution. It is also comparable to steel in strength but is much lighter.
- A high degree of dimensional stability - glulam is manufactured from seasoned timber and is therefore less prone to movement caused by changes in moisture content. However, care needs to be taken if they are used externally or in an environment with rapidly changing humidity (such as an indoor swimming pool). Swelling and shrinkage may lead to splitting or , in an extreme event, delamination of the beam.
- Reliability - glulam is manufactured to strict quality requirements from stress- graded timber of known structural capacity. There are glulam quality assurance programs operating in Australia, but not all manufacturers may belong to them.
- Chemical resistance - glulam is resistant to most acids, rust and other corrosive agents. Typical uses in corrosive situations include animal hide curing complexes, fellmongerys, fertiliser storage and swimming pools.
A truss is a structure comprising one or more triangular units. Each triangle is constructed with straight and usually slender members of timber, connected at the ends by joints. External loads, and the structure's reaction to those loads, act at the joints, resulting in forces that are either tensile or compressive.
The strength of a truss lies in its triangulation of banding members that work together to the advantage of the overall structure. For trusses, compression members often dictate the size of the elements, thus designs that have short compression members or restraint against lateral buckling are generally more efficient than trusses with longer compression members.
Within a building two forms of trusses can be found. Nail plated trusses are trusses hidden from view that use nail plates as connectors. Architectural trusses refer to those attractively detailed timber trusses, exposed to view. This guide focuses primarily on the application process of the latter.
The benefits of timber trusses are notable and numerous. Timber roof trusses are an ecologically sound choice, compared to conventionally pitched roofs, they use smaller dimension timbers that span greater distances and this in turn reduces the total timber volume contained within. Architectural timber trusses are lightweight, enabling speedy and efficient construction and installation that results that in a visual feature to be enjoyed for decades.
This article provides a comprehensive overview to the processes involved in specifying, assembling and installing an architectural roof truss.
Whether for structural or finished flooring applications, timber offers durability, versatility and adaptability. The warmth, strength and natural beauty of timber flooring has proved enduringly popular in a wide variety of interior settings.
Timber flooring is a timeless product, offering a warmth and natural beauty largely unmatched by other flooring options. This article provides an overview of the installation of solid timber strip flooring over bearers and joists, timber based sheet flooring products and concrete slabs. Timber flooring is typically supplied as either solid timber or laminated wood products, made from layers of bonded timber. It fits together with a tongue and groove joint and once in place, is sanded and finished. There is a wide variety of species to select flooring from and the right species for a given application will be dependent on numerous factors. Information relating to species selection, environmental assessment, finish selection and recommended maintenance routines are all provided in this section.
Lightweight timber construction typically comprises framed and braced structures to which one or more types of cladding are applied. Framing configurations can range from the closely spaced light timbers commonly seen in stud frame construction to large, more widely spaced timbers. A timber framed building can be placed on a concrete slab or on posts/poles or bearers resting on piers/stumps supported on pad footings.
Used in houses or multi-residential dwellings, lightweight timber construction offers the flexibility of a wide range of cost effective design options.
When the timber comes from sustainable sources, this construction method can be environmentally advantageous as it combines timber's low embodied energy with its capacity to store carbon.
Timber joinery products offer a classic, unique and stylish touch to any interior or exterior design. The products are produced for a variety of internal applications including door and window frames, cabinetry, skirtings, mouldings and architraves. When looking to the outdoors, joinery products range from decorative eaves and posts to eye-catching railings.
Many timber species are suitable for joinery products and care should be taken in selecting the perfect timber for the particular product and its intended finish. Rare and exotic species such as Teak and Rosewood can generate pieces of outstanding beauty but material cost and availability are also important considerations.
Commercially available species like Tasmanian oak, Australian cypress, spotted gum and the like, often make the more practical choice, with the added benefit that they can be easily matched with other timber products within the building, like flooring.
Solid timber for joinery products is generally supplied as ‘clear finish grade' but ‘paint grade' options are available and these are usually comprised of a composite material like MDF or glulam.
A large number of specialist suppliers and producers offer the consumer extensive choice of profiles for all of the most common and popular joinery products. Choice is in many cases, limited only by imagination.
Cabinetry is often associated with joinery and most typically includes, cupboards, benches and other similar ‘built in' furniture. Like joinery, cabinetry is generally specified as either paint or clear finish grade and naturally for clear finish grade timbers, appearance and surface finish are critical in achieving a successful application.
Timber mouldings add style, class and an elegant touch to any interior, offering a depth of beauty and warmth in a way only wood can. From period times to those more contemporary, timber mouldings have graced the most stylish and chic of interiors, decorating furniture, doors and windows. Decorative mouldings such as architraves, skirtings, cornices and ceiling roses remain an ever popular choice for designers seeking a finished result of beauty, style and quality. Like all timber products, mouldings are extremely versatile and durable, enhancing the aesthetics of any interior and functioning as the perfect finishing touch for designs with a focus on beauty and splendour.
Mouldings can be created from any commercially available species of timber and the moisture resistant wood product, MDF, is also a popular choice. When it comes to style and design, the sky is the limit with many suppliers offering custom matching to existing mouldings, as well as efficient supply of those that are individually designed. Installation is a breeze, with the majority of mouldings easily attached with a reputable wood adhesive. Finishes can be tailored by design requirements and the preferences of the end user, with mouldings commonly being both stained and/or painted.
Timber portal frames are one of the most favoured structural applications for commercial and industrial buildings whose functions necessitate long spans and open interiors. As a material choice, timber offers designers simplicity, speed and economy in fabrication and erection.
Timber portal frames offer a strong, sound and superior structure. Structural action is achieved through rigid connections between column and rafter at the knees, and between the individual rafter members at the ridge. These rigid joints are generally constructed using nailed plywood gussets and on occasion, with steel gussets.
From material selection to finishing, this application guide provides a comprehensive overview of the process of using timber in the specification, fabrication and erection of portal frame structures.
The versatility, strength and natural beauty of timber makes it the ideal material choice for external handrails and balustrades. Usually built from treated softwood and durable hardwoods these timbers can be turned to create a range of styles and designs, resulting in balusters that are unique as they are individual. Painting, staining and oil based finishes broadly cover the wide range of finishing options available and with the appropriate care and attention a timber balustrade can last a lifetime.
This guide provides general information on member sizes, connections and suitable materials to enable the construction of a long lasting, attractive and durable timber handrail or balustrade.