// TIMBER LAMINATIONS
Load-bearing structures use construction timber that is strength graded. For Glulam the beams are manufactured in accordance with EN 14080 and CE marked.Carefully selected raw material is checked for suitable moisture content and graded, board by board, using sound to detect density and solidity.
The boards are sorted to suit the lamella structure of the eventual beam grade. AJ Laminated Beams stock are in the main supplied as GL30c this comprises timber lamination’s graded in strength class T22 (between C35 & C40) in the outer laminations and T14 (equivalent C24) on the inner. GL30c is chosen to be strong in bending and have a higher modulus which will improve performance in deflection
// FINGER JOINTING
The basic concept of Glulam is making large section beams by bonding smaller sections which have smaller defects such as knots, to achieve long structural components. To achieve the long spans the individual lamella need to be jointed in length and this is done using finger joints.
After being graded, boards are scanned to ensure the ends do not contain knots. In the same scanning process, minor defects and knot clusters are identified and cut from the board. Automated finger-jointing machines then cut the finger joints in the board ends, apply glue and them connect them under pressure, producing a strong, durable joint. Finger joints are cured before moving on to the laminating process
The development of resin glues has contributed to the wide use of glued laminated timber in construction. After curing of the finger joints, each lamella is planed to the designated thickness and synthetic resin and hardener is applied to the upper face.
They are then stacked to make the required beam depth and put under pressure whilst the adhesive cures. For straight beams the curing is done by high frequency drying which produces beams at around 4 lineal metres per minute. Curved beams are held under pressure in a forming jig whist cold curing. After curing, the edges of the lamella, forming the face of the beam are planed to the final beam width.