Manufacture

All timber frame manufacure process is carried out in accordance with EN 14250:2010.

This European Standard specifies material, product and documentation requirements for prefabricated structural members (e.g. roof trusses, walls and floors, timber frames, timber trusses, composite beams and girders) for use in buildings made from solid structural timber according to EN 14081-1 with or without finger joints assembled with punched metal plate fasteners. This standard EN 14250:2010 is valid for trusses with lengths up to 35 m and for other prefabricated structural members with spans up to 12 m. To provide best quality at the time of fabrication we are using Wolf System Surface Press FST - III G.

This is strong press for highest productivity, especially suitable for the timber truss manufacture of wall segments and complex frameworks. It's high efficiency is also based on the fact that more than one pressing points can be processed simultaneously. In the upper chord of the press, a pressing plate is moved up and down by means of two hydraulic cylinders. Table width 4,2 m, lengths 15 m.

It's manufacturers responsibility to ensure that worker are properly trained for operation and work with any installation site, and it's a risk assessment provided for each operation, therefore:

• when timber is on the table check for visual defects;
• make sure that joint gaps within the area of the fastener at the time of fabrication will not exceed 1,5 mm;
• make sure that fasteners will not be misplaced by more than the amount considered in the structural design and not more than 10 mm in any direction in relation to the design position;
• make sure the plate projections of the fastener will be inserted perpendicular to the embedment surface of the timber and the plate surface will be free of distortion. Any gap between the timber surface and the underside of a punched metal plate fastener can't exceed 1 mm, and can't occur over more than 25% of teh anchorage area in any prefabricated timber structural member in any joint;
• make sure that punched metal plate fasteners will not protrude outside the outer edges of the prefabricated timber structural member. The lower edge of fastener intended to be located over a point of support shall be at least 3 mm from the lower edge of the member in contact with the support;
• when producing a large batch of trusses must check the height of each 20/30 truss.

Timber

Structural timber we use in manufacture process must be strenght graded using grading standards and methods complying with EN 14081-1. Timber also meet the following criteria for geometrical defects:

Timber can be without preservative treatment, then it shall have adequate natural durability for the intended use class and the durability class shall be declared. When timber is with preservative treatment, then the durability class, type of preservative, critical retention value and penetration class shall be declared. Max. moisture content of the timber and of timber wedges, if any, at the time of fabrication of the prefabricated timber structural member shall not exceed 22%.

Knots

Live knots shall be permitted within the anchorage area of the prefabricated timber structural member, provided that the plate projections are satisfactorily embedded without visible distortion of the fasteners or splitting of the timber outside the knot. 

Where a dead knot, knot hole or fissure occurs within the anchorage area of the prefabricated timber structural member, the area of effective plate projections, disregarding those in the dead knot, knot hole or on the line of the fissure shall be in accordance with that specified in the design. Fissures wich don't extend more than 50 mm from the tooth, burst or plate nail wich apparently caused them, shall be disregarded. 

Fasteners

Punched metal plate fasteners having integral projections punched out in one direction perpendicular to the base of the plate, being used to join two or more pieces of timber of the same thickness in the same plane, shall comply with EN 14545. In addition, when timber is treated against biological organisms with substances which cause corrosion, connectors made of austenitic stainless steel or galvanized can be used in use classes 1 and 2.