Sawn timber terminology
Sawn timber: Sawn timber is a general term for pieces of wood sawn from saw logs.
Deals and battens: Deals are pieces of sawn timber with a thickness of 38–50mm and width 75–150mm.
Spars: Spars are pieces of small square sawn timber with four sawn sides with a thickness of 75mm or more and with width the same as thickness, or with a deviation of not more than 25mm. Spars are usually sawn without splitting the heart, more wane is also allowed. The sawblade must, however, touch all four sides of the piece along the entire length. If the wane allowance is smaller it must be defined specifically in the contract.
Centre yield: Centre yield is the sawn timber produced from the central part of the log. Centre yield with a thickness of minimum 32mm is usually called battens.
Side yield: Side yield is sawn timber produced from the parts outside the centre of the log. Side yield with a thickness under 32mm is usually called boards.
Studs: Studs are pieces of sawn timber with a thickness of 38–50mm and 75–150mm in width. Beams with guaranteed sizes and form properties can be delivered on agreement. These pieces are normally meant for load bearing end uses, there are different grading rules for various strength grades.
Beams: Beams are large square pieces of timber, centre yield, with four sawn sides, intended for structural purposes, such as floor joists and load bearing elements in wall and rafter constructions. The difference between the width and thickness is usually more than 25mm. It is usually a requirement for structural timber that it is graded for strength, according to special rules.
Resawn timber: Example 1: 63×175 resawn to 32×175. Example 2: 32×175 resawn from 63×175.
In the first example the sawn timber has been sold as 63x175mm and graded accordingly without considering what the quality of the resawn 32×175 would be.
The second example assumes that the goods are resawn from 63×175 and that the normal negative size deviation 2mm caused by resawing is acceptable, but the goods are graded according to the rules for 32×175.
It has to be exactly defined in the contract according to which size the sawn timber shall be graded.
Battens and strips: Slating battens are resawn timber 12–38mm in thickness and 25–63mm in width. The normal negative size deviation 2mm caused by the resawing is normally acceptable.
Grades and terminology
The sawn timber is divided into the following classes according to the quality features. These are called grades:
Grade U/S
U/S is the highest main grade, which includes falling share of sub-grades U/S I – U/S IV from the production. Of these U/S I is the highest.
Grade V
Falling grade V at the grading of the production.
Grade VI
Falling grade VI at the grading of the production.
Grades V and VI are not divided into sub-grades.
Grade VII
No numerical values are given for Grade VII. In grade VII all features contained in a piece of sawn timber are permitted. The piece must, however, hold together. The sawblade must have touched the main part of all the sides of the piece. It can be accepted for side yield that 1/3 of the length on one side is not touched by the blade.
Sawn timber will be graded according to the contract with either each grade separately or by combining different grades e.g. according to the following examples:
Grade U/S + V
Often named SF (sawfalling) excluding sixths.
Grade U/S + V + VI
Often named SF (sawfalling) including sixths.
In the examples above, the unspecified distribution of each grade can be different:
- in different geographical locations
- in different dimensions
- between different sawmills even in the same regions
Other grade combinations are also possible by agreement.
Schaalboards
Schaalboards are side yields of standard thickness and 75-125mm in width.
Schaalboard
Schaalboard (in Finland called export schaalboard) fulfil at least grade VI requirements and have at least 25% wide sawn surface in each edge and the outside face throughout the whole length of the piece. Deviating requirements for the size of sawn surface must be defined in the contract.
Schaalboard VII
Schaalboard VII (in Finland called domestic Schaalboard) fulfil at least grade VII requirements. The sawblade must have touched 85% of the length of the outside face. The wane edges can be 100% of timber thickness, however the width must be fulfilled on the inside face of the board. Any other diverting demands in the quality Schaalboard VII must be mentioned in the contract.
Knotfree, three sides
The outside face and both edges have to be fully knotfree and have to fulfil other features of grade U/S I requirements. The inside face has to fulfil grade U/S III requirements. Wane requirements are defined in the contract.
“Halvrena”
The term is divided into two categories:
a.“Halvrena” side yield has to fulfil Grade U/S requirements or in contract named grade with minimum ó sawn surface in the outside face and each edge throughout the whole length ofthe piece.
b.“Halvrena” centre yield has to fulfil grade VI requirements with minimum 1/3 sawn surface in the outside face and each edge throughout the whole length of the piece.
Market and customer oriented end-use grading
Grademix
This is specifying a mix of grades for a specific and use with permitted wood features from main grades U/S, V, VI and VII. The grades and the features which are included in the mix shall be specified in the contract.
Knotty sawn timber
Knotty sawn timber is a special grade. The number and size of sound knots and other requirements are set according to the agreed grademix, but usually the number and size of sound knots is not limited.
Classification tables
The values for wood features are presented in tables. The content has been grouped according to various end use requirements, presenting the maximum permitted values for grades U/S, V and VI.
The features have been grouped into knots, fissures, wane and other properties. There are also some specific rules to assist the evaluation of the grade.
