FARM FORESRY TIMBERS STRUCTURAL GRADES

Our grades are designed to comply with structural requirements of the building code (See End-uses >> Structural).

Note: Farm Forestry Timbers have determined the Characteristic Stresses of No. 1 Structural grade for the following species:

These species can be used for structural applications under the building code using NZS 3603, by involving an engineer in the design.

All Grades:

Structural timber shall be dry to 18% moisture or below.

Species meeting durability performance requirements set out in NZS 3602:2003 for structural grades:

Cypress species including Macrocarpa, Lusitanica, Lawsons and Leyland cypress.

Larch (Characteristic stresses are not available for this species)

No. 1 Structural grade rules

Distortion

Knots, holes, voids, bark-inclusion, bark-pockets, resin pockets, pith, decay, wane, skip, sloping grain that exceeds 1 in 10 (including sloping grain surrounding spike knots: Sloping grain surrounding spike knots, being a significant weakness causing defect, must be taken into account when determining the cross section of the spike knot.) and other weakness-causing defect:

No voids ["Voids" include holes, bark-pockets, resin pockets and bark inclusion] longer than the width of the face of the piece. Where bark inclusion and associated voids do not exceed 5% of the cross section the length is not restricted.

Checks are not restricted.

Pith includes surrounding wood to a radius of 10 mm.

Wane and skip are to be kept to a minimum. No more than 5% of cross section.

Splits not allowed. Shakes not allowed.

Maximum sloping grain: 1 in 10

Spike knots: The length of the longest edge [i.e. as seen on the face of the piece and where adjacent sloping grain is greater than 1 in 10] of a spike knot must not be greater than 75% of the width of the face of the piece. Where structural members are of square cross section this does not apply.

Sapwood shall be treated to h1.2.

No. 2 framing grade rules

For use in non-loadbearing situations

Distortion

Knots, holes, voids, bark-inclusion, bark-pockets, resin pockets, pith, decay, wane, sloping grain greater than 1/6 and other weakness-causing defect:

No voids longer than double the width of the board.

Checks, collapse are not restricted.

Wane and skip No more than 10% of cross section.

Visible shakes not allowed

Splits not allowed.

Maximum sloping grain: 1 in 6

 

General and Responsibilities

At least 95% of the consignment of graded timber shall meet the grade specifications above upon despatch.

For tallying volumes call dimensions shall be used.

Call sizes (mm) 25 40 50 75 100 125 150 200 225 250 300
Actual dressed dry size (mm) 19 35 45 70 90 115 140 180 205 230 280

 

Once despatched the seller shall not be responsible for any subsequent deterioration of condition of the timber or defects arising from further processing. 

Farm Forestry Timbers reserve the right to revise our grading rules without notice. Grade revision 1.0 January 2012.

See Glossary for explanation of terms.