Building Construction Handbook, Eighth Edition

PSB ~ otherwise known as a parallam beam. Fabricated from long

strands of softwood timber bonded with a phenol-formaldehyde

adhesive along the length of the beam to produce a structural

section of greater strength than natural timber of equivalent section.

Used for beams, lintels, structural framing and trimmer sections around

floor openings in spans up to 20 m. Can also be used vertically as

columns.

Standard sizes ~ range from 200¾45 mm up to 406¾178 mm.

longitudinal strands

of softwood timber

adhesive coated

and bonded under

heat and pressure

Standard lengths 12, 15 and 18m

Typical grade stresses [N/mm^2 ] (compare with sw timber, page 115) ~

Variation ~ for spans in excess of 20 m or for high loads, a flitch

beam as shown on the previous page can be made by bolting a

steel plate (typically 10 or 12 mm) between two PSBs.

Ref. BBA Agrement Certificate No. 92/2813.

Bending parallel to grain 16.8

Tension parallel to grain 14.8

Compression parallel to grain 15.1

Compression perpendicular to grain 3.6

Shear parallel to grain 2.2

Modulus of elasticity (mean) 12750

Average density 740 kg/m^3

Parallel Strand Beam (PSB)