PURLINS & GIRTS

FLOOR JOIST SPAN TABLE
HST
SINGLE SPAN (M)
DOUBLE SPAN (M)
JOISTS SPACING (MM)
JOISTS SPACING (MM)
400MM 450MM 600MM 400MM 450MM 600MM
IMPOSED FLOOR ACTIONS: UNIFORMLY DISTRIBUTED ACTIONS = 1.5 KPA OR CONCENTRATED ACTIONS = 1.8KN (GENERAL RESIDENTIAL BUILDING)
15012 3.6 3.5 3.2 4.1 4.0 3.6
15015 4.0 3.8 3.5 4.5 4.3 3.9
15018 4.2 4.1 3.7 4.8 4.6 4.2
20012 4.7 4.5 4.1 5.3 5.1 4.6
20015 5.1 4.9 4.5 5.8 5.6 5.1
20018 5.5 5.3 4.8 6.1 6.0 5.4
25013 5.9 5.7 5.1 6.5 6.3 5.8
25015 6.1 6.0 5.4 6.7 6.5 6.1
25018 6.5 6.3 5.8 7.1 6.9 6.4
30015 7.0 6.8 6.3 7.7 7.4 6.9
30018 7.4 7.2 6.7 8.1 7.8 7.3
30024 7.7 7.4 6.9 8.3 8.1 7.5
30030 8.1 7.9 7.3 8.8 8.6 8.0
35018 7.7 7.5 7.0 8.4 8.2 7.6
35024 8.4 8.2 7.6 9.2 8.9 8.3
35030 8.9 8.7 8.1 9.7 9.4 8.8
40020 8.7 8.4 7.8 9.4 9.1 8.5
40024 9.2 8.9 8.3 9.9 9.7 9.0
40030 9.7 9.4 8.8 10.5 10.2 9.5
IMPOSED FLOOR ACTIONS: UNIFORMLY DISTRIBUTED ACTIONS = 3.0 KPA OR CONCENTRATED ACTIONS = 2.7KN (GENERAL OFFICE BUILDING)
15012 3.0 2.9 2.6 3.4 3.3 3.0
15015 3.3 3.2 2.9 3.7 3.6 3.2
15018 3.5 3.4 3.1 4.0 3.8 3.5
20012 3.9 3.8 3.4 4.4 4.2 3.8
20015 4.3 4.1 3.7 4.8 4.6 4.2
20018 4.5 4.4 4.0 5.1 4.9 4.5
25013 4.9 4.7 4.3 5.5 5.3 4.8
25015 5.2 5.0 4.5 5.8 5.6 5.1
25018 5.5 5.3 4.8 6.2 6.0 5.4
30015 6.1 5.9 5.4 6.7 6.5 6.0
30018 6.4 6.2 5.8 7.0 6.8 6.3
30024 6.9 6.7 6.2 7.5 7.3 6.8
30030 7.3 7.1 6.6 7.9 7.7 7.1
35018 6.9 6.7 6.3 7.6 7.4 6.9
35024 7.6 7.3 6.8 8.3 8.0 7.4
35030 8.0 7.8 7.2 8.7 8.5 7.9
40020 7.8 7.5 7.0 8.5 8.3 7.7
40024 8.2 7.9 7.4 9.0 8.7 8.1
40030 8.7 8.4 7.9 9.5 9.2 8.6
IMPOSED FLOOR ACTIONS: UNIFORMLY DISTRIBUTED ACTIONS = 5.0 KPA OR CONCENTRATED ACTIONS = 4.5 KN (LIGHT STORAGE BUILDING)
15012 2.6 2.5 2.3 2.9 2.8 2.6
15015 2.8 2.7 2.5 3.2 3.1 2.8
15018 3.0 2.9 2.6 3.4 3.3 3.0
20012 3.4 3.2 2.9 3.8 3.6 2.9
20015 3.7 3.5 3.2 4.1 3.9 3.6
20018 3.9 3.8 3.4 4.4 4.2 3.8
25013 4.2 4.0 3.7 4.7 4.4 3.5
25015 4.4 4.3 3.9 5.0 4.8 4.4
25018 4.8 4.6 4.2 5.4 5.2 4.7
30015 5.3 5.1 4.6 5.9 5.4 4.3
30018 5.7 5.4 4.9 6.3 6.1 5.6
30024 6.2 6.0 5.5 6.7 6.5 6.1
30030 6.5 6.3 5.8 7.1 6.9 6.4
35018 6.2 6.0 5.5 6.8 6.6 5.6
35024 6.8 6.6 6.1 7.4 7.2 6.7
35030 7.2 7.0 6.5 7.8 7.6 7.1
40020 7.0 6.8 6.3 7.6 7.4 6.6
40024 7.4 7.2 6.7 8.0 7.8 7.3
40030 7.8 7.6 7.1 8.5 8.3 7.7
Notes:
1. Floor joists designed to support the floor loads only. The above table assumes the use of standard particleboard or plywood for flooring.
2. The dynamic performance of the floor system meets the criteria in NASH Standard: Residential and Low-rise Steel Framing-Part 1 (2009).
3. For increased performance where ceilings are not installed, the use of a transverse brace is recommended (eg. Ceiling batten – CB20 or similar,
to the underside of the floor joists at 3 metre centres typical).
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