Deck Joists – Single/Continuous

Size (mm)	Single Span Deck Joists – Joist Spacing (mm)
Size (mm)	300	400	450	480	600
140×42	3.6	3.2	3.1	3.0	2.9
190×42	4.8	4.5	4.3	4.3	4.0
240×42	5.7	5.3	5.2	5.1	4.9
290×42	6.5	6.1	5.9	5.9	5.6
140×65	4.1	3.8	3.6	3.6	3.4
190×65	5.2	4.9	4.8	4.8	4.5
240×65	6.2	5.8	5.7	5.6	5.4
290×65	7.0	6.7	6.5	6.4	6.1
Size (mm)	Continuous Span Deck Joists – Joist Spacing (mm)
Size (mm)	300	400	450	480	600
140×42	4.4	4.1	3.7	3.6	3.4
190×42	5.5	5.1	5.0	4.9	4.6
240×42	6.6	6.1	5.9	5.8	5.5
290×42	7.6	7.1	6.9	6.7	6.4
140×65	4.9	4.5	4.4	4.3	4.1
190×65	6.2	5.7	5.6	5.5	5.2
240×65	7.4	6.8	6.6	6.5	6.2
290×65	8.5	7.9	7.7	7.5	7.1

Span values are in metres

Loading Data:

Dead Load of floor maximum 40 kg/m2
(Covers standard residential deck materials, including possible plasterboard ceiling below)

Live Load for decks & verandahs over 1m above ground level 2.0kPa (with a check on a concentrated live load of 1.8kN anywhere)

ETH LAM GL beams are manufactured straight, without any camber built into the beams.
Deck Joist design criteria in accordance with methods presented in AS1684.1-1999, and structural timber design in accordance with AS1720.1-2010.

Notes:

Minimum bearing lengths for support of deck joists: 30mm on end supports, and 45mm internal supports.
The span value shown is the distance between centrelines of supports.
For continuous spans, the adjacent deck joist spans may be different, but look up the larger of the spans, and the shorter span must be more than 50% of the larger span. If this rule is not met, then consider the deck joists are simply supported, and look up the larger span in the single span table.
Deflection criteria: for permanent load combinations, the lesser of Span/300, or 12mm, and for Floor Live Loads, the lesser of Span/360, or 9mm.
For deck joists the lateral restraint is assumed to be achieved via the fixing of flooring direct to the top edge. No restraint of the bottom edge of the joist is assumed.
Where there are conflicts in design between loading codes (AS/NZS1170 series), timber code (AS1720.1-2010) and AS1684.1-1999, the loading codes and timber codes take preference.
Floor dynamic load check is made for a 1kN concentrated load to ensure less than 2mm deflection.
These deck joist designs assume the joists are initially seasoned, but may be wet in service, with an average moisture content less than 20%.

The above span table values have been designed in accordance with the following codes:

AS1720.1-2010 Timber Design Code
AS1170.0, .1, .2-2002 Loading Codes for Limit State design, Live Loads, and Wind Loads respectively.
AS1684.1-1999 Design Criteria for Residential Timber Framing.

News & Media

Magna beams available up to 8m in length

Magna have responded to customer requests and have recently installed new equipment to make Magna Beams longer than 6 metres.