72 timber floor slabs 721 timber species lumber for

7.2 Timber floor slabs
7.2.1 Timber species
Lumber for floors shall be selected in accordance with the recommended use for different species in
Table 4-4.
7.2.2 Structural framing
7.2.2.1 Method of construction
Figure 7-8 gives details of the method of construction of timber flooring systems.
7.2.2.2 Allowable joist spans
Spans for floor joists shall be in accordance with Table 7-3 .
Table 7-3 Floor joist span for common lumber species
Maximum floor joist spans Joist
spacing
50mm x 150mm
Joist
50mm x 200mm
Joist
50mm x 250mm
Joist
50mm x 300mm
Joist
300mm 3.3m 4.2m 5.1m 6m
400mm 3.0m 3.6m 4.5m 5.2m
500mm 2.6m 3.3m 4m 4.6m
600mm 2.3m 3m 3.6m 4.2m
NOTE The above spans are calculated based on the following: dead load =1.0 KN/m
2
; live load =1.5 KN/m
2
.

PCTTS 599: 20XX
129
Figure 7-8 Timber flooring & supports
Double joist under bearing
partitions
Foundation
Sill plate
Solid blocking
Band, rim or header joist
Wood structural panel
Optional floor finish
Bottom wall plate
Studs
Subfloor or
floor sheathing
Sill plates
Joists
pipe in partition
Strut

PCTTS 599: 20XX
130
7.2.2.3 Joists under bearing partitions
Joists under parallel bearing partitions shall be doubled or a beam of adequate size shall be provided
to support the load. Double joists, which are separated to permit the installation of piping or vents,
shall be full depth , solid blocked with lumber not less than 50 mm in nominal thickness spaced not
more than 1200 mm on centre.
7.2.2.4 Allowable header spans
The allowable spans of headers shall not exceed the values set forth in Tables 7-4 and 7-5 .
7.2.2.5 Bearing
7.2.2.5.1 General
The ends of each joist beam or header shall have not less than 50 mm of bearing on wood or metal
and not less than 75 mm on masonry or concrete.
7.2.2.5.2 Floor systems
Joists framing from opposite sides over a bearing support shall lap a minimum of 75 mm and shall be
nailed together. A wood or metal splice with strength equal to or greater than that provided by the
nailed lap is permitted.
7.2.2.5.3 Joist framing
Joists framing into the side of a wood header shall be supported by approved framing anchors or on
ledger strips not less than nominal 50 mm by 50 mm.
7.2.2.6 Lateral restraint at supports
Joists shall be supported laterally at the ends by full-depth solid blocking not less than 50 mm nominal
in thickness; or by attachment to a header, band or rim joist, or to an adjoining stud; or shall be
otherwise provided with lateral support to prevent rotation.
Joists exceeding a nominal 50 mm x 150 mm shall be supported laterally by solid blocking, diagonal
struting (wood or metal), or a continuous 25 mm by 75 mm strip nailed across the bottom of joists
perpendicular to joists at intervals not exceeding 2400 mm.
7.2.2.7 Drilling and notching
Structural floor members shall not be cut, bored or notched in excess of the limitations specified
Figure 7-9.