Roof form and framing: original details
Though most houses had relatively steep hip or gable roofs, form and framing changed during the 1960s. Framing may be undersized by modern standards.
The house roofs of the 1940s-60s typically had a simple roof form, with either a hip (Figure 1) or a gable and a relatively steep pitch, typically between 30° and 40°.
Lean-to roofs, dormers and other roof features were not incorporated on the roofs of state or privately built houses although some state houses had Dutch gable roofs.
By the end of the 1960s plan books showed a wider range of roof forms such as the Mansard, the lean to or mono-pitch, the Dutch gable, a reverse mansard and the Japanese. Though roofs were usually constructed with a roof space, from the mid 1960s onwards skillion roofs, particularly over the living areas, became more common.
Architect-designed houses sometimes had lower pitch roofs with wider eaves, though some architect-designed houses had no eaves.
Hip and gable roofs
The roof structure was typically a nailed timber roof frame constructed on site in either a hipped or gabled configuration.
The rafters of a hipped roof, which span between the ridge board, hip rafter or valley rafter and the wall framing top plate, may be common, hip, valley and jack rafters.
Gabled roofs were generally couple-close construction, i.e. where each pair of rafters spanning between the ridge board and the top wall plate are tied by ceiling joists, connecting rafters at their base to prevent spreading (Figure 2).
Rafters consisted of rough sawn 4 x 2” (100 x 50 mm) or 5 x 2” (125 x 50 mm) were typically spaced at 20” (480 mm) centres. Ridge boards were typically 6 x 1” (150 x 25) or 8 x 1” (200 x 25 mm).
Where the rafter span was too great for the depth of the rafters, they were supported at mid-span by underpurlins and struts that transferred the load to an internal loadbearing wall. By today’s standards, the roof framing was undersized, particularly where the roof has concrete or clay tiles.
Gable roofs were braced with diagonal braces that were either 6 x 1” (150 x 25 mm) solid bracing cut in between rafters, or a surface brace fixed below the rafters (Figure 3). Roof space bracing was provided by a bracing member running from the ridge board at the gable end to an internal wall top plate (Figure 4). In hipped roofs, the hip rafters also act as roof space bracing, so additional bracing was not required.
Skillion roofs incorporated a ridge beam or internal loadbearing wall to support the roof apex and generally had the ceiling lining fixed to the underside of the rafters with the roof cladding installed as done when there was a roof space.
Sarking and purlins
Depending on the roofing cladding, roofs were either sarked or had purlins. Sarking was generally used to support asbestos-cement shingle roofing, and purlins were generally used with corrugated asbestos-cement sheet roofing, but this was not always the case. Where the roof was tiled, battens were installed to support and secure the tiles.
Sarking consisted of 1” (25 mm) wide, close-butted boards that were laid either perpendicular to the rafters or on the diagonal. When laid diagonally, sarking also provided roof plane bracing.
As an economy measure ‘hit and miss’ sarking, where every second board is omitted, was sometimes used.
Purlins were laid perpendicular to the rafters to provide support and fixing for the roofing material. They were either 2 x 2” (50 x 50 mm) or 3 x 2” (75 x 50 mm) and typically spaced at 36” (900 mm) centres or to suit the length of the roofing material.
Where installed, roofing underlay was supported by galvanised wire netting when purlins were used, or laid directly over the sarking. In some cases, and particularly where tiles were installed, roofing underlay was not used.
Roof eaves and gables
The eaves of 1940s-1950s houses were narrow, generally 12” (300 mm) wide, and lined on the underside with 3/8” (5mm) or ¼” (6 mm) asbestos-cement sheet (Figure 5). A 4 x 1” (100 x 25 mm) fascia board provided support for the gutter. Eaves became wider during the late 1950s and into the 1960s, typically 18–24” (450–600 mm) although eaves up to 4’6” (1350 mm) were sometimes used.
Gables were plain, with the cladding in the triangular section of the gable wall often of the same material as the principal wall cladding. A development in the 1960s, with the use of skillion roofs typically over living areas, was glazing up to the gable end roofline.
Sometimes a contrasting cladding material was used, such as asbestos-cement sheet with timber battens to contrast with weatherboards, or bevel-back weatherboards to contrast with brick veneer. Barges were typically faced with 6 x 1” (150 x 25 mm) boards.
Gutters and downpipes
Gutters and downpipes were made of galvanised mild steel until PVC and fascia gutter systems became available towards the end of the 1960s.
Metal gutters were an ogee profile and fixed with external brackets to the fascia board. They were available in 8’ (2.4 m) lengths and joints were soldered on site. Downpipes were round, galvanised steel pipes, 2½" (63 mm) in diameter and supplied in 8’ (2.4 m) lengths. They discharged into stormwater drains, water tanks or to soak pits.