STRUCTURAL DESIGN FOR ARCHITECTURE

Structural Design for Architecture

Fig. 6.48 Timber wallframe - platform frame type. In the

platform frame the individual wall and floor panels are

independent of each other. The sequence of construction

is that the ground-floor walls are erected first, followed by

the floors. These form a 'platform' on which the first-floor

walls are then erected. The system lends itself to prefabri-

cation and has the additional advantage that none of the

individual elements is of great length. Its disadvantage is

that the level of structural integrity is lower than with other

types of arrangement.

6.7.3 Timber wallframe structures

Timber wallframes are a type of loadbearing-

wall structure. They are sometimes called

simply timber frame structures but they are not

true skeleton frames. In wallframes, timber

wall-panels (stud panels) consisting of

elements of small cross-section placed at close

centres are used to support traditional forms

of roof and floor structure (Figs 6.48 to 6.51).

The overall size of the structure is usually

small: there are rarely more than two storeys

and floor spans are in the range 3.5 m to 5 m

with roof spans of around 6 m to 12 m. The

Fig. 6.49 Timber wallframe - balloon frame type. In the

balloon frame the studs which form the walls are continu-

ous through two floors and the floor joists are attached

directly to them. This arrangement provides better struc-

tural integrity than the platform frame and produces a

weathertight enclosure more quickly. It cannot be prefabri-

cated, however, and requires the use of very long timber

elements.

system is used principally for domestic

buildings.

The basic planning requirements for timber

wallframe buildings are the same as for all

loadbearing-wall structures. The wall plan,

which must be more-or-less the same on every

storey, must be capable of supporting all areas

of roof and floor and, as both the floor and

roof structures are one-way-spanning systems,

this requires an arrangement of primary

loadbearing walls which are parallel to each

other and spaced at roughly equal distances

222 apart. Atypical arrangement is shown in

Head binder.

Head plate

Floor joists

Boarding

-Sole plate

Studs

Boarding

Sole plate

Base wall

Header

Header

Head plate

Head binder

Floor joists:

Cill plate

Head binder

Head plate

Floor joists

Cavity barrier

Ledger

Cavity barrier

Floor joists

Sole plate

Base plate

Cill plate

Plywood

subfloor

Studs

Plywood

subfloor