ELEVATED FLOORS

Floor slabs not resting directly on the ground can be constructed using a variety of methods. This also applies to ground floors that rest on piers, as well as first and subsequent floors of a cottage. Elevated floors can be built out of either timber, steel, or concrete.

Floor not resting directly onto ground may be constructed as follows:

A. Timber framed on brick piers, steel posts or treated timber posts

timberflrfrm
Timber first floor framing

TABLE 1
Supporting timber floor only
BEAM SPAN BEAM SIZE
4.0m maximum 180UB
5.0m maximum 200UB
6.5m maximum 250UB
7.5m maximum 310UB
TABLE 2
Supporting timber floor and tiled roof
BEAM SPAN BEAM SIZE
4.0m maximum 200UB
5.5m maximum 250UB
6.5m maximum 310UB

B. Suspended concrete decks using either:

  • Cast in-situ concrete with reinforcing steel using uncompacted soil for formwork, conventional formwork or steel decking such as "Bondek" for formwork and slab reinforcement.
  • Precast concrete units such as "Ultra-floor" or hollow core concrete planks with a cast in-situ topping.  Steel or concrete beams and columns may be used to support the concrete floor slab.

  • CONCRETE SLAB, STYLE 1

    slabstyle1
    Concrete floor slab, style 1

    TABLE 1
    Continuous slab over 2 spans, supporting timber framed walls only
    SLAB SPAN SLAB THICKNESS
    2100mm maximum 100mm minimum
    3500mm maximum 125mm minimum
    4500mm maximum 150mm minimum
    5500mm maximum 170mm minimum
    TABLE 2
    Continuous slab over 2 spans, supporting brick walls
    SLAB SPAN SLAB THICKNESS
    3000mm maximum 125mm minimum
    4000mm maximum 150mm minimum
    4800mm maximum 175mm minimum

    CONCRETE SLAB, STYLE 2

    slabstyle2
    Concrete floor slab, style 2

    TABLE 1
    Supporting concrete floor and timber walls
    BEAM SPAN BEAM DEPTH
    6000mm maximum 350mm minimum
    8000mm maximum 450mm minimum
    9000mm maximum 550mm minimum
    TABLE 2
    Supporting concrete floor and brick walls
    BEAM SPAN BEAM DEPTH
    5000mm maximum 350mm minimum
    6800mm maximum 450mm minimum
    7800mm maximum 550mm minimum

    CONCRETE SLAB, STYLE 3

    slabstyle3
    Concrete floor slab, style 3

    TABLE 1
    Supporting concrete floor and timber walls
    BEAM SPAN BEAM SIZE
    4.5m maximum 250UB
    5.5m maximum 310UB
    6.5m maximum 360UB
    TABLE 2
    Supporting concrete floor and brick walls
    BEAM SPAN BEAM SIZE
    4.0m maximum 250UB
    4.8m maximum 310UB
    5.5m maximum 360UB
    6.2m maximum 410UB

    In any case, whenever a designer of a building needs advice on the structural system for his building please contact Kneebone & Beretta Group on This email address is being protected from spambots. You need JavaScript enabled to view it. and an engineer will get back for your assistance.