Floor Construction Methods 1. Platform Framing
2. Balloon Framing
3. Sawn Timber Joists Method
4. Joist Hanging Method
Platform Framing • sill plate attached to the foundation • joists run perpendicular from the sill plate • a joist header attaches to the
end of each joist • the studs are then attached to the joists running the ceiling height of the floor • the subflooring is installed on top of the joists • a sole plate is then installed on top of the subflooring material • Each floor is constructed as its own unit, helping to prevent
fire from spreading between floors.
• sill plate attached to the foundation
• joists run perpendicular from the sill plate • the studs are then attached to the joists • the subflooring is installed on top of the joists. • Fire stopping is added to the spaces between the studs, which provides a space for mechanical system installation
Each floor’s joists are run off of the same stud members that continue through the height of the house. In order to hang the joists, ribbon members are installed to the studs. • This type of construction provides great stability. • Fire stopping is included in the stud bays.
Studs run the entire height of the house
Sawn Timber Joists Method • The ends of joists or beams are built into the walls of a block building, and are therefore directly supported by the wall structure. • Sometimes joist ends rest on wooden wall plates secured to the wall surface. Old lumber joists secured within a wall may eventually become damp, and might need replacing over time. • Shown
herringbone struts and blocking, and are covered using straight-edged or tongue-and-groove boards.
Joist Hanging Method • Joist depths, widths and designs
vary, so there is a wide range of hangers available to match. • Metal lateral joist straps are used to brace joists in position. One end of the strap is attached to the exterior wall, and the other end is attached to joists
Joist hanger attached directly to the wall face.
(either across or in line with them), to secure their position. • Lateral joist straps are mainly used in new building projects. • Shown here, the joists are attached to the wall using joist hangers, and the joists are
braced with lateral restraint straps and metal herringbone struts.
Brick or Block hanger top section is installed into the mortar.
Wood Joists Simplest and most common method of constructing upper floors
Joists are typically 50 x 150 mm or 50 x 200 mm in cross-section.
Joists are spaced 305, 406 or 610 o.c.
Prevents the lower edges twisting
Cavities can accommodate piping, wiring, and thermal insulation
Ceiling applied to joists
See Picture 1 Picture 2
Timber herringbone strutting
No bigger than 50x50 mm
See Picture 2
The direction of the floor boards is a result of the direction of the floor joists
The greater strength of steel beams is often used to reduce the span of timber beams
Timber joists may rest on top of steel beams (see
picture 1) or, they may be supported directly on the lower horizontal flange of an I-section (see picture 2)
Steel Joist Types
Steel Framing •
Recently, steel framing has begun to make strong inroads into the residential building market.
Steel homes use nearly the same framing techniques
buildings, and construction costs run about the same. •
Unlike wood, however, steel is impervious to termites. It provides added resistance to fire
and earthquake. •
Steel ceiling joists can span greater distances than wooden ones, allowing new design possibilities for architects and builders.
Concrete Floor Systems Precast concrete slabs, beams, and structural tees are one-way spanning units that may be supported by site cast concrete, precast concrete, or masonry bearing walls, or by steel,
site cast concrete, or precast concrete frames.
Concrete topping reinforced with steel fabric or reinforcing bars bonds with the precast units to form a composite structural unit (see picture on top right)
Underside of precast slabs may be caulked and painted; a ceiling finish may also be applied to or be suspended from slab.
Precast concrete units
Adjustable Risers Moisture Control Without adequate ventilation, a floor void over contaminated or wet ground can become
filled with stagnant air, moisture and contaminants that can encourage mould growth and the eventual decay of building materials. Adjustable risersâ€™ system â€“ with mechanical ventilation and moisture barriers - can help maintain a high standard of indoor air quality.
Sound dampening helping to silence everyday noises from footsteps, doors and floor based appliances and underfloor ventilation units. It also provides airborne sound insulation from voices, TV etc.