Construction information Extension size Installing UB's Cross-section detail
Floor framing Staircase detail Staircase void Riser calc.

Assignment 1

UPPER STOREY EXTENSION
(Lot 22)

Construction Information

► Existing buildings' footing system is 450 x 250 separate edge beam perimeter concrete strip, with a 100    thick slab on ground floor slab, thickened under internal walls as well as external walls in accordance with    BCA figure 3.2.5.5.
► 200 UB's at position shown on the Upper Floor Extension Sketch. The bottom of the UB's is 11 mm    above the top of the ceiling joists.
► Upper floor joists 240 x 35 F.5 seasoned softwood, spaced at 450mm centres running across the    extension.
► Sheet platform floor 19mm particleboard to dry area floor, 18mm compressed sheet to wet area. o Wall    frame materials 90 x 35 F.5, seasoned softwood studs at 450 centres, top plate 90 x 45, noggins and    bottom plates 90 x 35.
► Roof frame is pine F.5 trusses at 600 max. centres; truss design as in CONSTRUCTION 2 text book,    pages 83-87 and NOTES.
► Upper floor eaves overhang boxed, and lined with 4.5mm 'Hardiflex' then finished with metal fascia and    gutter.
► Roof covering materials, eaves overhang and pitch to match ground floor existing. o Upper floor cladding    to be Hardie's 'Prime Line' weather boards.
► Upper floor lining to be 'Gyprock' 10mm thick sheets (to walls and ceilings) with 75mm cove cornice. o    Extension wall height 2700mm.
► Window sizes and positions in the extension walls are at the candidate's discretion but must be meet BCA    requirements and, be from a stated fabricator's catalogue.
► Step Going: 275mm
► Stair width between strings: 1010mm
► Stair strings: 240 x 45
► Existing ground floor walls top plate: 35 x 90 F.5 seasoned softwood
► Existing ground floor ceiling joists: 90 x 35 F.5 seasoned softwood
► Stair newel posts: 120 x 120 o Stair treads: 45 thick o Stair handrail: 120x45 on edge
► Existing ground floor rafters: 120 x 35
► Roof truss top chord: 120 x 35, web members 90 x 35
► Roof tile battens: 50 x 25 at 320 centres approx.
► Roof tiles: 400 x 25 o Eaves joists: 70x35

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Extension size and position in roof

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Installing UB's

Before you start drawing the Plan (Sheet 1) you need to do some inquiries.


Firstly you need to know how thick the entire thickness of the floor construction will be.

Secondly how big the opening for the staircase will be.

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Floor detail (cross-section)

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Floor frame

According to the AS 1684 no blocking at midspan is needed. However, the 240x35 mm floor joist can easily twist when installing the particleboard flooring. For this reason it is recommended to place additional blocking at midspan of the floor joists.

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Staircase detail

To find the dimensions for the staircase opening you need to draw the stair detail first. All necessary dimensions for the stair components are listed in the specifications. Check all dimension of the stair detail before you finalise the stair void size in your plan.

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Staircase opening

As soon as you have established the dimensions for the staircase opening you can to draw the final plan (Sheet 1) and section (Sheet 3)

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Riser calculation

To calculate the riser-height divide the height from FFL to FFL by the number of required steps (refer to BCA for min & max height-measuremnets). The rule is one going plus two riser should be 625 mm (G+2R=625mm)

Stair Detail


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