BUILD COMPASS AU · NCC 2022 · Part 4

Read the change before the pour

Use a fictional finishes revision, column relocation and wall schedule to practise reading six local details. Check the edition and jurisdiction applying to your job. Site classification and the approved design govern the route.

When a wall changes, trace what supports it

Clause 4.2.17 pairs the actual external and internal walls to an equivalent construction type for footing selection. For example, full masonry outside with framed internal walls points to articulated full masonry in Table 4.2.17b. The wall schedule still describes the walls being built. Mark both wall types on the current drawing before looking up the footing.

Read clause 4.2.17 in the ABCB Housing Provisions

External masonry, internal frame. Which schedule do you bring? Both internal and external walls Only the façade

A masonry fireplace needs its own detail

Clause 4.2.18 covers Class A and S sites. Its fireplace pad is integral with the slab, with SL72 mesh at top and bottom. The stated single-storey case uses a 150 mm pad (one trafficable floor, wall height up to 4.2 m). The two-storey case uses 200 mm (two trafficable floors, wall height up to 8 m). Allow 300 mm beyond the masonry except at an edge flush with the outer wall. A fireplace added during selections deserves a marked-up location and a footing detail.

Read clause 4.2.18 in the ABCB Housing Provisions

Can you use the fireplace pad example on Class M by changing its depth? Add 50 mm Refer the Class M detail to the designer

A tile selection can change the pour conversation

The trigger in 4.2.19 is brittle floor covering across more than 16 m². A 3 m by 6 m tiled kitchen is 18 m². The clause offers several routes: increase shrinkage reinforcement to SL92 or equivalent across the affected area, use mesh sheets top and bottom there, select bedding for the expected slab movement and covering, or defer laying for at least three months after the pour. Agree which route the project uses before promising an installation date.

Read clause 4.2.19 in the ABCB Housing Provisions

The floor schedule changes to 18 m² of ceramic tiles. What do you clarify? Which shrinkage-control option the project uses Tile colour alone

A steel post puts load into one spot

Clause 4.2.20 deals with concentrated loads from structural steel columns. The local thickening sits centrally under the column and uses SL72 reinforcement with at least 50 mm cover. The correct table depends on floor and roof construction and the areas feeding load to that point. Moving a column 200 mm on the architectural plan calls for coordination with the structural drawing before the crew sets out the thickening.

Read clause 4.2.20 in the ABCB Housing Provisions

A steel post moves. What else needs checking? Only the post base plate The centre of its local thickening

Read the width at the base of the rebate

On footing slabs, 4.2.21 measures the edge beam where the rebate bottoms out. The minimum there is 200 mm. A reduction to 150 mm depends on the specified vertical-force ties: R10 or N10 at 900 mm spacing, or equivalent. Measure at the level shown in section. A dimension across the top can describe a different width.

Read clause 4.2.21 in the ABCB Housing Provisions

The edge beam measures 150 mm at the rebate base. What evidence matters? Tie detail and spacing or equivalent provision Width of brickwork above

Check how deep the bathroom set-down goes

Under 4.2.22, compare the recess depth with half the nominal slab thickness. At or below half, measure a mesh lap of at least 400 mm from the inside face of the recess. Above half, the top mesh overlaps the bottom mesh by at least 400 mm and the bottom has two layers of SL72. Both routes retain the cover requirements in 4.2.11(5). In a fictional 100 mm slab, a change from 50 mm to 55 mm crosses the threshold. Five millimetres on the finishes drawing can change the reinforcement detail.

Read clause 4.2.22 in the ABCB Housing Provisions

The recess changes from 50 to 55 mm in a nominal 100 mm slab. What changes? The shallower lap detail still applies The deeper recess reinforcement arrangement applies

Write the drawing query

Your finishes schedule now asks for a 55 mm recess in a nominal 100 mm slab. The structural section still shows 50 mm. Record the location, both revisions, the difference and who needs to resolve it.

Compare with a worked record

Ensuite, grid B2. Finish schedule F03 rev C shows 55 mm. Slab S02 rev B shows 50 mm. Builder to seek the structural designer’s revised recess, mesh and cover detail before forming the affected area. Record the response and brief the crew.

Download the pre-pour change record