What tools do I need for lay concrete footings for a house extension?

This guide includes a comprehensive tools list. Key building & construction tools are detailed in the Tools Required section.

What is the Australian standard for residential footings?

The primary Australian standard for residential footings is AS 2870:2011, 'Residential slabs and footings – Construction'. This standard outlines requirements for design and construction based on site classification and soil conditions. Compliance is mandatory under the National Construction Code (NCC).

How much concrete cover is required for reinforcement in footings?

According to AS 3600:2018, 'Concrete Structures', the minimum concrete cover for reinforcement in footings is typically 50mm for normal exposure conditions. This cover protects the steel from corrosion and ensures structural integrity, with specific requirements varying based on exposure class and concrete type.

What PPE is mandatory for concrete footing work in Australia?

Mandatory PPE for concrete footing work in Australia includes a hard hat, safety glasses, hearing protection, high-visibility clothing, steel-cap boots, and gloves. According to SafeWork Australia guidelines, additional respiratory protection may be required when cutting or grinding concrete to prevent silica dust inhalation.

How to lay concrete footings for a house extension

Concrete footings for a house extension must be set out, excavated, reinforced and poured to suit the structural design, site classification and ground conditions. For Australian projects, footing construction must comply with the engineering documentation, NCC requirements, and relevant standards i

Skill level: Advanced
Time: 1–3 days for small extension footings, plus curing and inspection time
Trade: Building & Construction
Updated: 4 November 2026

Tools you will need

Tape measures in 5 m and 30 m lengths
Marking paint and chalk line
Mini excavator in 1.7 t
Reinforcement cutters and rebar bender
Tie wire reels and nips
Concrete chairs/bar chairs with suitable rating and height
Concrete vibrator or pencil vibrator
Screeds, rakes and concrete shovels
Wheelbarrows or powered buggy for limited access pours

🧱 How to Lay Concrete Footings for a House Extension

What is involved in laying concrete footings for a house extension?

A proper footing installation is a critical structural element, not a guesswork task. Depth, width, founding material, reinforcement cover, and concrete strength must all match the approved plans and engineer’s details, with council and certifier inspections completed at the required stages.

What skill level is required for house extension footings?

Advanced — Estimated time: 1–3 days for small extension footings, plus curing and inspection time

What tools are essential for concrete footing construction?

Rotary laser level or dumpy level with staff for accurate set-out and excavation depth control

Tape measures in 5 m and 30 m lengths

String line, string line reels and profile boards/batter boards

Marking paint and chalk line

Mini excavator in 1.7 t–3.5 t class, or trenching equipment suited to access conditions

Shovels, trenching spades and crowbars for trimming and hand cleaning

Plate compactor where founding layer preparation or adjacent backfill compaction is required

Reinforcement cutters and rebar bender

Tie wire reels and nips

Concrete chairs/bar chairs with suitable rating and height

Formwork system, including timber, pegs, braces and nails/screws where trench sides are not self-supporting

Hammer drill and starter bar epoxy system if tying into existing footings/slabs

Concrete vibrator or pencil vibrator

Screeds, rakes and concrete shovels

Wheelbarrows or powered buggy for limited access pours

PPE including hard hat, gloves, eye protection, hearing protection, steel-cap boots and high-vis clothing

What materials are needed for concrete footings?

Concrete to engineer’s specification, typically 20 MPa, 25 MPa or higher depending on design

Cement, sand and aggregate if site-mixing is approved; general-purpose mix ratio 1:2:3 and structural mix ratio 1:1.5:2.5 where applicable, though extensions generally use premixed engineered concrete

N12, N16 or other reinforcement bars to engineer’s schedule

Trench mesh or footing cage components as specified

Tie wire

Bar chairs and spacers to maintain minimum cover

Formwork timber, usually 90 mm x 45 mm, 140 mm x 45 mm or plywood form materials as needed

DPM or separation layer if detailed on plans or where forming interfaces require it

Starter bars/dowels for connection to existing structure where specified

Approved epoxy anchoring system for drilled dowels

Termite management components where required by design and state regulations

Survey pegs, profile boards and string line

Water for cleaning and controlled curing

Curing compound or plastic sheeting if specified for curing control

Safety Requirements

Footings for house extensions are structural work and must be constructed strictly to the structural engineer’s drawings and specifications.

Compliance typically includes AS 2870 for residential slabs and footings, AS 3600 for concrete structures, and AS 3700 where masonry loads or masonry construction interfaces are involved.

Confirm local council, private certifier and state authority inspection hold points before pouring concrete.

Dial Before You Dig / Before You Dig Australia service location checks are mandatory before excavation.

All excavation work must be assessed for trench collapse risk, underground services, spoil placement and plant movement.

Use trench support or battered excavation where soil conditions are unstable; do not allow workers into unsafe trenches.

Maintain safe manual handling practices when placing reinforcement and formwork.

Concrete burn protection is mandatory: gloves, long sleeves, long pants and eye protection.

If working around existing walls or structures, temporary support and sequencing may require engineering certification.

Scaffolding, edge protection and site access controls must comply with WHS requirements where excavations or height differences create fall risks.

Step-by-Step Guide

Step 1: Set out the footing lines and confirm engineering details

1️⃣ Review the structural documentation

Check the approved architectural drawings, structural footing plan, reinforcement schedule, soil classification and any geotechnical report. Confirm footing type, such as strip footing, pad footing, deepened edge beam or pier/beam arrangement, and verify the required widths, depths and step locations.

Confirm all dimensions against the extension layout and existing building interface. Typical strip footing widths may range from 300 mm to 600 mm or more, with depths commonly 300 mm to 900 mm+, but the engineer’s design governs all sizing.

Mark inspection stages, including pre-pour footing excavation and reinforcement inspection if required by the certifier.

Step 2: Establish profiles, levels and datum

2️⃣ Set accurate control lines

Install profile boards clear of the excavation zone and run string lines to define wall lines, footing centres and offsets. Use a laser or dumpy level to establish a site datum and transfer all footing RLs.

Mark top of footing, underside of footing and any stepped changes in level. Extensions often tie into existing floor levels, so verify the relationship between finished floor level, slab thickness, brickwork set-downs and footing depth before excavation begins.

💡 For renovation work, always cross-check the existing structure for out-of-square walls and actual floor heights rather than relying solely on old drawings.

Step 3: Locate services and prepare the excavation area

3️⃣ Clear the work zone and identify underground risks

Before digging, locate sewer, stormwater, water, gas, electrical and communications services. Mark known service routes physically on site and pothole by hand or vacuum excavation where needed.

Remove vegetation, topsoil, debris and unsuitable material from the footing area. Establish plant access, spoil stockpile zones and truck access for concrete delivery. Keep spoil heaps back from trench edges to reduce surcharge loads and collapse risk.

If the extension adjoins an existing house, protect nearby walls, drainage and paving from undermining or vibration damage.

Step 4: Excavate to line, depth and founding material

4️⃣ Dig footings to engineer’s requirements

Excavate the trench or pad locations to the required width and depth, allowing for any formwork where trench sides are not stable or neat enough to cast against ground. Trim trench bases clean and level by hand.

Found footings into natural ground or approved founding material as specified. Do not pour onto loose fill, organic matter, mud or disturbed trench bottoms unless the engineer has approved remediation.

Where reactive clay, soft spots or over-excavation are encountered, stop and obtain direction from the engineer. Remedial measures may include deeper excavation, compacted engineered fill, blinding concrete or redesigned footing dimensions.

For stepped footings, keep each step square and to detail, ensuring bearing is maintained across transitions.

Step 5: Inspect trench condition and place any blinding/formwork

5️⃣ Prepare the base for reinforcement

Check that trench bottoms are firm, level and dry enough for placement. If the excavation is rough, contaminated or likely to collapse, install formwork to maintain dimensions and edge quality.

Where specified, place a blinding layer to provide a clean working surface and prevent contamination of the structural concrete. Formwork should be straight, braced and set to correct levels so the finished footing can be struck accurately.

Confirm minimum cover requirements before reinforcement is placed. In ground-contact footings, reinforcement cover is critical for durability and must match the engineer’s documentation and AS 3600 requirements.

Step 6: Install reinforcement, dowels and connection steel

6️⃣ Fix the footing cage correctly

Place trench mesh, longitudinal bars, ligatures and any starter bars as shown on the structural details. Support steel on approved bar chairs and spacers so it maintains correct position during the pour.

Tie all intersections securely with tie wire. Maintain lap lengths, hook details and bar spacing exactly as scheduled. Reinforcement should be free from heavy mud, loose scale, oil or contaminants that may affect bond.

If the new footing must tie into existing construction, drill and epoxy starter bars to the specified embedment depth and spacing. Clean drilled holes thoroughly before applying adhesive and inserting bars.

Typical issues in extension work include:

insufficient bar cover due to steel sitting on the trench bottom

missed dowels at articulation or wall intersections

incorrect lap lengths

poor alignment of starter bars for masonry or wall framing

💡 Photograph reinforcement prior to pour, particularly connection points and cover arrangements, for QA records and certifier support.

Step 7: Complete pre-pour checks and mandatory inspections

7️⃣ Verify compliance before concrete arrives

Inspect:

footing width and depth

trench cleanliness

founding material condition

reinforcement size, placement and laps

bar chair height and cover

dowels and hold-downs

formwork stability

termite management components if applicable

Arrange certifier, council or engineer inspections where required. Do not pour until all hold points are signed off.

Also check weather, access, concrete ordering details, slump requirements and pour sequence. For restricted access extensions, confirm pump set-up, wheelbarrow run distances and washout location.

Step 8: Pour the concrete footing

8️⃣ Place concrete without segregation or displacement

Order the specified concrete strength and slump to suit placement method. For most extension footings, premixed concrete from a reputable supplier is the commercial standard and far more reliable than site-mixing.

Place concrete continuously to avoid cold joints, especially in strip footings supporting loadbearing walls. Discharge as close as possible to final position and use shovels or rakes to move concrete into place without excessive rehandling.

Use a vibrator carefully to consolidate the concrete, particularly around reinforcement, step-downs and dowels. Do not over-vibrate, as this can cause segregation.

Strike the footing off to level where required. Some trench footings will simply be filled to a nominated level below finished masonry or slab build-up; others may require a formed top surface to precise RL.

Step 9: Finish, cure and protect the footing

9️⃣ Control early-age performance

Once placed, protect the footing from rapid moisture loss, rain damage, contamination and premature loading. Apply curing compound or cover with plastic sheeting if specified and practical.

Do not allow bricklaying, wall framing or backfilling to commence until the concrete has gained sufficient strength and the engineer’s or supplier’s minimum timeframes are met. Early loading can compromise bearing performance and crack the footing.

Where starter bars protrude, cap them for site safety.

💡 In hot or windy weather, organise the pour early in the day and have curing materials on site before the truck arrives.

Step 10: Backfill and prepare for next stage works

🔟 Backfill only after approval

After the footing has cured sufficiently and inspections are complete, backfill with suitable material in controlled layers if required. Compact in lifts appropriate to the material and access, taking care not to damage waterproofing, termite systems or adjacent services.

Prepare the footing for follow-on works such as masonry, slab preparation, retaining interfaces or subfloor construction. Reconfirm set-outs before proceeding, especially where extension wall lines tie into existing external walls.

Common Mistakes to Avoid

1.Excavating to approximate depth without confirming actual RLs, resulting in incorrect footing embedment or slab/floor level mismatches.

2.Pouring onto soft, wet or disturbed trench bottoms instead of stopping for engineer review and remediation.

3.Allowing reinforcement to sit on the ground with inadequate cover, leading to durability issues and non-compliance with AS 3600.

4.Missing inspections or pouring before certifier/engineer hold points are signed off.

5.Using the wrong concrete strength or adding excess water on site, which reduces design performance and can cause shrinkage and durability problems.

Pro Tips

💡 For extension work against existing houses, expose and verify the existing footing depth early. This avoids late redesigns where new and old foundations must interact.

💡 Use profile boards well outside excavation lines so they remain intact through excavation, steel fixing and pumping.

💡 For long strip footings, pre-plan truck sequencing and pump hose reach to avoid delays that can create cold joints.

💡 Hire a mini excavator and concrete vibrator if used only occasionally; purchase is usually only economical for crews doing regular footing packages.

💡 Keep a reinforcement checklist on site covering bar size, spacing, laps, cover and dowel positions. It saves expensive rectification once concrete is placed.

Recommended Tools

Rotary laser level with receiver — essential for footing depth, step-down and top-of-concrete accuracy

1.7 t–3.5 t mini excavator — best value for most residential extension access conditions; usually better to hire unless in constant use

Pencil concrete vibrator — critical for proper consolidation around reinforcement and dowels

Rebar tier/nips and bar bender — improves speed and consistency in steel fixing

Formwork peg driver and circular saw — useful for accurate, efficient footing form construction

Frequently asked questions

What is involved in lay concrete footings for a house extension?: Concrete footings for a house extension must be set out, excavated, reinforced and poured to suit the structural design, site classification and ground conditions. For Australian projects, footing construction must comply with the engineering documentation, NCC requirements, and relevant standards i
What skill level do I need for lay concrete footings for a house extension?: Advanced — Estimated time: 1–3 days for small extension footings, plus curing and inspection time
What are common mistakes when lay concrete footings for a house extension?: 1. Excavating to approximate depth without confirming actual RLs, resulting in incorrect footing embedment or slab/floor level mismatches. 2. Pouring onto soft, wet or disturbed trench bottoms instead of stopping for engineer review and remediation. 3. Allowing reinforcement to sit on the ground with inadequate cover, leading to durability issues and non-compliance with AS 3600. 4. Missing
What tools do I need for lay concrete footings for a house extension?: This guide includes a comprehensive tools list. Key building & construction tools are detailed in the Tools Required section.
What is the Australian standard for residential footings?: The primary Australian standard for residential footings is AS 2870:2011, 'Residential slabs and footings – Construction'. This standard outlines requirements for design and construction based on site classification and soil conditions. Compliance is mandatory under the National Construction Code (NCC).
How much concrete cover is required for reinforcement in footings?: According to AS 3600:2018, 'Concrete Structures', the minimum concrete cover for reinforcement in footings is typically 50mm for normal exposure conditions. This cover protects the steel from corrosion and ensures structural integrity, with specific requirements varying based on exposure class and concrete type.
What PPE is mandatory for concrete footing work in Australia?: Mandatory PPE for concrete footing work in Australia includes a hard hat, safety glasses, hearing protection, high-visibility clothing, steel-cap boots, and gloves. According to SafeWork Australia guidelines, additional respiratory protection may be required when cutting or grinding concrete to prevent silica dust inhalation.

Written by Bricko, the Building & Construction specialist at Aus.Tools.