Deck quotes and contracts

A deck project usually starts with a quote and, for anything substantial, ends up as a contract. Understanding both helps you compare builders fairly and avoid disputes. We don't publish deck prices: costs vary widely with size, height, materials, site access and timing, so written quotes are the only reliable guide.

This guide is general information, not legal advice. For your rights and obligations, check Consumer Affairs Victoria's domestic building guidance.

What a good quote covers

A useful quote is specific. Look for:

• site preparation and demolition, including removing an old deck and disposing of rubbish;
• footings, including type, number and depth, and what happens if rock or services are found;
• framing: bearers, joists, their size, spacing and timber grade or treatment;
• decking: the product, species or brand, board size, colour and fixing method;
• stairs, balustrades and handrails, with materials and heights;
• finishes, such as oil or stain, and whether the first coat is included;
• design, engineering and permit costs, and who arranges each;
• inspections required by the building surveyor;
• timing, including start date, duration and what affects it, such as weather;
• payment schedule and what each payment relates to;
• warranties on workmanship and materials;
• exclusions, clearly listed.

If two quotes differ a lot, compare them line by line. The cheaper one may exclude items the other includes.

When a contract is required

Consumer Affairs Victoria says builders must be registered and use a major domestic building contract if the work costs more than $10,000. The contract should set out the work, price, payment stages, timing, plans and specifications, and how variations are handled.

Read the contract carefully before signing. If anything is unclear, ask questions or get independent advice.

Insurance

Consumer Affairs Victoria explains that builders must take out insurance for domestic building work above a set contract value. Its guidance says that before 1 July 2026, domestic building insurance applied to work costing more than $16,000, and from 1 July 2026 Home Warranty insurance applies to work over $20,000. Ask for evidence of cover before you pay a deposit, and check the current threshold on the Consumer Affairs Victoria website.

Deposits and progress payments

Victorian law limits the deposit a builder can ask for under a major domestic building contract, and progress payments should relate to stages of work completed. Check Consumer Affairs Victoria for the current rules. Be wary of a builder who asks for a large payment before work starts.

Variations

A variation is any change to the agreed work. Variations are a common cause of disputes. Agree to every variation in writing, with the cost and any change to timing, before the work is done. Keep a record.

Prime cost and provisional sums

Some quotes include allowances for items not yet finalised (sometimes called prime cost items) or for work whose extent isn't known (provisional sums), such as excavation in rock. Ask how these were estimated and what happens if actual costs differ.

Handover

At the end of the job, ask for:

• the occupancy permit or certificate of final inspection, as applicable;
• product information and maintenance instructions for your decking and finishes;
• warranty documents;
• a final invoice that matches the contract and variations.

If something goes wrong

Raise it with the builder in writing first. If you can't resolve it, the Building and Plumbing Commission offers free domestic building dispute resolution for eligible disputes. See building disputes.

Planning a realistic budget

We don't publish prices, because they vary with design, materials, site and timing. Instead, think about the things that drive cost so you can plan sensibly and compare quotes:

• size and height: larger and higher decks need more materials and more structure;
• site: slopes, poor access, rock or reactive soils add work;
• materials: board type, species or product, and fixing system;
• extras: stairs, balustrades, built-in seating, lighting, screens, roofing;
• demolition of an existing deck and rubbish removal;
• design, engineering and permit fees.

Allow a contingency for surprises, such as rock in footing holes or rot found when an old deck is removed.

Warranties and guarantees

Several kinds of protection may apply to your deck: your builder's workmanship warranty, manufacturers' warranties on boards, fixings and coatings, and statutory warranties under Victorian domestic building law. Read warranty terms carefully. Many manufacturers' warranties depend on installation following their instructions and on regular maintenance. Keep receipts, product details and installation records, and register products where manufacturers require it.

Timing your project

Spring and early summer are popular times to build decks, so builders and surveyors can be busy then. Planning ahead gives you more choice. Allow time for design, quotes, engineering, permits and, where needed, planning approvals before construction starts. Weather can delay footings, concreting and coating, and some timbers or finishes perform best when applied in mild, dry conditions. Ask your builder for a realistic timeline and what could delay it.

At the end of the job

Before final payment, walk around the deck with your builder. Check that the work matches the plans and contract, that boards are evenly spaced and securely fixed, that balustrades are firm, and that the site has been cleaned up. Ask for the final inspection documentation from your building surveyor, product and maintenance information, and warranty documents. Note any defects in writing and agree on when they'll be fixed.

Keep a deck file

Keep a simple folder, paper or digital, for your deck. Include the building permit and inspection records, plans and engineering details, the contract and any variations, product names and colours for boards and coatings, warranty documents and receipts. Add photos taken during construction, especially of the frame and footings before they're covered. This file is invaluable when you need repairs, make a warranty claim, sell your home or resolve a dispute, and it saves the next owner a lot of guesswork.

Before work starts: a quick checklist

• Do I have the building permit (and any planning permit or Report and Consent)?
• Have I checked the builder's registration and insurance?
• Is the contract signed, with the full scope, price, payment stages and timing?
• Have underground services been checked with Before You Dig Australia?
• Do the neighbours know when work will start?
• Is there safe access and somewhere to store materials?
• Do I know which inspections are required and when?

Our deck calculator can help you sense-check quantities in the quote.

Deck terms explained

• Bearer: a main horizontal beam supported by posts or stumps.
• Joist: a smaller beam on or between bearers that supports the boards.
• Ledger: a member fixed to the house to support one side of an attached deck.
• Footing: the concrete pad or pier that transfers loads into the ground.
• Balustrade or barrier: the railing system that prevents falls.
• Nosing: the front edge of a stair tread.
• BAL: bushfire attack level, a measure of a site's bushfire exposure.
• Hazard class (H class): the treatment level for preservative-treated timber under AS 1604.
• Building surveyor: the registered professional who issues building permits and inspects work.

Spas, planters and heavy loads

A spa full of water and people, large planter boxes filled with wet soil, a masonry barbecue or an outdoor kitchen can put far more load on a deck than furniture and people alone. If you're planning anything heavy, tell your designer and builder at the start so the footings and framing can be designed for it. Adding a spa to an existing deck without checking the structure is risky. A structural engineer can assess whether a deck can carry the extra load.

Key points

• A good quote is detailed and lists exclusions.
• A major domestic building contract is required for work over $10,000.
• Check the current insurance threshold and ask for proof of cover.
• Put every variation in writing before the work is done.
• We don't publish prices; get written quotes.