Choosing a deck builder

A deck is a structure people stand on, entertain on and let their children run around on. It has to carry loads safely for many years, in Melbourne's mix of hot summers, wet winters and the occasional downpour. Choosing the right builder is one of the most important decisions you'll make.

This guide is general information, not legal advice. Check current rules with Consumer Affairs Victoria and the Building and Plumbing Commission (BPC).

Registration: the first check

In Victoria, the people who build decks are building practitioners, and many must be registered. According to Consumer Affairs Victoria, a builder or tradesperson must be registered with the BPC to carry out work worth more than $10,000, and that includes carpenters, bricklayers and concreters. There are exceptions for work involving only one of certain trades, such as painting or attaching external fixtures, but a deck usually involves several kinds of work.

Consumer Affairs Victoria also notes that a person must be registered if they're going to do work that requires a building permit for certain kinds of work, regardless of value, and that they must be registered in the right class and category for the work.

How to check: use the BPC's online "find and check a practitioner" search. Check the name, registration number and category against the details on the quote and contract. If the builder isn't properly registered, Consumer Affairs Victoria warns you can't get Home Warranty insurance.

Insurance

Consumer Affairs Victoria explains that builders must have domestic building insurance for work above a set value, which covers you if the builder dies, disappears or becomes insolvent. From 1 July 2026, its guidance refers to Home Warranty insurance applying for work over $20,000; before that date, domestic building insurance applied above $16,000. Check the current threshold and ask for proof of cover before you pay a deposit.

Ask about public liability insurance too. It's separate from domestic building insurance.

Where to find builders

• Recommendations from neighbours, friends and family who've had decks built recently. Ask to see the deck if possible.
• Your building surveyor or designer, who may know builders who work in your area.
• Online directories and reviews, read with caution. Look for detailed reviews that describe the job, and check the builder's registration independently.
• Industry associations, whose members may follow a code of conduct. Membership isn't the same as registration, so check both.

Questions to ask

• Are you registered with the BPC, and in which category?
• Will you organise the building permit, or should I?
• Who will design the deck, and will an engineer be involved?
• What timber or composite product do you recommend, and why?
• Who will do the work: you, your employees or subcontractors?
• How long will it take, and when can you start?
• What warranties apply to your workmanship and to the materials?
• Can I speak to recent clients or see completed decks?
• How do you handle variations?

Comparing quotes

Ask each builder to quote the same scope. A cheap quote may leave out items that another includes, such as demolition of an old deck, rubbish removal, stairs, balustrades, permit fees or oiling. See quotes and contracts for a detailed checklist.

Warning signs

Be cautious if a builder:

• can't or won't give a registration number;
• asks for a large cash payment up front;
• pressures you to sign quickly;
• suggests skipping the permit;
• won't put the quote or contract in writing;
• has no fixed business address or ABN.

Consumer Affairs Victoria's domestic building guide explains your rights and what a builder must do.

During the job

Keep communication in writing where possible, keep copies of plans, approvals and invoices, and take photos as work progresses. If you have concerns, raise them early. If you can't resolve a problem, 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.

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.

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.

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.

Key points

• Check BPC registration and category for work over $10,000.
• Check the current insurance threshold and ask for proof of cover before paying.
• Compare written quotes covering the same scope.
• Ask about permits, design, products, timing and warranties.
• Walk away from cash-only, no-permit or high-pressure offers.