How To Build a Deck

How do you build a timber deck, and where does adhesive fit into it?

A deck extends your living space outdoors and adds value to the house. The build sequence is: get council approval, plan and clear the site, set posts and bearer stirrups in concrete, fix bearers and joists, then lay the decking with Selleys Liquid Nails Heavy Duty under every board as well as screwing it down, and finally clean and coat the timber.

The adhesive is the part most people skip, and it is the reason some decks stay tight and quiet for years while others develop squeaks and cupped boards. A screw holds a board down at one point; a bead of adhesive holds it across the whole bearing surface, which is what stops the small movements that eventually work fasteners loose.

What you need

Why Liquid Nails Heavy Duty for decking

Liquid Nails Heavy Duty is a solvent-based, non-slump construction adhesive rated for interior and exterior use on timber, MDF, plasterboard, masonry, concrete, particle board, metals, rubber, glass, tiles, ceramic and plastics. It comes in a 350 gram cartridge and is brown.

TechnologySolvent based
ColourBrown
Density1.21
Cure time8 hours (before removing temporary fasteners)
RepositionableUp to 20 minutes after fitting
Strong bond24 hours; continues to strengthen for 2–3 days; cure for 7 days

Indicative data only, not intended for preparation of specifications.

Three things follow from those figures. Twenty minutes of repositioning time is generous — enough to lay a board, check your spacing, and nudge it straight before you drive the screw. Mechanical fasteners are usually only needed for 8 hours on porous surfaces, which on a deck is academic because the screws stay in permanently, but it tells you the deck can be walked on the next day. Full cure is 7 days, and the bond keeps strengthening for 2–3 days after the initial 24 hours, so schedule your coating work rather than the structural work around it.

Expect longer times for thicker applications and in cold weather.

Step 1 — Get council approval

Apply for and receive any applicable local government approvals before construction starts. This is not optional and it is far cheaper to do first.

Step 2 — Prepare the area and plan

Lay out the shape of your deck by planting the corner posts and marking the edges with string. Work out how water drains across the site, and if there is a risk of water pooling under the deck, dig a drain. Water sitting under a deck is what rots the underside of boards you can never inspect.

Rake the area clear of weeds and debris, then map out the plan for your joists and bearer structures and make sure you have enough timber.

Step 3 — Create the foundation

Mark where your posts and bearer stirrups will go and dig holes in the marked areas. Lay a base of 100 mm of concrete in each corner hole and place your posts in them. Brace the posts so they stand level, then fill the rest of the hole with concrete.

Set the bearer stirrups in concrete in their holes, making sure all are at the correct height so the bearers will be level. Allow at least 24 hours for the concrete to dry.

Fix the bearers to the posts and into their stirrups with bolts, using the spirit level to check they are squared up and level — these carry the load of the deck. Keep the final deck height in mind as you measure. Then measure out your joists and screw them to the bearers.

Step 4 — Lay out your decking

Lay the decking timber over the joists, spacing each piece equally from its neighbours. The width of a nail is a good gap; you can make handy spacers by putting a nail through small offcuts of timber.

Apply an "S" shape of Liquid Nails Heavy Duty to the underside of each decking board, where the board and joists will meet. Check the board is level and flush with your bearers, then fix it down with one screw per joist.

Repeat for each board, using your spacers throughout to keep the gaps even. Trim any overhanging timber with the circular saw or hand saw.

Before you cut the cartridge, make sure the surfaces are free from oil, grease and dust, and wipe off any pooled water from wet timber. Cut the cartridge tip, pierce the foil, fit the nozzle and cut it to a 5 mm opening.

Step 5 — Protect and finish

Once the structure is complete, the timber needs a coating to protect it from weather. Some timbers, such as Merbau, should be weathered for a few weeks before coating. Merbau in particular leaches tannin, and coating it too early traps that in the finish.

Clean the deck of dust, dirt and stains with a stiff brush and Cabot's Deck Cleaner, or a pressure cleaner. Stubborn stains can be removed by rubbing the affected area with a turpentine-soaked cloth.

Once the deck is dry, apply Cabot's Aquadeck or your chosen stain or oil. Stir the can, cut in the border areas with a paint brush, then use a roller or decking applicator on 3 or 4 boards at a time along the length of the deck — working a few boards at a time along their full length is what gives an even finish rather than visible lap marks. Allow around 2 hours to dry before applying a second coat.

Always follow the manufacturers' instructions on all products you use.

Limitations — what Liquid Nails Heavy Duty will not do

Clean up uncured product with mineral turpentine. Cured product has to be scraped or sanded off.

Safety: you are applying this adhesive at ground level, all day

Liquid Nails Heavy Duty is solvent-based and carries the signal word Danger: H225, highly flammable liquid and vapour; H336, may cause drowsiness or dizziness; H315, causes skin irritation; H319, causes serious eye irritation.

H225 matters here because of where the bead goes. The method above puts an "S" of adhesive on the underside of every board — which means you are working low, often kneeling or reaching in between joists, over a deck frame that sits close to the ground and usually hard against the house. The vapour from a solvent adhesive is heavier than air. It sinks into that subfloor space and pools there rather than drifting away, and the things that sit at exactly that height beside a house are subfloor vents, a gas bayonet, a hot water unit and an air conditioner condenser. Turn off any pilot in range and do not run a grinder, heat gun or soldering iron near the frame while beads are curing.

H336 is about duration, not dose. A deck is not one bead — it is a cartridge every few square metres for most of a day, applied at the same low level. Accumulated vapour causing headache or dizziness is manageable at a bench and genuinely dangerous when you are next reaching for a circular saw. Work upwind, take the cartridge out from under the frame between boards, and break for air.

H315 and H319 are the routine pair: nitrile gloves and eye protection. Mineral turps for clean-up is flammable too — spread used rags out to dry rather than binning them balled up.

The damp-timber swap trades one hazard set for a worse one. The questions below send you to Liquid Nails Rapid Cure for damp or poorly seasoned timber. That product is also Danger, but for different reasons: H334 (may cause allergy or asthma symptoms or breathing difficulties if inhaled — respiratory sensitisation, Category 1), H372 (causes damage to organs through prolonged or repeated exposure, Category 1), H351 (suspected of causing cancer — Category 2, suspected rather than established), H317, H332, H335, H315 and H319.

H334 is the one to weigh. Respiratory sensitisation is permanent once acquired, and afterwards far smaller exposures provoke wheeze or an asthma attack. It develops from repeated exposures that feel like nothing at the time — which is precisely a day of cartridges under a deck frame. If you use Rapid Cure, ventilate the space, work in stages, and treat a respirator as reasonable rather than excessive.

There is a third option worth comparing. Liquid Nails Exterior is described as ideal for decking and is rated for wet and dry timber, and it is signal word Warning with only H317 and H319 — no flammability classification, no respiratory sensitisation, no carcinogenicity. Compare the two product pages before you buy a box of cartridges.

Poisons Information Centre — 131 126 in Australia, 0800 764 766 in New Zealand.

Common questions about building a deck

Do I really need adhesive if I am screwing the boards down?

The guide specifies both. Adhesive spreads the hold across the whole bearing surface rather than at the screw alone, which is what keeps a deck tight. It should never be the only fixing — the data sheet says not to use it as the sole bonding agent for structural bonding.

How much adhesive goes on each board?

An "S" shape on the underside of the board where it meets the joists. Cut the nozzle to a 5 mm opening.

How long can I reposition a board after laying it?

Up to 20 minutes after fitting.

When can I walk on the deck?

The adhesive reaches a strong bond in 24 hours and continues strengthening for 2–3 days, with full cure at 7 days. Mechanical fasteners are usually only needed for 8 hours on porous surfaces.

Can I glue to damp timber?

Wipe off any pooled water from wet timber first and make sure the surface is free from oil, grease and dust. For genuinely damp or poorly seasoned timber, Liquid Nails Rapid Cure is the product that specifically adheres to damp surfaces.

How long does the concrete need before I load the bearers?

At least 24 hours.

How wide should the gaps between boards be?

The width of a nail is the guide given. Make spacers from offcuts with a nail through them so every gap is identical.

Can I oil the deck straight away?

Not always. Some timbers such as Merbau should be weathered for a few weeks before coating. Clean the deck first, let it dry, then coat.

How long between coats of decking oil?

Around 2 hours before the second coat, following the coating manufacturer's instructions.

How do I get adhesive off my hands and tools?

Mineral turpentine while it is still wet. Cured product must be scraped or sanded.

Will this adhesive stick to a metal bearer?

Liquid Nails Heavy Duty is rated for metals, but not for metals that may be heated by direct sunlight — bonds weaken at higher temperatures.

What if the ground under the deck holds water?

Dig a drain before you build. Water pooling under a deck is the single most common cause of premature rot in the boards you cannot see.

What is the difficulty level and estimated time required to build a deck according to Selleys?

Building a deck is rated as an Advanced difficulty project (the guide lists Beginner, Intermediate, Advanced options but the deck project itself takes around 7 days to complete).

What is the first step before starting deck construction?

The first step is to get council approval — it's important to apply for and receive any applicable local government approvals prior to construction.

What materials and tools are needed to build a deck?

You need Selleys Liquid Nails Heavy Duty, Cabots Deck Cleaner, a Cabots decking applicator, Cabots Aquadeck or your choice of stain or oil, timber for posts, bearers, joists and decking slats, galvanised steel bearer stirrups, string, a tape measure, bolts/nuts to secure bearers, coach screws for joists and decking slats, nails, a caulking gun, a shovel, concrete, a spirit level, a hammer, a circular saw or hand saw, a stiff brush, a pressure cleaner, and a pencil and carpenters square.

How do you prepare the area before building a deck?

Lay out the shape of the deck by planting corner posts and marking the edges with string, check for drainage issues and dig a drain if water pooling is a risk, rake the area clear of weeds and debris, and map out the plan for joists and bearer structures while ensuring sufficient timber supplies.

How do you create the foundation for a deck?

Mark where posts and bearer stirrups will go, dig holes, lay down 100mm of concrete in each corner hole, place posts and brace them level, then fill the remainder with concrete. Set bearer stirrups in concrete at the correct height so bearers will be level, and allow at least 24 hours for the concrete to dry. Then set bearers to the posts and bearer stirrups with bolts, using a spirit level to ensure they are squared up and level, keeping the final deck height in mind. Finally, measure out joists and screw them to the bearers.

How should decking timber be laid out and fixed to the joists?

Lay decking timber over the joists with equal spacing between pieces (the width of a nail is desirable, using nail-and-timber-offcut spacers). Apply an 'S' shape of Selleys Liquid Nails Heavy Duty to the underside of the decking timber where it meets the joists, ensure it is level and flush with the bearers, then fix it down with one screw per joist. Repeat for each piece using spacers, then trim any overhanging excess timber with a circular saw or hand saw.

How do you protect and finish a completed deck?

Coat the timber to protect it from weather (some timbers like Merbau should be weathered a few weeks before coating). Clean the deck of dust, dirt or stains using a stiff brush and Cabot's Deck Cleaner or a pressure cleaner, removing stubborn stains with a turpentine-soaked cloth. Once dry, apply Cabot's Aquadeck or your chosen stain/oil, cutting in border areas with a paint brush and using a roller or decking applicator for 3-4 boards at a time for an even finish. Allow around 2 hours to dry before applying a second coat.

What handy tips does Selleys give for building a deck?

Some timbers like Merbau should be weathered a few weeks before coating, and you should always follow the manufacturers' instructions on all products used to complete the task.

Which Selleys product is recommended for fixing decking timber to joists?

Selleys Liquid Nails Heavy Duty is recommended, applied in an 'S' shape to the underside of decking timber where it meets the joists, providing an extra strong bond suitable for wood, metal, and more.

Images on This Page