Maintaining Outdoor Timber and Decks
How do you maintain outdoor timber, decks and furniture?
Exposed timber takes a beating from heat, sunlight and rain, which leads to weathering, rotting and boards loosening around their fastenings. Three jobs cover most of what a deck and its surrounds need: stopping board movement with Selleys Liquid Nails Rapid Cure, repairing timber furniture and handrails with Selleys Aquadhere Exterior, and rebuilding rotted timber with Selleys Knead It Multipurpose.
The common thread is that all three are about movement. A deck board that can move works its screws loose and squeaks; a chair joint that can move fails; rot spreads because water gets into a gap that opened up. Stop the movement and the timber lasts.
1. Maintain your deck
When you fasten deck boards to the joists, bond them as well as screwing them. Liquid Nails Rapid Cure uses polyurethane technology and expands slightly as it sets, filling gaps and reducing movement — which is what makes a deck tight and quiet rather than springy and noisy.
| Technology | Polyurethane |
| Colour | Translucent |
| Density | 1.13 g/ml |
| Initial cure | 10 minutes |
| Working time | 5 minutes |
| Full cure | 24 hours |
| Repositionable | Up to 5 minutes after fitting |
| Initial bond strength (hoop pine, 1 hour @ 23°C, 50% RH) | 3 MPa |
| Bond strength in tensile shear (pine/pine, 24 hrs @ 23°C, 50% RH) | 7 MPa |
| Service temperature | -15°C to 100°C |
| Gap bridging | Up to 3 mm |
| Packaging | 325 gram cartridge |
Indicative data only, not intended for preparation of specifications. Liquid Nails Rapid Cure is waterproof and meets BS-EN 204 D4.
What those numbers mean when you are laying boards
A 5 minute working time is genuinely short. Apply the adhesive to one board at a time, position it, and screw it. Do not run a bead down four joists and then start fitting boards — you will be fighting a skinned adhesive by the third one. You can reposition for up to 5 minutes after fitting.
Initial cure at 10 minutes, then 15–20 minutes for porous surfaces before removing temporary fasteners or clamps. Full cure is 24 hours. On a deck the screws stay in permanently, so the practical reading is that you can keep working along the deck immediately, and the structure is at strength the following day.
It adheres to damp and poorly seasoned timber, which is the property that separates it from most construction adhesives. Polyurethane cures on moisture, so damp timber helps rather than hinders — the data sheet even suggests spraying surfaces with a very light mist of water to speed up cure on very dry timber, heavier objects or less porous surfaces. Drying times vary with temperature, humidity and how porous the materials are.
It bridges gaps up to 3 mm and can be used on rough and ill-fitting surfaces — useful on reclaimed or cupped decking where the board does not sit flat on every joist.
Its limitations: not suitable for bonding polypropylene and polyethylene; should not be applied below 5°C; not for permanent water immersion; and do not use it as the sole bonding agent for structural bonding. Wet product cleans up with acetone or mineral turps; dry product must be chiselled, scraped or sanded off.
2. Repair outdoor timber furniture
A wobbly outdoor table or a loose handrail can be repaired with Aquadhere Exterior, a high-strength adhesive designed for exterior woodworking. It withstands tough weather conditions and can be painted over for a professional finish.
It is an industrial-grade polyaliphatic cross-linking PVA that produces bonds stronger than most woods, and it sticks softwoods, hardwoods, particleboard, chipboard, plywood and MDF. Coverage is approximately 5 m² per litre, and it comes in 250 mL, 500 mL, 1 L and 4 L bottles.
Using it properly
- Make sure the surfaces to be bonded are close fitting, dry and clean. A PVA needs contact — it is not a gap filler.
- Shake the bottle before use.
- Apply the adhesive liberally to one surface only.
- Clamp for 30 minutes for softwoods and 1 hour for hardwoods. Do not stress the joint for 24 hours.
- Wipe off excess adhesive with a damp cloth while it is still wet.
- Maximum strength is attained in 24 hours, but longer in cold, damp conditions or with dense timbers.
To fill small gaps, Aquadhere can be mixed with sawdust. Longer clamping times may be required for joints under high stress.
Its limitations: not recommended for joints subjected to constant high stress; not suitable for below-waterline applications or continuous submersion; and it will stain brown or black if contaminated with rust (iron oxide) or in the presence of tannins in many woods — so avoid contaminating it with iron and steel, such as nails. On tannin-rich hardwoods, expect some darkening at the glue line.
Uncured product cleans up with water; cured product must be sanded or scraped.
3. Repair rotting timbers
Older homes often have outdoor timber that has been damaged or eaten away by rot. Selleys Knead It Multipurpose is a hand-kneadable two-part epoxy that can be shaped and worked into the space to rebuild or replace what is missing.
| Working time | 3 to 5 minutes at 25°C |
| Initial cure | 60 minutes |
| Full cure | 24 hours at 25°C |
| Heat resistance | Up to 120°C continuous |
| Colour | Off-white |
Indicative data only, not intended for preparation of specifications.
Three to five minutes of working time is very short. Cut and knead only as much as you can place in that window, and do the next section as a separate mix. After 60 minutes the repair can be drilled, sawed, sanded, filed and machined, and it can be painted once cured — which is what lets you blend a rebuilt section into the surrounding timber. It will not sag, run or drip while you shape it.
Its limitations: it does not adhere to polyethylene, polypropylene or PTFE; it is not recommended for filling joints and cracks subject to movement, because the cured product is extremely hard and inflexible; and it is not intended for structural applications. That last point matters with rot — Knead It rebuilds a damaged section cosmetically and mechanically, but it does not restore the structural capacity of a rotted bearer or post. If the rot is in something carrying load, the timber needs replacing, not filling.
Safety: three products, three completely different hazard profiles
| Product | Classification |
|---|---|
| Liquid Nails Rapid Cure | Danger — H334 may cause allergy or asthma symptoms if inhaled (Category 1); H372 causes damage to organs through prolonged or repeated exposure (Category 1); H351 suspected of causing cancer; plus H317, H332, H335, H315, H319 |
| Knead It Multipurpose | Warning — skin sensitisation Category 1A, may cause an allergic skin reaction; skin irritation; serious eye irritation |
| Aquadhere Exterior | Not classified as hazardous |
Five of Rapid Cure's eight classifications concern the respiratory tract, and that is the point. H334 is respiratory sensitisation: the immune system learns to react to the material, the change is generally permanent, and afterwards an exposure far below the one that sensitised you provokes wheeze, chest tightness or an asthma attack. H372 sits at Category 1, the tier used where there is evidence in humans rather than inference from animals. None of that describes one careful cartridge in the open. All of it describes a working life of small, unventilated exposures.
Which is exactly the shape of job 1 above. Gluing a deck is not one bead — it is cartridge after cartridge, board after board, over a day or two. And the places a deck actually needs it are the worst ones for air: under a low deck, in the subfloor, between joists, with your face close to the work. If you have to get underneath, work in stages with breaks out in the open, or provide forced ventilation. This is the product in the range for which a respirator is a reasonable purchase rather than an over-reaction, and gloves are not optional — H317 is on it too.
Knead It is hand-kneadable, and that is the trap. Rebuilding rotted timber means mixing a two-part epoxy putty until the colour runs uniform, which fingers do better than anything. Category 1A skin sensitisation is the sub-category for strong evidence in humans. It is permanent once acquired. Gloves before you cut the stick.
The furniture repair in job 2 is the clean one. Aquadhere Exterior carries no classification at all — that is a definitive statement from its own safety data sheet, not an absence of information — and it bonds stronger than most timbers. Where a repair can be made with a clamped PVA joint rather than a polyurethane bead, it is the lower-hazard route to the same result.
Poisons Information Centre — 131 126 in Australia, 0800 764 766 in New Zealand.
Common questions about maintaining outdoor timber
Which adhesive stops deck boards squeaking?
Liquid Nails Rapid Cure, applied when you fasten the boards to the joists. It expands slightly as it sets to fill gaps and reduce movement.
Can I glue damp decking?
Yes. Liquid Nails Rapid Cure adheres to damp and poorly seasoned timber and other damp surfaces, and it needs moisture to cure. Remove any pooled water first.
How long do I have once I apply Rapid Cure?
Working time is 5 minutes, and pieces can be repositioned for up to 5 minutes after fitting. Initial cure is 10 minutes and full cure is 24 hours.
How big a gap will Rapid Cure bridge?
Up to 3 mm, and it can be used on rough and ill-fitting surfaces.
Can I glue a deck in winter?
Liquid Nails Rapid Cure should not be applied below 5°C, and drying times lengthen in cold weather.
Which glue for a wobbly outdoor chair?
Aquadhere Exterior. Clamp for 30 minutes on softwoods or 1 hour on hardwoods, and do not stress the joint for 24 hours.
Should I glue both faces of a timber joint?
No — apply Aquadhere Exterior liberally to one surface only.
Why has my glue line gone black?
Aquadhere stains brown or black if it is contaminated with rust or in the presence of tannins in many woods. Keep steel and iron away from wet glue.
Can I fill rot rather than replace the timber?
Knead It Multipurpose can rebuild and reshape damaged timber, and it can be drilled, sawed and painted after 60 minutes. It is not intended for structural applications, so load-bearing timber that has rotted needs replacing.
Can I use Knead It in a joint that moves?
No. It is not recommended for filling joints and cracks subject to movement — the cured product is extremely hard and inflexible.
How long do I have to shape Knead It?
Three to five minutes at 25°C. Mix small amounts and work in stages.
How do I clean up each product?
Liquid Nails Rapid Cure: acetone or mineral turps while wet, chisel or sand when dry. Aquadhere Exterior: water while wet, sand or scrape when cured. All three cure hard, so cleaning up early saves work.
What is the main goal of maintaining outdoor timber and decks?
The main goal is to apply protective coatings and perform regular cleaning in order to protect timber surfaces from weather exposure and extend their lifespan.
What product does Selleys recommend for cleaning decks before applying a protective finish?
Selleys Outdoor Multi-surface Cleaner is recommended, as it is specifically formulated to clean hard exterior surfaces including decks and patios, effectively removing dirt, grease, and grime without staining the surface.
How should you clean a deck for light versus deep cleaning?
For light cleaning, spray the cleaner on, let it sit, and rinse off. For deep cleaning, spray the cleaner on, scrub the surface, and then rinse off thoroughly.
What manual methods can be used to clean dirt and debris from a deck?
You can use a stiff brush and pressure cleaner to remove dirt and debris from the deck surface.
How can stubborn stains on a timber deck be removed?
Stubborn stains on timber decks can be treated by rubbing down the affected area with a turpentine-soaked cloth.
Why must a deck be completely dry before finishing it?
The deck must be completely dry before proceeding to the next step so that the protective coating or finish can be applied properly and effectively.
Do all timber types require weathering before coating, and what is an example?
Some timber types require special preparation before coating; for example, timbers like Merbau should be weathered for several weeks before coating or staining can be applied, allowing the timber to acclimate to outdoor conditions.
What should you check before weathering or coating a specific timber?
You should always check and follow the manufacturer's specific instructions and recommendations for the particular timber type you are using.
What products are suggested for protecting and finishing a deck once it is clean and prepared?
Cabots Aquadeck or a chosen decking stain or oil are suggested as products that provide weather protection for timber surfaces.
How should a protective finish product be applied to a deck?
The product should be stirred well and then applied to border areas of the deck as part of the application process.