Assessing the Damage Before You Start

Before reaching for tools, walk the jetty slowly. Look for soft spots underfoot, boards that flex, rust stains around fixings and dark, crumbly timber. Press a flat-blade screwdriver into suspect areas – if it sinks in easily, rot has begun. Check the underside too, especially where boards meet bearers and where the structure meets the shore. Algae and moss often hide damp timber, so scrape a little away as you go.

Work at low tide if your jetty sits on tidal water, and never go out alone on a slippery landing stage. Wear gloves, eye protection and non-slip footwear. If the main supporting piles are moving, call in a qualified contractor. For localised rot, simple repairs are well within reach.

Replacing Rotten Boards

Mark the extent of rot with chalk. If several adjacent boards are soft, replace them together. Use a jemmy bar to lift the old board. Stubborn fixings can be cut with a reciprocating saw, but take care not to damage the joist below.

Measure the opening and cut a replacement from treated timber of the same thickness and width. Pressure-treated softwood is fine for freshwater; for coastal sites choose oak or iroko. Pre-drill and countersink screw holes to avoid splitting.

• Leave a 3–5 mm gap between boards for drainage.
• Ensure each board end lands on a joist with at least 40 mm bearing.
• Use stainless steel screws – A4 for coastal, A2 for inland.
• Treat fresh cuts with end-grain preservative.

If the joist beneath is soft, replace that first. A joist carries your weight, so cut out the rotten section and splice in new timber using galvanised hangers or bolts.

Tightening and Upgrading Loose Fixings

Nails work loose and screws corrode. Walk the jetty and check every fixing. A loose board is a trip hazard and lets water sit between board and joist. Replace old nails with screws – they grip better and are easier to tighten later.

For bolts and coach screws holding bearers or piles, check tightness with a socket set. Tighten until snug, but do not overtighten. Replace rusty washers. If a screw hole is enlarged, glue in a hardwood dowel, then re-drill and fit a new screw. Alternatively, use the next screw size up.

• Check joist hangers and brackets for corrosion.
• Replace fixings with deep pitting or white rust.
• Add extra screws where boards feel springy.
• Clean bolt threads with a wire brush before tightening.

Cleaning and Preparing the Timber

Before treatment, the timber must be clean and dry. Sweep off leaves and silt. Scrub algae with a stiff brush and warm water with mild detergent. A pressure washer on low setting can help, but keep it moving and avoid joints and fixings.

Let the jetty dry for at least 48 hours in dry weather. Sand rough patches. Treat fresh cuts with preservative and let that dry too.

Applying the Right Wood Treatment

Choose a penetrating wood preserver first, then a decking oil or water-based stain with UV protection. Avoid varnish and paint – they crack and trap moisture.

Apply on a dry day with no rain forecast for 24 hours. Brush or roller the product into the grain, especially end grain and joints. Two thin coats are better than one thick coat. For slippery boards, add an anti-slip additive to the final coat or fit grip strips.

Reapply every year or two. A spring check will tell you if the surface is still beading water.

Seasonal Checks and Simple Habits

After winter, clear drainage channels and remove debris. Trim overhanging vegetation, which keeps the deck damp. After storms, look for lifted boards, missing fixings or new soft spots. Keep a small box of stainless steel screws handy.

Use fenders and avoid ropes chafing the deck edge. Sweep fallen leaves in autumn – they hold moisture. These habits take minutes but add years to your landing stage, keeping it ready for quiet mornings by the water.