When to sand and re-oil your deck

A deck doesn't tell you it needs help. It just slowly stops looking like a deck — and by the time you've actually noticed, you've usually missed the easy fix and stepped into the harder one.

Most decks in the Geneva area need attention every two or three years. Some need it sooner; some last longer. The right time to do something isn't on a calendar, it's when you start seeing one of the signs below.

The four signs

1. The colour has gone flat and grey

A bit of silvering is fine — and on larch and cedar, it's even attractive in its own right. The problem is when the silver has gone matte and dusty, and water no longer beads on the surface. That means the protective oil is gone and UV is now eating directly into the wood fibres.

2. Splinters are coming up

Run a hand (carefully) along a board. If it grabs at your skin, the surface fibres have lifted. This is the moment a sand-and-oil rescue still works. Wait another year and you'll be replacing boards instead.

3. Black or green patches that won't wash off

Mildew or moss. Common on shaded sides, around planters, anywhere that stays damp. A scrub with a stiff brush and a deck cleaner will lift most of it. If it comes back within a season, the wood is too saturated and probably wants resurfacing rather than just cleaning.

4. Boards starting to cup

Look down a row of boards from one end. If they curve upward at the edges (the cross-section looks like a shallow U), water is sitting on them and not draining off. This isn't fatal, but it's a sign the boards are tired — and worth catching before any one board fully splits.

What you can do yourself

Before calling anyone — including me — there are three or four things genuinely worth trying:

• Sweep, then wash. A stiff brush, warm water, and a dedicated deck cleaner. Two thirds of decks I get called to look at just need a proper clean.
• Spot-oil the dry patches. If sections look thirsty (matte, no beading) but the rest is fine, top up just those areas. Saturated boards don't accept more oil and will go tacky if you over-apply.
• Tighten loose screws. Walk every board, listen for squeaks, look for raised heads. A wandering screw is the first step toward a split board.
• Clear the gaps. Pine needles, leaves, and dirt packed between boards trap moisture against the joists below. A thin blade or a stiff card pushed through every joint, once a year, adds years to a deck.

When it's time to call someone

If a thumb pressed into a board leaves a mark, the wood is gone. No amount of oil will bring it back.

At that point you're either replacing individual boards (if the substructure is still good) or you're looking at a renewal — sand the whole deck back to fresh wood, replace the dead boards, re-oil the lot. Done well, a renewal often comes in at half the cost of building a new deck and the result feels almost identical underfoot.

The trick is timing. Catch a deck early and the renewal is straightforward. Wait too long and you cross over into rebuild territory — same price, much more disruption. So: walk your deck once a spring, look for the four signs, and act before the wood does.