Preparing your wooden deck for the season

After winter, a wooden deck often needs attention before the first warm days of spring. Algae, dirt, grey or rough wood and loose boards may all need dealing with. The key is to work in the right order and suitable weather. This guide takes you through preparing your deck for the season.

When should you prepare the deck?

Timing matters more than most people think. You can sweep and clean the deck as soon as the snow is gone, but the oil treatment, which protects the wood, requires the right weather. The wood must be dry, and the temperature must be high enough for the oil to penetrate and cure properly.

As a guide, oil the deck in dry weather with temperatures consistently above about 10-15 degrees Celsius and a forecast of several dry days. Prepare in spring so it is ready for summer, but wait for suitable oiling conditions. In Denmark, that often means May onwards, when warm, dry weather is more reliable.

Wait until nights no longer bring heavy dew and no rain is forecast for the first day or two after oiling. You can clean earlier and allow the deck to dry while waiting for suitable weather.

Step 1: Inspect the deck

Inspect the deck before cleaning and oiling. A check of about fifteen minutes helps you identify repairs and plan the work.

• Loose boards and screws. Walk across the deck and step on the boards. If anything feels loose or creaks, tighten the screws or replace any that have come loose. This is easiest to do now, while the deck is being worked on anyway.
• Rot and moisture damage. Check board ends, areas close to the ground and places where water collects. Soft or crumbling wood may be rotten and should be repaired or replaced before the rest of the work.
• Grey, rough wood. A grey, rough surface shows weathering from sun and rain. Greying alone does not mean structural damage, but rough wood needs sanding before oiling for an even result.
• Algae and slippery growth. Note where it's worst. North-facing and shaded areas typically collect the most, and this tells you where to focus your efforts during cleaning.

Once you know the condition, plan the work. Cleaning and oiling a sound deck may take a weekend. Extensive weathering or loose boards need more attention and may justify professional help.

Step 2: Thorough cleaning

Sweep away leaves, twigs and loose debris, including material trapped between boards. Clearing these gaps helps prevent moisture from being held against the wood.

Wash with a deck cleaner or gentle wood cleaner, a stiff brush and water. Work along the grain and rinse thoroughly. For heavier algae growth, choose a product approved for the intended use and allow the treatment time stated on the label.

Take care with pressure washers on wood. Excessive pressure raises fibres, roughens the surface and can damage boards, leaving them more vulnerable to moisture and algae. If using one, choose low pressure, keep a good distance and move along the grain. For more on gentle maintenance, read our guide to maintaining your balcony and wooden deck.

Let the washed deck dry for at least a day in dry weather, preferably a couple of days. The wood must be dry throughout before oiling. Excess moisture is a common reason for a short-lived finish.

Step 3: Sanding, if necessary

Grey, rough or splintered wood needs sanding before oiling. Sanding removes the weathered outer layer and exposes fresh wood that can absorb the oil. Applying oil over a damaged surface instead gives a patchy, short-lived result.

A small deck can be sanded with a random orbital sander, starting with a coarse grit and finishing finer. It is dusty, time-consuming work, and uneven sanding can cause the oil to absorb inconsistently. Specialist equipment and professional help are useful for larger areas or when an even finish is especially important. See our guide to sanding balconies and wooden decks for the process and key steps.

If the wood is sound but looks dull and grey, find out how to bring back its warmth in our guide to a grey wooden deck.

Step 4: Oil the wood for protection

Oiling protects the wood for the season. It penetrates the fibres, brings out the natural colour and improves resistance to moisture, sunlight and wear. Well-maintained wood is better protected than bare decking exposed to the weather.

Oil a completely clean, dry surface in dry weather. Aim for mild conditions, preferably 15 to 20 degrees Celsius. Apply evenly along the grain, allow it to soak in and wipe away excess oil so no shiny patches remain. Many decks benefit from two coats with drying time between them. Allow the finish to cure for a day or two before use.

Which oil to choose and how to apply it correctly is covered in our guide to deck oiling. If you do it correctly this spring, the wood will be protected all summer, and next year's preparation will be much less work.

Spring preparation checklist

Keep this sequence handy. Dry weather and thoroughly dry wood are essential throughout the process.

• Wait for the weather. Dry weather and stable temperatures above approximately 10-15 degrees Celsius before oiling.
• Inspect. Check for loose boards, screws, rot and grey, rough wood. Deal with repairs first.
• Sweep and clean. Remove leaves and dirt, wash with deck cleaner and a stiff brush, rinse.
• Let the deck dry. At least a day in dry weather, preferably a couple of days.
• Sand grey or rough wood if needed. Expose fresh wood so the oil can penetrate.
• Oil. Use a clean, dry surface, preferably at 15-20 degrees Celsius. Apply evenly and wipe away excess oil.
• Let it cure. One to two days before the deck is used again.

Prepare it yourself or hire a professional?

You can clean and oil a small deck in good condition on a dry weekend. Professional help is useful for large areas, heavily weathered wood that needs sanding, or loose boards and rot requiring repairs first.

For professional deck sanding and oiling, send photographs and the approximate area for a fixed quotation, with a reply within 24 hours, or call 20 98 88 11. Do not assume that this work qualifies for tax relief: deck sanding and oiling are not listed in the Danish Tax Agency's eligible services for 2026. Read more about our balcony sanding service.

Frequently asked questions

When should you prepare a wooden deck for the season?

You can clean after winter, but oiling needs dry weather and temperatures consistently above about 10-15 degrees Celsius. Prepare in spring, then wait for a dry spell without heavy overnight dew so the oil can penetrate and cure.

Does a wooden deck need to be sanded every spring?

No. Sanding is needed when the surface is grey, rough or splintered and oil cannot penetrate properly. A well-maintained deck may only need a thorough clean and fresh oil. Sanding is usually required every few years, while cleaning and oiling are normally annual tasks.

How long after cleaning should the deck dry before oiling?

Allow at least a day in dry weather, preferably a couple of days. The wood must be dry throughout, as oil does not penetrate wet wood properly. Oiling too soon traps moisture and shortens the life of the finish. Choose a dry spell for cleaning and the days afterwards.

Can I prepare the wooden deck myself?

Yes, for a small deck in good condition. The work becomes more demanding if sanding or repairs are needed. Professional help is useful for large areas or when you want a consistently even finish.

What does it cost to have a wooden deck professionally prepared?

The price depends on the area, wood condition and whether sanding is needed as well as cleaning and oiling. A sound deck that only needs routine maintenance costs less than one requiring full restoration. We give you a fixed price before starting and respond within 24 hours.