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Shed maintenance: treatment, roofs and damp
A well-kept wooden shed can last many years, while a neglected one can rot in a few. Here is a simple routine.
Why maintenance matters
Wood absorbs moisture, and the constant cycle of wetting and drying causes rot, warping and splitting. Most of the maintenance in a wooden shed is about keeping water out and letting air in. Cheap overlap cladding, around 7 mm thick according to one supplier guide, has small gaps and tends to need more attention than thicker tongue and groove. See cladding.
Yearly checklist
- Look at the roof. Check felt for tears, lifted edges and ponding. Re-fix or replace as needed. Felt is often the first thing to fail.
- Check the walls and corners. Look for cracks, soft spots and open joints.
- Re-treat the timber. Brush on a suitable preservative or stain. Many suppliers suggest re-treating every year or two, but check the manufacturer's advice for your product.
- Look underneath. Check the floor and bearers for damp, fungus and insect damage. A good base keeps this to a minimum: see bases.
- Check doors and windows. Ease sticking doors, tighten hinges and replace cracked glazing.
- Clear gutters and surroundings. Keep vegetation, leaves and soil away from the walls, and leave a gap for air. Do not stack wood or compost against the walls.
- Test the lock and hinges. See security.
Damp and condensation
Condensation forms when warm moist air meets cold surfaces. Air vents high and low help, as does keeping the floor dry and avoiding storing wet items. In a garden room, a vapour control layer and ventilation are part of the build. See garden offices.
Roof care
- Remove leaves and moss, which hold water.
- Don't walk on a felt roof in hot weather.
- Replace felt before it fails. A leaking roof causes damage quickly.
- Gutters and a water butt can reduce splashback and protect the lower boards.
Wood treatment tips
- Apply on dry weather to dry timber.
- Treat end grain and the bottom of boards, where water gets in.
- Check whether the supplier's guarantee depends on a particular treatment schedule.
Dealing with rot
Poke suspect timber with a screwdriver. If it's soft, cut it out and replace it. Small patches can be repaired; widespread rot in the floor or frame may mean replacing the shed. If you have a sound structure, better ventilation and a better base could extend its life.
Winter and storms
Strong winds can lift a light shed or roof. Check the shed is fixed down if exposed, and clear heavy snow from the roof. Move vulnerable items off the floor in case of flooding.
When to replace
Once the floor, frame and roof are failing, the cost of repairs rises. That's the time to consider a new building. Use sizes and prices to plan, and check the planning rules if the new one is bigger.
Prices on this page are typical estimates for November 2026, not quotes. They vary with size, timber grade, supplier, delivery, VAT and installation. Check current prices before you decide.
Frequently asked questions
How often should I treat a wooden shed?
Many suppliers suggest every year or two. Follow the preservative maker's advice and your shed's guarantee.
Why is my shed damp inside?
Common causes are a leaking roof, a damp base, poor ventilation and condensation. Check each.
How long does shed felt last?
It varies with quality and exposure. Inspect it every year and replace at the first sign of failure.
Can I fix a rotten floor?
Small areas can be repaired. Widespread rot may need a new floor or shed.