Wood impregnation

Outdoor timber turns grey, cracks and starts to rot wherever water collects. Wood treatment protects decking, fences, summerhouses, timber cladding and garden furniture from damp, fungus and sun. It needs repeating every so often and is priced per square metre.

How wood treatment is done

• cleaning dirt, algae and flaking old coatings off the wood, often with a pressure washer or a brush;
• drying: treatment only goes onto dry timber;
• sanding back the greyed surface and splintered spots, especially on decking;
• applying the treatment by brush, roller or spray, with careful coverage of board ends;
• a second coat if the product calls for it or the wood is very absorbent.

Oil, woodstain or preservative

Decking oil soaks into the wood and brings out the grain, but needs renewing more often, usually every season or two. Woodstain forms a thin pigmented film that shields against sunlight and changes the colour. Fungicidal preservative goes on the undersides of boards and in permanently damp spots. The handyman picks the product to suit the timber and whatever is already on it, as not every oil will take over old woodstain.

When and in what conditions

Treatment is done on a dry day with no rain forecast for the next 24 hours, within the temperature range the maker gives. Late spring or early autumn is best. In full sun the product dries too fast and leaves streaks, so the handyman plans the work for the right time of day.

Common questions