Tarred wood is maintained by keeping it clean, checking for bare or cracked areas, repairing damp problems, and applying light renewal coats before the timber loses protection.
Maintenance starts with observation. A tarred surface that looks dull but still sheds water may not need immediate work. A surface with pale exposed wood, deep cracks, lifting edges, soft timber, or green growth needs attention. The condition of the wood matters more than the age of the coating.
Clean the surface without damaging sound material. Remove dirt and algae from places where water sits, especially lower boards, joints, post tops, and sheltered corners. If moisture is trapped because of bad drainage or contact with soil, fix that cause first. Tar cannot maintain wood that is kept permanently wet.
Renew with light coats. Repeated heavy applications can create a sticky, brittle, or uneven surface. The best maintenance keeps the finish alive and repairable: enough tar to darken and protect exposed areas, not so much that the wood disappears under a thick black crust.