Teak planks are made by taking teak logs to the sawmill northeast of Varrock and asking the sawmill operator to convert the logs into planks, at the cost of 500 coins per teak plank. Players can send their servant to the sawmill, but it will still cost the 500 coins per plank.
Teak planks can be used for Construction training. Pieces of furniture between level 35 and 65 often require teak planks to be built. If teak planks are used, people usually make flat-packs of teak chairs and then eventually, teak dining tables, which is a popular way of levelling Construction. Each teak plank is worth 90 Construction experience, so the maximum experience per inventory available is 2160 for 6 dining tables. Teak garden benches are also a better alternative at higher levels.
It should be noted that assembling Mythical Cape (mounted), in a quest hall, boosts the xp gained drastically - 370xp can be gained from using three teak planks (normally 270xp) and the re-usable cape. This provides an extremely efficient method of construction training.