Preservative treatment of Dryobalanops aromatica, as roof truss in building construction

Dryobalanops aromatica, commonly known as kapur in the trade, belongs to the family Dipterocarpaceae. The timber is relatively heavy with its density ranging from 575 to 815 kg m³, averaging 800 kg m³ air-dried. Its sapwood is well defined from the heartwood that is rosered or dark red in colour. The timber is durable and difficult to treat. It is somewhat proned to splitting and surface checking. Despite its shallowly or heavily interlocked and sometimes spiral grain, the timber is moderately easy to work. It falls under Strength Group B and can be used for various building constructions, posts, beams, joints, ratters, door and window frames, flooring, framework of boats, carriagce and motor vehicle frames, heavy duty furniture, heavy duty flooring, veneer and plywood. The timber is commonly used in roof truss as evidenced from the wood samples received by the Forest Research Institute Malaysia (FRIM). Over a 3-year period (1999-2001) a considerable number of samples of kapur roof trusses were received for dry salt retention test. The number of these samples destined for roof truss is comparable to those of the more popular species in the building construction, such as kempas (Koompassia malacecensis). Kempas is a Strength Croup A timber that is commonly specified in the building construction and used as a reference. Its density range from 770 to 1120 kg m³ and averages 890 kg m³. Within the same period of study, samples of kempas received for similar testing were much more than those of kapur. Although kempas is less durable than kapur, it can be easily treated with preservatives. A comparison was made between kapur and kempas within the same density range in terms of the dry salt retention and distribution or CCA with respect to their wood structures.