Conventional wood preservatives are not only toxic to target bio-deterioration organisms but also to man, other organisms and the environment. In an effort to find preservatives that are less or non- toxic to man, other organisms and the environment, efficacy of branch bark and heartwood water extracts (0.65g/ml) of Erythropleum suaveolens (potrodom) and Distemonanthus benthamianus (bonsamdua) respectively were tested on five selected less used timer species (LUS): Sterculia oblonga (ohaa), Antiaris toxicaria (kyenkyen), Canarium schweinfurthii (bediwonua), Celtis zenkeri (esa-kokoo) and Cola gigantea (watapuo) following a modified EN 252. Regardless of extract retention in selected LUS, potrodom extract improved their durability more than that of bonsamdua. Improved durability of immersed and brushed selected LUS was ranked as follows: C. gigantea > C. zenkeri > S. oblonga > A. toxicaria > C. schweinfurthii. Though extracts showed reduced efficacy with time, indications were that they could be employed to control pests in low durability woods.