Using wood as a construction material comes with the problem of degradation due to material resistance and exposure to favourable conditions conducive to fungal growth. This study investigated the resistance of treated commonly used wood species (Triplochiton scleroxylon, Gmelina arborea, and Terminalia superba) to fungal decay in construction in Nigeria. The selected wood species were treated with neem oil, moringa seed oil, and castor oil as preservatives. The treatability and physical properties of the treated wood samples were assessed, including moisture content, density, absorption, and retention of preservatives, to ascertain the suitability of oil preservatives. An accelerated fungi infestation test was carried out on the treated wood samples by inoculating them with Gilbertella persicaria for 7 weeks, and visual observation was done every week. The weight loss due to infestation was calculated after the 7th week of exposure to fungi. The wood species exhibited varying moisture content and density with Afara having (27.66 % and 508.61 kg/m3), Gmelina wood (21.00 % and 528.07 kg/m3), and Obeche (16.83 % and 531.75 kg/m3), respectively. For the rate of absorption, Afara recorded (5.06 %, 4.18 %, and 6.58 %), Gmelina wood (9.35 %, 7.61 %, and 8.50 %) and Obeche (0.95 %, 4.22 %, and 8.15 %) when treated with neem oil, moringa seed oil, and castor oil, respectively. Treated wood samples demonstrated significantly lower volumetric swelling and weight loss compared to untreated samples. Castor oil treatment, especially on Gmelina wood, emerged as effective in minimizing dimensional changes and fungi infestation, making it a promising choice for applications requiring stability, leaching resistance, and protection against fungi infestation.
