Total volatile organic compounds (TVOCs) are widely used to assess indoor air quality (IAQ). However, because TVOCs combine diverse compounds into a single metric, they cannot distinguish individual emission sources or chemical characteristics. Indoor environments with natural materials such as wood may emit biogenic volatile organic compounds (BVOCs), elevating TVOC concentrations and limiting the interpretation of indoor air quality. This study evaluated TVOC concentrations and chemical composition before and after installing wooden interiors in 36 public facilities in South Korea, including daycare centers, nursing homes, and welfare facilities. Domestic wood species, including Chamaecyparis obtusa, Larix kaempferi, and Cryptomeria japonica, cover approximately 49% of the interior surfaces. Major regulated VOCs, including benzene and toluene, did not increase significantly after installing wooden interior materials. Mean TVOC concentrations increased from 244.2 ± 139 to 640.1 ± 542.3 μg/m³, accompanied by significant increases in several terpene-related BVOCs, including α-pinene, myrcene, and cymene, as well as an increase in the absolute concentration of unidentified VOCs. Elevated TVOC concentrations in wood-based indoor environments may reflect compositional changes rather than poorer indoor air quality. Therefore, TVOC concentrations should be interpreted alongside compound-specific analyses rather than relying solely on a single TVOC indicator.