The shift from fossil fuels to bioenergy has led to increased wood ash output. Since a large proportion of this waste ends up in landfills, recycling wood ash in construction materials is one of sustainable approaches of managing this by-product. However, the amount of biomass ashes currently recycled in building materials is still limited. This study therefore explored the feasibility of valorising four different types of wood ashes in large quantities in the production of lightweight building materials. Thirty pastes with different levels (80, 90, 95 and 100 wt%) of wood ash and (0, 5, 10 and 20 wt%) of natural hydraulic lime (NHL) or ordinary Portland cement (PC) were developed. Partial replacement of wood ash (WA) by NHL or PC accelerated the setting and improved the mechanical properties of blended pastes. The initial and final setting times decreased with increasing NHL or PC content in the mixes. The strength of the pastes increased with increasing NHL or PC levels and curing time. However, wood bottom ash (WBA) mixes were controversial because their mechanical properties gradually weakened over time. For WA-NHL blends, the 28-day flexural and compressive strength ranged from 0.02 to 1.12 MPa and from 0.05 to 2.59 MPa, respectively. On the other hand, for WA-PC pastes, the flexural and compressive strengths at 28 days varied from 0.07 to 2.72 MPa and from 0.13 to 5.49 MPa, simultaneously. These results prove that wood ash can be used effectively as a main component of binding matrices for lightweight building materials.