It also can be glued directly to a concrete slab which means it can be used below grade. The most common is the familiar wood strip. But it is also available in wider width planks or as parquet squares. Itl very durable and easy to maintain. Unfinished floors, installed on-site, give you many choices for colorations and durability.
Most solid flooring is unfinished while most engineered is prefinished.
All pre-engineered floors offer multiple layers of factory applied and cured urethane finishes.