“Renovate and lay” on the old wooden floor

If you intend to lay new flooring directly on top of the old one, or refurbish the old flooring by sanding it:

Direct laying of new flooring (leveling is crucial): If you intend to directly lay SPC (Stone Plastic Composite) flooring or new solid wood flooring on top of the existing floor, the old floor must be sufficiently flat (with a height difference of no more than 3 millimeters within a 2-meter area). You can use a level meter to measure, and any uneven areas should be leveled with self-leveling cement. Additionally, it is essential to lay a moisture-proof membrane on the old floor, otherwise, moisture may seep through the gaps and cause white foam in the future.

Sanding and refurbishment (thickness is the bottom line): If you want to sand off the surface layer of solid wood flooring and repaint it, make sure the thickness of the surface layer is over 4mm. Sanding will remove about 2mm, and if it’s too thin, it may wear through the tenon joints, rendering the entire flooring piece useless. After sanding, it is recommended to apply water-based paint, which is environmentally friendly and dries quickly, allowing you to walk on it within two days.