Replacing old wood baseboards with PU baseboards is a common renovation project, because the new PU is more durable, more stable, and easier to maintain than the old wood. The project can be completed in a day for a single room, with basic tools and a moderate budget.
The first step is to remove the old baseboards. The old baseboards are carefully pried off the wall with a flat pry bar, starting at a joint and working along the length. The old baseboards can be saved for reuse in a utility area, or they can be disposed of. The nails or screws holding the old baseboards are removed from the wall.
The second step is to prepare the wall. The wall behind the old baseboards is inspected for damage, with any holes or imperfections filled with patching compound. The wall is then wiped clean, and any loose paint is removed. The new baseboards will sit on a clean, sound surface.
The third step is to measure the new baseboards. The wall is measured, and the new baseboards are cut to length with a miter box and a fine-tooth saw. The outside corners are mitered at 45 degrees, and the inside corners are coped or butted into a corner block.
The fourth step is to dry-fit the new baseboards. The new baseboards are placed on the floor against the wall, and the joints are checked for fit. Any adjustments are made before the adhesive goes on.
The fifth step is to install the new baseboards. A continuous bead of construction adhesive is applied to the back of the baseboard, the baseboard is pressed to the wall aligned with the layout marks, and a few brad nails are driven to hold the baseboard in place while the adhesive sets. The joints are filled with paintable caulk.
The sixth step is to finish the baseboards. The nail heads are set below the surface and filled, the caulk is allowed to dry, and the painter's topcoat goes on the next day.
A practical note on the shoe molding. If the old baseboards had a separate shoe molding (a small strip at the bottom that covers the expansion gap between the floor and the baseboard), the new PU baseboards should be installed with a matching PU shoe molding. The shoe molding covers the gap and gives the install a finished look.
A practical note on the floor. The new baseboards should be installed with the floor in its final state. If the floor is being replaced, the floor goes in first, and the baseboards go on after. If the floor is staying, the baseboards can be installed on top of the existing floor, with a small gap at the bottom that's covered by the shoe molding.
---
Frequently Asked Questions
Q: What is polyurethane (PU) decorative material?
A: Polyurethane (PU) decorative material is a high-density closed-cell polymer molded into architectural profiles such as cornices, ceiling medallions, wall panels, columns, and skirting boards. It replicates the appearance of plaster, carved wood, or stone at one-quarter the weight, is fully waterproof, impact-resistant, and arrives factory-primed for paint.
Q: How does PU compare with plaster and wood mouldings?
A: PU is lighter than plaster (no scaffolding required), impact-resistant during transport, and immune to cracking. Compared with wood, PU does not warp, split, or attract termites, and it tolerates moisture in bathrooms and kitchens. The trade-off: PU cannot be refinished the way solid wood can, but its lifespan is 20–30+ years with minimal maintenance.
Q: How do you cut and finish PU mouldings?
A: Cut PU mouldings with a fine-tooth miter saw (40+ teeth for a 10-inch blade) to avoid chipping the molded edge. Sand the cut edge with 220-grit, then apply two coats of interior latex paint. Mitre joints at corners, fill seams with lightweight spackle, sand smooth, and finish with one final top coat.
Q: Is PU moulding safe for indoor air quality?
A: Yes. Premium PU mouldings are manufactured without formaldehyde, asbestos, or VOCs. They meet EN 13501-1 Class E fire classification as a minimum, with Class B fire-retardant versions available for commercial projects. The factory-applied water-based primer further reduces off-gassing once installed.