When installing cabinet crown molding, the backing strip serves as the critical, yet often invisible, component that ensures a clean, professional finish. This narrow strip of material is fixed directly to the wall surface behind the molding, creating the necessary gap for caulk insertion and establishing a secure anchor point.
The primary function of a cabinet crown molding backing strip is to bridge the gap between the back of the molding and the wall. Without this spacer, the molding would sit flush against the wall, leaving no room for the flexible caulk that conceals the joint. This gap is essential for accommodating minor wall imperfections and allowing the molding to be securely fastened without damaging the drywall surface behind it.
Material Choices and Their Impact
The choice of material for your backing strip significantly influences the stability of the installation and the longevity of the finish. The most common options include:
- Wood Strips: Traditional and easy to work with, wood provides a solid nailing surface. However, it must be precisely cut to the length of the cabinet top to ensure a level installation.
- Flexible PVC: Ideal for walls with slight undulations, flexible PVC molding strips bend to follow the wall's contour. They are resistant to moisture and paint, making them a low-maintenance choice.
- Rigid PVC or ABS: These offer the stability of wood without the risk of shrinking or warping over time. They are particularly useful in environments with high humidity, such as bathrooms or kitchens.
Installation Techniques for a Perfect Gap
Proper installation of the backing strip is crucial for achieving the consistent 1/8-inch gap preferred for caulking. The strip should be mounted horizontally along the wall, directly behind the intended location of the crown molding. Utilizing a high-quality painter's tape as a temporary guide helps maintain this precise gap. By pressing the tape against the wall where the bottom edge of the molding will sit, you create a visual reference that ensures the backing strip is installed at the correct height.
Securing the strip requires careful placement of fasteners to avoid splitting or displacement. For wood strips, fine-gauge brad nails or small finishing screws driven into the wall studs provide the necessary holding power. When using PVC strips, a high-adhesion construction adhesive is often sufficient, though discreet nails can be used for additional support in areas of heavy vibration. The goal is to create a stable plane that prevents the crown molding from bowing or sagging over time.
Addressing Wall Imperfections
One of the most significant advantages of using a dedicated backing strip is its ability to compensate for uneven wall surfaces. Older homes often feature walls that are not perfectly straight or plumb. A rigid backing strip installed directly over these irregularities allows the crown molding to follow a straight path, effectively "skating over" the bumps and dips below. This results in a seamless appearance that masks the underlying construction flaws without the need for extensive wall repair.
Furthermore, the backing strip acts as a protective buffer between the hard cabinet and the plaster or drywall. In the rare event of minor settling or vibration, the flexible caulk-filled gap allows for slight movement without causing stress cracks in the paint or the molding itself. This subtle flexibility is vital for maintaining the integrity of the finish and preventing costly repairs down the line.
