Architectural Round Arch Trim: Dimensioning and Fitting Guide

Polyurethane arch trims are manufactured from high-density rigid polyurethane featuring a closed-cell physical structure. The material features an average density ranging between 150-220 kg/m³ (production target ~160 kg/m³). This high density ensures physical stability and edge crispness while maintaining low overall weight.

Material performance parameters include an operational temperature resistance from -100 °C / +80 °C and a water absorption rate under 1%. The components come pre-coated with a factory-applied primer; applying an additional primer layer prior to final painting remains optional based on site requirements. These decorative elements are non-load-bearing and must never be specified as structural supports.

Accurate measurement is critical when selecting polyurethane arch profiles for wall openings. Measure the total opening width, arch depth, and radius at three separate points to account for wall irregularities. Profile cross-sections must be selected in proportion to ceiling height and adjacent wall space to maintain balanced architectural visual scale.

• Calculate total inner perimeter length to order sufficient linear trim quantity.
• Add a 10% allowance to total linear material calculations to cover miter cuts and alignment trimming.
• Verify wall thickness to select profile depths that fit flush with existing drywall or plaster coatings.

Proper installation requires dual-action fixing comprising chemical adhesive bonding and mechanical anchoring. The application surface must be thoroughly cleaned, dry, and free of loose debris before mounting begins. Polyurethane (PU) assembly adhesive must be used across all rear contact surfaces.

Silicone adhesives are strictly prohibited because they lack structural shear strength and prevent proper joint sealant bonding. Mechanical fixing using countersunk screws is mandatory to anchor the trim securely while the adhesive cures. Screw anchor spacing should be kept consistent along the curved profile to avoid surface distortion.

Joining curved trim sections to straight vertical jambs requires accurate field cuts. All profile joints must be executed using a precise 45-degree miter angle to maximize surface area contact at the adhesive seam. Polyurethane adhesive should be applied directly inside the joint seam during connection.

Once mounted, screw heads and joinery seams must be filled with a compatible exterior-grade architectural filler or putty. After complete curing, sand all filled areas using 180-220 grit sandpaper until the surface is flush and uniform. Proper joint sanding prevents visible seam lines after paint application.

Final paint finishes protect the polyurethane substrate and ensure uniform color across all installed profiles. While factory priming is present, site surface preparation after sanding dictates whether a secondary localized primer is beneficial. Two final coats of quality paint should be applied to achieve complete coverage.

For exterior installations, the use of UV-resistant exterior paint is mandatory. Standard interior paints lack the UV absorbers necessary to prevent color degradation and material surface wear when exposed to direct sunlight over extended periods.

Before ordering, field teams should systematically verify all structural conditions. Common installation mistakes include relying solely on adhesive without mechanical screws, using silicone, or treating decorative trims as weight-bearing components. Polure specifies verifying the following parameters prior to material delivery:

• Confirm opening radius and width symmetry across the wall depth.
• Ensure wall substrate is dry, dust-free, and capable of holding mechanical anchors.
• Verify adequate clearance for door swings or adjacent architectural moldings.
• Confirm that UV-resistant topcoats are selected for outdoors.