Plain Molding Corner Selection and Installation Guide

Rigid polyurethane plain molding corners are manufactured with a high-density, closed-cell structure engineered for dimensional stability. Standard production targets a density of approximately 150-220 kg/m³ (production target ~160 kg/m³), within a technical range of 150 to 150-220 kg/m³ (production target ~160 kg/m³). This high density ensures that the decorative profile resists impact and deformation during daily building operation.

Thermal and environmental performance parameters allow these corners to endure extreme conditions without cracking or expanding. The operational temperature resistance spans from -100 °C / +80 °C, while water absorption rates remain strictly below 1%. Because the material does not absorb moisture, it prevents swelling and joint separation common in traditional wooden or plaster moldings. These physical properties make rigid polyurethane suitable for both humid interior zones and demanding exterior environments when correctly finished.

Selecting plain molding corners requires aligning profile depth and width with overall wall proportions and ceiling heights. In standard residential interiors with a 2.70-meter ceiling height, molding cross-sections between 20 mm and 40 mm maintain balanced spatial geometry. For commercial spaces or larger rooms exceeding 3.00 meters in ceiling height, wider profiles ranging from 50 mm to 80 mm are recommended to prevent the framing from appearing undersized.

Architectural layout guidelines dictate that wall paneling frames should maintain consistent spacing from door frames, baseboards, and ceiling cornices. Corner elements must match the exact width and cross-sectional projection of the straight molding profiles to which they connect. Mismatched projection depths create uneven junction planes that are difficult to bridge with joint compound. Evaluating the scale of the room and selecting matching profile depth ensures clean transitions across all wall panels.

Accurate measurement for plain molding corners requires counting total panel frames and calculating the specific corner piece requirements prior to ordering straight moldings. Each rectangular wall frame utilizes four 90-degree corner pieces, which reduces the total length needed for straight profiles. Calculate the total perimeter of all planned frames, subtract the combined length of the corner components, and add a material allowance for site cutting.

Technical site measurement steps include:

• Determine the total number of wall panels and multiply by four to identify the exact quantity of plain molding corners required.
• Measure the total linear meters of straight molding needed, deducting the length occupied by the prefabricated corner units.
• Incorporate a 10% to 15% wastage margin to account for straight molding miter trims and site modifications.
• Verify wall flatness using a straightedge; uneven plaster surfaces exceeding 3 mm variations must be corrected before installation.

Installing plain molding corners requires systematic surface preparation and proper chemical bonding agents. Substrates must be completely clean, dry, structurally sound, and free from dust or loose paint. A precise 45-degree miter cut on the adjoining straight moldings ensures a flush connection against the prefabricated corner element. Silicone-based adhesives are strictly forbidden as they lack structural shear strength and cannot be painted over effectively.

Bonding must be executed using a high-strength polyurethane (PU) assembly adhesive applied along the rear contact channels of the profile. In professional applications, such as those specified in Polure project details, mechanical fixing with screws or brad nails into the wall substrate is mandatory. Mechanical fasteners hold the corner firmly while the PU adhesive cures, preventing joint movement caused by substrate settling or vibration.

After mechanical and adhesive mounting is complete, profile joints require proper surface finishing to achieve continuous wall integration. Joint gaps and screw countersinks must be filled with a non-shrinking acrylic or polyurethane filler. Once cured, sand the joint smooth using 180-220 grit sandpaper to eliminate height differences between the corner piece and the straight molding.

Factory-applied primer comes standard on rigid polyurethane profiles. Applying an extra coat of field primer is optional depending on the chosen paint system, but claiming that no primer is ever needed is technically incorrect. For interior walls, apply two coats of high-quality acrylic or latex paint. For exterior facade installations, applying a UV-resistant topcoat paint is mandatory to prevent material degradation from solar radiation. Note that polyurethane molding profiles and decorative columns are strictly non-load-bearing structural elements and must never support vertical loads.

Before purchasing plain molding corners for residential or commercial projects, technical teams should execute a pre-installation checklist to prevent site delays and structural failures. Polure technical specifications recommend reviewing material density, adhesive compatibility, and environmental exposure before final procurement.

Key checklist items for procurement:

• Confirm that the corner profile cross-section matches the linear molding depth and width exactly.
• Verify material density is within the 150-220 kg/m³ (production target ~160 kg/m³) technical specification.
• Ensure polyurethane (PU) assembly adhesive and proper mechanical fasteners are specified; avoid silicone products.
• Check that 180-220 grit sandpaper and compatible non-shrinking joint filler are available on site.
• Confirm topcoat specifications: standard interior paint for indoor zones, UV-resistant paint for exterior facades.