| 1 | Panel thickness | Select an 18–25 mm panel for most standard indoor shelves. Thinner boards may be suitable for light-duty storage or short spans, while thicker boards provide greater stiffness and a more substantial appearance. | Common nominal thicknesses: 12, 15, 18, 22, and 25 mm. For a panel of the same material and width, bending stiffness increases approximately with the cube of thickness. |
| 2 | Shelf span between supports | Keep the unsupported span as short as practical. Add a center divider, rear cleat, or front stiffening strip when a long shelf must carry books, files, or other concentrated loads. | A shelf spanning 800 mm is substantially less prone to sag than the same shelf spanning 1,200 mm. Deflection is highly sensitive to span length. |
| 3 | Shelf depth | Match the depth to the stored items and avoid unnecessary overhang. Moderate depths improve accessibility and reduce the bending load on the front edge. | Typical indoor shelving depths are approximately 250–400 mm. Deeper shelves hold more weight and usually require stronger support or a shorter span. |
| 4 | Panel material and density | Compare the board’s material, density, and internal construction—not thickness alone. Higher-density panels generally offer better screw-holding and stiffness, but they also weigh more. | Approximate panel mass can be estimated as: Mass per m² = thickness × density. At 650 kg/m³, an 18 mm panel weighs about 11.7 kg/m², while a 25 mm panel weighs about 16.3 kg/m². |
| 5 | Edge support and finishing | Support all shelf edges where possible and protect exposed edges with edging, a solid lipping, or a suitable finish. A thicker front edge can also improve perceived rigidity. | A front stiffening strip or lipping increases the effective section depth. Fasteners should be selected according to panel type and installed without splitting or over-tightening. |
| 6 | Moisture and environment | Use panels intended for the installation environment. Seal cut edges in kitchens, utility rooms, garages, and other areas where humidity or occasional moisture is possible. | Dry indoor areas are generally less demanding. Moisture exposure can cause dimensional change, swelling, or loss of strength, especially at unsealed cut edges. |
| 7 | Load, safety, and appearance | Estimate the stored load, distribute heavy items, and verify the support hardware. Choose 22–25 mm when a shelf must look more substantial or carry heavier, frequently used contents. | Do not rely on thickness alone for a safe load rating. Actual capacity depends on material, span, depth, support spacing, fasteners, load distribution, and the allowable deflection specified for the project. |