This standard outlines the specifications for wooden flush door shutters with cellular and hollow cores faced with plywood. It details the materials, construction methods, dimensions, workmanship standards, and testing protocols to ensure the doors' durability and performance. It is primarily intended for professionals involved in the design, manufacture, and specification of plywood-faced flush doors in various building types.
Overview
This standard outlines the specifications for wooden flush door shutters with cellular and hollow cores faced with plywood. It details the materials, construction methods, dimensions, workmanship standards, and testing protocols to ensure the doors' durability and performance. It is primarily intended for professionals involved in the design, manufacture, and specification of plywood-faced flush doors in various building types.
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Contents
Structure
Frequently Asked
As per the code, timber species for the core should be selected from those listed in Appendix A, including durable hardwoods such as Sal, Teak, and Deodar. The door frame components must use hardwood with a minimum width of 75 mm, while battens inside the frame should be at least 25 mm wide, ensuring well-distributed voids not exceeding 500 cm² per segment. Particle boards utilized for cores must conform to IS 3087:1965, with phenol formaldehyde adhesives. This selection guarantees structural robustness and durability.
The standard plywood thickness for flush doors varies by core type: cellular core shutters require a minimum of 3 mm plywood, while hollow core shutters require at least 6 mm, except for 25 mm thick doors where 4 mm is permissible. Two-ply face skins, consisting of a cross-band and face veneer, are allowed for cellular cores with combined thickness of 4 mm or more. Veneer thickness ranges from 0.5 to 1.5 mm for commercial veneers and 0.5 to 1.0 mm for decorative veneers, ensuring appropriate durability and finish quality.
The adhesion test involves cutting two 150 mm by 150 mm samples from door corners and immersing them in boiling water at 100°C for 4 hours. After immersion, samples are dried at 27 ± 2°C with 65 ± 5% relative humidity for 24 hours. The specimens are then inspected for delamination along all plywood edges and glue lines. Acceptable criteria include no delamination at plywood glue lines and no individual delamination exceeding 50 mm in length and 3 mm in depth at assembly glue lines. Delamination at natural wood defects is disregarded. Passing both samples indicates satisfactory adhesion.
Decorative flush door shutters must use face veneers conforming to Grade 1 decorative plywood as per IS 1328-1970, with thickness between 0.5 mm and 1.0 mm. The plywood forming the face panels should be at least 3 mm thick for cellular cores and 6 mm for hollow cores (4 mm allowed for 25 mm thick doors). Two-ply face skins combining cross-band and face veneer are permitted for cellular core shutters with a combined thickness of at least 4 mm. All veneers must be pressure-glued on both faces of the core to ensure durability and aesthetic quality.
Sampling is determined by lot size according to Table 3. For lots between 26 to 50 units, 8 samples are taken with zero permissible defects; for 51 to 100 units, 13 samples with one permissible defect, and so forth up to lots larger than 500 units, where 80 samples are taken with two allowable defects. Lots with 25 or fewer units have mutually agreed sampling. Acceptance requires the number of defective shutters in the sample not to exceed the permissible number. Sub-samples are drawn for specific tests. Dimensional tolerances for width and height are ±8 mm, and thickness ±1.2 mm with uniformity variation not exceeding 0.8 mm.
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