Medium-density fibreboard and hardboard, also called high-density fiberboard, are stronger and denser than particleboard. Cork, plywood, hardboard, drywall, and foam insulation are common alternatives to Homasote. Interior lining could be horizontal corrugated iron or material like hardboard attached to the ribs. The floors had 2 layers of flameproof hardboard, covered with linoleum. Tempered hardboard is used in construction siding. Perforated hardboard is tempered hardboard which is pre-drilled with evenly spaced holes. Unlike solid wood, hardboard is very homogeneous with no grain. The exterior was clad with chamferboards and interior lined with hardboard sheeting. Internal partitioning consisted of timber frames with hardboard lining. Scratchboard itself comes either with a paper (cardboard) backing, or a hardboard support. Perforated hardboard and similar systems are designed to support peg hooks. Numerous materials can be used, such as wood, plastic, resin, and hardboard. Then it is pasted on a flat panel hardboard sheet. Alpena has a hardboard manufacturing facility owned by Decorative Panels, International. Other sheet products are hardboard, softboard and ply.