A multiple support wall structure according to the present invention includes: a pair of top and bottom support plates that has a plurality of rectangular projective islands separated by lattice-shaped projections protruding in the shape of a go board, and protruding upward in the opposite direction to the lattice-shaped projections; and a intermediate reinforcing plate that is disposed between the top and bottom support plates, has upward projective insertions protruding in a shape corresponding to the rectangular islands to be fitted in the rectangular islands of the top support plate, has top grooves formed laterally and longitudinally between the upward projective insertions to fit the lattice-shaped projections, has downward projective insertions formed in the same shape as but in the opposite direction to the upward projective insertions in spaces diagonally adjacent to the upward projective insertions, and has bottom grooves formed laterally and longitudinally between the downward projective insertions.

A structural panel includes a core and first and second facing sheets. The core has bonding surfaces on first and second, opposite sides thereof. The first facing sheet is a non-thermoplastic, fire retardant facing sheet having an inner surface bonded to the bonding surface on the first side. The second facing sheet is bonded to the bonding surface on the second side. The first facing sheet is fire retardant or non-flammable and the core is at least fire retardant. The structural panel finds particular utility as a building-cladding panel.

A multiple support wall structure according to the present invention includes: a pair of top and bottom support plates that has a plurality of rectangular projective islands separated by lattice-shaped projections protruding in the shape of a go board, and protruding upward in the opposite direction to the lattice-shaped projections; and a intermediate reinforcing plate that is disposed between the top and bottom support plates, has upward projective insertions protruding in a shape corresponding to the rectangular islands to be fitted in the rectangular islands of the top support plate, has top grooves formed laterally and longitudinally between the upward projective insertions to fit the lattice-shaped projections, has downward projective insertions formed in the same shape as but in the opposite direction to the upward projective insertions in spaces diagonally adjacent to the upward projective insertions, and has bottom grooves formed laterally and longitudinally between the downward projective insertions.

A multiple support wall structure according to the present invention includes: a pair of top and bottom support plates that has a plurality of rectangular projective islands separated by lattice-shaped projections protruding in the shape of a go board, and protruding upward in the opposite direction to the lattice-shaped projections; and a intermediate reinforcing plate that is disposed between the top and bottom support plates, has upward projective insertions protruding in a shape corresponding to the rectangular islands to be fitted in the rectangular islands of the top support plate, has top grooves formed laterally and longitudinally between the upward projective insertions to fit the lattice-shaped projections, has downward projective insertions formed in the same shape as but in the opposite direction to the upward projective insertions in spaces diagonally adjacent to the upward projective insertions, and has bottom grooves formed laterally and longitudinally between the downward projective insertions.

A structural panel includes a core and first and second facing sheets. The core has bonding surfaces on first and second, opposite sides thereof. The first facing sheet is a non-thermoplastic, fire retardant facing sheet having an inner surface bonded to the bonding surface on the first side. The second facing sheet is bonded to the bonding surface on the second side. The first facing sheet is fire retardant or non-flammable and the core is at least fire retardant. The structural panel finds particular utility as a building-cladding panel.

A multiple support wall structure according to the present invention includes: a pair of top and bottom support plates that has a plurality of rectangular projective islands separated by lattice-shaped projections protruding in the shape of a go board, and protruding upward in the opposite direction to the lattice-shaped projections; and a intermediate reinforcing plate that is disposed between the top and bottom support plates, has upward projective insertions protruding in a shape corresponding to the rectangular islands to be fitted in the rectangular islands of the top support plate, has top grooves formed laterally and longitudinally between the upward projective insertions to fit the lattice-shaped projections, has downward projective insertions formed in the same shape as but in the opposite direction to the upward projective insertions in spaces diagonally adjacent to the upward projective insertions, and has bottom grooves formed laterally and longitudinally between the downward projective insertions.