A building component comprising first and second high density foam panels 312, 314 each having inner 318, 330 and outer 320, 332 surfaces, top 334 and bottom 336, and first 326, 338 and second 328, 340 ends, said panels arranged in spaced parallel relationship with their inner 318, 330 surfaces facing each other; and at least two bridging members 342 extending between and connecting said panels, comprising at at least one end of and integral with said first and second panels 312, 314, a first end part 344, 346 protruding longitudinally from a part of said at least one end 326, 338; 328, 340 of said panels, said end part 346, 344 having mating means for mating with a complementary end part 346, 344 on a second said component, such that the longitudinal direction of said component is at an angle to the longitudinal direction of said second component; and wherein, in use, said spaced relationship is maintained uninterrupted through said component and said second component and said end parts.