The pattern of brick courses or layers is a good indicator of whether a wall is veneer or solid. Solid walls have two parallel layers, with alternating layers of bricks laid across them to tie the two sections together. That means some bricks will have 2-inch ends showing rather than 8-inch long sides. Any brick wall that has end bricks every two or three courses is solid, because those bricks are connecting the two sides of the wall.
Brick veneer walls can be made to resemble solid walls, but this requires cutting a lot of bricks in half, so one course has bricks laid with 8-inch sides showing, the next course has brick ends, but extends only the 4-inch width of the full brick. Brick veneer can be installed over basic walls of concrete, concrete block or traditional wood framing, with 16-inch spaced studs and wood sheathing. It is fastened to wood sheathing with metal lath, which holds mortar to join the brick and metal.
Solid brick walls require a deep and strong foundation of concrete, poured at least 16 inches wide and to a depth below the frost line, or the area where the ground freezes in winter. A solid brick wall will be at least 8 inches thick; some are much thicker, with a center gap that is filled with concrete to make the wall even stronger. Any interior insulation must be added inside that wall, so a finished solid brick wall may be a foot or more thick.
Veneer also must be secured with a concrete base, but typically only 4 inches wide and usually poured as part of the basic house foundation. Brick veneer is only 4 inches wide; wall sheathing and framing studs typically add another 4 inches or so. Insulation is installed between the interior studs, making the brick veneer wall sturdy, attractive and more comfortable.
Both solid and veneer brick walls are installed with mortar--a mixture of cement, sand and water--which is more subject to water seepage than the solid bricks. This often is a problem with solid walls as moisture percolates through the mortar joints and can create dampness inside the brick wall. Brick veneer is installed over a moisture barrier, like house wrap, and is less subject to seepage penetrating the wall.