There are two types of hollow terra-cotta blocks, one which builds with
cells vertically and the other which builds with cells horizontally.
This latter is generally an interlocking tile. The strongest wall for
vertical-load resistance is built with vertical-cell tiles.
[Illustration: 20. Support of floor-joists 18. 12" Hollow-tile wall
Cells Horizontal]
All hollow-tile should be laid in Portland-cement mortar, and the webs
should be arranged so that they build over one another. The bearing of
floor beams and girders on walls, built with blocks of vertical cells,
should be made by covering the tile with templates of terra-cotta
slabs, filling them with concrete or protecting them with plates of
steel. Where chases are required for pipes they should not be cut into
the wall, but special blocks should be used to build around them. All
lintels under 5 feet should be constructed with tile arches, reinforced
with concrete and steel rods inside of their webs.
[Illustration: 17. Vertical cell Hollow-tile wall]