Figure 6-6.—Wind block (parquet) laminated flooring.
anchored to the existing slab. Shims can be used, when
necessary, to provide a level base. Strips should be
spaced no more than 16 inches on center (OC). A good
waterproof or water-vapor resistant coating on the
concrete before the treated strips are installed is usually
recommended to aid in further reducing moisture
movement. A vapor barrier, such as a 4-mil polyethylene
or similar membrane, is then laid over the anchored
1- by 4-inch wood strips and a second set of 1 by 4s
nailed to the first. Use 1 1/2-inch-long nails spaced 12
to 16 inches apart in a staggered pattern. The moisture
content of these second members should be
approximately the same as that of the strip flooring to
be applied. Strip flooring can then be installed as
previously described.
When other types of finish floor, such as a resilient
tile, are used, plywood underpayment is placed over the
1 by 4s as a base.
WOOD BLOCK FLOORING
Wood block (parquet) flooring (fig. 6-6) is used to
produce a variety of elaborate designs formed by small
wood block units. A block unit consists of short lengths
of flooring, held together with glue, metal splines, or
other fasteners. Square and rectangular units are
produced. Generally, each block is laid with its grain at
right angles to the surrounding units.
Blocks, called laminated units, are produced by
gluing together several layers of wood. Unit blocks are
commonly produced in 3/4-inch thicknesses. Dimen-
sions (length and width) are in multiples of the widths
of the strips from which they are made. For example,
squares assembled from 2 1/4-inch strips are 6 3/4 by
6 3/4 inches, 9 by 9 inches, or 11 1/4 by 11 1/4 inches.
Wood block flooring is usually tongue and groove.
UNDERLAYMENT
Flooring materials, such as asphalt, vinyl, linoleum,
and rubber, usually reveal rough or irregular surfaces in
the flooring structure upon which they are laid.
Conventional subflooring does not provide a
satisfactory surface. An underpayment of plywood or
hardboard is required. On concrete floors, a special
mastic material is sometimes used when the existing
surface is not suitable as a base for the finish flooring.
An underpayment also prevents the finish flooring
materials from checking or cracking when slight
movements take place in a wood subfloor. When used
for carpeting and resilient materials, the underpayment
is usually installed as soon as wall and ceiling surfaces
are complete.
Hardboard and Particleboard
Hardboard and particleboard both meet the
requirements of an underpayment board. The standard
thickness for hardboard is 1/4 inch. Particleboard
thicknesses range from 1/4 to 3/4 inch.
This type of underpayment material will bridge
small cups, gaps, and cracks. Larger irregularities
should be repaired before the underlayment is applied.
High spots should be sanded down and low areas filled.
Panels should be unwrapped and placed separately
around the room for at least 24 hours before they are
installed. This equalizes the moisture content of the
panels before they are installed.
INSTALLATION.— To install hardboard or particle-
board, start atone corner and fasten each panel securely
before laying the next. Some manufacturers print a
nailing pattern on the face of the panel. Allow at least a
1/8- to 3/8-inch space next to a wall or any other vertical
surface for panel expansion.
Stagger the joints of the underpayment panel. The
direction of the continuous joints should be at right
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