13–11 LAMINATED BEAMS
AND ARCHES
Laminated structural members are pieces of lumber glued
under controlled temperature and pressure conditions. The
glue used may be either interior or exterior. They may be
rectangular beams or curved arches, such as parabolic, bow-
string, V, or A (Figure 13.58). The wood used includes Dou-
glas fir, southern pine, birch, maple, and redwood. Spans just
over 300 feet have been built by using laminated arches in a
cross vault. They are generally available in three grades:
industrial appearance, architectural appearance, and pre-
mium appearance grades. The specifications should be care-
fully checked so that the proper grade is used. They are also
available prefinished.
Specifications. Check for quality control requirements,
types of adhesives, hardware, appearance grade, finish, pro-
tection, preservative, and erection requirements.
Estimating. The cost of materials will have to come
from the manufacturer or supplier, but the estimator per-
forms the takeoff. The takeoff should list the linear footage
required for each type and the size or style of beam or arch.
Note also the type of wood, appearance grade, and finish-
ing requirements. If the laminated shapes are not prefin-
ished, be certain that finishing is covered somewhere in the
specifications.
If the laminated beams and arches are to be installed by
the general contractor, consider who will deliver the material
to the site, how it will be unloaded, where it will be stored,
and how much equipment and how many workers will be
required to erect the shapes. Erection time varies with the
complexity of the project. In a simple erection job, beams
may be set at the rate of six to eight lengths per hour, while
large, more complex jobs may require four hours or more for
a single arch. Carefully check the fastening details required—
the total length of each piece, how pieces will be braced dur-
ing construction, and whether an arch is one piece or
segmental.13–12 Wood Decking
Wood decking is available as a solid-timber decking, plank
decking, and laminated decking. Solid-timber decking is
available either in natural finish or prefinished; the most
common sizes are 2 6, 3 6, and 4 6. The most com-
monly used woods for decking are southern pine, western
red cedar, inland white fir, western white spruce, and
redwood.
Plank decking is tongue-and-groove decking fabricated
into panels. The most common panel size is 21 inches wide;
lengths are up to 24 feet. Installation costs are reduced by
using this type of deck. Note wood species, finish, size
required, and appearance grade.172 CHAPTER THIRTEEN
FIGURE 13.58.Typical Laminated Shapes.