Through Fastening - Plexiglas may be easily attached to other surfaces using
round head wood screws, round head bolts, sheet metal screws, oval head screws
or bolts used in conjunction with finishing washers, and threaded rod used with
cap (Acorn) nuts. Flat head screws, bolts and other fasteners which require
countersinking should not be used, because a countersunk hole is almost the
same as a notch and a potential fracture point. The countersunk fastener also
does not provide freedom of movement for expansion and contraction. Holes for
fasteners should be drilled oversized to allow for thermal movement of the
Plexiglas. Remember, acrylic and metal have different expansion rates. Always,
use a Plexiglas Drill Bit or regrind your steel bit to a 60 degree included tip
angle. A minimum oversize for each drilled hole is recommended in the table
below in accordance with the size of the Plexiglas part and the temperature
range to which the part is exposed:
OVERSIZE HOLE RECOMMENDATIONS FOR THROUGH-BOLTING PLEXIGLAS
Degree of Size of Temperature Change for Plexiglas
10 15 20 30 40 50 60
12" 1/16 1/16 1/16 1/16 1/16 1/8 1/8
24" 1/16 1/16 1/16 1/16 1/8 1/8 1/8
36" 1/16 1/16 1/16 3/8 1/8 3/16 1/4
48" 1/16 1/16 1/8 1/8 3/16 1/4 1/4
60" 1/16 1/16 1/8 1/8 1/4 1/4 3/8
72" 1/16 1/8 1/8 1/8 1/4 5/16 3/8
84" 1/8 1/8 3/16 3/16 5/16 5/16 1/2
96" 1/8 1/8 3/16 1/4 5/16 3/8 1/2
Whenever possible locate holes to provide at least 1/4" of material from edge
of hole to edge of Plexiglas sheet. If possible smooth inside of hole by
wrapping 320 grit wet or dry sand paper around a wood dowel and sanding until
smooth. Bring fastener up snug and then back off 1/4 turn, again to provide for
natural movement of the material as it expands and contracts. Again, the types
of recommended fasteners: round head screws or bolts, oval head screws or bolts
used in conjunction with finishing washers, and threaded rod used with cap
(Acorn) nuts
SKYLIGHTS & PATIO WINDBREAK FENCING
1. Always use 1/4" thickness of Plexiglas for all skylight applications.
Thinner grades will deflect due to gravity and may cause water puddles to
collect. When covering lath type structures with shading type framework,
thinner grades of Plexiglas may be used, but are not recommended.
Through-fastening is not advised but with proper drilling techniques with
oversize holes and Plexiglas bits, it can be used satisfactorily.
2. With patio wind break fencing spans of more than 2' x 4' must 1/4" Plexiglas
due to wind load deflection. Spans of more than 4' should have a top cap of
wood to enclose the upper portion of the Plexiglas panel. This may be left off,
but the top of the Plexiglas panel will have a slight curvature. Be sure to
allow for this movement in the framing. Patio glazing must be framed in other
wood or metal channel frames.