Siding panel with interlock

a siding panel is provided for attachment to a structure and connection to a similar overlapping siding panel in interlocking relationship. The panel includes a strip for attachment, such as by nailing, to a supporting structure, a receiver formed by outer and inner bends, at least one stretch extending away from the strip and presenting a gap between the outer bend and the stretch, a base and a projection, all extending the length of the panel. The projection is configured to interfit with a receiver of an adjacent panel, with the projection including a flange, a return bend and a cantilever leg. The projection snap fits into the receiver, with the cantilever leg deflecting as the return bend flexes to permit passage of the projection into the receiver.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates generally to a panel with an elongated, normally 
horizontal interlock useful for holding overlapping panels in engagement 
and presenting a pleasing ornamental appearance. More particularly, it is 
concerned with a panel having an improved interlock structure which 
provides improved attachment, increased durability, and greater rigidity 
to the panel. 
2. Description of the Prior Art 
Vinyl and metal siding is used to provide a decorative and protective 
sheathing over buildings. The siding is typically nailed to the underlying 
structure, with successive overlapping courses of siding panels nailed to 
the building walls. Most typically, the siding presents the appearance of 
clapboards in lapping arrangement which provides a decorative appearance 
and sheds rain or other moisture. 
It is desirable to provide an interlock structure to connect adjacent 
overlapping siding panels. A decorative siding interlock panel is shown in 
U.S. Design Pat. No. 382,351, which provides a panel which includes an 
interlock but hides the interlock from the view of an observer when 
applied to a building. While this siding panel design has ornamental 
advantages, it is believed that structural improvements would enhance the 
performance of the panel in use. 
Thus, there has developed a need for a siding panel which is not only 
attractive, but also provides improved rigidity, durability, and 
interlocking performance. 
SUMMARY OF THE INVENTION 
These objects have largely been solved by the siding panel of the present 
invention. That is to say, the siding panel hereof retains the attractive 
appearance of the prior art panel, but yields improved performance and 
resists damage during installation by providing a superior interlock 
design. 
The siding panel hereof is preferably formed as an elongated panel 
presenting a nailing strip along the top with a receiver positioned just 
below the nailing strip in normal orientation. The receiver is configured 
to present a recess formed by bending the panel to project forwardly of 
the surface of the underlying structure and then returning in a pair of 
lower and upper bends forming a serpentine loop. A stretch portion of the 
panel projects downwardly and adjacent the surface of the underlying 
structure from the serpentine loop. One or more stretches extend 
downwardly to the bottom of the panel, which is provided with a projection 
for insertion in snap-fitting relationship with the receiver. The 
projection is formed by bending the panel inwardly toward the structure 
from the lowermost stretch, providing a second bend extending normally 
upwardly, and a third or return bend forming a hairpin with the free leg 
oriented normally downwardly and away from the top of the panel. 
The projection preferably has a greater transverse dimension than the 
clearance between the lower bend and the stretch portion of the panel 
located above and adjacent thereto, so that an interference fitting is 
created. As a result, a positive and audible "snap" sound is created when 
the projection moves past the clearance into the receiver. Moreover, the 
free leg serves to bias the projection against the receiver of the next 
upper panel, to enhance the holding power of the connection. Because of 
this holding relationship, as the panel forming a part of an adjacent and 
upper course has its projection inserted into the receiver of the lower 
panel already nailed in place, the installer may use the interlock thereby 
created to hold the panel in position while retrieving a level, hammer or 
other tool before nailing the upper panel in place. This greatly 
facilitates the installation of the panels and reduces labor. Moreover, 
the configuration of the interlock permits easy disconnection between 
adjacent panels by simply pulling downwardly on the uppermost panel to 
release the connection. As an added benefit, the improved panel 
configuration has been found to provide substantial improvements in 
rigidity in resisting deflection of the panel, wherein testing has 
revealed improvements of up to 40% for 12 foot length panels. In addition, 
the rounded edge of the projection is less likely to catch or bind during 
insertion into the receiver, and less likely to break since the free edge, 
which typically thins out during manufacturing, is oriented away from the 
direction of insertion. 
As a result, a superior panel is provided which provides both qualitative 
and quantitative levels of improvement over prior art panels. The benefits 
noted above and other improvements will be readily apparent to those 
skilled in the art with reference to the drawings and the attached 
description.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawing, a siding panel 10 in accordance with the 
present invention is preferably manufactured as single elongated article 
from a unitary sheet of synthetic resin such as polyvinyl chloride. One 
preferred technique is extruding the panel 10 which is shaped by passing 
through dies to achieve the desired configuration. The panel presents a 
front side 12 which may be embossed with a pattern such as simulated 
woodgrain and a back side 14 which typically lacks such embossing. Broadly 
speaking, the panel presents a nailing strip 16, a receiver 18, at least 
one and preferably a plurality of stretches 20 and 22, and a base 24 
having a projection 26. The panel 10 hereof is described in its typical 
generally horizontal orientation as shown in FIG. 1, but may also be 
oriented vertically or at other angles as desired. 
The nailing strip 16 is positioned uppermost on the panel 10 and includes a 
substantially flat span extending downwardly from edge 28, the strip 16 
presenting a plurality of perforations 30 therein. The perforations 30 are 
typically elongated horizontally to permit expansion and contraction along 
the length of the panel 10 due to changes in temperature. The receiver 18 
is positioned just below the nailing strip 16 to allow adjacent panels 10A 
and 10B to overlap as shown in FIGS. 3 and 4, thereby aiding in shedding 
precipitation. The receiver 18 includes a forward bend 32 to provide space 
for folding of the panel 10 to receive a projection 26 of an adjacent 
panel, and a curved face 34 which combine to present an ornamentally 
pleasing configuration. The curved face 34 extends normally downwardly to 
an outer hairpin bend 36 which routes the following arc segment 38 
upwardly and toward the nailing strip 16 as shown in FIG. 2. The outer 
hairpin bend 36 includes an inner edge 40. Arc segment 38 continues in a 
curved presentation to inner bend 42 which ends in first stretch 20. A 
serpentine loop 44 is presented by outer hairpin bend 36, arc segment 38 
and inner bend 42, with a recess 46 presented thereby. A gap G between 
inner edge 40 and first stretch 20 has a reduced transverse dimension 
which is smaller than the transverse dimension of the widest dimension R 
within the recess 46. 
The first stretch 20 continues downwardly toward the base 24. A second 
stretch 22 is normally located below the first stretch 20, and is 
staggered below the first stretch by a lap 50. Stretches 20 and 22 are 
shown in a conventional straight clapboard presentation, but may be 
provided in other well-known presentations such as dutch lap or ship lap 
stylings. Lap 50 is intended to present the appearance of clapboard wood 
siding and includes a nose 52, a shelf 54 and a trough 56. Base 24 is 
positioned at the bottom of second stretch 22, and configured to be 
similar in appearance to lap 50 when panels 10A and 10B are interlocked 
and viewed facing the front side 12. 
The base 24 includes an elbow 58 and a rearwardly projecting base leg 60. 
Crook-shaped projection 26 extends upwardly toward nailing strip 16 from 
the base curve 62 at the rear portion of base leg 60. The projection 26 
includes a flange 64 and a cantilever leg 66 which is oriented opposite 
the flange 64 and joined thereto by a return bend 68. Return bend 68 
causes the angle between the flange 64 exiting the base curve 62 and the 
tip 70 at the end of cantilever leg 66 to be more than 90 degrees, and 
preferably more than 180 degrees. The flange 64 is curved at its upper end 
72 adjacent return bend 68, causing projection 26 and base curve 62 to 
have a serpentine appearance. 
The configuration of projection 26 and receiver 18 is complemental to 
permit interlocking of overlapping panels 10A and 10B as illustrated in 
FIGS. 3 and 4, where the panel 10A is shown fixed to a supporting 
structure 74 such as a building by nails 76 inserted through projections 
30 and pounded into the structure 74. In FIG. 3, the projection 26 of the 
upper panel 10B is shown moving upwardly just prior to locking into the 
receiver 18 of lower panel 10A. The cantilever leg 66 is flexing toward 
flange 64 to permit the projection 26 to move past gap G. The unflexed 
transverse dimension P of projection 26 is normally greater than the 
dimension G of gap, but by flexing the return bend 68 and the bending of 
cantilever leg 66 toward the flange 64, the projection 26 is able to slide 
into the recess 46 in receiver 18 as shown in FIG. 4. The curved upper end 
72 of flange 64 facilitates the movement of projection 26 pasts gap 48, 
and because return bend 68 presents an outside convex surface 78 and is 
located uppermost on the projection 26 as it moves into receiver 18, entry 
of the projection is facilitated and not hindered by any sharp edge. 
Further, the tendency of the tip 70 to thin out as it leaves the mold is 
of less importance as the return bend 68 enters the recess 46 first and 
thereby acts as a leading edge effectively protecting the tip 70 at the 
trailing end of the projection. 
After entry of the projection 26 into the recess 46 in interlocking 
relationship as shown in FIG. 4, the cantilever leg 66 flexes back to its 
original position to further facilitate a good interlocking relationship. 
Cantilever leg of uppermost panel 10B provides a biasing force away from 
the first stretch 20 of panel 10A and thus serves to restore the unflexed 
transverse dimension P and thus resist downward movement of the panel 10B 
out of interlocking engagement with panel 10A. This permits the installer 
to let go of the upper panel 10B temporarily while it remains attached to 
the lower panel 10A. The strip 16, receiver 18, stretches 20 and 22, base 
24 and projection 26 extend substantially the length of the panel 10, 
which are typically available in elongated lengths of twelve feet, sixteen 
feet or even longer. 
It may thus be seen that without materially changing the outward appearance 
from that shown in U.S. Design Pat. No. 382,351, a superior panel 10 is 
provided with improved rigidity, interlocking, and protection during 
connection.