Self aligning three dimensional support structure for a roof constructed with prefabricated components

Abstract

The invention provides a method for easy prefabrication of a self aligning three dimensional roof support and roof structure, such as a dormer or porch roof, which is fully constructed of sheet goods with tab and slot interconnecting components. The roof support structure is constructed of a parallel aligned space series of substantially rigid sheet truss members and a parallel aligned space series of substantially rigid purlin members running perpendicular to the truss members and interlocked with the truss members with opposing interlocking slots to form a self- aligning three dimensional support structure whereby the flush upper sheet ends provide support for roof sheathing. The roof sheathing and additional side fascia members are fit to the substructure with inter-engaging tabs and slots.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages hereinafter in the following description and claims. The accompanying drawings show, for the purpose of exemplification, without limiting the scope of the invention or the appended claims, certain practical embodiments of the present invention wherein:

FIG. 1 is a perspective view of a fully assembled and installed porch constructed in accordance with the teachings of the present invention;

FIG. 2 is an isometric diagrammatic view of a porch roof of the type illustrated in FIG. 1 indicating the input variable dimensions utilized to construct the components with the use of a CNC router machine and computer spread sheets;

FIGS. 3 a and 3b are computer diagrammatic layout sheet drawings representing the plan view of all framing components to be cut out by a CNC router machine for subsequently assembling the subassembly of the self aligning three dimensional support structure of the present invention;

FIGS. 4 a and 4b are computer diagrammatic layout sheet drawings illustrating in plan view all of the finish trim parts or components for the prefabricated roof structure of the present invention;

FIG. 5 is a perspective view of the subassembly of the support structure of the present invention without the application of the roof sheathing; and

FIG. 6 is an enlarged plan view of one end of a truss member utilized in the construction of the support structure of the present invention illustrating the detail of the tab and slot construction created in the sheet goods through the use of a CNC router machine for permitting accurate and close fit of the tab and slot interlocking engagement between the sheet goods.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

A completed embodiment of a porch roof structure manufactured with tab and slot self aligning three dimensional construction in accordance with the teachings of this present invention is illustrated in FIG. 1. In this example a porch roof structure 10 is illustrated at the front entrance of a building 11 and is supported with columns 12. While a porch roof is here illustrated, the principals of the present invention are equally applicable to the construction of a dormer.

The porch roof structure 10 is constructed fully of sheet goods, such as plywood, for the subassembly and weather impervious PVC sheet goods for the exposed trim, by the utilization of a CNC router machine and the use of computer spread sheets for the variables. As is illustrated in FIG. 2, the only variables which need to be inserted into the CNC machine are the dimension A for projection, the dimension B for width between beams and the dimension C for height from ridge to soffit. If an arch is also incorporated as illustrated in FIG. 2, then the dimension D for arch height is also inserted into the CNC machine.

The CNC machine then automatically cuts all the sheet components for the sub-framing or subassembly as illustrated in FIGS. 3a and 3b.

The subassembly framing is all constructed of sheet goods, such as plywood, and includes three to five truss members depending upon the projection dimension A, two sub-rake members 14, two roof sheathing members 15, two sub-fascia members 16, two sub-beam side members 17 and seven purlin members 18. Each of these members is cut by the CNC machine with protruding tabs 20 and with corresponding receiving slots 21 which do not change in size throughout the entire sub framing.

The key shown in FIGS. 3a and 3b designates the dimensions F which are fixed and the dimensions V which are variable, as determined by the input dimensions illustrated in FIG. 2. CL indicates center line.

Because a router bit does not cut square corners, but instead cuts round corners, the CNC router is programmed to cut all inside corners of tabs and slots open so that there is a complete inter fit between all tabs 20 and slots 21 as is illustrated in FIG. 6. For example with regard to the tabs 20, the inside corners 22 are extended by the router as are the inside corners 23 of slots 21 so that all tabs 20 will fully seat within corresponding slots 21.

The subassembly 24 of all the framing components illustrated in FIGS. 3a and 3b are assembled with the tab and slot assembly as illustrated in FIG. 5. The roof sheathing 15 is not applied to the subassembly 24 as shown in FIG. 5 to provide a clear view of the self aligning three dimensional interior features of the support structure. The tab and slot joints may be further secured with wood glue, hot glue or fasteners (brads or staples) as desired. The assembled parts substantially hold themselves together which provides for little clamping and requires no extra hands for assembly.

The utilization of laminated plywood of one sheet size to do all structural components minimizes the quantity of material required to be maintained in stock.

Turning next to FIGS. 4a and 4b, the finished trim parts are also manufactured of sheet goods. However, in this instance the sheet goods are preferably impervious to weather, such as PVC sheet goods. These trim components are also cut out through the use of a CNC machine and include two finish fascia members 24, two finish beam side members 25, two box return members 26, two rake soffit members 27, two finish soffit members 28, one gable face member 29, one gable rake member 30.

Some of these members are also provided with dados 31 as a decorative feature. When all members are assembled, the complete porch roof product appears as illustrated in FIG. 1. Additional trim features, such as moldings and corbels, may be added as desired to further dress the roof structure.

In the event that the porch roof or dormer is wider than standard sheet goods, two pieces of sheet goods may be engaged and interlocked with each other to provide a longer continuous piece for fabrication of the subassembly components of the present invention. For example, two sheets of plywood may be joined with an interlocking seam as by dovetail or bow tie jointing and thereafter applying a gusset to the joint thereby providing doubling of the basic sheet size to be incorporated into the structure. This principal may also be taken advantage of for the purposes of shipping, thereby maintaining the largest product to be no larger than a standard size sheet of plywood.

The exterior finish parts are components as illustrated in FIGS. 4a and 4b which also may be cut out by a CNC router machine. The finish parts fit together in more of a tongue and groove arrangement thereby providing the advantage of a furniture-like joint for easy assembly with forgiveness to the assembler.

The ceiling portion of the porch structure 10 can be protected with wood boards or paneling which provides an authentic tongue and groove bead board look or the like to close it in and provide an authentic finished appearance.

Claims

1. A prefabricated self aligning three dimensional support structure for a roof, such as a dormer or a porch roof, the support structure comprising: a parallel aligned spaced series of substantially rigid sheet truss members;a parallel aligned spaced series of substantially rigid sheet purlin members running perpendicular to said truss members and interlocked with said truss members with opposing inter-engaging slots to form a self aligning three dimensioned support structure with flush upper sheet edges for supporting roof sheathing.

2. The support structure of claim 1, including substantially rigid sheet end truss members inter-engaged at right angles with opposite ends of said purlin members with intermeshing tabs and slots.

3. The support structure of claim 2, including substantially rigid sheet fascia members inter-engage at right angles with opposite ends of said truss members with intermeshing tabs and slots.

4. The support structure of claim 3, including substantially rigid roof sheathing covering and inter-engaging upper edges of said members with intermeshing tabs and slots.

5. The support structure of claim 4, wherein upper edges of said truss members form a center ridge peak.

6. The support structure of claim 4, wherein selected exterior exposed surfaces of said structure are covered with weather impervious sheet material.

7. The support structure of claim 4, wherein selected inter-engaging connections between said members, and between said members and said sheathing, are secured with fasteners or glue.

8. The support structure of claim 4, wherein said members and said sheathing are cut to appropriate size, shape and dimension with a preprogrammed CNC router programmed whereby a minimum of only projection, width and height to ridge dimensions need be input into said CNC router to provide production of all the prefabricated parts, with slots and tabs as required, for assembly of the structure.

9. The support structure of claim 4, wherein said substantially rigid sheet members are comprised of plywood.

10. The support structure of claim 9, wherein said sheathing is comprised of plywood.