Combination screw

Claim 2

A fastener unit for use in metal building construction comprising a screw in combination with a compressible sealing washer, the screw including a head, threaded shank and entering point, the threaded shank having a first portion of threads with a uniform crest diameter, a second portion of threads having a crest diameter greater than the crest diameter of the first portion, the second portion leading into the first portion to present a continuous set of thread convolutions on the shank, the second portion of threads extending downwardly from a clamping surface on the head for a limited axial extent, the axial extent of the second portion generally not exceeding the uncompressed axial extent of the sealing washer, whereby the fastener can be used to fasten two relatively thin sheets of material by pulling the sheets Up the axis of the shank onto the threads of the second portion, while also being capable of attaching a thin sheet of material to a thicker piece of material without substantial resistance between the fastener and the thicker piece of material.

Claim 3

A fastener unit as set forth in claim 1 wherein the first and second portion of threads have different root diameters and a constant helix angle.

Claim 4

A fastener unit as set forth in claim 1 wherein the second portion of threads has a crest diameter at least 10 percent greater than the crest diameter of the first portion.

Claim 5

A fastener unit as set forth in claim 1 wherein the first and second thread portions have the same thread angle.

Claim 6

A fastener unit as set forth in claim 1 wherein the first and second thread portions have different thread angles.

Claim 7

A fastener unit as set forth in claim 1 wherein the axial extent of the second portion is substantially equal to the uncompressed axial extent of the associated sealing washer.

Claim 8

A fastener unit comprising a screw having a head with a clamping face thereunder and a threaded shank portion, a compressible sealing washer operatively associated with the screw underneath the clamping face, the threaded shank portion including an upper and lower axial portion of threads, the upper portion of threads leading into the lower portion thereby forming continuous thread convolutions throughout the threaded shank portion, the lower portion having a substantially uniform crest diameter, the upper portion having a crest diameter greater than the crest diameter of the lower portion and having an axial extent greater than the axial extent of the compressed sealing washer but not substantially exceeding the axial extent of the uncompressed sealing washer whereby the fastener unit is adapted to either fasten a pair of relatively thin sheets of material or fasten a thin sheet of material to a thicker piece of construction material while retaining a high degree of sealing between the unit and the materials to be fastened.

Claim 9

A fastener unit comprising a screw having a head with a clamping face thereunder and a threaded shank portion, a compressible sealing washer operatively associated with the screw underneath the clamping face, the threaded shank portion including an upper and lower axial portion of threads, the upper portion of threads leading into the lower portion thereby forming continuous thread convolutions throughout the threaded shank portion, the lower portion having a substantially uniform crest diameter, the upper portion having a crest diameter greater than the crest diameter of the lower portion and having an axial extent greater than the axial extent of the compressed sealing washer but not substantially exceeding the axial extent of the uncompressed sealing washer whereby the fastener unit is adapted to either fasten a pair of relatively thin sheets of material or fasten a thin sheet of material to a thicker piece of construction material while retaining a high degree of sealing between the unit and the materials to be fastened.

Claim 10

A fastener unit as set forth in claim 7 wherein the axial extent of the upper portion is approximately equal to the uncompressed axial extent of the sealing washer.

Claim 11

In a metal building construction section, the combination comprising a threaded fastener having a shank and a head with a clamping surface thereunder, a compressible sealing washer located beneath the clamping surface, at least one workpiece of relatively thin material, the shank of the fastener having axially upper and lower threaded portions forming a continuous thread convolution, the lower portion of threads having a uniform crest diameter, the upper portion of threads having a larger crest diameter than said lower portion, the axial length of the upper portion being greater than the compressed height of the sealing washer but not substantially exceeding the uncompressed height of the sealing washer, whereby the fastener is driven through the workpiece to such an extent as to compress the washer while the upper portion of threads contacts and extrudes the workpiece upwardly toward the clamping surface in such a manner as to further compress the inner peripheral portion of the sealing washer thus enhancing the sealing characteristics of the building section.

Claim 12

In a metal building construction section, the combination comprising a threaded fastener having a shank and a head with a clamping surface thereunder, a compressible sealing washer located beneath the clamping surface, at least one workpiece of relatively thin material, the shank of the fastener having axially upper and lower threaded portions forming a continuous thread convolution, the lower portion of threads having a uniform crest diameter, the upper portion of threads having a larger crest diameter than said lower portion, the axial length of the upper portion being greater than the compressed height of the sealing washer but not substantially exceeding the uncompressed height of the sealing washer, whereby the fastener is driven through the workpiece to such an extent as to compress the washer while the upper portion of threads contacts and extrudes the workpiece upwardly toward the clamping surface in such a manner as to further compress the inner peripheral portion of the sealing washer thus enhancing the sealing characteristics of the building section.

Claim 13

A building section as set forth in claim 8 which includes a relatively rigid structural member positioned behind the relatively thin material in such a manner as to retain a closely juxtaposed position thereto thus enabling the section to be tightly sealed upon the tightening of the threaded fastener.

Claim 14

A building section as set forth in claim 8 which includes a second workpiece of relatively thin sheet material immediately beneath the first workpiece, said second workpiece being extruded up onto the upper portion of threads upon tightening the fastener to such an extent as to compress the sealing washer, the second workpiece thereby placing additional axial stress on the undersurface of the first workpiecE and the inner periphery of the sealing washer thus increasing the sealing characteristics of the building section.