Patent Application
20120159896
The present invention relates to a connection, in particular the connection between purlins and hip roof trusses, for hip roof construction. A hip roof, or hipped roof, is a type of roof where all sides slope downwards to the walls, usually with a fairly gentle slope. Thus it is a house with no gables or other vertical sides to the roof. A square hip roof is shaped like a pyramid. Hip roofs on rectangular houses will have two triangular sides and two trapezoidal ones. A hip roof on a rectangular plan has four faces. They are almost always at the same pitch or slope, which makes them symmetrical about the centerlines. Hip roofs have a consistent level fascia, meaning that a gutter can be fitted all around. Hip roofs often have dormer slanted sides.
Hip roofs are more difficult to construct than a gabled roof, requiring somewhat more complex systems of trusses. Although the roof itself is harder to construct, the walls that carry the roof are easier to build, being all one level. Hip roofs can be constructed on a wide variety of plan shapes. Each ridge is central over the rectangle of building below it. The triangular faces of the roof are called the hip ends, and they are bounded by the hips themselves. The hips sit on an external corner of the building and rise to the ridge. Where the building has an internal corner a valley makes the joint between the sloping surfaces. They have the advantage of giving a compact, solid appearance to a structure.
In modern domestic architecture, hip roofs have been seen to represent comfort, practicality, and solidness. They are thus commonly seen in bungalows and cottages, and have been integral to styles such as the American Foursquare. However, the hip roof has been used in many different styles of architecture and in a wide array of structures. A hip roof is self-bracing. It does not need the same amount of diagonal bracing (wind bracing) that a gable roof requires.
A hip roof is also ideal to have in hurricane regions. It holds up much better to high winds. In areas like Northern Australia, or the Gulf Coast of the Southeastern United States, that are subject to high wind loadings and strict construction codes this could be a factor in deciding which type of roof to build. If the slope of the roof from horizontal is 35 degrees or greater it will reduce/eliminate the airfoil effect of extreme high winds that blow over the roof and a hip roof is far less likely to peel off the house than a gable end roof. To this end, since 2001 the State of Florida has required insurance companies to offer a premium discount to customers who can prove they have a hip roof, which they do by obtaining a windstorm inspection. The hip roof also exhibits increased survivability in tornado winds and hurricanes. They are stable.
One advantage of a hip roof is that it has eaves all round. These protect the walls from the weather and help to shade the walls (and the windows in them) from the sun, thus reducing the power needed to cool the structure in warm climates. A gable roof does not shade the walls at the gables.
In architecture or structural engineering or building, a purlin is a generally horizontal structural member in a roof. Purlins support the loads from the roof deck or sheathing and are supported by the principal rafters and/or the building walls, steel beams etc. The use of purlins, as opposed to closely spaced rafters, is common in pre-engineered metal building systems and some timber frame construction.
In lightweight timber roof construction under purlins are used to support rafters over longer spans than the rafters alone could span. Under purlins are typically propped off internal walls. For example, an 8×4 under purlin would support the center of a row of 6×2 rafters that in turn would support 3×2 roof purlins to which the roof cladding was fixed.
In traditional timber truss construction purlins are supported by the principal rafters of the truss.
In all metal or mixed building roof systems, purlin members are frequently constructed from cold-formed steel, (or roll formed) C or Z sections. The Z sections can be lapped and nested at the supports which creates a continuous beam configuration between the bays. When C and Z sections are used in wall construction it is normal to call them girts.
The present invention replaces cut-to-size (and angle) purlins and temporary braces with permanent connectors that brace the connected structural members and permit sheathing to be applied directly thereover. The present invention provides a sloped surface for attaching the sheathing or decking of the roof in a convenient and efficient manner when stepped hip ridge trusses are used, without having to shape the top chords of the trusses to the particular slope of the roof or to cut individual purlins.
The present invention is a connection, preferably between step-down trusses in hip roof framing. The connection of the present invention is based on a structural purlin that also serves as an installation lateral restraint and spacer during the truss erection process. The connector attaches to the leading edge of step-down hip trusses, eliminating the need for drop-top chords, 2× lumber, gable end fillers or C-stud fillers. The interlocking design of the connectors allows them to install linearly, aligned with the end jacks, to maintain framing spacing from eave to hip or peak. Roof sheathing or decking attaches directly to the purlin with knurled pneumatic fasteners or low-profile head, self-drilling screws. Adjustable in length, the connector is designed to accommodate a pitch range of 3/12 to 9/12 as a structural purlin and up to 12/12 as an installation lateral restraint and spacer. The purlin accurately spaces the installed trusses and helps meet temporary top-chord lateral restraint recommendations on step-down hip ends.
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The first connector 6 comprises a first elongate component 110 that has a first elongate web 107 and a first elongate flange 108. The first elongate web 107 and the first elongate flange 108 are angularly joined along a first elongate juncture 109. Preferably, the connector 6 of the present invention is formed from sheet metal, specifically 33 mil (20 gauge) galvanized sheet steel, but it can be made from any suitable material such as cast aluminum. If the connector 6 is made from sheet metal, the junctures will be bends.
In the connection 1 of the present invention, the first connector 6 is attached to said lower structural member 2 and to the upper structural member 4. The attachments are preferably made with separate mechanical fasteners such as nails or screws, but they can be made in any suitable way such as with welds or adhesives.
The upper structural member 4, where the first connector 6 is attached, is elevated higher in the structure 100 than said lower structural member 2, where the first connector 6 is attached. In the most preferred embodiment, the connector 6 is attached to the top chords of two step-down hip trusses in a roof. The nature of step-down trusses is that the top chords in any pair are at different elevations in the building.
The first elongate web 107 of the connector 6 extends from the first lower juncture 102 in the first lower structural member 2 to the first upper juncture 105 in the upper structural member 4. In this manner, the connector 6, and any number of connectors 6, can be used to connect a pair of structural members, or any number of structural members, while presenting a planar surface that can accept sheathing without gaps or steps.
The first elongate web 107 extends from the first lower juncture 102 to the first upper juncture 105. The first elongate web 107 does not contact said first lower inner edge 103. Preferably, it also does not contact the first upper inner edge 106. In other words, the first elongate web 107 preferably angles away from the adjacent surfaces of the structural members. The first elongate web 107 runs between the upper outer edges of adjacent pairs of structural members.
The first elongate flange 108 does not pass through the lower structural member 2 and it also does not pass through the upper structural member 4. Preferably, the first elongate flange 108 tapers adjacent the structural members so that it does not make contact with either.
As shown in
The first elongate member 7 preferably has a first body portion 27 and the second elongate member 13 preferably has a second body portion 33. The two body portions are preferably in sliding or telescoping engagement with each other before being mutually connected and fixed, preferably with separate mechanical fasteners.
Preferably the first body portion 27 has a first web portion 28 with a first upper surface 8 and a first lower surface 9, a lower attachment end 10 and an upper end 11. The lower attachment end 10 includes a first angularly-adjustable lower tab 12. The first body portion has a first lower flange portion 29 that is angularly joined to the first web portion 28 along a first lower juncture portion 32 and has a first lower edge 37.
Preferably, the second body portion 33 has a second web portion 34 with a second upper surface 14 and a second lower surface 15, an upper attachment end 16 and a lower end 17. The upper attachment end 16 includes a first upper angularly-adjustable tab 18. The second body portion 33 has a first upper flange portion 35 that is angularly joined to the second web portion 34 along a first upper juncture portion 36 and has a first upper edge 38.
The first web portion 28 of the first body portion 27 and the second web portion 34 of the second body portion 33 are parts of the first elongate web 107. The first lower flange portion 29 and the first upper flange portion 35 are parts of the first elongate flange 108.
As shown in
The first upper edge 38 of the first upper flange portion 35 preferably tapers toward the upper juncture portion 36 proximate the first upper tab 18.
Preferably, the attachment end 10 of the first web portion 28 includes a second angularly-adjustable lower tab 12. The first and second lower tabs 12 preferably are joined to the first body portion 27 of the first elongate member 7 at first and second lower angular junctures 19. The first upper tab 18 is joined to the second body portion 33 of the second elongate member 13 at a first upper angular juncture 20. Preferably, the angular junctures can be field bent or adjusted to accommodate different pitches between the connected structural members. The first upper tab 18 is preferably attached with two #10 screws. Preferably, the first and second lower tabs 12 are each attached with one #10 self-drilling tapping screws when the structural members are cold-formed steel.
The first and second lower junctures 19 are preferably discontinuous. Preferably, the first upper tab 18 has a first width 21. The first and second lower tabs 12 are separated by a spacing 22 that is at least equal to the first width 21. Ideally, the first width 21 and the spacing 22 are almost identical, so that the upper tab 18 of one connector 6 fits exactly between the lower tabs 12 of the next, higher, connector 6, and connectors 6 can be installed inline and in series, as shown in
As shown in
The first elongate member 7 is preferably fastened to the second elongate member 13 with a plurality of mechanical fasteners 26, and the mechanical fasteners 26 preferably are screws 26, as shown in
Preferably, the first lower surface 3 of the lower structural member 2 is a substantially vertical outer attachment surface 3 and the first upper surface 5 of the upper structural member 4 is a substantially horizontal upper attachment surface 5. The outer attachment surface 3 faces away from the greater part of the connector 6, and the upper attachment surface 5 is above the greater part of the connector 6. Because the connector 6 interfaces with the outer attachment surface 3 at one end and to the upper attachment surface 5 at the other, the connector can resist the tension of these surfaces pulling apart.
The first and second lower tabs 12 are preferably fastened to the outer attachment surface 3 with one or more separate fasteners 30. The first upper tab 18 is fastened to the upper attachment surface 5 with one or more separate fasteners 30. The fasteners 30 are orthogonal to the tabs and the attachment surfaces are at acute angles to the connector 6, which allows the tab attachments to resist in both tension and compression.
Preferably, the first elongate member 7 is formed at least in part as a first channel 31 wherein the first body portion 27 has a first web portion 28 with a first upper surface 8 and a first lower surface 9, a first lower side flange portion 29 and a second lower side flange portion 46 of a second elongate flange 108. The second elongate member 13 is formed at least in part as a second channel 47 that has a second web portion 34 with a second upper surface 14 and a second lower surface 15, a first upper side flange portion 35 and a second upper side flange portion 51 of the second elongate flange 108. Each pair of side flanges is preferably connected with two #10 screws 26.
As shown in
The first elongate member 7 preferably broadens at the lower attachment end 10 so that the first web portion 28 also broadens, creating space for two lower tabs 12 separated by a slot 23. The first lower side flange portion 29 tapers toward the first lower tab 12, and the second lower side flange portion 46 tapers toward the second lower tab 12. Preferably, the first upper side flange portion 35 tapers toward the first upper tab 18, and the second upper side flange portion 51 also tapers toward the first upper tab 18. The side flanges taper so that connector 6 does not interfere with the structural members 2, 4.
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Preferably, the first and second angularly-adjustable lower tabs 12 of the second connector 6 are not in the same plane as the first upper angularly-adjustable tab 18 of the first connector 6. The first and second angularly-adjustable lower tabs 12 of the second connector 6 preferably are orthogonal to the first upper angularly-adjustable tab 18 of the first connector 6.
As shown in
Substantially flat sheathing 98 (shown in
For wood installations, prior to installation, the connectors 6 are preferably set to the proper length and the two tube or channel-shaped elongate members 7, 13 are preferably fastened together with four #10×¾″ self-drilling screws 26 through round holes 41 in the side flanges for pitches between 3/12 and 9/12; and in the triangular and upper round hole 41 when the connector will be used as an installation restraint and spacer at pitches 9/12 up to 12/12.
For trusses 2, 4 spaced 24″ on center, the pitch markings 42 on the inner tube or channel-shaped elongated member 13 may be used to line up the elongated members 7, 13 to the correct length for a given pitch. For other spacings, the length of the connector 6 must be set to the calculated sloping length (from leading edge to leading edge of the framing members, which are the first lower juncture 102 and the first upper juncture 105).
To install the connectors 6 on wood trusses 2, 4, preferably use four 10d (0.148″×3″) nails 30 when the wood trusses 2, 4 have 2×4 top chords, as preferred. The two nails 30 at the bottom of the part 6 (the yoke, or lower attachment, end 10 of the first elongate member 7) are preferably clinched, or bent over.
Sheathing 98 is preferably attached to the connector 6 with knurled pneumatic fasteners or low-profile-head, self-drilling screws. For efficiency, the connectors 6 should be installed in line with the end jacks 99 so that framing alignment can be maintained from eave to hip/ridge.
For cold formed steel installations, prior to installation, the connector 6 must be set to the proper length and the two tube or channel-shaped elongate members 7, 13 are preferably fastened together with four #10×¾″ self-drilling screws 26 through the round holes 41 in the side flanges for pitches between 3/12 and 9/12; and in the triangular and upper round hole 41 when the connector 6 will be used as an installation restraint and spacer at pitches 9/12 up to 12/12.
For trusses 2, 4 spaced 24″ on center, the pitch markings 42 on the inner tube or channel-shaped elongated member 13 may be used to line up the elongated members 7, 13 to the correct length for a given pitch. For other spacings, the length of the connector 6 must be set to the calculated sloping length (from leading edge to leading edge of the framing members, which are the first lower juncture 102 and the first upper juncture 105).
To install the AHEPs on CFS trusses 2, 4, preferably use four #10×¾″ self-drilling screws 30.
Sheathing 98 is preferably attached to the connector 6 with knurled pneumatic fasteners or self-drilling screws.
For efficiency, the connectors 6 should be installed in line with the end jacks 99 so that framing alignment can be maintained from eave to hip/ridge.
