US20080286038A1

US20080286038A1 - Retrofitting apparatus for reinforcement of roof frame structure

Info

Publication number: US20080286038A1
Application number: US11/748,588
Authority: US
Inventors: Stephen F. OGDEN; Robert E. Platts
Original assignee: Individual
Current assignee: Individual
Priority date: 2007-05-15
Filing date: 2007-05-15
Publication date: 2008-11-20

Abstract

A retrofitting apparatus for reinforcement of an existing roof frame structure includes first and second plates normal to each other and mounted to a roof support member and a side of a roof frame, respectively. A load bearing member with a free end projects from a top en of the second plate to engage the roof frame at the side of the roof frame in order to prevent the roof frame from moving upwardly under uplift forces.

Description

TECHNICAL FIELD

The present invention relates to reinforcement of wooden roof structures of houses and low-rise buildings, and more particularly to a retrofitting apparatus and method for reinforcement of roof frame structures.

BACKGROUND OF THE INVENTION

Many millions of houses and small buildings located in hurricane or tornado areas in, for example, the United States, are at high risk of damage from the strong winds of hurricanes or tornadoes. Recent studies of hurricane damage indicate that the most extensive damage to a house occurs when the roof is torn off, allowing the rain which often accompanies strong winds, to ruin the contents of the house and often allowing walls to collapse.
There is a great need for affordable retrofitting methods for reinforcement of wooden roof frames. While prior art connectors of steel strip tie-down types excel as affordable connectors of roof structures to underlying walls in new construction of houses and small buildings, they are not as applicable when retrofitting existing roof frame structures. These fittings pose difficulties in retrofitting applications because an upper portion of the steel-strip tie must extend over the top of a rafter/truss and down the other side in order to ensure adequate tie-down strength, by applying the restraining force mainly at the top of the roof frame, as compression across the grain, which wood withstands quite well. If the tie-down connectors are simply nailed into the side of the rafter/truss, as commonly done in the prior art, localized tensions are induced across the grain of the wood such that the rafter/truss member tends to split under high uplift conditions, which can release the connector's nails.
The over-the-top method is now widely recommended or required in the “Hurricane Belt” of the United States, even for retrofits of existing buildings. During retrofitting however, accessing the top portion of the rafter/truss requires removal and later restoration of an area of roofing and sheathing, which are laborious and costly operations, and thus tend to discourage such retrofit upgrading of the existing housing and building stock.
Prior art efforts to devise retrofits for reinforcement of roof structures have also been made. A number of United States patents as examples of such efforts are briefly discussed below.
In U.S. Pat. No. 5,257,483 (Netek) discloses some of the complications of retrofitting by installing anchor points in fascia and the wall below, allowing temporary placement of ties in the face of an impending storm. Winger, in U.S. Pat. No. 5,319,816, and several other inventors, disclose various temporary arrangements of multiple cables or nets over the roof which are anchored to the ground. Such temporary devices demand that the householder be at home through the hurricane season, ready to react to storm warnings quickly and competently.
In U.S. Pat. No. 5,311,708, Frye shows a retrofit roof tie-down method in which lag screws are installed upwardly through a steel angle into the lower edges of the rafter/trusses, a lower leg of the steel angle being lag-screwed into the underlying wall. Frye's lag screws into the narrow edge of the rafter/truss would however invite splitting and cause tension failure. Furthermore, only the screws near the junction of rafter/trusses with the top of the wall would contribute effectively, and the usual absence of a stud directly under a rafter/truss would leave Frye's wall lag screws rather ineffective.
Thompson, in U.S. Pat. No. 6,763,634, tries to resolve the retrofit problem by inserting ties down through the roofing and sheathing from above, with one strip on each side of the rafter/truss to form a saddle across it, which is able to effectively hold down the roofing and sheathing together with the rafter/truss. Thompson's ties extend down to connect to the underlying wall below. All this entails laborious and uncertain sealing of the roof penetrations, and interferes with any subsequent re-roofing job.
Therefore, there is a need for an improved retrofitting apparatus and method for reinforcement of roof frames structures.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a retrofitting apparatus and method for reinforcement of roof frame structures.
In accordance with one aspect of the present invention there is a retrofitting apparatus provided for reinforcement of an existing roof frame structure which comprises a first plate adapted to be mounted to a surface of a roof frame support member; a second plate connected with the first plate, adapted to be mounted to a first side of a roof frame supported by said roof frame support member, the second plate being substantially normal to the first plate; and a substantially flat load bearing member with a free end, projecting from a top end of the second plate for securing the roof frame at the first side of the roof frame.
In accordance with another aspect of the present invention, there is a method for reinforcement of an existing roof frame structure which comprises (a) providing a retrofitting apparatus having at least a first mounting plate and a second mounting plate substantially normal to the first mounting plate, the second mounting plate having a load bearing member with a free end extending away from a top end of the second plate; (b) positioning the retrofitting apparatus to allow the first and second mounting plates to be placed against a surface of a wall and a side of a roof frame supported on the wall, respectively, thereby causing the load bearing member to engage the roof frame at a location adjacent to an under side of a roof panel mounted on a top of the roof frame; and (c) securing the first and second mounting plates to the surface of the wall and the side of the roof frame, respectively by means of fasteners in order to prevent the roof from moving upwardly under uplift forces.
Other features and advantages of the present invention will be better understood with reference to the preferred embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the accompanying drawings showing by way of illustration the preferred embodiment of the present invention, in which:

FIG. 1 is a partial elevational isometric view of a roof frame structure reinforced by a retrofitting apparatus according to one embodiment of the present invention, with roof panels removed to show a load bearing member of the retrofitting apparatus;

FIGS. 2A and 2B are partial elevational side views of the roof structure of FIG. 1 with roof panels, showing exemplary locations to position the load bearing member of the retrofitting apparatus;

FIG. 3A is an isometric view of a retrofitting apparatus according to another embodiment of the present invention;

FIG. 3B is a side elevational view of the retrofitting apparatus of FIG. 3A, showing an angular position of the load bearing member of the apparatus;

FIG. 4 is a top plane view of a sheet metal blank of the retrofitting apparatus shown in FIG. 3A;

FIG. 5 is a partial perspective view of a roof frame structure (with roof panels removed) incorporating the retrofitting apparatus of FIG. 3;

FIG. 6 is an isometric view of a retrofitting apparatus according to a further embodiment of the present invention;

FIG. 7 is a top plane view of a sheet metal blank of the retrofitting apparatus shown in FIG. 6; and

FIG. 8 is a partial isometric view of a roof frame structure (with roof panels removed) incorporating the retrofitting apparatus of FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1, 2A and 2B illustrate an existing wooden roof frame structure incorporating one embodiment of the present invention for reinforcement of the existing roof frame structure in a retrofitting job. In a wooden roof frame structure, rafters and trusses are roof structure members and usually present similar rectangular cross-sections. Rafters and trusses generally extend partially or wholly between exterior walls and provide locations for reinforcing the structure where rafters and trusses cross over such walls. In order to denote a roof structure member without the need for unnecessary distinction between rafters and trusses, such roof structure members are referred to as a “roof frame” throughout the text of this specification and the appended claims, and are indicated by numeral 10 in the drawings. The roof frame 10 has two opposed relatively narrow sides referred two as top and bottom 12, 14 and two opposed relatively wide sides referred to as first and second sides 16, 18 thereof. The roof frame 10 sits on a portion of a wall which is generally a load-bearing exterior wall. An underlying wall 20 denotes such a portion of the wall. A roof sheathing panel 22 is attached to the top 12 of the roof frame 10 and represents the roof sheathing which ties the roof frames together and supports the roofing material (not shown).
A retrofitting apparatus generally indicated by numeral 24, according to one preferred embodiment of the present invention, includes a first mounting plate 26 to be mounted to a surface of a roof frame support member, for example the underlying wall 20, and a second mounting plate 28 which is substantially normal to the first mounting plate 26. The second mounting plate 28 is adapted to be mounted to the first side 16 of the roof frame 10, and is connected to the first mounting plate 26, preferably but not necessarily in an integral form. In this embodiment the first and second mounting plates 26, 28 are made from a single metal strip which is twisted at a middle portion such that a lower section thereof (which forms the first mounting plate 26) and an upper portion (which forms the second mounting plate 28) are twisted about 90 degrees with respect to each other. The second mounting plate 28 includes a free end projecting from a top end of the second plate 28 to form a substantially flat load bearing member 30 which may be substantially normal to the second mounting plate 28. The load bearing member 30 functions to secure the roof frame at the first side 16 thereof, near the top 12, to the underlying wall 20. In this embodiment, the load bearing member 30 can be conveniently made by bending a top section of the second mounting plate 28 into a right angled position with respect to the remaining section of the second mounting plate 28.
When the respective mounting plates 26, 28 are mounted to the surface of the underlying wall 20 and the first side 16 of the frame 10 as illustrated in FIG. 1, the load bearing member 30 is pressed from the first side 16 of the frame 10 either into the frame 10 or into a location to engage the top 12 of the frame 10.
There are usually little or no gaps between an under side of the roof sheathing panel 22 and the top 12 of the roof frame 10, and therefore even when the load bearing member 30 is inserted along the interface between the under side of the roof sheathing panel 22 and the top 12 of the frame 10, as shown in FIG. 2A, the load bearing member 30 is likely pressed somewhat into the body of the roof frame 10. Therefore, it is optional to provide the load bearing member 30 with a tipped free end such as in a tipped tooth configuration, in order to provide convenience for engagement of the load bearing member 30 with the roof frame 10. With such a tooth configuration, the load bearing member 30 can also be selectively positioned, for example, as illustrated in FIG. 2B in contrast to the position shown in FIG. 2A, in order to engage the frame 10.
The engagement position of the load bearing member 30 with roof frame 10 is preferably but not necessarily adjacent to the under side of the roof sheathing panel 22, or close to the top 12 of the roof frame 10 in order to allow a maximum cross-section of roof frame 10 to bear a load under uplift forces caused by wind passing over the attached roof sheathing panels 22 while the roof frame 10 is restrained by the load bearing member 30 of the retrofitting apparatus 24, from moving upwardly relative to the underlying wall 20.
The load bearing member 30 may be in an angular position less than 90 degrees with respect to the first mounting plate to substantially match the roof angle in order to achieve an engagement position as shown in FIG. 2A. This will be further discussed hereinafter with reference to another embodiment of the present invention.
The respective first and second mounting plates 26, 28 may have one or more mounting holes 32, 34 for receiving fasteners extending therethrough. Optionally, mounting hole 34 in the second mounting plate 28 may be located near the top end of the second mounting plate 28 and may have a relatively larger diameter. When the retrofitting apparatus 24 is placed in position as shown in FIG. 1, a drilling tool (not shown) may be guided by the hole 34 of the second mounting plate 28 to drill a hole (not shown) through roof frame 10 from side to side for receiving a bolt (not shown) extending therethrough. Such a bolt functions as both a fastener to secure the attachment of the second mounting plate 28 to the side 16 of roof frame 10 and as another load bearer to share with the load bearing member 30 a load through the roof frame 10 caused by an uplift force thereon.
In FIGS. 3A, 3B, 4 and 5 a retrofitting apparatus generally indicated by numeral 36 is illustrated according to another preferred embodiment of the present invention. The retrofitting apparatus 36 includes a first mounting plate 38 adapted to be mounted to a surface of, for example, the underlying wall 20, and a second mounting plate 40 adapted to be mounted to the side 16 of the roof frame 10. A substantially flat load bearing member 42 with a free end projects from a top end of the second mounting plate 40. Optionally, the substantially flat load bearing member 42 may be in a normal position relative to the second mounting plate 40, may also be in a angular position of less than 90 degrees with respect to the first mounting plate 38, for a better engagement position with the roof frame 10, similarly to that of the load bearing member 30 of the retrofitting apparatus 24, shown in FIGS. 1 and 2A. The load bearing member 42 may optionally have a tipped free end to form a tooth configuration.
The retrofitting apparatus 36 further includes a third mounting plate 44 which may be similar to the second mounting plate 40, adapted to be mounted to side 18 of the roof frame 10 opposite to the side 16. The third mounting plate 44 is substantially parallel to the second mounting plate 40 and is spaced apart from same at a distance slightly greater than the thickness of the roof frame 10 such that the roof frame 10 is fitted into the space between the second and third mounting plates 40, 44 when the retrofitting apparatus 36 is in position, as shown in FIG. 5. A substantially flat load bearing member 46 is provided, projecting from at top end of the third mounting plate 44 and extending toward the load bearing member 42 of the second mounting plate 40. It is desirable but not necessary that load bearing members 46 and 42 are similar and substantially defined in one plane.
The first, second and third mounting plates 38, 40 and 44 are connected together, for example, by a further plate 48 substantially normal to each of the respective mounting plates 38, 40 and 44. The fourth plate 48 is connected with an upper end of the first mounting plate 38 and with lower ends of the second and third mounting plates 40, 44.
In this embodiment, the retrofitting apparatus 36 is made from a single piece of sheet metal blank indicated as 36 a in FIG. 4. The sheet metal blank 36 a includes a generally rectangular portion 50 and a strip portion 52, configured symmetrically about a central line 54. Mounting holes 56 and 58 are also drilled through the metal sheet blank 36 a in locations as shown in FIG. 4. It is preferable but not necessary, to position the respective mounting holes 58 close to the opposite ends of the strip portion 52. An additional aperture 60 may optionally be provided in the generally rectangular portion 50. The sheet metal blank 36 a is marked with lines 62, 64, 66, 68 and 70. The generally rectangular portion 50 is bent along line 62 in one direction, for example, toward the inside of the paper about 90 degrees with respect to the strip portion 52, thereby forming the first mounting plate 38 of the retrofitting apparatus 36. The right and left sections of the strip portions 52 are bent along respective lines 64, 66 towards an opposite direction, for example, away from the paper about 90 degrees thereby, forming the substantially parallel second and third mounting plates 40 and 44. The remaining center section defined between the lines 64, 66 therefore forms the connecting plate 48. Two corner portions defined by respective lines 68, 70 at opposite ends of the strip portion 52, are bent along the respective lines 68, 70 about 90 degrees with respect to the second and third mounting plates 40, 44, towards each other, to form the load bearing members 42, 46 respectively.
It should be noted that lines 68 and 70 might not be parallel to lines 64, 66, but may define an angle A with respect to line 62 (also the longitudinal edges of the strip portion 52). When the corner sections of the opposite ends of the strip portion 52 are bent along lines 68, 70, the resulting substantially flat load bearing members 42, 46 have an angular position resulting from the angle A, as shown in FIG. 3B. When the angle A is less than 90 decrees and is substantially equal to the roof angle between the roof sheathing panel 22 and a vertical direction, the load bearing members 42, 46 are substantially parallel to the roof sheathing panel 22 and can therefore be positioned adjacent to the under side of the roof sheathing panel 22, as illustrated in FIG. 2A.
When the retrofitting apparatus 36 is placed in position as shown in FIG. 5, standard fasteners (not indicated) may be received in mounting holes 56 to secure the first mounting plate 38 to the underlying wall 20. Similar to the mounting process of the retrofitting apparatus 24, a bolt may be used to extend through mounting holes 58 in the respective second and third mounting plates 40, 44 and through a hole drilled through the roof frame 10. The bolt serves to force the load bearing members 42, 46 into place and also itself functions as a back-up load bearer. A nut and washers (not shown) may be used to fasten the bolt to secure both second and third mounting plates 40, 44 to the roof frame 10, thereby causing the load bearing members 42, 46 to be in position to securely engage the roof frame 10.
Referring now to FIGS. 6, 7 and 8, a retrofitting apparatus generally indicated by numeral 72 is illustrated according to a further embodiment of the present invention. Given the detailed description of the previous embodiments, it is easy to understand the retrofitting apparatus 72 which includes first and second mounting plates 74, 76 and substantially flat load bearing members 78 a or 78 b in similar relations one to another and for similar functions as those components of the previously described embodiments. These similarities will not be repeated herein and the description of this embodiment will merely focus on the specific configuration of the retrofitting apparatus 72 in contrast to the configurations of the previously described embodiments.
In this embodiment, the first mounting plate 74 of the retrofitting apparatus 72, projects from a side edge (not indicated) of the second mounting plate 76 and extends away from one side of the second plate 76 while one substantially flat load bearing member 78 a with a free end (may have a tip to form a tooth configuration) projects and extends away from an opposite side of the second mounting plate 76. In addition, the substantially flat load bearing member 78 b with a free end, similar to the load bearing member 78 a, projects from a bottom end of the second mounting plate 76, and is substantially normal to the second mounting plate 76. The load bearing member 78 b also defines an angular position less than 90 degrees with the first mounting plate 74 but is not parallel to the angularly positioned load bearing member 78 a. It is preferable but not necessary that the angularly positioned load bearing members 78 a and 78 b are symmetric about a central axis 80 of the second mounting plate 76, as shown in FIG. 6. With such a configuration, the retrofitting apparatus 72 can be mounted to the roof structure at either side 16 or 18. When the second mounting plate 76 is to be mounted to the opposite side 18 of the roof frame 10 instead of to the side 16, the retrofitting apparatus 72 must be positioned upside down in contrast to the position at side 16 of the roof frame 10 and the load bearing member 78 b instead of load bearing member 78 a will engage the roof frame 10, as shown in FIG. 8.
Mounting holes (not indicated) are provided in the respective first and second mounting plates 74, 76. The specific shapes of the respective first and second mounting plates 74, 76 as illustrated in this embodiment, are a choice of design, and any other appropriate shapes such as simple strips may be selected.
The retrofitting apparatus 72 may be made from a single sheet metal blank 72 a in a similar process, as described with reference to FIG. 4. Therefore, the formation process of retrofitting apparatus 72 from the sheet metal blank 72 a will not be further described herein.
The present invention advantageously facilitates retrofitting an existing roof frame such that it is securely anchored to the main body of the structure without having to remove the roof shingles or roof deck which is generally referred to as roof sheathing panels or roof panels throughout this specification and the appended claims. The present invention provides a simple means for reinforcing the hold-down strength of a roof frame and thus resists upward loads on the roof typically caused by winds. The present invention will also reduce the risk of wood splitting problems inherent in other retrofitting devices caused by insertion of screws or nails.
Changes and modifications to the embodiments of the present invention described above may be made without departure from the spirit and scope of the invention. For example, other configurations may be developed as a result of the implementation of the general and common concept incorporated into the above-described embodiments. Such modifications fall within the scope of the present invention and will be apparent to those skilled in the art in light of a review of this disclosure, and such modifications are intended to fall within the appended claims.

Claims

1. A retrofitting apparatus for reinforcement of an existing roof frame structure, comprising:

a first plate adapted to be mounted to a surface of a roof frame support member;

a second plate connected with the first plate, adapted to be selectively mounted to one of opposed first and second sides of a roof frame supported by said roof frame support member, the second plate being substantially normal to the first plate, the first plate projecting away from the second plate in a first direction; and

a substantially flat first load bearing member with a free end, projecting away from a first end of the second plate in a second direction opposite to the first direction for securing the roof frame when the second plate is selected to be mounted to the first side of the root frame; and

as substantially flat second load member with a free end, projecting away in the second direction from a second end of the second plate which is opposite to the first end of the second plate, for securing the roof frame when the second plate is selected to be mounted to the second side of the roof frame.

2. The retrofitting apparatus as defined in claim 1 wherein the respective first and second load bearing members are normal to the second plate, and in an angular position less than 90 degrees with respect to the first plate.

3. The retrofitting apparatus as defined in claim 1 wherein the free end of each of the first and second load bearing members comprises a tip.

4. The retrofitting apparatus as defined in claim 1 wherein the respective first and second plates comprise at least one mounting aperture extending through the respective first and second plates.

5. The retrofitting apparatus as defined in claim 4 wherein the at least one mounting aperture in the second plate is located in a position close to each of the opposed first and second ends of the second plate.

6. The retrofitting apparatus as defined in claim 1 wherein an upper end of the first plate and a lower end of the second plate are integrated together with a twisted middle section.

7. The retrofitting apparatus as defined in claim 2 further comprising:

a third plate substantially parallel to the second plate, adapted to be mounted onto a second side of the roof frame; and

a supplementary substantially flat load bearing member with a free end, projecting from a top end of the third plate and extending toward the load bearing member of the second plate, for securing the roof frame at the second side of the roof frame.

8. The retrofitting apparatus as defined in claim 7 wherein the substantially flat load bearing members of the respective second and third plates are defined substantially in one plane.

9. The retrofitting apparatus as defined in claim 7 further comprising a connector for connecting an upper end of the first plate with lower ends of the second and third plates.

10. The retrofitting apparatus as defined in claim 9 wherein the connector comprises a fourth plate substantially normal to the first, second and third plates.

11. (canceled)

12. (canceled)

13. (canceled)

14. A method for reinforcement of an existing roof frame structure, comprising;

(a) providing a retrofitting apparatus having at least a first mounting plate and a second mounting plate substantially normal to the first mounting plate, the second mounting plate having a load bearing member with a free end extending away from a top end of the second plate;

(b) positioning the retrofitting apparatus to allow the first and second mounting plates to be placed against a surface of a wall and a side of a roof frame supported on the wall, respectively, thereby causing the load bearing member to engage the roof frame at a location adjacent to an under side of a roof panel mounted on a top of the roof frame; and

c) securing the first and second mounting plates to the surface of the wall and the side of the roof frame, respectively, by means of fasteners in order to prevent the roof frame from moving upwardly under uplift forces.

15. The method as defined in claim 14 wherein, in step (b) the load bearing member is inserted from the side of the roof frame along an interface between a top of the roof frame and the underside of the roof panel.

16. The method as defined in claim 14 wherein, in step (b) a third mounting plate substantially parallel to the second mounting plate, is allowed to be placed against an opposite side of the roof frame, thereby causing a load bearing member with a free end which extends away from a top end of the third plate, to engage the roof frame at another location adjacent to the under side of the roof panel.

17. The method as defined in claim 14 wherein, in step (c) a hole is drilled through the roof frame, aligning with mounting apertures in the respective second and third mounting plates, near to the top thereof, and wherein a bolt is then inserted through the hole to secure the second and third mounting plates to the roof frame and to function as a back-up load bearer.

18. The retrofitting apparatus as defined in claim 2 wherein the first and second load bearing members are substantially symmetric about a central axis of the second plate.

19. The retrofitting apparatus as defined in claims 18 wherein the first plate is connected to a side edge of the second plate and extends along an entire length of the side edge of the second plate.