Static structures (e.g. – buildings) – Assembled in situ-type anchor or tie – Sheet or wire tie
Reexamination Certificate
2001-06-12
2003-12-16
Friedman, Carl D. (Department: 3635)
Static structures (e.g., buildings)
Assembled in situ-type anchor or tie
Sheet or wire tie
C052S712000, C052S715000
Reexamination Certificate
active
06662517
ABSTRACT:
BACKGROUND
1. Field of Invention
This invention is a continuation-in-part of Ser. No. 09/516,655, filed Mar. 7, 2000 and relates to an innovative connector that permanently connects the roof to the outside wall to create buildings that are stronger and more resistant to hurricanes and earthquakes.
2. Description of Prior Art
BACKGROUND
Recent studies of hurricane damage on wood-frame buildings indicate that extensive damage was generated to a house by strong winds, when the roof rafters or roof trusses twisted or were pulled up from the outside wall, along with the roof sheathing.
Roof sheathing ties all the rafters or purlins together on a wood frame house, and the roof sheathing ties all the roof trusses together when a masonry or wood-frame house is constructed with trusses. If the rafters or trusses rack or twist from the wind forces, the roof sheathing can detach from the roof allowing rain to enter the house.
Sheathing that is tightly secured to the rafters or trusses and subsequently fastened to the walls, helps transfer uplifting forces to the walls and henceforth to the foundation. The leading edge of a roof is the weakest point of sheathing uplift during strong winds, and this invention helps prevent any roof uplift. Adding more nails to the sheathing just splits the sheathing and the underlying structural member making the connection weaker.
Failure of the outside wall sheathing is also common during hurricanes, because of inadequate fastening of the wall sheathing to the underlying structural members. This invention helps prevent the wall sheathing from splitting, racking, and detaching from the wall. The extreme negative pressure of a hurricane blows out the sheathing from walls, but this invention holds the sheathing tight to the walls, as sheet metal joints perform better than nailed joints in high winds and during seismic activity. Adding more nails just splits the sheathing and underlying structural members.
Hurricanes
Studies of damage after Hurricane Andrew show several problems with the attachment of roof rafters, roof trusses, roof sheathing, and wall sheathing that this invention solves.
Roof overhangs act like wings, creating huge uplifting forces during strong winds. This uplift tears apart the rafters that are toe-nailed to the header or top plate. The uplift can also twist rafters and roof trusses weakening the toenailed connections and causing detachment of the structural members and roof sheathing.
The one thing that ties together the top plate, studs, and sill plate is the outside sheathing. This invention effectively ties together the rafter, top plate, and outside wall sheathing to form a continuous load-path to the sill plate. Attaching my invention to the rafter and top plate junction puts the nails perpendicular to the uplifting force and would require shearing the nails in order to lift the rafter or truss.
On newer stud-wall construction, we have seen that studs rarely line up directly under the rafters. We saw houses where the walls have studs 16-inches on center, constructed with a roof that had rafters 24-inches on center. This means the only rafter and stud that will line up to form a continuous load-path is every fourth stud or every other rafter. The odds are low that they will exactly line up.
Another problem with home construction is on mis-installation of prior art hurricane clips that are made for new construction and covered by wall sheathing. After Hurricane Andrew, there were many examples of careless and inferior attachment of hurricane clips or they were entirely missing. One company has visited new construction sites and documented many examples of shoddy and incorrect application of their products.
To achieve a continuous load-path on existing houses the outside sheathing must be taken into account. The most important tie in an existing house is between the rafter and top plate or roof truss and top plate. Any uplifting wind force on the roof must be transferred to the walls. In tropical climates, the roof purlin, an intermediate structural member, may separate from the rafter along with the roof sheathing.
My invention effectively ties together the roof, rafter or roof truss, top plate, and outside sheathing (and indirectly, the wall studs) to form the most practical and economical continuous load path from the roof to the foundation.
Earthquakes
During an earthquake, the wall and roof diaphragms undergo shearing and bending. Because of the difference in weight, a roof can move at different speeds than the walls. The shear forces from the roof boundary members are transferred to the top of the shear wall by way of toenails to the top plate. To withstand and transfer the shear loads, the connection between the roof and wall must be stronger than toenailing.
The outside sheathing provides lateral stability to the walls, preventing racking. The sheathing also absorbs and transfers earthquake forces by becoming a shear wall.
An earthquake can send motion into a house and separate the sheathing from the walls. The sheathing can come loose from the walls by the nails popping out or the plywood splitting away from the nails driven on it's edge. This invention helps prevent the outside sheathing from pulling away from the wall during earth movements.
Steel connectors, between different components of a wood-frame buildings superstructure, provide continuity so that the building will move as a unit in response to seismic activity (Yanev, 1974). This invention ties the walls securely to the roof, so the house will move as one unit.
This invention ties the roof sheathing to the rafter and top plate. This invention can help transfer loads acting on the roof to the walls and foundation. It can also help transfer loads acting on the walls to the roof, which can help absorb and dissipate the loads to different walls.
Prior Art
A number of connectors have been developed to tie together the structural members of a house under construction. Up until this invention, nobody had seen how to make a retrofit connector that could tie sheathing to the underlying structural members and connect to the side or “meat” of a rafter or roof truss without having material hanging down.
The leading manufacturer of wood construction connectors, the Simpson Strong-tie Company, has a variety of connectors for use in new construction that tie the rafter to the top plate including: H
1
, H
2
, H
2
.
5
, H
3
, H
4
, H
5
, H
6
, H
10
, H
9
, H
7
, H
15
, H
10
-
2
, and HS
24
. None are shown tying the wall sheathing to the wall, or the roof sheathing to the rafter and top plate.
There are a number of ties that fasten the rafter to the top plate while a house is being constructed including: Knoth U.S. Pat. No. 5,561,949, McDonald U.S. Pat. No. 5,560,156, Colonias U.S. Pat. No. 5,380,115, Stuart U.S. Pat. No. 5,335,469, Callies U.S. Pat. No. 5,230,198, Colonias et al U.S. Pat. No. 5,109,646, Commins U.S. Pat. No. 4,714,372, Gilb U.S. Pat. No. 4,572,695, Gilb et al U.S. Pat. No. 4,410,294, and Maxwell et al U.S. Pat. No. 2,413,362.
These are good inventions, but they are difficult to retrofit onto existing houses without demolition of existing parts on a house. None were designed or patented to be retrofit on to an existing house, hold down roof sheathing, or work on roofs of different pitches.
The prior art hurricane clips provide little lateral strength, even when using a left and right. The prior art doesn't tie the outside sheathing to the underlying top plate and roof rafter, so they cannot prevent the outside sheathing from being sucked off during the extreme negative pressure of a hurricane.
The prior art inventions do not prevent the outside sheathing from splintering and disconnecting during earth tremors. They do not have multiple uses such as tying the roof sheathing to the rafter and top plate at the top of the wall, which is one the weakest points in a wood-frame house during a hurricane or tornado, especially on weak toe-nailed connections.
Frye's anchor system, U.S. Pat. No. 5,311,708, is patented as a retrofit, but it does not tie the ra
Friedman Carl D.
Varner Steve
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