Gable End Bracing

Your house has a gable end if you have a sloped roof with a vertical wall that forms a triangle under the end of the roof.

gable_end

Gable end walls and the roof sheathing at the gable end can take a tremendous beating during a hurricane, and if not properly attached and braced, they fail and cause catastrophic damage to your home. However, of all the possible structural retrofits, gable end walls can be the easiest to strengthen and should be a high priority on your retrofit list.

damaged_gable

Areas of concern:

  • The number one issue with gable ends is the attachment of the roof sheathing at the gable end. If you have re-roofed and re-nailed the rood deck, you have gone a long way towards reducing damage at gable ends. If you have not strengthened the roof sheathing attachment, you can use adhesives to temporarily strengthen the sheathing attachment.
  • Most gable end walls of older houses are weaker than they should be to withstand a hurricane and are poorly connected and braced.

The following actions are recommended to strengthen and properly brace a gable end wall.

  1. Anchor and brace the bottom of the gable end’s triangular wall to the ceiling joists or ceiling framing.
  2. Strengthen the gable end wall studs.
  3. Brace the top of the gable end wall by tying it to the rafters or tops of the trusses.

The completed gable end bracing, accomplished using the steps outlined below, should look like the light colored framing shown in the picture below.

gable-bracing-pic

toolbox

Handy Tip!

Attach tool box to board that will span over the space between truss bottom chords/ceiling joists and rest on top of adjacent bottom chords/ceiling joists.

Step 1 : Determine several things about your specific location and the gable end wall on your house.

  1. Find out the design wind speed for the location of your house. You can call the local building department or look it up on the map in the ICC building code. Alternatively: view our summary of State wind maps.
  2. Look at the area surrounding your house. If the wind approaching your house from any direction blows over a lake, an open field or the fairway of a golf course, and this open area is 300-feet wide or wider and is located within about 1500 feet of your house, your house is located in exposure category C. Otherwise, use exposure category B.
  3. Find out the orientation of the vertical studs in the gable end wall. If the wide face is parallel to the wall, then you have a “truss framed” gable end wall. If the wide face of the studs is perpendicular to the wall, you have a “conventionally framed” gable end wall.
  4. Measure the lengths of the wall studs in the gable end that are more than 3-feet tall.
  5. Use the wind speed from (1), the exposure from (2) [C or B], and the length of each stud to determine the appropriate retrofit condition from the Table below.

gable_fig1

Step 2 : Install floor braces first (this also gives you more of a surface to walk on.)

Install 2×4 floor braces on the top surface of the ceiling joists or ceiling framing members. This connects the bottom of the gable end wall to the ceiling so that the wall is braced against wind forces that try to pull it away from the house or push it into the attic space.

Use screws to attach the braces because driving nails in could knock loose the drywall ceiling or fixtures below. Use three screws at each connection between the brace and one of the ceiling framing members, and stagger fasteners so they’re not lined up. Repeat at every place the brace crosses a ceiling joist or the bottom cord of the roof truss. Make sure the brace extends across at least three interior joists or trusses to better distribute the force. The brace should extend at least 3″ beyond the joist or truss to prevent splitting of the brace.

Install floor bracing at every existing stud that is longer than 3′.

wires

Handy Tip!

Don’t pinch wires or cables. If you run across something that blocks one of the braces, (see guide for work-around suggestions).

Step 3 : Install bracing to bottom edge of rafters or top chord of trusses.

Hold the brace overhead to mark where screws will be installed, then take the brace down so you can start fasteners before trying to secure them overhead. Make sure the brace goes on the same side of the existing wall stud as the bottom brace.

Step 4 : Install retrofit studs and strapping to reinforce existing wall studs and strengthen connections to the floor and roof braces.

Attach metal strap using the required number of fasteners per strap. Make sure the last fastener is at least 2 ½” away from the end. Install straps at both ends on the same side of the stud in the same direction. (See chart for number of fasteners for installation and length of strapping required per wind speed zones).

gable_fig2

Next, attach retrofit studs to the horizontal braces at the top and bottom with the same number of fasteners in the metal strap that were used to attach the strap to the retrofit stud. You may need to move strap to line it up properly with the brace. The strap does not have to be in the middle of the brace, but we recommend a ½” clearance from the edge of the stud. Attach the retrofit stud to the existing stud using 3″ long fasteners at approximately 6″ on center.

Attach compression block at top and bottom of brace, over top of the strap. Make sure screws don’t hit metal strap. Purpose of the compression block is to brace retrofit stud to keep wind forces from pushing in.

Step 5 : Install right angle brackets or fasteners to connect the bottom of the gable end wall to the top of the wall below.

If the gable end wall framing, as determined in step 2 – item (3) is a “truss framed” wall, use a right angle metal bracket to connect the bottom of the gable end wall to the top of the wall below as shown in the Figure below.

gable_brace_install

If the wall below is wood frame, use 3″ long screws of the size specified by the bracket manufacturer to connect the bracket to the wall below and use 1-1/4″ long screws to attach to the bottom chord of the truss. If the wall below is masonry, use masonry screws of the diameter specified by the bracket manufacturer that are long enough to extend at least 2-3/4″ into the top of the masonry wall and use 1-1/4″ long screws to attach to the bottom chord of the truss. While most of these brackets have holes for four fasteners on each leg of the right angle bracket, it is only necessary to install two of the fasteners on each leg. The right angle brackets should be spaced, according to the exposure category and design wind speed, as indicated in the Table below.

gable_fig3

If the gable end wall framing, as determined in step 2 – item (3) is a “conventionally framed” wall, install screws to directly connect the bottom plate of the conventionally framed gable end wall to the top of the wall below. If the wall below is wood frame, use 4-1/2″ long 1/4″ diameter lag screws. If the wall below is masonry, use 1/4″ diameter masonry screws that are long enough to go through the bottom plate of the gable end wall and extend at least 2-3/4″ into the top of the masonry wall. These fasteners should be spaced at one half the spacing indicated in the Table above and should be located at least 1-1/2″ from the edge of the wall below.