Home/Firefighting

“DIAGONAL BRACE, STEP BY STEP”

September 1, 1993

Fire Engineering Staff

DIAGONAL BRACE. STEP BY STEP

1. Measure the height of the wall. The top of the shore should contact the top plate where it intersects the adjoining wall. If the angle of the brace is 45 degrees and the wall is eight feet high, the bottom point of the diagonal brace will be eight feet out from the face of the adjoining wall. The bottom of the diagonal brace should not be closer to the adjoining wall than it is high. This will cause the brace to be more than 45 degrees, and as a result the shore will be less effective.

2. Cut the top angle. The 45-degree angle easily can be determined by using the steel square. Choose any number on the tongue of the square and its counterpart on the body of the square; align the number on the tongue and the body with the edge of the lumber. The corresponding angle is 45 degrees. By cutting along the line of the tongue you will get the top angle (45 degrees).

3. Determine the length of the brace. When the diagonal brace is installed at a 45-degree angle, several methods can be used to determine the length of the brace. One simple method is to multiply the height of the wall (in feet) by 17, which will give you the length of the brace, tip to tip, in inches. In the case of an eight-foot-high wall, the brace length will be 136 inches (11 feet 4 inches). Such a brace will fit in the top corner of the wall and contact the floor eight feet back from the base of the wall, giving you a 45-degree angle,

4. Cut the bottom angle. Move the square to the bottom of the brace and scribe a line in the same manner you used to cut the top angle. Remember, however, that the bottom angle is in the opposite direction from the top cut—if you forget this, the brace will not fit properly,

5. Install the brace. Anchor the brace to the top plate, making sure it is as snug to the adjoining wall as possible. Anchor the brace to the bottom

sill/floor plate. The tighter the fit to the floor, the better the brace will hold. If there is no contact with the floor, or if contact is loose, the wall will lean into the brace until it is tight—the wall will not be in compression. Studs that contact the brace should be anchored in at least three places per stud. Hex-head lag screws, set with a power tool to minimize vibrations, make excellent anchors. If the brace is erected properly and anchored securely, it will stabilize the wall and stop any further shifting or leaning. If an interior wall is to be shored, both sides of the wall can be braced.

Fire Department Leadership Firefighting FE Volume 146 Issue 9 Fire Engineering Magazine Premium