How to Connect a Fireplace Roof Brace to a Roof

Measure the outside diameter of your chimney, using a steel measuring tape.

Place the two halves of the support band from the chimney bracing kit edge-on, on a flat surface with the short end tabs facing forward. Overlap the two halves of the adjustable support band and slide them together until the combined length is just short of the diameter of the chimney; this will line up two holes from the row of connecting holes punched through the center line on each half of the support band.

Insert a flat-headed elevator bolt into the connecting holes on the support band from the back, facing the same way as the end tabs. Place a flat washer, followed by a lock washer, on the bolt, and secure it with a flanged nut. Tighten the nut securely with a wrench.

Form the band into a circle by bringing the two end tabs together. Connect the end tabs loosely with a pair of 2-inch bolts and square cage nuts.

Insert elevator bolts into two holes directly opposite each other through either the upper or lower row of holes punched through the support band. Place the bolts through the holes from the inside with the threads pointing outward.

Slide the support band over the chimney. Position the band approximately two-thirds of the way up the chimney. Move the band as close to a joint in the chimney as possible, and immediately above or below a chimney locking band. Snug down the tab bolts on the support band with a wrench, just tightly enough to hold the band in position.

Slide a hose clamp over the open end of the larger-diameter half of a telescoping support leg. Insert the smaller-diameter leg into the larger-diameter leg. Snug the hose clamp down over the split end of the larger-diameter leg, using a screwdriver, to hold the two halves together temporarily. Assemble the second support leg the same way.

Slide the flattened, angled end of each telescoping leg over the elevator bolts protruding from either side of the support band. Secure the legs with plain washers, lock washers and nuts, but don't tighten the nuts at this stage.

Attach an angle bracket to the bottom of each leg with 1-inch-long 1/4-inch-diameter bolts and flanged nuts, but don't tighten the nuts.

Snug down the attaching bolts on the support band fairly tightly, but loose enough to pivot the support legs slightly. Stretch out the support legs at approximately 45 degrees from the perpendicular, with one leg facing the roof ridge at 90 degrees and the other leg pointing toward the eaves. Make adjustments by collapsing or lengthening each support leg and sliding the support band up or down the chimney so that the bottom of the angle brackets lines up with the slope of the roof.

Locate the rafter or framing joist closest to each angle bracket while maintaining an approximate 45-degree slope on the support legs and a combined angle between the two support legs of approximately 60 degrees.

Smear a layer of outdoor-grade caulking compound over the bottom face of the angle brackets. Drill pilot holes with a cordless drill/driver, and attach each angle bracket into its selected rafter or framing joist with two 1/4-inch by 2-inch lag bolts. Tighten the lag bolts firmly with a socket wrench, and seal the bolts with a coat of caulking compound.

Have an assistant hang a plumb bob from the lip of the chimney while you place a spirit level horizontally across the top. Center the bubble on the spirit level from two directions and make sure the plumb line dissects the vertical center line of the chimney from two directions. Have a third assistant tighten the hose clamps holding each leg together, as well as the nuts securing both ends of the telescopic legs.

Stand back and inspect the installation from different directions to make sure the chimney looks plumb and level. Check all the required angles and dimensions, and make adjustments if necessary. Check-tighten all securing bolts and hose clamps.