How to Attach Roof Collars

Remove the shingles that surround the vent. Shingles are typically secured to the roof with a bead of roofer’s cement applied to the top of the backside of the shingle. Push a pry bar underneath the entire length of the shingle to cut through the cement, then pull the shingle away from the vent.

Remove the old roof collar. As with shingles, roof collars are generally secured to the roof with roofing cement applied along the underside edges. Some builders also drive nails through the edges of the collar and into the roof. Pry any nails out of the collar with the pry bar, then cut through the cement in the same manner used to remove the shingles. Lift the collar off of the roof.

Replace the roofing paper that surrounds the vent, if necessary. With the vent removed, this is the appropriate time to inspect the square piece of roofing paper that surrounds the vent for tears. Remove a damaged piece by prying the nails or staples that secure the paper to the roof away with the pry bar, then lift the paper away from the vent.

Install a new piece of roofing paper if the old paper was damaged. Cut an “X” into the center of the paper with a utility blade, then lower the paper over the vent. Guide the vent through the “X.” Staple or nail the edges of the paper to the roof, then apply roofing cement across all four edges of the paper with a caulking gun.

Apply a heavy bead of roofing cement along the underside edges of the new roof collar with the caulking gun, then lower the collar over the vent and press it onto the roof. If desired, drive roofing nails into the edges of the collar with a hammer.

Cut new shingles to match the curve at the top of the collar with a utility knife. It's important to leave the lower edge of the collar exposed. The exposed lower edge greatly assists in routing water away from the vent.

Apply a bead of roofing cement to the top of the underside of the new shingle, then lift the shingle above the vent and slide the new shingle into place.