Chimneys, like all roof penetrations, are common places for leaks on traditional roofs. These photographs show a preferred installation approach which should not develop a leak during the roof's lifetime.
Old roof and flashing. Note that the step flashing is made up of multiple pieces that are separating at the seams.
Old flashing removed.
WinterGuard, an elastic and sticky underlayment, is used as the base layer around the chimney. Traditional roofing would just lay thinner, less durable tar paper up to the chimney.
Roofing shingles are laid on top of the WinterGuard.
Base step flashing is woven between roofing shingles such that each one carries water above its corresponding roofing shingle.
Completing the base step flashing on one side of the chimney. Note that the roofing shingles cover the lower section of the flashing.
Completed base step flashing.
A single piece of apron flashing is custom made for the lower edge of the chimney.
Old sealant and nails are removed, and a slot is cut in the mortar to allow the insertion of new flashing.
The first of two pieces of cricket flashing has been installed on the high side of the chimney. (The next photograph shows this same scene from the other side.)
The peak on the upper side of the chimney is covered with WinterGuard, flashing and then roofing tiles. Note that only flashing from the far side was installed at the time of this picture. Additional flashing was installed after this picture was taken.
Custom-cut, single-piece counter flashing provides a cleaner look with fewer seams.
Stepped counter flashing is set into slits in the mortar and sealed. It lays outside of the base step flashing to ensure that no water can enter the house between the chimney and roof.
Installed counter flashing prior to sealing.
Ridge Vent Installation
Ridge vents allow rising hot air in the attic to escape at the top of the roof and be replaced by cooler air entering through a continuous soffit vent. Keeping the attic cooler will extend the life of roofing material and reduce home cooling costs.
Unvented ridge prior to installation.
Cutting a thin slit on both sides of the ridge allows hot air to escape the attic.
The sheathing along both sides of the ridge is removed, thus exposing the slot for air to escape.
The completed open slot along the ridge. Note that ridge vents installed without first creating this slot are not functional.
Ridge vents prior to installation. Note that the bottoms of the ridge vents are covered with a light blue filter to prevent insects from entering the attic.
The ridge vents are nailed to the roof on both sides of the ridge.
Ridge vents significantly extend beyond the slit and contain baffles to prevent even wind-driven rain from entering the attic.
Ridge vent pieces prior to nailing.
Ridge cap shingles are installed over the ridge vent.