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There have always been problems with the flashing details at Head Walls, Rake Walls, and Chimneys especially if stucco, brick or stone veneer is used.
All Cladding, whether it is wood siding, vinyl siding, brick or stone veneer, stucco, etc. must be kept up off the surface of the roof a minimum 1 ½, some manufacturer's of cladding require a minimum of 2". This is so the water on the roofs surface does not soak up and prematurely deteriorate the cladding material. All roof flashings must move freely behind the cladding no matter what the cladding is made of and should never be fastened to any wall.
The roofing contractor usually can slide the roof flashing up behind lapped siding but many times this can be a chore and sometimes the siding gets damaged in the process or it has to be removed. This becomes a real problem if the lapped siding has now been covered with vinyl siding.
Stucco, brick, or stone walls are a problem especially at rake walls where the step flashing is generally fastened to the walls prior to the roof being installed so the stucco, brick, or stone walls can be finished first. This does not allow the free movement needed for the roof flashing to be adjusted to the weather exposure of the the roofing material. What happens years down the road when the property owner changes the type of roofing material or the flashing has deteriorated?
The stucco, brick or stone veneer has to be replaced near the roof line for the new roof flashing. It is no longer acceptable to install the new roof flashing on the outside of the stucco, brick or stone veneer and then install flush mount or sawn in counter flashing. This is no longer a good idea because it traps moisture behind the stucco, brick or stone and will not let the moisture running down the house wrap to exit back onto the roof's surface as is required by code and manufacturer's specifications.
Today a lot of brick and stone veneer is used. Most of the time it is installed incorrectly over the roof flashing and completely down on the roofing materials surface. Because the roof flashing is now behind the brick or stone veneer, it does not properly extend out on to the roof past the surface of the brick or stone veneer as required. When the mortar of the brick or stone veneer is not up off the roof deck as it should be, it will rapidly deteriorate from soaking up water off the roof and from freeze thaw cycles we see here in Colorado.
The solution to the problem of properly flashing walls and chimneys is to use Vertical Blocking Lumber and Z Bar Flashing. This solution keeps the wall cladding, no matter what it is made of, and the roofing material separated. The roofing material can be changed or replaced in the future and the roof flashing can be easily replaced or adjusted to fit the roofing material or repaired without touching the cladding and vice versa. When completed, no one can tell if the walls and chimneys are made of faux brick or stone because it will look like the real thing.
Below are step-by-step detailed drawings of how to properly flash brick and stone veneer walls and chimneys. The Rocky Mountain Masonry Institute has reviewed the final drawing in the following sequence of drawings and has indicated its approval through an e-mail to me. The following flashing detail is good for any type of cladding including wood or vinyl siding. The thickness of the vertical blocking material will vary to match the thickness of the cladding. You will also see similar drawings throughout almost all installation manuals for various roofing materials. Why this detail is ignored I do not know.
The minimum size of the vertical blocking lumber is 1 ½ x 5 ½, the actual measurements of a standard nominal 2 x 6 piece of lumber. The thickness must be varied depending on the thickness of the brick or stone used on the walls and in height depending on the thickness of the roofing material. The Z Bar metal flashing is extended up the wall a minimum of 3 and covered with a weather resistant house wrap material. The Z Bar metal is sized to the thickness of the vertical blocking piece of lumber. It is extended down the face of the vertical blocking lumber and over the L Metal at Head Walls and the Step Flashing at Rake Walls a minimum of 2 ½ but above the roof's surface a minimum of 1 ½.
Where a rake wall extends to an eave a very small kick out of the metal wall flashing can now be used, now that the wall flashing is on the outside of a vertical blocking material of the same thickness as the wall cladding and is properly covered with the "Z" bar flashing. See our web pages Eave to Rake Wall Flashing and Tile Eave to Rake Wall Installation.
Remember never separate the "L" Metal and the 1st piece of Step Flashing with any roofing material. Think of them as one continuous piece of metal.
Remember to seal all corners.