Flashing

Flashing Against Vertical Sidewalls.

Roof planes that butt against vertical walls at the end of shingle courses are best protected by metal “flashing shingles” places over the end of each course. The method is called “step flashing.”

The metal flashing shingles are rectangular, 8” long and 2” wider that the expected exposure of the roofing shingles. For example, when used with laminate shingles 5 5/8” exposure, they are 8”x4”x4”. The 8” length is to extend 4” above the all surface. Each flashing unit is placed up-roof from the exposed edge of the shingle that will overlap it so that it is not visible when the overlapping shingle is in place.

Roofers use flashing to direct water.

Roof Flashing

To install step flashing, place the first flashing unit over the end of the starter strip and position it so that the end shingle in the first course covers it completely. Secure the horizontal flange to the roof with two nails. Do not nail flashing to the wall as differential movement of the wall and roof could damage the seal. Then apply the first course of shingles up to the wall. Position the second step flashing strip over the end shingle in the first course 5 58” up from the butt or the same distance as the shingle exposure so that the end shingle in the second course covers it completely. Fasten the horizontal flange to the roof.

The second course of shingle s follow; the end is flashed as in preceding courses and so on to the top of the intersection. Because the metal strip is 8” wide, when the roof shingles are laid with a 5 5/8” exposure, each flashing unit will overlap the one on the course below by at least 2”.

Bring wall siding down over the vertical sections of the step flashing to serve as counter flashing. Keep wood siding far enough away from the roof shingles so that it may be painted.

Flashing Against Vertical Front Walls

Sheet metal flashing protects the roof.

Step flashing

Apply shingles up the roof until a course must be trimmed to fit at the base of the vertical wall. Apply a continuous piece of metal flashing over the last course o shingles by embedding it in asphalt roof cement and nailing it to the roof. The metal flashing strip should be bent to extend at least 5” up the vertical wall and a least 4” onto the last shingle course. Do not nail the strip to the wall.

Optional method: Apply an additional row of shingles in asphalt roof cement, (conforming to ASTM D 4586) over the metal flashing strip, trimmed to the width of the strip.

Roof flashing asphalt shingles

Metal flashing

{Caution} Excessive used of asphalt cement may cause blistering.

Bring siding down over the vertical flashing to serve as cap flashing. Keep wood siding far enough away from the roof shingles so that it may be painted. Do not nail siding into the vertical flashing. If the vertical front wall meets a sidewall, as in dormer construction, cut flashing so that it extends at least 7” around the corner. Then continue up the sidewall with step flashing as described earlier.

Optional method: Apply an additional row of shingles in asphalt roof cement, (conforming to ASTM D 4586) over the metal flashing strip, trimmed to the width of the strip.

{Caution} Excessive used of asphalt cement may cause blistering.

Bring siding down over the vertical flashing to serve as cap flashing. Keep wood siding far enough away from the roof shingles so that it may be painted. Do not nail siding into the vertical flashing. If the vertical front wall meets a sidewall, as in dormer construction, cut flashing so that it extends at least 7” around the corner. Then continue up the sidewall with step flashing as described earlier.

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