The solution in this case — as in so many others like
it — was to tear off the improperly applied EIFS, repair
the underlying water damage and rot, and reapply the EIFS
system, this time leaving the required caulk spaces (Figure
4. In a correctly executed butt joint —
like the one in progress here — the edge of the
insulation board is held back 1/2 to 3/4 inch, then
backwrapped with mesh and base-coated. Note the backer
rod and the well-tooled bead of caulk.
Any joints between an EIFS wall and a flashed header should
also include a suitable caulk space. I prefer soldered copper
pan flashing in this application, because it's reliably
leakproof and will last at least as long as the wall itself
5. Headers and other horizontal surfaces must be
protected with flashing. In this case, the damaged EIFS
system has been stripped off, and a waterproof
fiberglass-faced gypsum board screwed to the studs. The
EPS board is attached to the sheathing with adhesive.
Once the reinforcing mesh has been turned up at the
front, the bottom edge of the sheet will receive a
layer of basecoat.
Better step flashing. Another common trouble
spot is the joint where a wall meets step flashing at the edge
of the roof. More often than not, the EIFS-covered beadboard is
simply butted and caulked against the shingles (Figure 6).
6. Contrary to the manufacturer's recommendation
and common sense, the EIFS applicator butted the edge
of the polystyrene directly against the roofing, with
no caulk space or counterflashing.
Once this makeshift seal fails — as it soon does
— the stage is again set for disaster as water wicks into
the polystyrene, over the vertical leg of the flashing, and
into the interior of the wall.