Several inspections in the l990s uncovered sand erosion through at least one weephole and significant flows running through the weepholes in the downstream retaining wall.
The findings led to several conclusions: significant groundwater flows were occurring around the existing cutoff wall and were merging with the natural groundwater movement from the upland area; a large area of loose, potentially unstable soil existed behind the downstream retaining wall; vertical seepage via connection with voids in the limestone aquifer was not believed to be a significant component of groundwater flows; and the downstream retaining wall's flexural capacity was unacceptable for groundwater elevations at or above the upper level of weepholes, but was acceptable for groundwater elevations at or below the lower level of weepholes.
The rainscreen approach has been advocated in Canada since the 1960s (Garden 1963) and typically procure a second line of defense including a vertical drainage plane behind the cladding, flashing, and weepholes
to ensure that any rainwater leaking through the outer veneer can effectively be drained back to the outside.
These openings, called weepholes, allow water to drain from behind the wall and may require respacing or notching of wall material to accommodate the pipe.
While weepholes and open wall joints are beneficial, supplemental drainage is recommended in any type of wall that exceeds 2 feet in height.
along the bottom butt edge of the siding allow condensation to drain out.
Carbary, a technical service specialist at Dow Corning, stresses the need for professionals well-versed in materials and methods, citing cases in which overzealous window washers caulked over weepholes
, and used highly durable silicone sealant inappropriately on painted masonry tilt-up construction.
Windows, doors, roof penetrations, cracks, weepholes
, and other junctures interrupt the surface.
Waterproofing, Flashing, and Weepholes
. Veneers set in front of wood backing walls require a sheet of waterproof sheeting be applied over the wood surface.
thick liners incorporating welded-wire fabric as reinforcement in many cases, in addition to weepholes
in sloped walls and varying types of joints.
. Openings in the face of a retaining wall that allow water to drain from behind the wall.