Common Cause of Water Infiltration
By Lawrence M. Otsubo, R.C.E.
Associate of Bausley & Associates, Inc.
During the course of investigating the source of water that migrates into a house, we often discover that the point of entry through which water enters a house is at the bottom of the stucco wall where water has passed through the stucco weep screed metal flashing.
This is where the bottom of the wooden framed stucco wall is supported on the top of the slab foundation wall. Homeowners are not aware that ½-inch holes are along the bottom of the stucco weep screed flashing, spaced 8 inches apart, for the purpose of draining moisture out the bottom of the stucco wall, which naturally absorbs into the porous stucco wall layer, during rainfall events or overspray during irrigation.
Moisture intrusion is imminent when a raised planter is installed along the front of the wall, above the stucco weep screed flashing or when soil is placed against the wall above the level of the stucco weep screed flashing. When moisture migrates into the wall it will flow past the sill plate and into the house at the floor level.
Recurring moisture intrusion not only causes damage to the floor coverings and contents, but it also causes long-term deterioration of the wall framing structure as a result of wood rot and/or termite damage.
The Uniform Building Code (UBC) prescribes provisions to prevent these problems from occurring, of which many homeowners and some contractors are not aware.
According to the UBC (1997 Edition), Section 1812.2 Area Drainage, "Adjacent ground surface shall be sloped away from the structure with a gradient of at least ½ inch per foot for a distance of six feet or more. Provisions shall be made for drainage to prevent accumulation of surface water.”
Also in the UBC, Section 1806.1 “Foundations supporting wood shall extend at least 6 inches above the adjacent finish grade.”
About Lawrence M. Otsubo
Lawrence M. Otsubo is a registered civil engineer, a general contractor, and a valued associate of Bausley & Associates, Inc. He has performed investigations on more than 2,000 structures. Mr. Otsubo is experienced in inspecting delamination of tiles, water leaks, driveways, walkways and retaining wall cracks.
He has more than 30 years experience in the design, estimating and construction of a variety of heavy civil projects as well as residential, commercial and industrial structures.
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