Moisture coming through Stucco Wall

[C. Bailey]

I just bought a house. The house is 3 years old. It has a stucco exterior. For the last day, it has been raining with a strong wind (we haven't had a lot of rain before this). The rain is hitting the walls (normally the eve protects the walls somewhat). I now have a constant drip from the top of one of my windows in the basement (walk out basement - drip is about 8 or 9 feet above grade). I pulled the insulation and discovered the plywood is saturated with water. I inspected the stucco exterior and it appears normal. I pulled insulation above a couple other windows. The plywood is slightly damper, but not dry like it should be. Any thoughts as to what the problem might be?

Is stucco a water proof coating, or is there supposed to be tar paper behind it?

Chris

[Sacramento Dave]

this same problem how I fixed it was to caulk were the stucco meet the overhang, then for added protection I put a 1X2 as trim I also caulked that.You might try spraying the area with a hose. See if that increases the drip. There should be tar paper behind stucco It's part of the lath.

[Rick]

haven't had a

appears

If you can find the July 2005 issue of the Journal of Light Construction, there's a good article called "Why Stucco Walls Got Wet"

caulked

increases the

[Travis Jordan]

Masonry of all types is not impervious to water. Stucco should be applied to a wall that has first been prepared by hanging a weather barrier (felt or tyvek or equivalent) overlaid with wire lath before the stucco is applied. Even so, the finished stucco is still slightly permeable.

Paint and elastomeric coatings prevent penetration of water on masonry surfaces. Many stucco homes are painted with latex acrylic paints, and are therefore more waterproof. However, during last year's hurricane season here in Florida it turned out that many newer homes with only one or two layers of paint still leaked.

Some homes are built with synthetic stucco (dryvit) and moisture penetration of this material is common.

[Norminn]

The news about wind-driven rain permeating concrete block/stucco was really interesting. That is what we have. Wind hard enough to drive water through cb/stucco would also, probably, find all the little wiggly, unfilled gaps and joints between members. Curious as to the windspeed when OP's house got wet. A benefit of our hurricane shutters is probably that we are a lot less likely to get water in closed windows/patio sliders. Tide surges and flying roofs are enough to handle :o) We had a 5'x15' foot skylight take flight last year, but a sturdy palm caught it :o)

Wind here can easily enter roof vents, soffit vents, etc. Our old condo has lotsa paint, so that is a surprising benefit.