- Q.We will soon be building a
stuccoed Tudor-style home. Standard practice in our area is to
fasten the wood trim directly to the sheathing, then apply a
three-coat stucco to the areas formed by the applied trim. How
can the trim-stucco joint be detailed to prevent water
A.Steve Thomas responds: The key to leak-free
details is to install "build-out boards" behind the trim. In
our area, 1x6 cedar is commonly used for Tudor trim. We center
the vertical and angled trim boards over a 1x4 build-out board
(see illustration, below). The smaller width build-out board
allows the two stucco base coats to be troweled in behind the
1x6. The finish stucco coat is run tight to the edge of the
overlapping 1x6 trim board, which discourages water from
working its way behind the base coats.
Unlike vertical trim, horizontal trim is held flush with the
upper edges of the build-out boards, and a galvanized cap
flashing is installed to prevent water infiltration.
It’s important to follow the proper sequence when
installing these Tudor trim assemblies. Horizontal assemblies
and cap flashings are installed first, housewrap or Class D
building paper is stapled to the sheathing, then vertical and
angled trim assemblies are installed.
If cedar trim is used, insist that it be prestained on all
sides before installation, and that all site-cut ends have
stain applied to them. Cedar contains extractives that can
"bleed out" if not properly sealed.
Formerly in the stucco trade, Steve Thomas is now a sales
representative for The Columbus Coal & Lime Co., a brick
manufacturer in Columbus, Ohio.