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Stucco Installation, Procedures and G»ldelines
The (lowing document is based on the 2010 FSC, FBCR, ASTM C926, ASTM C1063, and other
Application Guides regarding Stucco installation, procedures and practices. This document is not all
inclusive and does not cover all the requirements for compliant installation of stucco. This document is
meant to be used as a guide to address some of the common installation and proper application issues
found during field inspections.
Masonry:
• Conventional stucco over masonry surfaces may be applied with two or three coats. Two-coat systems
over masonry consist oft first coat=3/8 inch thick and finish coat= 1/8 inch thick-ar over East concrete
consist of first coat_ 1/4 inch thick and finish coat= 1/8 .inch thick. Three-coat systems consist of:
first coat = 1/4 inch thick, second coat = 1/4 inch thick; and finish coat = 1/8 inch thick over both
masonry and cast concrete,
• When required by ASTM C 926, Section 5-2.2; an exterior bonding agent, conforming to ASTM C 932,
shall be used on all masonry surfaces. In lieu of a bonding agent, a dash coat, roughing the surface, or
metal lath are also acceptable methods for bonding.
• FBC 2510.3 Installation, references ASTM C 926 requires form ties or other obstructions (including
masonry cut nails for clean out opening forms) to be removed or trimmed back even with the surface of
the solid base.In addition, if the nails are to be trimmed flush and left in place, they need to be corrosion
resistant as would be required for lath or other metal accessories, ASTM C 926 section 5.2 and C 1063
ction 6.
e
gWood:
Conventional stucco over wood should always be applied.as a three-coat system. Scratch coat 3/8 inch
thick, brown coat =3/8 inch thick, and fnish coat =1/8 inch thick, The scratch coat must be scored
horizontally on vertical surfaces. Successive coats should be applied as soon as possible after the
underlying coat has sufficient strength and rigidity to resist damage when the next coat is applied. A
mist cure shall be maintained as needed for climatic conditions.
• Where structural wood panels are used for sheathing, a minimum 1/8 inch separation shall be
provided.
• The weather resistant barrier(WRB)must be installed per Sections R703.6.3 of the Florida Building
Code'Residential and 1404.2.1 of the Florida Building Code, Where cement plaster(stucco) is to be
applied to lath over frame construction, measures shall be taken to prevent bonding between the
cement plaster and the water resistive barrier. A bond break shall be provided between the 'vvater
resistive barrier and the cement plaster(stucco) consisting of one of the following:
1- Two layers of an approved water resistant barrier material,or
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These installation recommendations are intended to be instruc- undue sagging.Then self-furring lath is installed over sheathing or
tional and accurate.This Is first a guideline,providing a general solid surface,the maximum spacing of supports maybe 24"on center.
overview and also equips the new steel lather with specific instal- *Note:Lath shall be furred away from vertical supports or solid sur-
lation details,based on ASTM 01063-99 Standard Specification faces at least 1/a".Self-furring lath"dimples""V-grooved"or"ribbed"
for Installation of Metal Lath. lath meets these furring requirements.See chart"Support Spacing for
Always consult your area building official before beginning any project Metal Lath"on page 3(Rib Lath).
to familiarize yourself with any local code requirements.This guide
should not replace the designs and judgments of a qualified engineer Cut and Trim to Fit
and/or architect Standard sheet shears or metal cutting scissors are effectively used for
notching and snipping.A conventional circular saw equipped with a met-
Lath Installation al cutting blade easily zips through steel lath to cut to desired lengths.
Begin at the right hand bottom comer of the wall.If paper baclsi ig
behind the lath is required,leave the paper over hanging at the top and Wire Tie
to the left of the sheet.Offset paper backing has the paper overlap- Lath is to be wire tied at 9"on center at edges,ends and at laps between
ping 1-1/2"on one end and one side and corresponding retracted on framing members.On plywood sheathing only,lath may be nailed or
the opposite end and side,the sheets should always be installed in a stapled in lieu of tying at the same center spacing noted above.
horizontal application perpendicular to the framing.
Laps:Minimum of 1"at edges with ends nested paper to paper,metal Accessories
to metal.Apply the second sheet to the left of the first sheet lapping Comer beads shall be used to protect all external corners with a plumb
paper over paper and lath over lath.Place the third sheet centered and true edge.Flashing shall be used where lath and stucco is to be
above the first two sheets.This process is similar to that of laying applied on walls.Intersection of roof plane(i.e.:bulkheads,sidewalls,
brick.This staggers the vertical butt joint seams and allows a more headwalls),a stucco stop,flashing/counter flashing shall be carried
uniform dispersal of stress. over the flashing to terminate the stucco.
Nailing Methods Important Installation Note
On horizontal applications all nails shall be driven flush with base Lath accessories are designed to make plaster jobs easier,more effi-
(driven home).On vertical applications nails shall be bent over to cient and provide the final product a more professional look.To ensure
engage at least 3 strands over and through rib on rib lath and bridge this,accessories should be attached every 18"with nails,staples or to
ribs with staples. wires.For expansion joint,comer and casing beads,the nose can be
used as a screed for the stucco brown coat,but must be embedded by
Lath Fasteners 1/8 inch thickness of plaster on the final coat.
To concrete:use(3/8"diameter shank,3/4"in length) Jointing for Cracking Control
To wood framing:use 11 gauge 1-1/2"length,7/16"head nails(roof- It is difficult to anticipate or prevent plaster cracks,but they can be
ing nails 4d 1-1/2"x1/4 head) largely controlled by means of expansion joints.The expansion joints
To sheathing wood:use 14 gauge,1.5"leg,3/4"crown staples should be installed between lath.The lath is to be broken underneath
To metal framing:use self drilling,self tapping#12 x 3/4"wafer head the expansion joint to function properly.Fasten the joints to the lath
screws.Use of powder actuated or power actuated fasteners is ac- using info found under"Lath Fasteners"section.
ceptable,but may cause spalling when shot to the substrate;follow Walls and ceilings that use metal lath for the plaster base should be
manufacturers instructions carefully. divided into rectangular panels with an expansion type control joint at
least every 18 feet or at the juncture of a dissimilar wail,or in either
Fastener Spacing direction in a length to width ratio of 2%2 to 1,or in ceilings or walls
Spacing of nails,staples or screws is 6"on center maximum along the exceeding 144'in area.
framing member(horizontal or vertical). Expansion or control joints shall be formed by using the single#15
*Note:Staples are not permitted on ceiling applications, expansion joint accessory or by installing casing bead back with a flex-
ible barrier membrane behind the casing bead.The separation spacing
Span Limitations shall be not less than 1/8".An expansion control joint shall be installed
Every finish material is subject to span limitations,which is the where an expansion joint occurs in the base exterior wall.
maximum distance between frame members.When sheathing is not
required,16"on center is the maximum spacing of framing to prevent
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® I NST'ALLA'T ioN DETAIL PH :)TOS
Attachment of Lath to studs Attachment of Rib Lath to ceilings
1) Wafer head screws are power driven to allow quick and easy 1) High(3/8")Rib Lath attached to ceiling joist,spaced at 24"o/c
attachment of Diamond Mesh Lath to framing members, max.Flat Rib Lath can span up to 16"o/c.
2) Diamond Mesh Lath can be cut to size with hand tools.
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_• u ``V-1 , ` I Attachment of trims/joints
1) Type"Ma'Expansion Joint is installed vertically over the window
opening allowing for expansion and contraction,
Attachment to solid surfaces
1) Self-Furred Diamond Mesh Lath is secured to masonry surfaces
with hardened concrete nails and power driven fasteners at the
furring dimples,Paper backed lath is often used In this type of jz� � {. �, •rte.K__ -
application as a bond breaker. t:1
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- a 2) AMIGO X-1 Corner Bead provides protection for outside corners
and a reliable straight ground for screeding,
2) The scratch coat is applied with complete embedment of the self-
furred lath in the plaster. r�,tera fa�ilesi}r1,4/1,r,r XO114Ortsdda }Sas;:, + ;}d�
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3) X-66 Expanded Casing Bead is typically installed at door and
3) Scratch coat is fully embedded in the lath and is isolated from window openings as a plaster stop.
supporting structure.Water resistant backing paper allows
controlled and uniform curing of this plaster foundation. � •� -�. ���� 1''_
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