Stucco Basics and BeyondStucco Basics and Beyond

AIA PresentationAIA Presentation

Master Wall Inc. is a Registered Provider with The American Master Wall Inc. is a Registered Provider with The American Institute of Architects Continuing Education Systems. Credit Institute of Architects Continuing Education Systems. Credit earned on completion of this program will be reported to the earned on completion of this program will be reported to the CES Records for AIA members. Certificates of Completion CES Records for AIA members. Certificates of Completion for non-AIA members are available on requestfor non-AIA members are available on request

This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing or dealing in any material or product. Questions related to specific materials, methods and services will be addressed at the conclusion of this presentation.

Thank You!

Learning ObjectivesLearning Objectives

What is Stucco?What is Stucco? Stucco Components and TermsStucco Components and Terms

– Water barriersWater barriers– Metal ReinforcementMetal Reinforcement– Stucco EnhancementsStucco Enhancements– Related Trims and ComponentsRelated Trims and Components

How to Specify and Design StuccoHow to Specify and Design Stucco

What is “Stucco”?What is “Stucco”? In its most basic form, stucco is a mixture of In its most basic form, stucco is a mixture of

Portland cement, sand and limePortland cement, sand and lime– Ratios of these products vary depending upon applicationRatios of these products vary depending upon application

Generally stucco is a field mixed product, although Generally stucco is a field mixed product, although concentrated versions are availableconcentrated versions are available

ASTM C926 is the standard specification the ASTM C926 is the standard specification the application of Portland Cement-Based Plasterapplication of Portland Cement-Based Plaster

ASTM C1063 is the standard specification for the ASTM C1063 is the standard specification for the Installation of Lathing and Furring to Receive Installation of Lathing and Furring to Receive Interior and Exterior Portland Cement-Based Interior and Exterior Portland Cement-Based PlasterPlaster

Basic Stucco ComponentsBasic Stucco Components

Substrate (if used)Substrate (if used) Weather-Resistive or water Weather-Resistive or water

barrierbarrier– Over sheathed applicationsOver sheathed applications

Metal Lath or reinforcementMetal Lath or reinforcement StuccoStucco

– Thickness varies by Thickness varies by applicationapplication

PrimerPrimer Finish CoatFinish Coat

International Building Code (IBC)International Building Code (IBC) Gypsum Board and Plaster are defined in Chapter 25 Gypsum Board and Plaster are defined in Chapter 25

of the IBCof the IBC Weather-resistant barriers are defined in Section Weather-resistant barriers are defined in Section

2510.62510.6– A weather-resistive vapor permeable barrier with a A weather-resistive vapor permeable barrier with a

performance at least equivalent to two layers of performance at least equivalent to two layers of Grade D paper.Grade D paper.

Exterior Plaster is defined in Section 2512Exterior Plaster is defined in Section 2512– Basically references ASTMBasically references ASTM– Typical nominal thickness is 7/8” over lath and 5/8” Typical nominal thickness is 7/8” over lath and 5/8”

over concrete & masonryover concrete & masonry

International Residential CodeInternational Residential Code Defined in Chapter 7 of the IRCDefined in Chapter 7 of the IRC Weather barriers are defined in Section R703.2Weather barriers are defined in Section R703.2

– ASTM D-226 asphalt felt, weighing not less than 14 lbs per 100 ASTM D-226 asphalt felt, weighing not less than 14 lbs per 100 square feetsquare feet

– Not required under paperbacked stucco lathNot required under paperbacked stucco lath

Section R703.6 defines Exterior PlasterSection R703.6 defines Exterior Plaster– Basically references ASTMBasically references ASTM

Table R702.1(1) lists nominal thicknessTable R702.1(1) lists nominal thickness– 5/8” over metal lath5/8” over metal lath– 7/8” over wire lath7/8” over wire lath– 1/2” minimum over masonry1/2” minimum over masonry– 7/8” maximum over concrete7/8” maximum over concrete

Components & TermsComponents & TermsKnow the lingoKnow the lingo

Weep ScreedWeep Screed A weep or sill screed is A weep or sill screed is

installed at the bottom edge of installed at the bottom edge of sheathed installations.sheathed installations.

The screed has a set The screed has a set GROUND (stucco thickness) GROUND (stucco thickness) that corresponds to the overall that corresponds to the overall nominal stucco thickness nominal stucco thickness (3/8”, 1/2” 5/8”, 3/4”, 7/8”) (3/8”, 1/2” 5/8”, 3/4”, 7/8”)

Place level, approximately 2” Place level, approximately 2” onto the foundation wall, but at onto the foundation wall, but at least 6” above gradeleast 6” above grade

Casing BeadsCasing Beads

Casing Beads are Casing Beads are used where the system used where the system ends – mainly windows ends – mainly windows and doorsand doors

Specify the sealant Specify the sealant joint width for the joint width for the anticipated movementanticipated movement

Control JointsControl Joints Control joints control Control joints control

movement within the movement within the stucco panelsstucco panels

Control joint locations Control joint locations should be clearly should be clearly shown on the drawingsshown on the drawings

Seal all joints, set Seal all joints, set control joint laps in control joint laps in sealant, improve sealant, improve detailing by specifying detailing by specifying peel and stick tape peel and stick tape under control jointsunder control joints

Inside CornersInside Corners

Use either casing Use either casing or control joints at or control joints at inside cornersinside corners

Metal LathMetal Lath

Several kinds availableSeveral kinds available– 2.5 or 3.4 #/sy most common2.5 or 3.4 #/sy most common

Self furred to space lath out Self furred to space lath out from wallfrom wall

Widths vary by manufacturerWidths vary by manufacturer– Each piece covers Each piece covers

approximately 16 square feetapproximately 16 square feet

Lath InstallationLath Installation Install with long dimension Install with long dimension

at right angles to framingat right angles to framing Lap seams at least ½”, Lap seams at least ½”,

sides at least 1”sides at least 1” Run at least 2” over Run at least 2” over

accessoriesaccessories Break at control jointsBreak at control joints Stagger pieces so laps Stagger pieces so laps

don’t line updon’t line up

Lath InstallationLath Installation

Plan your layoutPlan your layout It’s best to have lath It’s best to have lath

end at a structural end at a structural framing memberframing member

If not, wire tie lath If not, wire tie lath together every 6”together every 6”

Lath InstallationLath Installation

Plan for cornersPlan for corners– Lath may be cut at corners if Lath may be cut at corners if

corner bead or cornerite is corner bead or cornerite is usedused

– If not, lath must run If not, lath must run continuously to the first continuously to the first structural framing bay structural framing bay (minimum)(minimum)

– Attach through lath to Attach through lath to framing every 6”framing every 6”

Lath AttachmentLath Attachment

Attach to framing members Attach to framing members every 6”every 6”– Nails, some staples, lath locksNails, some staples, lath locks

Wire tie laps every 8”Wire tie laps every 8” Wire tie control joints every 6”Wire tie control joints every 6” Attach 9” x 12” diagonal Attach 9” x 12” diagonal

corner reinforcement at corner reinforcement at windows and doors that do windows and doors that do not have expansion jointsnot have expansion joints

Scratch CoatScratch Coat

The first coat of a The first coat of a stucco applicationstucco application

Applied to Applied to approximately half approximately half the final thicknessthe final thickness

Scratch or score Scratch or score the surface the surface horizontallyhorizontally

Brown CoatBrown Coat

The Brown Coat is The Brown Coat is started soon as the first started soon as the first coat is firm enough to coat is firm enough to hold ithold it

Additional material is Additional material is used to level the stucco used to level the stucco to the ground thicknessto the ground thickness

A rod or Darby is used A rod or Darby is used to level the surfaceto level the surface

Level or float the surface Level or float the surface to even the surfaceto even the surface

Stucco CuringStucco Curing Moist cure the stucco by fogging for Moist cure the stucco by fogging for

at least 48 hours at least 48 hours Spray down walls with gentle Spray down walls with gentle

pressure using clean, potable waterpressure using clean, potable water If humidity is high (75% plus) and If humidity is high (75% plus) and

wind movement is low fogging wind movement is low fogging requirements can be reducedrequirements can be reduced

Allow stucco to cure and harden. 7 Allow stucco to cure and harden. 7 days is currently promoted (specify)days is currently promoted (specify)

Additives can lessen curing timeAdditives can lessen curing time

Improving the Stucco MixImproving the Stucco Mix Acrylic added to the stucco will Acrylic added to the stucco will

improve the propertiesimprove the properties– Aids or reduces curing timesAids or reduces curing times– Increases compressive strengthIncreases compressive strength– Small amounts are beneficial, up to a Small amounts are beneficial, up to a

maximum of 10% acrylic solidsmaximum of 10% acrylic solids

EIFS Base Coats and Meshes EIFS Base Coats and Meshes improve performance and improve performance and appearanceappearance– Additional leveling coat and mesh to Additional leveling coat and mesh to

aid in reduced crackingaid in reduced cracking

Attaching and Adding Decorative Attaching and Adding Decorative Foam TrimFoam Trim

Cut insulation pieces to desired sizeCut insulation pieces to desired size Attach to wall using manufacturer-Attach to wall using manufacturer-

approved base coat or specialty approved base coat or specialty adhesivesadhesives

Rasp and mesh following Rasp and mesh following manufacturer-recommended manufacturer-recommended guidelinesguidelines

Do not run trim pieces through Do not run trim pieces through control joints or other expansion control joints or other expansion joints. Backwrap and use an joints. Backwrap and use an expansion joint if neededexpansion joint if needed

PrimingPriming

Priming the wall is Priming the wall is recommended recommended – To equalize absorption of To equalize absorption of

finishesfinishes– For better alkalinity For better alkalinity

resistanceresistance It may not be required by a It may not be required by a

manufacturer, so specify it manufacturer, so specify it for a better looking projectfor a better looking project

Textured FinishesTextured Finishes

Basic Finish TypesBasic Finish Types

Texture-TypeTexture-Type

Fine, evenFine, even

RiledRiled

Bold, evenBold, even

Heavy RiledHeavy Riled

Standard Formulations Standard Formulations work greatwork great

Elastomeric Formulations Elastomeric Formulations better bridge minor better bridge minor crackingcracking

Specifying StuccoSpecifying Stucco

Reference ASTM C926 and C1063 for stucco Reference ASTM C926 and C1063 for stucco and lath application guidelinesand lath application guidelines– These are also referenced in building codesThese are also referenced in building codes– Unless your understanding of stucco is high, Unless your understanding of stucco is high,

consult with a manufacturer for specificsconsult with a manufacturer for specifics Helpful groups include the Portland Cement Helpful groups include the Portland Cement

Association (PCA), Association of Wall and Association (PCA), Association of Wall and Ceiling Industries (AWCI) and Northwest Wall Ceiling Industries (AWCI) and Northwest Wall & Ceiling Bureau (NWWCB)& Ceiling Bureau (NWWCB)

Specifying Above CodeSpecifying Above Code

Specify peel and stick type water Specify peel and stick type water barriers around all penetrationsbarriers around all penetrations

Specify interior sealants at any Specify interior sealants at any wall penetration – usually minimal wall penetration – usually minimal expanding polyurethaneexpanding polyurethane

Always require full window Always require full window splining by the window installersplining by the window installer

Stucco DetailsStucco Details

Layout IsometricLayout Isometric

Substrate (if used)

Weather-resistive barrier

Metal Lath/Reinforcement

Stucco (1/2” to 3/4” thick)

Primer (if used)

Textured Finish

Cross SectionCross Section Typically up to 7/8” Typically up to 7/8”

thick on concrete thick on concrete and 1/2” thick on and 1/2” thick on masonrymasonry

Concrete/Masonry Substrate

Bonding Agent (if needed)

Stucco

Textured Finish

Cross SectionCross Section

Use ¾” grounds for 7/8” Use ¾” grounds for 7/8” Stucco, ½” grounds for Stucco, ½” grounds for 5/8” stucco5/8” stucco

Control Joint Accessory

Substrate (if used)

Water Barrier

Metal Lath

Stucco

Textured Finish

Show Control Joint LocationsShow Control Joint Locations Joints should be clearly shown on the drawingsJoints should be clearly shown on the drawings

– To limit cracking in the system at a maximum To limit cracking in the system at a maximum area of 144 ftarea of 144 ft22 (13.4 m (13.4 m22).).

– Length to width ratio should not be more than Length to width ratio should not be more than 2.5:1.2.5:1.

– At dissimilar substrates.At dissimilar substrates. Increase joint requirements where thicker Increase joint requirements where thicker

stucco or special structural conditions exist.stucco or special structural conditions exist. Typically control joints are tied to the metal Typically control joints are tied to the metal

lath, which is cut to make two discontinuous lath, which is cut to make two discontinuous slabs.slabs.

When stucco is bonded to a solid substrate When stucco is bonded to a solid substrate such as concrete or masonry the control joint such as concrete or masonry the control joint requirements may be revised. Control joints requirements may be revised. Control joints may be aligned with any control joints in the may be aligned with any control joints in the plaster base.plaster base.

Corner DetailCorner Detail

A corner joint A corner joint accessory or corner-accessory or corner-aid is usedaid is used

Corner Bead

Substrate (if used)

Water Barrier

Metal Lath

Stucco

Textured Finish

Clad Window HeadClad Window Head

Allow space for drainage Allow space for drainage at window headsat window heads

Textured Finish

Stucco

Metal Lath

Water Barrier

Stucco Casing Trim

Window Head Flashing (if needed)

Window

Clad Window with TrimClad Window with TrimTextured Finish

Slope 1:2 min

Primer (recommended)

Base Coat and Mesh

EPS Trim

Adhesive

Stucco

Metal Lath

Water Barrier

Stucco Casing Bead

Window Head Flashing (if needed)

Window

Window Jamb DetailWindow Jamb Detail

Textured Finish

Stucco

Metal Lath

Water Barrier

Casing Bead

Sealant – design & size for anticipated movement

Window

Window Jamb Detail with TrimWindow Jamb Detail with TrimTextured Finish

Primer (recommended)

Base Coat and Mesh

EPS Trim

Adhesive

Stucco

Metal Lath

Water Barrier

Stucco Casing Bead

Sealant – design and size for anticipated movement

Window

Window Sill DetailWindow Sill Detail

Window

Sealant – design & size for anticipated movement

Stucco Casing Bead

Textured Finish

Stucco

Metal Lath

Water Barrier

Window Sill with TrimWindow Sill with TrimWindow

Sealant – design & size for anticipated movement

Stucco Casing Bead

Slope 1:2 min

Textured Finish

Primer (recommended)

Base Coat and Mesh

EPS Trim

Adhesive

Stucco

Metal Lath

Water Barrier

Downspout DetailDownspout DetailDownspout Strap

Sealant

Fastener into solid substrate – set in sealant or with gasket, snug fit

Downspout

Textured Finish

Stucco

Metal Lath

Water Barrier

Floor Line Expansion JointFloor Line Expansion Joint

Substrate (if used)

Water Barrier

Casing Bead (shown) - could also use a control joint or reveal accessory

Sealant Joint – designed & detailed for anticipated movement (a 2x12 can shrink as much as ¾”)

Metal Lath

Stucco

Textured Finish

Pipe PenetrationPipe Penetration

Sealant

Pipe Penetration

Textured Finish

Stucco

Metal Lath

Water Barrier

Soffit/Gable DetailSoffit/Gable Detail

Trim – Extend about 2” over stucco

Textured Finish

Stucco

Metal Lath

Water Barrier

Light Fixture DetailLight Fixture DetailLight Fixture – sealed by electrician

Electrical Box (seal)

Optional Casing Bead

Textured Finish

Stucco

Metal Lath

Water Barrier

Dryer Vent DetailDryer Vent DetailFastener – snug fit

Dryer Vent – set in sealant

Sealant

Optional Casing Bead

Textured Finish

Stucco

Metal Lath

Water Barrier

Foundation DetailFoundation Detail

Textured Finish

Stucco

Metal Lath

Water Barrier

Stucco Weep Screed

Keep siding 6” to 8” above grade

Termination at DeckingTermination at Decking

Textured Finish

Stucco

Metal Lath

Water Barrier

Stucco termination – L bead shown, drainage casing beads also available

Deck flashing – secondary water barrier and peel and stick tapes are encouraged

Detail Under DeckDetail Under Deck

Deck flashing – secondary water barrier and peel and stick tapes are encouraged, lap flashing 2” over stucco, seal lower edge

Stucco Casing Bead

Textured Finish

Stucco

Metal Lath

Water Barrier

Coping Cap DetailCoping Cap DetailCoping Cap with secondary water barrier

Continuous Cleat – extend 2” over stucco

Optional Casing Bead

Sealant

Textured Finish

Stucco

Metal Lath

Water Barrier

EPS Shape DetailEPS Shape DetailSlope 1:2 min

Textured Finish

Primer (recommended)

Base Coat and Mesh

EPS Trim

Adhesive

Stucco

Metal Lath

Water Barrier

*Note: don’t run EPS shapes through control or expansion joints

Kick Out Flashing DetailKick Out Flashing DetailDesign Roof Flashing per National Roofing Contractors Association (NRCA) and code guidelines

Lap stucco water barrier onto flashing

Keep siding 1” to 2” above roof line

Kick Out Flashing/Sealant

Stucco

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