1. Stucco Basics and Beyond
AIA Presentation

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

3. Learning Objectives What is Stucco? Stucco Components and Terms
Water barriers
Metal Reinforcement
Stucco Enhancements
Related Trims and Components
How to Specify and Design Stucco

4. What is “Stucco”?
In its most basic form, stucco is a mixture of Portland cement, sand and lime
Ratios of these products vary depending upon application
Generally stucco is a field mixed product, although concentrated versions are available
ASTM C926 is the standard specification the application of Portland Cement-Based Plaster
ASTM C1063 is the standard specification for the Installation of Lathing and Furring to Receive Interior and Exterior Portland Cement-Based Plaster

5. Basic Stucco Components
Substrate (if used)
Weather-Resistive or water barrier
Over sheathed applications
Metal Lath or reinforcement
Stucco
Thickness varies by application
Primer
Finish Coat

6. International Building Code (IBC)
Gypsum Board and Plaster are defined in Chapter 25 of the IBC
Weather-resistant barriers are defined in Section
A weather-resistive vapor permeable barrier with a performance at least equivalent to two layers of Grade D paper.
Exterior Plaster is defined in Section 2512
Basically references ASTM
Typical nominal thickness is 7/8” over lath and 5/8” over concrete & masonry

7. International Residential Code
Defined in Chapter 7 of the IRC
Weather barriers are defined in Section R703.2
ASTM D-226 asphalt felt, weighing not less than 14 lbs per 100 square feet
Not required under paperbacked stucco lath
Section R703.6 defines Exterior Plaster
Basically references ASTM
Table R702.1(1) lists nominal thickness
5/8” over metal lath
7/8” over wire lath
1/2” minimum over masonry
7/8” maximum over concrete

8. Components & Terms
Know the lingo

9. Weep Screed
A weep or sill screed is installed at the bottom edge of sheathed installations.
The screed has a set GROUND (stucco thickness) that corresponds to the overall nominal stucco thickness (3/8”, 1/2” 5/8”, 3/4”, 7/8”)
Place level, approximately 2” onto the foundation wall, but at least 6” above grade

10. Casing Beads
Casing Beads are used where the system ends – mainly windows and doors
Specify the sealant joint width for the anticipated movement

11. Control Joints
Control joints control movement within the stucco panels
Control joint locations should be clearly shown on the drawings
Seal all joints, set control joint laps in sealant, improve detailing by specifying peel and stick tape under control joints

12. Inside Corners
Use either casing or control joints at inside corners

13. Metal Lath Several kinds available
2.5 or 3.4 #/sy most common
Self furred to space lath out from wall
Widths vary by manufacturer
Each piece covers approximately 16 square feet

14. Lath Installation
Install with long dimension at right angles to framing
Lap seams at least ½”, sides at least 1”
Run at least 2” over accessories
Break at control joints
Stagger pieces so laps don’t line up

15. Lath Installation Plan your layout
It’s best to have lath end at a structural framing member
If not, wire tie lath together every 6”

16. Lath Installation Plan for corners
Lath may be cut at corners if corner bead or cornerite is used
If not, lath must run continuously to the first structural framing bay (minimum)
Attach through lath to framing every 6”

17. Lath Attachment Attach to framing members every 6”
Nails, some staples, lath locks
Wire tie laps every 8”
Wire tie control joints every 6”
Attach 9” x 12” diagonal corner reinforcement at windows and doors that do not have expansion joints

18. Scratch Coat The first coat of a stucco application
Applied to approximately half the final thickness
Scratch or score the surface horizontally

19. Brown Coat
The Brown Coat is started soon as the first coat is firm enough to hold it
Additional material is used to level the stucco to the ground thickness
A rod or Darby is used to level the surface
Level or float the surface to even the surface

20. Stucco Curing Moist cure the stucco by fogging for at least 48 hours
Spray down walls with gentle pressure using clean, potable water
If humidity is high (75% plus) and wind movement is low fogging requirements can be reduced
Allow stucco to cure and harden. 7 days is currently promoted (specify)
Additives can lessen curing time

21. Improving the Stucco Mix
Acrylic added to the stucco will improve the properties
Aids or reduces curing times
Increases compressive strength
Small amounts are beneficial, up to a maximum of 10% acrylic solids
EIFS Base Coats and Meshes improve performance and appearance
Additional leveling coat and mesh to aid in reduced cracking

22. Attaching and Adding Decorative Foam Trim
Cut insulation pieces to desired size
Attach to wall using manufacturer-approved base coat or specialty adhesives
Rasp and mesh following manufacturer-recommended guidelines
Do not run trim pieces through control joints or other expansion joints. Backwrap and use an expansion joint if needed

23. Priming Priming the wall is recommended
To equalize absorption of finishes
For better alkalinity resistance
It may not be required by a manufacturer, so specify it for a better looking project

24. Textured Finishes

25. Basic Finish Types Standard Formulations work great
Bold, even
Fine, even
Heavy Riled
Texture-Type
Standard Formulations work great
Elastomeric Formulations better bridge minor cracking
Riled

26. Specifying Stucco
Reference ASTM C926 and C1063 for stucco and lath application guidelines
These are also referenced in building codes
Unless your understanding of stucco is high, consult with a manufacturer for specifics
Helpful groups include the Portland Cement Association (PCA), Association of Wall and Ceiling Industries (AWCI) and Northwest Wall & Ceiling Bureau (NWWCB)

27. Specifying Above Code
Specify peel and stick type water barriers around all penetrations
Specify interior sealants at any wall penetration – usually minimal expanding polyurethane
Always require full window splining by the window installer

28. Stucco Details

29. Layout Isometric Substrate (if used) Weather-resistive barrier
Metal Lath/Reinforcement
Stucco (1/2” to 3/4” thick)
Primer (if used)
Textured Finish

30. Cross Section
Typically up to 7/8” thick on concrete and 1/2” thick on masonry
Concrete/Masonry Substrate
Bonding Agent (if needed)
Stucco
Textured Finish

31. Cross Section
Use ¾” grounds for 7/8” Stucco, ½” grounds for 5/8” stucco
Control Joint Accessory
Substrate (if used)
Water Barrier
Metal Lath
Stucco
Textured Finish

32. Show Control Joint Locations
Joints should be clearly shown on the drawings
To limit cracking in the system at a maximum area of 144 ft2 (13.4 m2).
Length to width ratio should not be more than 2.5:1.
At dissimilar substrates.
Increase joint requirements where thicker stucco or special structural conditions exist.
Typically control joints are tied to the metal lath, which is cut to make two discontinuous slabs.
When stucco is bonded to a solid substrate such as concrete or masonry the control joint requirements may be revised. Control joints may be aligned with any control joints in the plaster base.

33. Corner Detail A corner joint accessory or corner-aid is used
Corner Bead
Substrate (if used)
Water Barrier
Metal Lath
Stucco
Textured Finish

34. Clad Window Head Allow space for drainage at window heads
Textured Finish
Stucco
Metal Lath
Water Barrier
Stucco Casing Trim
Window Head Flashing (if needed)
Window

35. Clad Window with Trim Textured 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

36. Window Jamb Detail Textured Finish Stucco Metal Lath Water Barrier
Casing Bead
Sealant – design & size for anticipated movement
Window

37. Window Jamb Detail with Trim
Textured 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

38. Window Sill Detail Window
Sealant – design & size for anticipated movement
Stucco Casing Bead
Textured Finish
Stucco
Metal Lath
Water Barrier

39. Window Sill with Trim Window
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

40. Downspout Detail Downspout Strap Sealant
Fastener into solid substrate – set in sealant or with gasket, snug fit
Downspout
Textured Finish
Stucco
Metal Lath
Water Barrier

41. Floor 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

42. Pipe Penetration Sealant Pipe Penetration Textured Finish Stucco
Metal Lath
Water Barrier

43. Soffit/Gable Detail Trim – Extend about 2” over stucco Textured Finish
Metal Lath
Water Barrier

44. Light Fixture Detail Light Fixture – sealed by electrician
Electrical Box (seal)
Optional Casing Bead
Textured Finish
Stucco
Metal Lath
Water Barrier

45. Dryer Vent Detail Fastener – snug fit Dryer Vent – set in sealant
Optional Casing Bead
Textured Finish
Stucco
Metal Lath
Water Barrier

46. Foundation Detail Textured Finish Stucco Metal Lath Water Barrier
Stucco Weep Screed
Keep siding 6” to 8” above grade

47. Termination 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

48. Detail 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

49. Coping Cap Detail Coping Cap with secondary water barrier
Continuous Cleat – extend 2” over stucco
Optional Casing Bead
Sealant
Textured Finish
Stucco
Metal Lath
Water Barrier

50. EPS Shape Detail Slope 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

51. Kick Out Flashing Detail
Design 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

52. ? Questions ? Thank You For Your Time
This concludes the American Institute of Architects Continuing Education Program