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One Coat Stuccos

One Coat Stuccos. AIA Presentation.

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One Coat Stuccos

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  1. One Coat Stuccos 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 One Coat Stucco (OCS)? • Stucco Components and Terms • Water barriers • Metal Reinforcement • Stucco Enhancements • Related Trims and Components • How to Specify and Design OCS

  4. What is “One Coat Stucco (OCS)”? • OCS is typically a proprietary blend of stucco components and typically reinforcing fibers • Typically OCS is installed thinner than traditional stucco normally 3/8” to 1/2” • Usually available in a concentrated form where sand is mixed on site and in ready mixed versions. • Unlike the name implies, typical applications use a “double back” process for applying the OCS

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

  6. Building Codes • One Coat Stuccos may be defined by building code or by a code report • Water Barriers and Fastening Patterns may vary by locality • Typically two layers are required

  7. Components & Terms Know the lingo

  8. Weep Screed • A weep or sill screed is installed at the bottom edge of sheathed installations. • The screed has a set GROUND (OCS thickness) that corresponds to the overall nominal OCS 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

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

  10. Control Joints • Control joints control movement within the OCS 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

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

  12. 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

  13. 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

  14. 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”

  15. 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”

  16. 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

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

  18. 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 OCS to the ground thickness • A rod or Darby is used to level the surface • Level or float the surface to even the surface

  19. Stucco Curing • Moist cure the OCS 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 OCS to cure and harden. 7 days is currently promoted (specify) • Additives can lessen curing time

  20. Improving the Stucco Mix • Acrylic added to the OCS 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

  21. 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

  22. 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

  23. Textured Finishes

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

  25. Specifying OCS • Reference ASTM C926 and C1063 for stucco and lath application guidelines • These are also referenced in building codes • Unless your understanding of OCS is high, consult with a manufacturer for specifics • Reference approved manufacturer or by description (such as ½” thickness and lath type) • Helpful groups include the Portland Cement Association (PCA), Association of Wall and Ceiling Industries (AWCI) and Northwest Wall & Ceiling Bureau (NWWCB)

  26. 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

  27. Stucco Details

  28. Layout Isometric Substrate (if used) Weather-resistive barrier Metal Lath/Reinforcement OCS (3/8” to 1/2” thick) Primer (if used) Textured Finish

  29. Cross Section • Typically 3/8”-1/2” thick Concrete/Masonry Substrate Bonding Agent (if needed) Stucco Textured Finish

  30. Cross Section • Sometimes as thin as 3/8”, although 1/2” is more typical Control Joint Accessory Substrate (if used) Water Barrier Metal Lath Stucco Textured Finish

  31. 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 OCS 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.

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

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

  34. Clad Window with Trim Textured Finish Slope 1:2 min Primer (recommended) Base Coat and Mesh EPS Trim Adhesive OCS Metal Lath Water Barrier OCS Casing Bead Window Head Flashing (if needed) Window

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

  36. Window Jamb Detail with Trim Textured Finish Primer (recommended) Base Coat and Mesh EPS Trim Adhesive OCS Metal Lath Water Barrier OCS Casing Bead Sealant – design and size for anticipated movement Window

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

  38. Window Sill with Trim Window Sealant – design & size for anticipated movement OCS Casing Bead Slope 1:2 min Textured Finish Primer (recommended) Base Coat and Mesh EPS Trim Adhesive OCS Metal Lath Water Barrier

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

  40. 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 OCS Textured Finish

  41. Pipe Penetration Sealant Pipe Penetration Textured Finish OCS Metal Lath Water Barrier

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

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

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

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

  46. Termination at Decking Textured Finish OCS Metal Lath Water Barrier OCS termination – L bead shown, drainage casing beads also available Deck flashing – secondary water barrier and peel and stick tapes are encouraged

  47. Detail Under Deck Deck flashing – secondary water barrier and peel and stick tapes are encouraged, lap flashing 2” over OCS, seal lower edge OCS Casing Bead Textured Finish OCS Metal Lath Water Barrier

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

  49. EPS Shape Detail Slope 1:2 min Textured Finish Primer (recommended) Base Coat and Mesh EPS Trim Adhesive OCS Metal Lath Water Barrier *Note: don’t run EPS shapes through control or expansion joints

  50. Kick Out Flashing Detail Design Roof Flashing per National Roofing Contractors Association (NRCA) and code guidelines Lap OCS water barrier onto flashing Keep siding 1” to 2” above roof line Kick Out Flashing/Sealant OCS

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