Minnesota Stucco Guide

STUCCO IN RESIDENTIAL CONSTRUCTION Moisture Intrusion: Stucco great success in the Twin Cities for over 110 years! The history does not problem or construction begin there however. Long before the problem? invention of portland cement, poz- zolana stucco was used on some of man’s oldest and most widely recog- The “hole” is greater than the sum nized wonders of the world: The Aq- of the parts ueducts in Rome, the Colosseum, the Forum are just some examples. In “Stucco is only one small piece of a Europe lime stucco can be seen on very complex puzzle. The composite of almost everything. In the United any construction relies on the syner- States, Benjamin Henry Latrobe at gism of all the pieces working together. the behest of Thomas Jefferson de- The stucco is not the cause of a win- (Continued on page 3) dow or roof leak, or the reason the sheathing and studs are rotting in walls. We can prove these facts every time.” -Steven Pedracine, Executive Direc- tor, Minnesota Lath & Plaster Bureau A Brief History Lesson Portland cement plaster, otherwise known as stucco has been used with A publication of the... “Promoting the Industry Since 1953” Index • Introduction……………….. Pages 1 & 3 • Stopping Stucco @ • Disclaimer ………………... Page 2 Windows……………………. Page 17 • Selecting Sheathing …….. Page 4 • Selecting Sealants………… Page 17 • Building Paper……………. Page 5 • Deck Attachment…………… Pages 18 & 19 • Metal Lath…………………. Pages 5 & 6 • Deck Handrail Attachment… Page 20 • Weep Screeds……………. Page 6 • Pipe and Vent Sleeves……. Page 20 • Other Terminations………. Page 7-8 • Hose Bibs and • Local Suppliers…………... Page 8 Dryer Vents…………………. Page 21 • Roof Line Issues • Light Fixtures and Chimneys...………………… Page 9 Outlets………………………. Page 21 Roof / Wall Intersections…. Page 9 • Downspouts………………… Page 22 Kick-out Flashings…………. Page 10 • Decorative Foam Soffits……………………….. Page 11 Quoins / Bands…………….. Pages 22 & 23 • Windows……………………. Pages 11-16 • Other Useful Contacts…….. Page 23 Minnesota Lath and Plaster Bureau Disclaimer 820 Transfer Road The text, drawings and related notes contained St. Paul, MN 55114 herein are typical of stucco installations in Minne- sota. Please see the Uniform Building Code for Phone (651) 645-0208 specific requirements. Examples illustrated are not Fax: (651) 645-0209 called out in the code in all cases. E-mail: [email protected] This guide contains general information on stucco installation and related materials. It is provided as a guide only and is not intended for any specific construction project. The Minnesota Lath and Plaster Bureau makes no express or implied warranty or guarantee of the techniques, construction methods, materials and details identified herein, nor does it assume any liability for the use of this information. It is the sole responsibility of any architectural or construction industry professional to apply their professional knowledge in utilizing the information contained in this publication. The Minnesota Lath and Plaster Bureau has promoted the industry since 1953. It is To the best of our knowledge, this information is recognized as an education and technical correct and up to date as of the July 2000 printing. spokesman for the plastering industry. It To ensure that you have the most current version provides services to architects, the con- please contact the Minnesota Lath & Plaster Bu- struction community and the public on a reau. variety of matters relating to the plastering trades. Reproduction of this material is not permitted without the expressed written permission of the ©Copyright Minnesota Lath & Plaster Bureau, July 2000 Minnesota Lath and Plaster Bureau. 2 (Continued from page 1) this often results in condensation problems, signed many important Washington landmarks mold and decay growing in and on walls, ice with stucco as the cladding. In this century dams and wood rot among other maladies. who can define modern architecture better than Frank Lloyd Wright who favored a The Tip of the Iceberg smooth portland cement stucco finish on much of his prairie and contemporary style work. The problems we are seeing are not confined to dwellings with stucco as the cladding. Brick, Yes, stucco is as enduring as time itself. So stone, vinyl, wood, wood composites, shakes, why are so many fingers pointing at stucco as cement board, metal, have all been affected. the reason for moisture intrusion issues? The Because stucco is monolithic (it has no seams) answer is not a simple one, however we can it appears the phenomenon has defined itself state unequivocally that construction has more quickly than in other claddings. Stucco is evolved dramatically in just the past 10-15 in fact better than many conventionally clad years. homes because it keeps the building more com- fortable by slowing down air infiltration. This The Mc Mansion Phenomenon same benefit however, can create a wall that is slower to dry when it does become wet from How has construction evolved? Look around condensation, leaking windows or improperly you; have you seen flashed details. any conventional “If you can’t figure out how to “Raised Ranches” So why can’t we build or “Ramblers” going up flash it, should you really be like we use to? lately? Good economic building it?” times bring bigger more This is a frequently asked expensive homes. “Mc Mansion” is the buzz- question. But we live in an age of enlightened word today, with multiple steeply pitched roofs concern for conserving our natural resources. and dormers, large expanses of glass, decks We could go back to building inefficient, drafty and impressive projecting facades with more homes, but it would be at the cost of higher en- angles than Isosceles ever thought about. ergy consumption and less comfort. This would This extends to the inside environment where obviously be a step in the wrong direction. we cannot live without our vaulted ceilings, skylights, garden tubs and indirect can light- Complex problem straightforward solution ing. Okay, so what really is the problem? What we Buildings today are much more energy effi- are seeing is the beginning of a construction cient. This has been a marked improvement in problem, not a stucco problem. What can we keeping us warm in the winter and cool in the do? We can have a better understanding of summer. But these improvements in comfort how building materials integrate with one an- seem to come at the cost of durability in the other. The answer is communication. overall construction. Homes built today are much tighter. We use more insulation, more For it’s small part in this complex puzzle, the thermally efficient windows, more caulk, more Minnesota Lath and Plaster Bureau presents glue, better vapor barriers, building wraps, air this handbook as a proactive approach to this tight outlet boxes etc. The result is fewer holes end. and lower air exchange between the inside and the outside. Without adequate ventilation Note: The intent of any of the details that fol- this has created an interior environment with low is to keep water out. There are other op- more concentrated pollutants and elevated tions that may be equal or even more effec- moisture levels. And, If improperly addressed, tive. 3 Selecting Sheathing Sheathing performs the function of sub- Installation Comments: The Engineered Wood strate back-up to the stucco. When choosing Association (APA) and International Bildrite, Inc a sheathing substrate for stucco, considera- recommend that their sheathings be spaced at tion should be given to the product’s vapor all edges and ends 1/8” between adjacent pan- permeability (ability to pass moisture in its els. This is to minimize the effects of swelling of gaseous state), it’s ability to withstand expo- the sheathing due to moisture. For more infor- sure to moisture and it’s structural character- mation contact APA or Bildrite. Those phone istics. Each sheathing product has their own numbers are listed on page 23. set of attributes and deficiencies. For this reason special considerations are necessary for the proper installation of each. COMPARING SHEATHING PERMEANCE Types of Sheathings Available: 45.00 40.00 40.00 Ligno-Cellulosic Fiber Board a.k.a. 35.00 30.00 Bildrite lists a vapor permeability rating of 30.00 28.00 30 Perms. 25.00 23.00 20.00 Exterior Gypsum Sheathing (5/8”) typically 15.00 has a vapor permeance value of 40 Perms. 10.00 Another gypsum product often seen on com- 5.00 0.80 0.91 mercial buildings is Georgia-Pacific’s 0.00 1. PLYWOOD 1. OSB (7/16") 2. BILDRITE 3. DENS-GLASS 4. FIBEROCK 3. GYPSUM Dens-Glass Gold. This product offers supe- (3/8") (25/32") GOLD (1/2") AQUA TOUGH SHEATHING (5/8" = 12) (1/2") (1/2") rior moisture resistance with a glass mat sur- (5/8" = 35) facing and comes with a six month in-place PERMS (DRY CUP METHOD) open exposure warranty. United States Gypsum also promotes a similar product called Fiberock Aqua-Tough which comes “Wood structural panels used as wall sheathing are with a one year in place open exposure war- susceptible to fungal decay (rot) if exposed to moisture ranty . content, generally considered to be greater than 20% for an extended period of time. These panels are manu- factured with adhesive systems that withstand extreme Wood sheathings available are Exposure 1 moisture conditions in uncovered conditions such as Plywood, Exposure 1 Oriented Strand when fully exposed during construction. However Board and Exterior Grade Plywood. Struc- when covered as they are in wall systems, moisture in- turally, wood sheathing panels are the pre- trusion can lead to conditions where the panels cannot ferred sheathing in the residential market be- dry. Extended periods where the panels remain at ex- cessive levels of moisture can lead to fungal deteriora- cause they provide the best shear value and tion of the wood itself.

Load more