CONTENTS
Prelude To Stucco
An Introduction to Conventional Stucco
Preliminaries
The Application of Stucco
Phase One: The Preparations for Stucco
The Initial Preparations
Lath for Stucco
Scaffolding for Stucco
Phase Two: Membrane Development
Stucco Mortar
The Application of Stucco Mortar
Phase Three: The Stucco Finishes
Details Affecting All Stucco Finishes
Specifics of the Individual Finishes
Additional Aspects of Stucco
Working With Existing Stucco
Stucco Defects
Clean Up
Appendices
Glossary
Stucco Tools
Regulated Requirements
Index
ABOUT THIS BOOK
Various parts of this manual will be of interest to different readers.
Chapter 1, An Introduction to Conventional Stucco, contains describes introduces
Chapter 2, Preliminaries,
Chapter 3, The Initial Preparations
Chapter 4, Lath for Stucco
Chapter 5, Scaffolding for Stucco
Chapter 6, Stucco Mortar
Chapter 7, The Application of Stucco Mortar
Chapter 8, Details Affecting All Stucco Finishes
Chapter 9, Specifics of the Individual Finishes
Chapter 10, Working with Existing Stucco
Chapter 11, Stucco Defects
Chapter 12, Clean Up
Appendix A, Glossary
Appendix B, Stucco Tools
Appendix C, Regulated Requirements
Appendix D, Index
PRELUDE TO STUCCO
An Introduction to Conventional Stucco
Foreword
What is Stucco?
The Stucco Finishes
The Stucco Membrane
An Introduction to Conventional Stucco
Foreword
Due to numerous misconceptions about stucco, a significant part of being a stucco contractor involves clarifying what stucco is, how it’s produced, its properties, and what truly constitutes a high quality application. These misconceptions are usually due to a general lack of awareness of the intricacies, requirements, limits, and vast potential of stucco. I wrote this manual to produce, hopefully, an understanding of the many varied aspects of stucco applications.
Prepared as the source reference standard for conventional stucco, The Complete Guide to Stucco contains comprehensive information that, to my knowledge, has never before been collected into one manual. Its contents should be helpful to architects, specification writers, city planners, developers, general contractors, stucco contractors, stucco journeymen and apprentices, building supply dealers, and homeowners. The Complete Guide to Stucco covers all subjects pertaining to stucco and its application. It makes extensive use of diagrams and pictures that aid in clarifying even the most difficult aspects of stucco applications. Other manuals written about stucco are designed to ensure the use of adequate materials and workmanship by listing various minimum requirements. In contrast, The Complete Guide to Stucco presents recommended procedures based on methods that have produced excellent quality stucco applications that far exceed the minimum standards.
The information contained in this manual has been reviewed by many authorities throughout the stucco and related industries. This author gratefully acknowledges the assistance of the following persons and organizations:
· Anton Friedrich, Friedrich Plastering, retired Business Agent, Plasterers Union, Local 779.
· Shaun Friedrich, Friedrich Stucco.
· John Marshall, Occupational Safety Officer, Research and Standards Department, Worker's Compensation Board of British Columbia.
· Eleanor Florence, Communications Coordinator, Occupational Safety and Health Division, Worker's Compensation Board of British Columbia.
· Bill Hardman, Business Agent, Plasterers Union, Local 779.
· Michael Cleeter
· Joyce Friedrich
· John Tracy
· Georg Jendrossek
· Garry Elmitt, Elmitt Construction.
What is Stucco?
‘Stucco’ refers to the branch of the plastering industry that manipulates portland cement based mortars, usually on exterior surfaces. In some localities the term ‘stucco’ is limited, and is only used to refer to a factory prepared finish coat mixture. This artificial limitation is questionable, however, since it severely restricts the understanding of stucco’s vast potential, and the wide array of available stucco finishes.
Stucco is a surface coating that provides superior qualities unmatched by any other available siding. Adaptable to, and applicable over, a wide variety of surfaces, it provides a strong, firm, fire and weather resistant membrane. Stucco will not deteriorate, resists rot and fungus, and has proved to be a durable wall covering in both warm and very cold climates. Possessing properties similar to reinforced concrete, stucco provides long term protection to any surface. It is economical and requires little maintenance. Stucco provides several distinct finishes, and all stucco finishes include a wide variety of texture and color options.
Stucco can be considered as one component of a structure’s wall and ceiling assembly. It is usually either the last, or next to last, element to be installed. Stucco is selected because it possesses characteristics which no other component of the assembly can provide. Among its major functions, stucco serves as a refining element insofar as it can conceal and correct minor deviations in the alignment of the other system components, and provide a base for decoration.
The Stucco Finishes
This section is a visual showcase of the varied stucco finishes. It is put here to give the reader initial insight into what is possible. Then the book begins to address the steps required to achieve their chosen finish.
The Stucco Finishes page 2
This section is a visual showcase of the varied stucco finishes. It is put here to give the reader initial insight into what is possible. Then the book begins to address the steps required to achieve their chosen finish.
The Stucco Membrane
Produced in separate successive stages, a conventional stucco application incorporates portland cement based mortar and internal metal reinforcement to produce a stucco membrane. The internal reinforcement also acts to secure the membrane to the supporting structure.
Diagram 1
The typical stages required to produce a stucco membrane include the application of lath, the scratch coat, and the brown coat. The membrane may then decorated with one of the stucco finishes.
The terms used to describe the dimensions of the membrane include: surface plane, backing plane, perimeter, profile, and thickness.
As their names imply, the surface plane describes the plane formed by the exposed surface of the membrane, while the backing plane describes the plane formed by the rear of the membrane. Although the surface plane must be uniformly flat, the uniformity of the backing plane may vary depending on the surface offered by the supporting structure.
A perimeter is formed by any interruption in the continuity of a stucco membrane. Several things may produce an interruption, including: stucco stop, projecting or reentrant corners, control joint, flashing, door or window frames, vents, and trim.
The profile and thickness describe similar but different aspects of the membrane. The profile describes the distance the surface plane is from set guide points, and is a constant measure. The thickness describes the distance between the backing plane and the profile of the surface plane. Unlike the profile, the thickness may vary to compensate for any irregularities in the membranes backing plane.
The aim of any conventional stucco application is to form a stucco membrane possessing certain desired characteristics. The membrane must conform to the planes, profiles, and perimeters, required by the specified architectural form; be adequately secured to its supporting structure; have high strength; possess both uniform suction properties and uniform appearance; and if so required, be prepared to receive further applications or treatments such as paint, acrylic, wood trim, or tile.
The Characteristics of a Stucco Membrane
Membrane Strength
The strength of the stucco membrane is determined by: the stucco mortar strength, the bond between the separate laminations of mortar, the extent and effectiveness of internal reinforcement, and the thickness of the membrane.
Mortar strength
If correctly produced and properly hydrated, stucco mortar is an extremely strong and durable substance. For a complete study of the factors that determine the strength of stucco mortar, see Stucco Mortar, page 55.
Bond between laminations
The bonds between the supporting structure, the lath, and the laminations of stucco mortar are produced by chemical or mechanical processes. A chemical bond is formed between the layers of different stucco mortar applications. A mechanical bond is formed between the supporting structure and the lath, the lath and the stucco mortar, and between the different layers of stucco mortar.
Internal reinforcement
The lath's sources of interlock not only provide a means of securing the stucco mortar to the supporting structure, but it also provides internal reinforcement for the stucco membrane. Additional internal reinforcement is also provided by the larger aggregates used for dry dash and wet dash finishes.
Membrane thickness
A significant factor in the ultimate strength of the stucco membrane, the minimum membrane thickness is determined by the structural integrity of the supporting structure, the elastic properties of the membrane, and to a lesser extent, the chosen stucco finish.
Stucco membranes are usually produced in thicknesses of either 13 mm (½ inch) or 19 mm (¾ inch). Although no dimension should ever fall below the minimum specified in your local building code, the thickness of a conventional stucco membrane should not be less than 13 mm (½ inch). Some stucco finishes, particularly float finishes, benefit as the thickness of the membrane approaches 19 mm (¾ inch).
Fire Protection
Possibly the most vital function of stucco is its ability to confine flame, smoke and superheated gases to the area in which a fire originated, and protect the supporting structure against exposure and collapse. This property places stucco in a class by itself among surface materials.
The performance of a stucco membrane with regard to fire resistance is measured in terms of the period (in hours) between the time of initial exposure to a controlled fire, and the time at which failure occurs as determined by standard criteria. The fire resistance properties exhibited by a stucco membrane depend on the quality of the application. Since building codes recognize only those ratings that are based on actual tests, the quality of an application, with regard to fire resistance, depends upon how precisely the rated application is duplicated on a project.
Resistance to Impact and Abrasion
Stucco provides a durable surface with ample resistance to withstand the impacts and abrasions encountered under normal conditions.
The Structural Functions of Stucco
Stucco performs no function that could be classified as purely structural, and must not be expected to assist the structural frame in supporting its loads.
Weather Resistance
A material's resistance to weather is its ability to resist the penetration of moisture, and to maintain its surface integrity when exposed to extreme cycles of temperature and moisture variation. The required degree of weather resistance depends upon the severity of climate and the degree of exposure. In all climates and conditions, stucco has been proven to provide excellent weather resistance.
PRELUDE TO STUCCO
PRELIMINARIES
Finding a Stucco Contractor
Estimating the Costs of Stucco
Acquiring Estimates
Awarding the Contract
Prelude to Stucco
Major decisions are made prior to any stucco application: choosing a stucco finish, finding and choosing a stucco contractor, estimating the cost of the project, and coming to an contractual agreement with a stucco contractor. The Prelude to Stucco section discusses the options available to a homeowner or a general contractor in finding and hiring a competent stucco contractor.
Finding a Stucco Contractor
The best way for a homeowner or a general contractor to find a stucco contractor is through the positive recommendations from people who have previously hired one. In this way the homeowner or general contractor can receive comments on how the stucco contractor conducted himself, as well as preview his previous work. Keep in mind that the stucco finish you preview may not necessarily be the finish that you request.
Another way to determine a possible stucco contractor is by contacting your local stucco supply dealers, and inquire about their stucco contracting customers. Those stucco contractors that most frequently purchase stucco related materials are usually the busiest. If these stucco contractors regularly pay their bills on time, and keep their accounts in good order, then these facts display a certain positive character.
A contractors track record of previously completed projects is the single greatest influence on the demand for that contractor's services. The best stucco contractors are always in the most demand. The extent that a stucco contractor is in demand can be judged by the time period between when you originally contact him and his earliest available start date. It follows that the contractors in the most demand usually have the longest waiting periods. For this reason it is wise to plan ahead and secure the stucco contractor early, usually months before your expected stucco start date.
Since the structure may not even be built at that time, the stucco contractor must be capable of giving a qualified estimate after viewing the appropriate blueprints to the project. Obviously, if the blueprints affecting the stucco performance change in any way, the stucco contractor must be contacted and his stucco estimate may change accordingly.
Although all stucco applications require a certain minimum number of workers, stucco of the highest quality is usually performed by small crews. This is especially true for the application of the finish coat. Since each stucco applicator leaves his own signature style to any finish, ideally only one applicator should produce the final texture for any project. When different applicators work on the same section, the result is non uniformity. The extent that non uniformity is accepted is directly related to the amount of quality expected.
Some stucco contractors do not perform the actual stucco application. Instead, they hire or subcontract crews for this. This type of stucco contractor makes his profit through the difference between what he must pay his subcontractors and what he charges the homeowner or general contractor. Since he does not participate in the stucco application, he has less control over the resulting quality of the application.
Other stucco contractors are "hands on". That is, they actually perform at least some part of the stucco application. A hands on stucco contractor who personally applies the stucco is usually more expensive than a stucco contractor who hires out, or subcontracts the actual application. However, if the stucco contractor is hands on, he has a larger stake in the outcome and professionalism of the project. Consequently, a homeowner or general contractor can usually expect a higher quality application from a stucco contractor who personally applies the stucco.
If a homeowner or a general contractor do decide to hire a stucco contractor who is not hands on, then they should inquire as to how the contractor plans to reimburse his or her crew. A hired crew will generally spend more time and leave a better application if paid by an hourly wage. However, if subcontracted by the amount of surface area or as a set contracted price, a hired crew will generally spend less time on the same application. The resulting quality of the application may suffer accordingly.
Estimating the Costs of Stucco
Stucco is a labour intensive exercise. Therefore, all stucco quotations are based mainly on the amount of time that a particular stucco project will require. Some types of stucco finishes require more time than others. Additional factors that must be addressed include the cost of hired labour, materials, scaffolding, the movement of mortar, and clean up.
The cost of labour is based on the availability and skill of the worker. The better the stucco tradesman, the more the stucco contractor must pay him to secure his services. The costs of all materials must be accounted for, especially the more expensive materials such as acrylic coatings and some types of stucco bead. Scaffolding, when required, and the ease to which mortar is transferred to the applicators, directly affects the efficiency and effectiveness of the stucco project. Clean up costs, including precautions prior to and during application, as well as site clean up after completion, are another important expense to consider.
A stucco contractor must never underbid a project just to secure the work. All quotations must allow for the amount of time, and therefore money, to effectively complete the project without cutting corners. All stucco projects are effective advertisements to the extent of a stucco contractor's ability and integrity. There is no better way to gain a positive reputation than to leave a high quality product. Conversely, a low quality product left on a project usually translates in less demand for your future services and therefore lowers the market value that your company can effectively charge in the future. Never leave a project that can not be used as positive advertisement to the general quality of your stucco company. It is always better not to work at all, than to work, lose money, and damage your reputation to the extent of your ability and integrity.
In many areas, stucco is a seasonal industry. Wise stucco contractors budget for these cycles.
A high quality application requires a greater amount of time and skill than a poor application. A highly qualified stucco tradesman demands a higher market value for his services than a less qualified stucco tradesman. It follows that a customer who truly seeks a high quality stucco application must understand these facts, and hire accordingly.
How to estimate the costs of stucco
For many larger stucco projects, the costs required for completion depends mainly on the surface area to be stuccoed. Consequently, many stucco contractors estimate their costs by simply calculating the surface area to be stuccoed, and multiplying that quantity by the dollar amount they have determined for each type of finish. Other cost variables mentioned, such as ease of access and scaffolding, can then be added. Unfortunately, in many instances this method of estimation is unreliable.
All aspects of the application of the stucco membrane are easiest and least time consuming when performed on continuous, non interrupted, flat, horizontal wall sections.
If all stucco projects were the same, the costs of performing the application would quickly become readily apparent. However, due to the divergent array of stucco projects, a method must be available to correctly estimate the costs of the project before attempting them. Although not perfect, two methods of cost estimation have performed well in certain instances.
One method of cost estimation, mentioned above, is by calculating the entire surface area to be stuccoed and multiply this amount by the cost per unit area. This method works best on sections of the project that are continuous in form. Its main advantage is that it combines the cost of both labour and materials. Its main disadvantage is that it is unable to correctly identify instances when different sections of the same project require much different cost per unit values.
For instance, a continuous wall section requires much less time, and therefore cost per area unit, than a section having the same amount of area, but with non continuous features. These non continuous features might include corners, vents, windows, doors, and any other impediment that slows the continuous application of the stucco membrane. For example, a wall with many corners or interruptions to the perimeters of the stucco membrane will inevitably require more time to complete than if the wall was straight and uninterrupted.
Another method of cost estimation is by calculating the time required to complete the entire project. This time value is multiplied by the cost of labour, and then the material costs are added. This method requires knowledge of what time value is required for a particular section of the project.
Depending on the architectural form, sometimes estimating by the time required is appropriate. Other times the estimation due to surface area is best. Unfortunately for most projects, using just one method or the other is inadequate to achieve a fair and true cost estimation. The proper method to estimate the costs of a stucco project must attempt to eliminate the inconsistency of estimating only by the time required or only by the surface area.
Combining the two basic forms of estimation provides a basis for achieving a fair estimation of the actual costs of the project. For sections of the project that are continuous in form the cost per unit area method is used. For non continuous, or "cut up" sections, the time method is used.
Larger projects tend to rely more so on the cost per unit area method. While smaller projects, such as renovations, additions and patches, tend to rely more so on the time method.
With experience, an estimator will learn the time required for certain aspects of the project.
Acquiring Estimates
Unless you are entirely confident in the fair market value of the stucco project, more than one estimate is required. To a homeowner or general contractor, the only indication of an inadequate quote may be the comparison of it to a competitors quote. Therefore, the more estimates that the homeowner or general contractor receives, the clearer that the fair market value of the project becomes. Quotations that appear to be exaggerated as compared to the others, may indicate a lack of understanding of what the project requires. Weigh the quoted prices against the quality and professionalism of the stucco contractors previous work.
Beware of low bids. Some contractors, trying to secure work, may under-bid their competitors and through inexperience or irresponsibility, quote prices that are insufficient to properly complete the stucco application. Consequently, this inevitably leads the stucco contractor to make one of four possible decisions:
1. Complete the project and lose money.
2. Complete the project by cutting corners and leaving a lower quality application.
3. Ask for more money from the homeowner or general contractor.
4. Stop work and abandon the project.
Since some contractors are better than others, never award the contract to any contractor without personally viewing the contractors previous work.
Awarding the Contract
Once you have chosen the stucco contractor that you want to perform on your project, the next step is to draw up a written contract between you and the stucco contractor. The contract should specify the responsibilities and obligations of each party involved. It must specify the address of the project, be dated, and mention the timetable of work, and schedule of payments. The contract can never be too specific. What follows is a basic sample contract.
Contract
| To The homeowner or general contractor |
The Date |
Address
Dear Sir:
The undersigned proposes to furnish all materials and perform all labour necessary to complete all the work described below:
To Lath and Stucco the house and garage at specific address of project.
The Stucco texture is to be a typical Brocade finish, 3/4" thick.
The color of the finish is to be Specify the color and means by which it is attained.
All windows and vents are to be flashed with typical 1 1/4 " window flashing.
Typical expansion bead shall be used on joists where required.
The building paper used shall be typical tar paper.
All other flashings, expansion beads, control joints, reveals, and building papers, are extra.
No soffits are to be stuccoed.
Any patching of the Lath or Stucco, due to damage, after the initial Lath or Stucco, shall be charged as extra.
All encumbrances to the efficient installation of the Lath and Stucco shall be fixed or removed by homeowner or general contractor.
All of the work is to be completed in a good and workmanlike manner for the sum of ---------------------------------Twenty one thousand --------------------xx/100 Dollars ($21,000.00)
Payments are to be made as follows:
Upon completion of the Lath stage: $7,000.00
Upon completion of the Scratch coat: $7,000.00
Upon completion of the Finish coat: $7,000.00
This proposal is made on the basis of current material and labour costs. A delay in acceptance of more than ten days will require a review of the proposal and re-dating before the agreement becomes binding.
|
The Stucco Contractor
Street Address City Phone Number |
Respectfully submitted,
___________________________________________ |
Acceptance
You are hereby authorized to furnish all materials and labour to complete the work mentioned in the above proposal, for which the undersigned agrees to pay the amount mentioned in said proposal, and according to the terms thereof.
| Date ___________________ | __________________________________________________________ |
The Application of Stucco
Phase One: The Preparations For Stucco
The Initial Preparations
Determining the Start Date and Time Frame
Preliminary Inspection
WCB and Building Codes
The General Contractor
The Structure
The Application of Stucco
There are three distinct phases to a typical stucco project: preparations for stucco, membrane development, and the stucco finish. The preparation phase includes the initial inspection, lath, and scaffold stages. The membrane development phase includes the application of the scratch and brown coats. The final phase includes the finish coat and other details such as acrylic or paint treatments. This book discusses each phase in its chronological order.
Phase One: The Preparations For Stucco
The preparations for the lath and stucco application influence the effectiveness of the entire stucco project, including the efficiency of application and the quality of the finished work.
The Initial Preparations
Determining the Start Date and Time Frame
The initial considerations of stucco preparation are the expected start date and time frame of the stucco project. The lath and stucco application must not begin until the full supporting load is on the structure, and the roof, including roof flashing, is completed. Furthermore, the installation of all exterior electrical outlets, vents, windows, and doors, should be completed prior to lath application and must be completed prior to stucco mortar application. Unless the installation of the gutters provides vital drainage protection, it is usually preferable to install them after the completion of the stucco application.
Preliminary Inspection
Once the structure has achieved the point of construction required for stucco, the next step is a preliminary inspection of the structure by the stucco contractor, specifically the framing, sheathing and foundation.
In addition to the official inspection performed by a building inspector, a personal inspection by the stucco contractor is essential. Due to the intricacies of lath and stucco application some factors of the sheathing and foundation pertaining to stucco may not be covered by the official inspection.
The features confirmed in the inspection should include the following: the framing must be true and plumb; the spacing between sheathing must be 6 mm (¼ inch) to 13 mm (½ inch); the plane of the sheathing must correspond to the plane of the joists; and the plane of the sheathing should be either slightly proud of or aligned with the plane of the foundation.
Workman's Compensation Board
Strict adherence to WCB standards is essential to create a safe work environment.
Building Codes
Building codes are put in place for the benefit and protection of all, and adherence to all pertinent building codes is mandatory. However, various localities may have different building codes. For this reason some information discussed in this manual may not meet the building codes for some areas. For instance, this manual describes membrane thicknesses of both 13 mm (½ inch) and 18 mm (¾ inch). If your local building code limits the minimum membrane thickness to 18 mm (¾ inch) then 13 mm (½ inch) must not be used. It is essential that the pertinent building codes for your locality be consulted and adhered to.
The General Contractor
The proper management of the work site is crucial for the effective application of stucco. All working conditions that are unfavorable to the effective application of lath and stucco, including interference, hindrance, or damage to the stucco application, must be addressed and resolved. Conditions such as scheduling difficulties and problems due to other sub trades must be resolved by the general contractor. In addition, the general contractor must provide the stucco tradesmen unrestricted use of at least one exterior water tap for the duration of the mortar application.
The Structure
Since the performance quality of the supporting structure directly influences the resulting performance of the stucco, the design and construction of the supporting structure must be suitable for stucco application. See Stucco Defects: Design and construction flaws, page 108.
Exposed wood trim should be coated with primer before the stucco application begins, and the last coat of paint should be applied after the stucco application is fully completed.
All factors that pose obstacles to the efficient application of lath and stucco, such as sheathing problems or the existence of non-stucco scaffolding, must be corrected or removed prior to the lath and stucco application.
Continuing preparations for stucco
Although the lath and scaffold stages are accomplished most efficiently when combined and performed simultaneously, they are discussed separately.
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