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September 25, 2017

Auburn Historic District Preservation Guidelines

 

Auburn Historic District Guidelines

 

https://www.nps.gov/tps/standards/treatment-guidelines-2017.pdf

 

Retaining the historic quality of a district is im­portant for the sake of historic preservation but there are also other important benefits to a com­munity. By utilizing the guidelines in this docu­ment the Auburn Historic Preservation Board also looks to:

Enhance the environmental quality. Improv­ing and maintaining individual buildings cu­mulatively enhances the overall quality of the downtown environment. The quality of the individual stores in a downtown is very im­portant but the overall environment should attract people to the district. The downtown should be perceived as a district that people want to spend time in both shopping and ex­ploring.

 • Improve the economic potential. Heritage tourism and the attraction of unique  com­mercial districts are becoming more and more attractive to local and regional mar­kets. Establishing a quality environment will attract both visitors and new businesses. Auburn’s proximity to the Omaha and Lincoln markets offers great opportunities. Visitors, looking for single-day outings to interesting destinations are an im­portant economic opportunity for Auburn.

 • Strengthen property values. The stabilization and improvement of property values benefits ev­eryone in the city. The buildings in the downtown district account for a significant portion of the city’s overall property valuation. Stabilizing the property values in this district is a benefit to build­ing owners, but also the entire city’s tax base.  

 

Standards for Rehabilitation

The guidelines established in this document follow the Secretary of the Interior’s "Standards for Rehabilitation." The standards are intended to be a guide to building owners, contractors and project reviewers prior to work being initiated. The "Standards" define rehabilitation as the act or process of making possible a compatible use for a property through repair, alterations, and additions while preserving those portions or features which convey its historical, cultural, or architectural values. The "Standards for Rehabilitation" are:

1. A property shall be used for its historic purpose or be placed in a new use that requires minimal change to the defining characteristics of the building and its site and environment.

2. The historic character of a property will be retained and preserved. The removal of historic materials or alteration of features of features and spaces that characterize a property shall be avoided.

3. Each property will be recognized as a physical record of its time, place, and use. Changes that create a false sense of historical development, such as adding conjectural features or elements from other historic buildings, shall not be undertaken.

4. Changes to a property that have acquired historic significance in their own right shall be retained and preserved.

5. Distinctive  features, finishes, and construction techniques or examples of craftsmanship that characterize a property shall be preserved.

6. Deteriorated historic features shall be repaired rather than replaced. Where the severity of deterioration requires replacement of a distinctive feature, the new feature shall match the old in design, color, texture, and other visual qualities and, where possible,materials. Replacement of missing features will be substantiated by documentary, physical, or pictorial evidence.

7. Chemical or physical treatments, such as sandblasting, that cause damage to historic materials shall not be used. The surface cleaning of structures, if appropriate, shall be undertaken using the gentlest means possible. Treatments that cause damage to historic materials shall not be used.

8. Significant archeological resources affected my a project shall be protected and preserved. If such resources must be disturbed, mitigation measures shall be undertaken.

9. New additions, exterior alterations, or related new construction shall not destroy historic materials that characterize the property. The new work shall be differentiated from the old and shall be compatible with the massing, size, scale, and architectural features to protect the historic integrity of the property and its environment.

10. New additions and adjacent or related new construction shall be undertaken in such a manner that if removed in the future, the essential form and integrity of the historic property and its environment would be unimpaired.

Planning for Your Project

 

When building owners decide to work on their historic commercial building several challenging questions face them.

If the façade is fairly intact but deteriorated, what repairs should be done first?

If significant alternations have been made, should they be kept, should the building be restored to its original appearance, or should another approach be taken?

If the building is no longer in commercial use, can the new use be accommodated while retaining the commercial appearance of the building?

What is an appropriate and acceptable budget for the building owner?

One of the biggest questions for building owners when considering work on their building is "where to begin?" This section is designed to provide some general assistance in the process of working on a historic structure.

Building Assessment

Before beginning a project, an assessment, or "physical exam", of the building should be completed.   A more detailed exam of an individual building should provide a historical summary of the building but more importantly it should lay the ground work for the project approach. In addition to providing base information on the historical context of the building, the report should:

Evaluate Existing Conditions. The report should inventory the existing condition of the building and relate it back to treatment types. Most importantly it should answer the questions "what needs attention and why".

Work Description. A description of what work would be needed to stabilize the building, meet specific treatment types, and most importantly what will be needed to accomplish the owner’s goals.

Prioritizing Projects. Often a building has more projects than an owner can finance. Understanding the priority of projects can put the investment to best use. Critical projects should be done first with more cosmetic projects waiting until last.

Set a Budget

Once the building owner decides what projects have to be completed first, a budget should be established. The building assessment and budget could drive the treatment type selected by the owner. Treatment type is very important and should be considered throughout the assessment and budgeting process.

Apply the Design Guidelines

The design guidelines outlined in this document are established to assist building owners who bring projects before the Auburn Historic Preservation Board. In addition, the Board can provide important guidance to projects that do not require a Certificate of Approval. By applying the guidelines in this document, the Board and City strive to promote and preserve the historic character of the business districts in Auburn.

Elements of a Streetscape

Building Exterior Masonry

 The longevity and appearance of a masonry wall is dependent upon the size of the individual units and the mortar.

 Stone is one of the more lasting of masonry building materials and has been used throughout the history of American building construction. The kinds of stone most commonly encountered on historic buildings in the U.S. include various types of sandstone, limestone, marble,               granite, slate and fieldstone.

Brick varied considerably in size and quality. Before 1870, brick clays were pressed into          molds and were often unevenly fired. The quality of brick depended on the type of clay available and the brick-making techniques; by the 1870s--with the perfection of an extrusion process--bricks became more uniform and durable. Terra cotta is also a kiln-dried               clay product popular from the late 19th century until the 1930s. The development of the steel-frame office buildings in the early 20th century contributed to the widespread use of architectural terra cotta. Adobe, which consists of sun-dried earthen bricks, was one of the earliest permanent building materials used in the U.S., primarily in the Southwest where it is still popular.

Mortar is used to bond together masonry units.  Historic mortar was generally quite soft, consisting primarily of lime and sand with other additives.  After 1880, portland cement was usually added resulting in a more rigid and non-absorbing mortar.  Like historic mortar, early stucco coatings were also heavily lime-based, increasing in hardness with the addition of portland cement in the late 19th century. 

 
Concrete has a long history, being variously made of tabby, volcanic ash and, later, of natural hydraulic cements, before the introduction of portland cement in the 1870s.  Since then, concrete has also been used in its precast form.

While masonry is among the most durable of historic building materials, it is also very susceptible to damage by improper maintenance or repair techniques and harsh or abrasive cleaning methods.

Masonry: Identify, retain and preserve

Recommended:

Identifying, retaining, and preserving masonry features that are important in               defining the overall historic character of the building such as  walls, brackets, railings, cornices, window architraves, door pediments, steps, and columns; and details such as tooling and bonding patterns,  coatings, and color.

Not recommended:

Removing or radically changing masonry features which are important in defining           the overall historic character of the building so that, as a result,  the character is diminished.

Replacing or rebuilding a major portion of exterior masonry walls that could be repaired so that, as a result, the building is no longer historic and is essentially new construction

Applying  paint or other coatings such as stucco to masonry that has been historically unpainted or uncoated to create a new appearance.

Removing paint from historically painted masonry

Radically changing the type of paint or coating or its color 

Protect and Maintain

Recommended:

Protecting  and maintaining masonry by providing proper drainage so that water             does not stand on flat, horizontal surfaces or accumulate in curved  decorative features.

Cleaning masonry only when necessary to halt deterioration or remove heavy               soiling.

Carrying  out masonry surface cleaning tests after it has been determined that such cleaning is appropriate. Tests should be observed over a sufficient period of time so that both the immediate and the long  range effects are known to enable selection of the gentlest method possible.

 Cleaning  masonry surfaces with the gentlest method possible, such as low               pressure water and detergents, using natural bristle brushes.

 Inspecting painted masonry surfaces to determine whether repainting is necessary.              

 Removing damaged or deteriorated paint only to the next sound layer using the gentlest method possible (e.g., handscraping) prior to repainting.               

 Applying compatible paint coating systems following proper surface preparation.               

 Repainting with colors that are historically appropriate to the building and               district.

 Evaluating the overall condition of the masonry to determine whether more than               protection and maintenance are required, that is, if repairs to the masonry features will be necessary.

Not Recommended:

Failing to evaluate and treat the various causes of mortar joint deterioration such as leaking roofs or gutters, differential settlement of the building, capillary action, or extreme weather exposure.

Cleaning masonry surfaces when they are not heavily soiled to create a new             appearance, thus needlessly introducing chemicals or moisture into historic materials.

Cleaning masonry surfaces without testing or without sufficient time for the testing results to be of value.

Sandblasting brick or stone surfaces using dry or wet grit or other abrasives. These methods of cleaning permanently erode the surface of the material  and accelerate deterioration.

Using a cleaning method that involves water or liquid chemical solutions when there is any possibility of freezing temperatures.

Cleaning with chemical products that will damage masonry, such as using acid on limestone or marble, or leaving chemicals on masonry surfaces.               

Applying high pressure water cleaning methods that will damage historic masonry and the mortar joints.

Removing paint that is firmly adhering to, and thus protecting, masonry surfaces.               

Using methods of removing paint which are destructive to masonry, such as sandblasting, application of caustic solutions, or high pressure waterblasting.

Failing to follow manufacturers' product and application instructions when repainting masonry.

Using new paint colors that are inappropriate to the historic building and district.

Failing to undertake adequate measures to assure the protection of masonry features.

Masonry Repair:

Recommended:

Repairing  masonry walls and other masonry features by repointing the mortar               joints where there is evidence of deterioration such as disintegrating mortar, cracks in mortar joints, loose bricks, damp walls, or damaged  plasterwork.

Preparation for stucco repair.

Removing deteriorated mortar by carefully hand-raking the joints to avoid damaging the masonry.

Duplicating  old mortar in strength, composition, color, and texture.

Duplicating old mortar joints in width and in joint profile.

Repairing stucco by removing the damaged material and patching with new  that duplicates the old in strength, composition, color, and texture.               

Using mud plaster as a surface coating over unfired, unstabilized adobe because the mud plaster will bond to the adobe.

Cutting  damaged concrete back to remove the source of deterioration (often corrosion on metal reinforcement bars). The new patch must be applied carefully so it will bond satisfactorily with, and match, the historic  concrete.

 

Replacement                     stones tooled to match original.

 

Repairing masonry features by patching, piecing-in, or consolidating the masonry using recognized preservation methods. Repair may also include the limited replacement in kind--or with compatible substitute material--of  those extensively deteriorated or missing parts of masonry features when there are surviving prototypes such as terra-cotta brackets or stone balusters.

 Applying new or non-historic surface treatments such as water-repellent coatings  to masonry only after repointing and only if masonry repairs have failed to arrest water penetration problems.

Not Recommended: 

Removing nondeteriorated mortar from sound joints, then repointing the entire               building to achieve a uniform appearance.

Loss                     of the historic character due to insensitive repointing.

Using electric saws and hammers rather than hand tools to remove deteriorated mortar from joints prior to repointing.

Repointing with mortar of high portland cement content (unless it is the content  of the historic mortar). This can often create a bond that is stronger             than the historic material and can cause damage as a result of the differing coefficient of expansion and the differing porosity of  the material and the mortar.

Repointing with a synthetic caulking compound.

Using a "scrub" coating technique to repoint instead of traditional repointing methods.

Changing the width or joint profile when repointing.

 Removing sound stucco; or repairing with new stucco that is stronger than he historic material or does not convey the same visual appearance.             

Applying cement stucco to unfired, unstabilized adobe. Because the cement  stucco will not bond properly, moisture can become entrapped between    materials, resulting in accelerated deterioration of the adobe.               

Patching concrete without removing the source of deterioration.

Replacing an entire masonry feature such as a cornice or balustrade when repair of the masonry and limited replacement of deteriorated of missing parts are appropriate.

Using a substitute material for the replacement part that does not convey the visual appearance of the surviving parts of the masonry feature or that is physically or chemically incompatible.

Applying waterproof, water repellent, or non-historic coatings such as stucco to masonry as a substitute for repointing and masonry repairs. Coatings are frequently unnecessary, expensive, and may change the appearance of historic masonry as well as accelerate its deterioration.

Replace:

Recommended:

Replacing in kind an entire masonry feature that is too deteriorated to repair--if               the overall form and detailing are still evident--using the physical evidence as a model to reproduce the feature. Examples can include large sections of a wall, a cornice, balustrade, column, or stairway.  If using the same kind of material is not technically or economically  feasible, then a compatible substitute material may be considered.

Not Recommended:

Removing a masonry feature that is unrepairable and not replacing it; or               replacing it with a new feature that does not convey the same visual appearance