Few things can alter the appearance of a historic structure more quickly than an ill-planned addition. Additions can not only radically change the appearance of a structure to passersby, but can also result in the destruction of much of the significant historic material in the original structure. New additions within an HPOZ are appropriate, as long as they do not destroy significant historic features, or materials, and are compatible with both the neighborhood and the building to which they are attached.

Careful planning of additions will allow for the adaptation of historic structures so that they may meet the demands of the current owner, while preserving their historic character and materials, and ensuring compatibility with the surrounding streetscape. The following guidelines apply to additions planned for Contributing structures in the HPOZ. Additionally, because additions to Non-contributing structures  can  have an equally negative impact to the surrounding context, guidelines that involve site planning, mass, height and roof forms also apply to Non-Contributing structures and sites.



While additions to primary structures may be appropriate, special care should be taken to ensure that the addition does not disrupt the prevailing architectural character of the district or of the structure itself. Additions that are small in size, located to the rear of existing structures, and  that  replicate  existing  building  patterns  such  as  roof forms and fenestration, tend to be more  successful  than  those that do not. Great care should be taken with additions so as not to communicate a false sense of history within the district with respect to the size and arrangement of structures. For example, a massive second-story addition that maximizes buildable floor area on a single story Craftsman bungalow in a district comprised of similarly sized single-story Craftsman bungalows would be inappropriate regardless of whether or not the addition is adorned with historic appearing architectural features.


1. Additions should be located at the rear of the structure, away from the street-facing architectural façade.

2. Additions that break the plane established by the existing rooffline or side facades of the house are discouraged.

3. Two-story structures in Jefferson Park are rare. Additions that comprise a new floor (for instance a new second floor on a single- story house) are discouraged. Where additions that comprise a new floor can be found appropriate, such additions should be located to the rear of the structure.

4. Additions should use similar finish materials and fenestration patterns as the original structure. A stucco addition to a wood clapboard house, for example, would be inappropriate.

5. Additions should utilize roof forms that are consistent with the existing house to the greatest extent possible, but should be differentiated by virtue of scale and volume. Attention should be paid to eave depth and roof pitch replicating these to the greatest extent possible.

6. The original rooflines of the front facade of a structure should remain readable and not be obscured by an addition.

7. Additions should distinguish themselves from the original structure through the simplified use of architectural detail, or through building massing or subtle variations of exterior finishes to communicate that the addition is new construction.

8. Enclosure of part or all of a street visible historic porch is discouraged. However, enclosures that are comprised primarily of glazing (windows), that do not obscure or remove important porch features such as piers, balustrades, columns and  roof forms,  that do not involve removal of original exterior walls, doors or windows and that are not disruptive to the surrounding streetscape may be considered through a Certificate of Appropriateness.

9. The enclosure of rear porches, when found to be appropriate, should preserve the overall look of the porch to the greatest extent possible with respect to railings, balusters, openings and roofs, and should use reversible construction techniques.

10. Additions should utilize fenestration patterns that are consistent with the existing house to the greatest extent possible, though simplified window types may be an appropriate means to differentiate the addition from the original structure. For instance, if windows on the original structure are multi-pane 8-over-1 light windows, simple 1-over-1 light windows may be appropriate.

11. Additions should be subordinate in scale and volume to the existing house. Additions that involve more than a 50% increase in the ground floor plate are generally inappropriate.

12. Additions that extend the existing side facades rearward are discouraged. Additions should be stepped-in from the side facade.

13. Decorative architectural features established on the existing house should be repeated with less detail on the addition. Exact replicas of features such as corbels, pilasters, decorative windows etc. are inappropriate.

14. Additions that would necessitate the elimination of significant architectural features such as chimneys, decorative windows, architectural symmetry or other impacts to the existing house are not appropriate

15. Additions that would involve the removal or diminishment of open areas on Multi-family properties, such as the infill of a courtyard to be used for floor area, are inappropriate.

16. Additions that would require the location of designated parking areas within the front yard area are inappropriate.



Garages and accessory structures can make an important contribution to the character of an historic neighborhood. Although high style “carriage houses” did exist historically, garages and other accessory structures were typically relatively simple structures architecturally, with little decorative detail. Quite often these structures reflected a simplified version of the architectural style of the house itself, and were finished in similar materials.

Unfortunately, many historic garages and accessory structures have not survived to the present day, perhaps because the structures were often built flush with the ground, without a raised foundation. Therefore, many homeowners in historic areas may need to confront the issue of designing a new secondary structure.

For the rehabilitation of existing garages and accessory structures, follow the same guidelines throughout this as you would for the rehabilitation of a residential structure. The guidelines in this section are specifically targeted towards the addition or reconstruction of accessory structures on historic properties. I t will also be useful to consult the Setting guidelines of this Plan to determine the placement, dimensions, and massing of such structures on lots with existing historic buildings.


1. New accessory structures and garages should be similar in character to those which historically existed in the area.

2. Basic rectangular roof forms, such as hipped or gabled roofs, are appropriate for most garages.

3. New garages or accessory structures should be designed not to compete visually with the historic residence.

4. Detached garages are preferred. Attached garages, when found  to be appropriate should be located to the rear of the house unless the

5. HPOZ consists of homes that have a preponderance of street-facing garages.

6. New garages should be located behind the line of the rear wall of the house whenever possible.

7. New accessory structures, such as greenhouses, porches or gazebos should not take up more than 50% of the available back yard area.

8. Single-bay garage doors are more appropriate than double-bay garage doors on most historic properties.

9. Second floor additions to garages or carriage houses, when found to be appropriate, should not be larger than the length and width of a standard three-car garage.

10. Accessory structures should always be diminutive in height width and area in comparison to the existing primary structure.

11. Accessory structures should replicate  the  architectural  style  of  the existing house with respect to materials, fenestration, roof patterns etc., though architectural details such as corbels, pilasters or molding should be replicated with less detail on accessory structures.

12. Modifications to existing garages, carriage houses or accessory structures that would involve a loss of significant architectural details pursuant to the Rehabilitation Guidelines should be avoided. Special attention should be paid to preserving existing historic garage doors where they exist.