Roofs, Gutters and Chimneys

Roofs and rooftop features usually provide much of a building’s architectural character. For that reason, the Secretary of the Interior’s Standards generally require that their appearance remain unchanged. However, roofs also receive more wear and deterioration than other parts of a building. The Standards allow elements to be replaced if they are “beyond repair,” as long as the replacement matches the original in appearance and materials as much as possible. Guidelines on how to determine if roof components are beyond repair, and how to identify appropriate replacement materials, are provided on this page. 

 

This page also describes how to add new elements, such as mechanical equipment, to historic rooftops.  

Table of Contents:

1. Gutters and Downspouts
2. Replacement Roofing Materials
3. Eaves and Roof Shapes
   • Soffits and Fascia
   • Cornices and Decorative Trim
   • Dormers
   • Chimneys
4. Rooftop Structures
   • Penthouses and Mechanical Equipment
   • Antennas
   • Signs and Flagpoles
   • Decks and Furniture
5. Further Reading

Gutters and Downspouts

Gutter replacement is one of the most commonly approved items in Detroit’s historic districts.   

By definition, gutters are exposed to water, ice, and the elements, and typically wear out as the building ages. Consequently, their replacement, over time, is expected. New gutters should be of compatible historic materials—not vinyl—and match the location of the historic gutters. The color should match or complement the building’s trim color (see the page on Painting and Colors). 

At times, property owners may wish to add gutters that were not on the building historically. This is often acceptable, as long as the new gutters are concealed from view as much as possible and do not hide any architectural features. 

Despite the maintenance challenges that they can bring, box gutters and integrated gutters should always be repaired or rebuilt rather than eliminated.  

Flashing should always be replaced with matching materials—for example, copper should be replaced with copper. 

Replacement Roofing Materials

Asphalt shingle roofs

By far, asphalt shingles are the most common roofing material in Detroit’s historic districts. Their replacement after several decades is expected and generally approved. When they are replaced, the new shingles must be of a similar appearance to the old ones, but an exact match is not required. The color does not need to be the same, but it should not look out of place on the building or within the district.  

An application for replacement roofing must always include the color, materials, and dimensions of the proposed replacement. This can be done by including a product brochure, screenshot, or website link. 

Reroofing also often involves adding new roof vents or changing or moving plumbing stacks. This is generally acceptable if the new items are not too prominently visible. 

Replacing slate, tile, and wood shingle roofs

Many original slate and tile roofs are still present in Detroit’s historic districts. These are extremely important to the character of a building and, once lost, are irreplaceable. Wood shingle roofs are very rare, and also very important. For this reason, these roofs must be repaired rather than replaced whenever possible. Damaged or missing shingles or tiles should be replaced with matching, historic material. 

Slate roofs, especially, usually last about 100 to 150 years, which means that many of Detroit’s historic roofs are now reaching the end of their lifespan. Once about ten percent or more of the tiles are broken or missing—and especially if the secking or structure beneath has failed—repair of the roof becomes impractical and replacement of the entire roof surface may be needed. 

When replacing a slate, tile, or wood roof, replacing with the historic material is the best option and must be considered first. However, sometimes there are good reasons for replacing the roof with a material other than the original. Historic materials may no longer be available, there may be a lack of trained installers, or historically appropriate replacement may be cost prohibitive. (However, just because something is expensive does not mean that it is infeasible. On highly visible or distinctive roofs, or particularly prominent or significant buildings, replacement with original materials may be required regardless of the additional expense.) 

The Secretary of the Interior’s Standards direct the Historic District Commission to consider financial and technical feasibility. It is helpful for the applicant to include the following information when proposing to replace a slate, tile, or wood roof with a different material: 

• Two or more repair estimates from experienced roofing contractors, or statements as to why repair is not recommended. 
• Two or more estimates for replacement with matching, historic material (slate, tile, or wood). 
• A cost estimate for the proposed replacement with new materials (such as asphalt shingles or synthetic materials). 

When replacement with a different material is proposed, either asphalt shingles or a synthetic material should be chosen to match as closely as possible the scale, texture, and color of the original material. 

An application for replacement roofing must always include the color, materials, and dimensions of the proposed replacement. This can be done by including a product brochure, screenshot, or website link.  

Eaves and Roof Shapes

Elements that define the roofline of a historic building—eaves, fascia, decorative cornices, dormers, and chimneys—are important aspects of a building’s historic character. At the same time, their exposure to the elements often subjects them to deterioration to the extent that they must be repaired or, sometimes, replaced. 

Soffits and Fascia

The historic appearance and materials (usually wood) of soffits and fascia should be a guide for any repair or replacement. Vented vinyl soffits, though common in new construction, are almost never appropriate in historic districts, even on additions. Wood soffits, with vents located in unobtrusive locations if needed, are appropriate on most historic buildings. 

Cornices and Decorative trim

At the eaves, atop a parapet, or just below the roofline, historic buildings often feature ornate trim that is decorative rather than functional. Examples include the dentils and capitals on Classical buildings or brackets on Arts and Crafts or Craftsman houses.  

Due to their exposed, and sometimes ornate, nature, these items often deteriorate more quickly than other parts of the building, especially if they are not maintained through periodic cleaning and painting. Missing decorative trim should always be replicated with new elements that exactly match the measurements of the original. 

Dormers and Parapets

Projections such as dormers and parapets are an important part of a building’s overall shape, form, and character. Historic roof projections should be maintained and never removed. 

Likewise, it is usually not appropriate to alter the shape of a roof with new dormers or other projections. If they are added, they should be compatible with the architectural style of the building and located where they are not highly visible. Skylights, solar panels, and similar features can sometimes be added if they are hidden from view, such as on the sides or rear of a house, or out of sight on a flat roof. (See Signs, Lighting, and Other Work Items for more information on adding rooftop elements.) 

Chimneys

Repair of chimneys is usually limited to repointing (sometimes called tuckpointing) to replace mortar that has eroded away over time. Although this work is encouraged, the type of mortar and joint use will have a profound effect on the appearance of the building. A flush joint or concave joint, which fill the joint with a maximum amount of mortar, will cause the joints to stand out and give the entire chimney a bright, smooth, appearance that detracts from the building as a whole and is rarely appropriate for a historic building. Struck joints or weathered joints, where the mortar is recessed, are more common. 

Also, the use of incorrect mortar can cause damage to the brick. The correct mortar varies by building and location and can be determined by a professional mason. On most of Detroit’s older buildings, Type M and S mortars and masonry cement will cause the bricks to fall apart over time. 

Sometimes, a property owner wishes to remove a chimney entirely rather than undergo the expense of repairs and ongoing maintenance. This is usually not acceptable, as chimneys are an important part of a building’s architectural character. However, it is sometimes acceptable to remove or rebuild a non-prominent chimney, such as a utility chimney that is not easily seen from the ground. 

For additional guidelines on masonry and mortar, see Walls and Siding. 

Rooftop Structures

Especially on large-scale commercial and apartment buildings, rooftops are often the location of both historic features, such as signs, and newly added elements, such as rooftop decks and mechanical equipment. 

Signs, Flagpoles, and Other Historic Figures

Historic rooftop structures—even if they are not integral parts of the building—can often be of equal importance to the historic buildings upon which they sit. This is particularly true if such features are decorative in nature or if they express the historic function of the building, such as a flagpole on a civic or office building or a hose tower on a fire station. Such character-defining elements should always be preserved, even if the building is converted to a new use for which the structure is no longer needed.  

Historic, roof-mounted signs can also be of outstanding importance. For guidelines regarding signs, see Signs, Lighting, and Other Work Items. 

Decks and Furniture

Rooftop decks, railings, furniture, and lighting are sometimes installed to provide outdoor amenities on flat-roofed commercial or apartment buildings. Rather than extending up to the edge of the roof, these items should be set back to minimize their visibility from below. The exact distance of the setback will depend on the height of the features to be installed, as well as the surrounding environment. 

Penthouses and Mechanical Equipment

Adding mechanical equipment such as elevator penthouses or heating or air conditioning units to a roof is usually acceptable if it is inconspicuous, not visible from the ground, and does not damage any important historic features. Adding new rooftop equipment is particularly common on flat-roofed commercial or industrial buildings when rehabilitating them adapting them to a new use.  

Antennas

Communications antennas on historic buildings can range from small, household TV or satellite antennas to large telecommunications towers installed by utility companies. The Antenna and Satellite Dish Guidelines, adopted by the Historic District Commission in 2012, require such antennas to be located where they are not visible from the street, concealed as much as possible with painting or screening, and installed in a way that does not damage historic components of the building. More information on antennas is available on the Signs, Lighting, and Other Work Items page. 

Rooftop Additions

It is sometimes acceptable to adding an entirely new floor to a building. See New Buildings, Additions, and Demolitions.

Further Reading

National Park Service Preservation Brief 2: Repointing Mortar Joints in Historic Masonry Buildings

National Park Service Preservation Brief 4: Roofing for Historic Buildings

National Park Service Preservation Brief 19: The Repair and Replacement of Historic Wooden Shingle Roofs

National Park Service Preservation Brief 29: The Repair, Replacement, and Maintenance of Historic Slate Roofs

National Park Service Preservation Brief 30: The Preservation and Repair of Historic Clay Tile Roofs