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

A roof is the primary horizontal surface that protects a building (and its occupants) from rain, snow, sunlight and wind. It offers stability and shape to a building, as well a decorative feature due to its shape/massing, pitch (angle) and material. A roof and its supporting system is comprised of many components; elements that define the roofline of a historic building, in addition to the roofing material —eaves, fascia, decorative cornices, dormers, and chimneys—are important aspects of a building’s historic character. 

Roof Shapes - the most common roof shapes are listed here:

Gable (front- and side-facing)

Dutch Gable

Hip / Pyramid Hip

Gambrel

Shed

Flat

Parts of a Roof - Image here

Parapets and Dormers

Parapet

A parapet is a low masonry wall that extends above the surface of a roof. Historically, parapets ranged from 12 inches to many feet in height. The reason to include a parapet on a building is to hide rooftop projections (such as skylights, elevator/mechanical equipment), provide safety for workers and/or building occupants, as well as additional exterior wall surface for decorative features for the building (such as a cornice). 

The top surface of a parapet is covered by "coping", which is a protective, sloped cover designed to prevent water from entering the wall structure. Common materials include sheet metal (aluminum, copper), stone, concrete, or terra cotta. It is installed over a membrane to ensure water sheds toward the roof and drains, gutters and downspouts. 

Dormer

A dormer is a structure that extends vertically from a roof surface. It typically contains one or more windows, sometimes a vent, and always has a roof and walls. Dormers allow more light, and sometimes ventilation, into an interior living space. They might also increase the ceiling height of a room. They can be large or small, and are generally designed with materials and roof shapes that compliment the architectural style of the building. 

If dormers are added to an existing roof, 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.) 

Projections such as dormers and parapets are an important part of a building’s overall shape, form, and character and are generally distinctive character-defining features of a structure. Historic roof projections should not be removed; rather they should be maintained, repaired if needed, or replaced in-kind (if confirmed they are deteriorated beyond repair).  

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 dentils and capitals on Classical buildings or brackets on Arts and Crafts or Craftsman houses.  

Eaves: Soffit/Fascia

An eave is the end of the roof that overhangs the building's walls. The outer surface facing the street/yard is the fascia; the underside surface (facing the ground) is the soffit. Where the eave meets the building walls, depending on the building's architectural style, decorative (and sometimes structural) components, such as dentil trim, brackets or corbels, are installed here. Eaves can be shallow or extend a great distance from the building walls. The wider a roof's overhang/eave, the more protection it provides the building (exterior walls and windows and interior room temperatures) from sun, snow, rain and ice. 

Soffits and fascia were historically constructed of wood, with a painted finish. The historic appearance and materials of soffits and fascia should be a guide for any repair or replacement. Vented vinyl or aluminum soffits, though common in new construction, are almost never appropriate in historic districts. Wood soffits, with vents located in unobtrusive locations if needed, are appropriate on most historic buildings. 

Gutters and Downspouts

Gutters collect water running down the roof. They are horizontal fixtures and are attached at the outside edges of a roof on the fascia board. 

Downspouts are connected to the gutters and carry the water from the roof(s) down the side of the building. They are attached vertically to the building and should be positioned at the ground to release the water away from the house. 

Gutters and downspouts are commonly fabricated from aluminum, steel, and copper. The most commonly available gutter is the "K-style" gutter; however, half-round gutters (which were the most common shape in the early 20th century) are also available for use on historic and new houses. 

Downspouts should be placed in areas where they do not cover distinctive features of a building. Due to their exposure to water, ice and debris, 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 or masonry wall material (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 nor alter distinctive, character-defining 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. 

Roofing Materials

Clay 

Clay tiles are a highly distinctive, decorative roofing material due to the variety of shapes, profiles, colors, patterns and textures. Clay tile has one of the longest life expectancies among historic roofing materials, typically 100+ years. Tile roofs were often used with early 20th century architectural styles, including Mission, Spanish, Mediterranean, Georgian and Renaissance Revival. 

Clay tile roofing systems most commonly fail due to the breakdown of the material's fastening system, metal flashing, gutters (if not regularly cleaned, accumulated debris cause the water to back up and seep under the roofing tiles), and/or support system. 

Slate 

Slate is a natural forming material extracted from a quarry, and can last 60 - 125+ years, depending on the type of slate installed. The color, thickness, surface pattern/profile for slate tiles is incredibly varied. Historically, three types of slate roofing - standard, textural, and graduated - were available according to the architectural effect desired.  Standard - uniform appearance with consistent length, width and a smooth surface. Textural roofs incorporate slates of different thicknesses, colors, and a rougher texture. Graduated roofs use slate tiles of differing sizes, thicknesses and/or exposure (starting with the thinnest/smallest slates at the top (ridge) of the roof, and ending with the thickest and largest slates at the eaves/bottom roof edge).

The durability of a slate roof depends on the following factors: physical/mineral properties of the slate; the way in which it was fabricated/quarried, how it was installed, and regular/timely maintenance. Natural weathering is a slow process where the edges of the slate will chip away. 

Wood

Wood shingle roofs were a popular roofing material in the early 20th century. The size, shape and finish of the shingle determines the roof's texture, scale, and installation patterns. Due to their limited life span (very short when compared to clay and slate) of 15 to over 60 years, most historic wood roofs were replaced decades ago.

Asphalt

The mass production of this man-made product increased dramatically in the early 20th century and became a popular alternative (as well as replacement material) for wood roofs (which had a higher fire risk). Early shingle roofs were installed as single pieces and had varying shapes such as square, rectangular and diamond. 

Other - Metal, etc. 

A regularly scheduled maintenance program is necessary to prolong the life of any roofing system. 

Replacement of Existing 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

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. 

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. 

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.

Additional Information

National Park Service 

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

U.S. Department of Energy - Building America Solution Center

Roofs and Attics

HDC Staff Review Authority - More Information 

Administrative/General

In-kind* repair, contingent upon staff determination that such repair work is consistent with the Secretary of the Interior’s Standards for Rehabilitation; and, in-kind replacement, contingent upon staff determination that such replacement work is consistent with the Secretary of the Interior’s Standards for Rehabilitation; and specifically that the level of deterioration of any individual feature, element or assembly proposed for replacement is severe enough to be beyond reasonable repair per Standard 6.

   *“In-kind” is defined as faithfully reproducing original, historic, or documented character-defining features, elements, and assemblies with respect to design, color, finish, texture, craftsmanship, materials, relationship to other elements or spaces, and other visual qualities.

Removal of incompatible, non-historic, or historically inappropriate siding, finishes, or elements on any part of a resource, including but not limited to types of asphalt siding meant to convey an artificial “brick” appearance; e.g., “Insul-Brick”.

Removal and replacement of incompatible, non-historic, or historically inappropriate elements, including windows, doors, and storefront systems, on any part of a resource, with historically appropriate replacements.

Other work affecting only non-primary elevations/roof areas* not otherwise subject to public hearing under Section 21-2-77. 

Non-contributing resource: All work (not otherwise subject to public hearing-additions, demolition, new construction) is approvable by its staff under the condition that it is compatible with the massing, size, scale and architectural features to protect the historic integrity of the district and its environment. 

The Commission defines the term primary elevation to mean any street or public-facing elevation or roof area of a building (including side elevations along streets, but not alleys) and any additional elevation hosting the principal entrance to a building, if not already facing a street; and specifically excludes the sides of a building from being considered a primary elevation due only to increased visibility caused by any condition, current or proposed, on an adjacent parcel not under the same ownership.

*The Director (or their Deputy) shall continue to have the ability to refuse administrative approval and refer any administratively approvable scope to the Commission for disposition, regardless of staff authority pertaining to the proposed work. 

Roof/Gutters/Chimney

Antenna/Satellite Dish

Antenna and satellite dish installation provided the design and location meets the guidelines in the Historic District Commission’s Antenna and Satellite Dish Guidelines. 

Installation of new cellphone antennas and associated equipment at a building rooftop provided that the new cellphone antennas and associated equipment is finished the same color of the exterior surface to which it shall be affixed, and it is minimally visible from the direct right-of-way. 

Gutter/Downspouts

Gutter and downspout replacement, provided that: 

• quality materials like copper are not being removed and replaced, and 

• the design of gutters and downspouts closely resembles the original, and the routing of the downspouts is either the original or not so placed as to be intrusive in the design of the building, and 

• the colors meet the terms and conditions of the Detroit Historic District’s Style & Color Guide. 

Roofing

Re-roofing of an asphalt shingle roof with new asphalt shingles, provided that the shingles are of a color and texture resembling historic roofing materials used in the district and/or on the building in question. 

Replacement of an asphalt shingle roof with a wood shingle, tile or slate roof provided the owner or contractor can substantiate that wood shingles, tile or slate originally existed on the roof. 

Replacement of non-historic age asphalt roof shingles with new asphalt shingles under the condition that the design, dimension, profile, and color of the new/replacement asphalt shingles are compatible with the district’s Elements of Design and the building’s historic appearance. 

Replacement of siding on rooftop dormer walls or rear/side elevation walls, where non-historic synthetic siding, asphalt shingles, or other non-historic materials are present, with new cladding to include stucco, wood shake, horizontal clapboard/lapped wood siding (of 5/8-inch or more thickness in profile) or horizontal lapped composite siding (with a smooth finish and of 5/8-inch or more thickness in profile);

Skylights

Installation of new rooftop skylights, on the condition that:

• the new skylights are installed on a rear-facing roof surface, are low profile, and display a finish color that matches the existing roof covering,

• the installation must not result in the removal of historic roofing.

Solar Panels

Installation of solar panels, on the condition that: 

• the solar panels are installed in areas with limited to-no visibility to the public right-of-way, 

• roof-mounted panels shall be flat-mounted, located on a rear roof elevation and/or garage, with adequate distance from roof edges and ridge,

• panels shall have a matte, dark finish consistent with the color of the existing roofing material, 

• wall-mounted panels won’t cover existing architectural features, nor damage existing wall materials, 

• ground-mounted panels shall be located in the rear yard, and

• the installation(s) shall comply with the National Park Service, Technical Preservation Service document, Incorporating Solar Panels in a Rehabilitation Project (ITS Number 52).