Historic Zoning Commission

Old North Knoxville H: Level II

1-F-21-HZ

Applicant Request

Removal of original slate roof and replacement with new architectural shingle roof. Proposed replacement material is CertainTeed Grand Manor architectural shingles in Colonial slate.

Site Info

One-story frame residence with smooth stuccoed wall covering. House features a hipped roof with irregularly laid slate covering. Paired eight-light casement windows. Designed by Charles Barber.

1. 518 W. Glenwood Avenue is a contributing resource to the ONK National Register Historic District and local overlay. The house is a unique Charles Barber design in which the original roof is the major character-defining feature.

2. Most past HZC reviews of replacing original slate roofing materials with asphalt shingles have occurred in the Edgewood-Park City overlay. Most recently, Commission discussion regarding 1806 Washington Avenue (4-E-14-HZ) focused on the slate tiles being between 115-120 years old, reaching "the end of its functional life." This review also noted that "there is evidence within the district of an evolution of slate roofs to shingles, as the slate has deteriorated due to age and become very expensive to replace." At 1111 Luttrell Street in Fourth & Gill (8-B-02-HZ), asphalt shingles were approved as a replacement for slate with the condition that all roof ornamentation be reused on the shingle roof.

3. ONK slate roof precedent includes the replacement in-kind of a slate roof at 505 E. Scott Avenue (6-C-12-HZ), and projects in 2003 and 2012 at 222 E. Oklahoma Ave, where an asphalt roll roof was applied over the remnants of an existing slate roof prior to the overlay. There was not enough salvageable material to re-use for even partial re-roofing with slate, so all asphalt roll and slate were removed and replaced with asphalt shingles.

4. The slate roof is original to the structure, which was constructed in approximately 1925. The property owner has provided documentation of past repair efforts, including at least eight rounds of minor repair since purchasing the property in 1996. The original roof has not been neglected.

5. NPS Preservation Brief 29 notes "the relatively large percentage of historic buildings roofed with slate during the late nineteenth and early twentieth centuries means that many slate roofs, and the 60 to 125 year life span of the slates most commonly used, may be nearing the end of their serviceable lives at the end of the twentieth century." SOI Standards recommend replacing with materials "that match the old in design, color, texture and other visual qualities, and where possible, materials." Previous reviews of new slate roofing focus on the cost-prohibitive and labor-intensive nature of a new slate roof.

6. ONK Guidelines note that roofing materials shall duplicate roofing materials originally found in the neighborhood, including asphalt shingles, slate, etc, with a dark color to simulate the original roof colors, and that roofs visible from streets shall retain their original shapes. The submitted material does meet these guidelines.

7. The applicant has submitted material specs for the proposed replacement material, a high-end architectural shingle noted on its website as "intended to mimic slate roofing." The shingles use "random tabs accented by shadow lines" to "create a look of depth and dimension." The color is a dark grey "Colonial slate" color. While the texture and unique placement of the original slate shingles can't be replicated with a synthetic shingle, the proposed replacement is an adequate selection.