Historic Zoning Commission

Knollwood Individual H Landmark: Level II

6-B-22-HZ

Applicant Request

Comprehensive exterior rehabilitation, new secondary structure, and modifications to site design.

Repair scopes include:
- Repair and restoration of existing double-hung, one-over-one windows. Window repair to meet Secretary of the Interiors Standards for window repair. Installation of new pre-finished aluminum storm windows, custom built to fit existing openings, with meeting rails to align with meeting rails of existing windows.
- Repair to existing wood lintels, sills, and decorative medallions, including replacement in-kind to those elements which are deteriorated.
- Removal of non-original wood louvered shutters on the façade (south elevation) and installation of new shutters. See application packet for materials and design of shutters and shutter dogs; applicant proposes custom-made, smooth-finished, V-groove panel shutters with a decorative cut-out (applicant notes the cut-out is optional) made of Boral composite material, featuring simple shutter dogs appropriate for era of house.
- Removal of asphalt shingle roof and installation of new slate roof with copper flashing, new copper half-round gutters, and downspouts. Due to weight of slate roofing materials, roof repair will also require reconstruction of the roof with a structural steel frame. Original roofline will be maintained.
- Repair to existing dentiled wood cornice.
- Repair and repointing to any compromised mortar joints. Masonry restoration will also include removal of salmon-colored paint/stain on exterior brick through dry ice blasting.
- Repair to wood front door, transom, and sidelights.
- Repair as needed to front porch columns. Column work also includes raising the column torus (decorative raised base) to add 2" to existing concrete base, to accommodate new Tennessee marble terrace.
- Brick chimneys to be repointed or rebuilt from the roofline up, pending conditions assessment. Salvageable original brick will be saved and reused to reconstruct the chimneys. The reconstructed chimneys will reuse the first line of existing corbelling and add three courses of simple brick corbels to the top.
- New copper chimney flue caps (see two options in page 9 of application packet - louvered, flat copper chimney caps or half-barrel chimney caps).

New elements on primary structure include:
- Installation of one new window on first story, right (east) elevation, towards rear. New window will be vertically and horizontally aligned with existing windows, and feature a design, materials, and dimensions to match the existing (including wood lintel and sill).
- Installation of new entry on right side (east) elevation (currently a window). Half-light door will feature a header aligned with the adjacent sunroom headers, a transom, and sidelights.
- Reconstruction/opening of east (right side) sunroom. Sunroom was originally an open air porch and enclosed with wood single-light windows and lap siding. Concrete plank flooring, round wood columns, and roof joists are deteriorating and declared unstable by a structural engineer. Porch will be reconstructed with matching footprint and new roofline, roof details, columns, and balustrade to match the existing.
- Modification to sunroom on right side (east) and rear (north) elevation. Sunroom was enclosed with glass storefronts and wood lap siding; non-historic glass and wall enclosures will be replaced with paired French doors alternating with sidelights and transom windows. Original posts, decorative brackets, and roofline will be retained and repaired.
- Installation of new balustrade on flat-roof section of primary roofline. "Maintenance mezzanine" will be created with Trex decking and a simple 48" tall black iron railing.
- Two new dormers on the façade roof slope. Dormers would flank the front portico and match the existing c.1851 dormers on the east and west roof slopes in design, window proportions, and materials.
- North (rear) second-story balcony to receive a new exterior door, with new balustrade to match existing original balusters elsewhere on the house. New Trex decking on balcony.
- Replacement of rotted wood louvered vent on west elevation dormer with a copper louvered vent to match existing in dimensions, placement, and design.
- Replacement of low-slope TPO roof on north sunporch with a copper roof.
- New exterior light fixtures (see specifications in application packet).

New secondary structure (carriage house):
- New carriage house to be located in the northeast corner of the property. Carriage house will feature a primary hipped-roof massing, with two smaller hipped-roof massings projecting to the sides. Carraige house will be clad in a brick complimentary to main house, featuring one-over-one windows and trim details compatible with the primary house. Carriage house project also features a security gate for vehicular entrance and small hipped-roof gatehouse structure.

Site work includes: new landscaping and garden areas, new Tennesee marble steps accessing the porte cochere area, and a new Tennessee pink marble terrace on the façade elevation. New ramps for accessibility. New masonry "grotto" structure near east site stairs, integrated with existing and new hardscaping. See landscape drawing (sheet 1) for new site design, parking area, and landscaping elements.

CONDITIONS APPROVAL PER 6.21.22 HZC MEETING:
1) All brick masonry repair and paint removal to meet standards of NPS Preservation Brief 2;
2) Meeting all relevant standards of the City zoning code for off-street parking and landscaping;
3) Final site plan to meet City Engineering standards, with minor revisions to be approved by staff
4) and providing final details on carriage house windows and doors to staff for approval.

Site Info

See attached designation report and design guidelines for architectural description of house.

1. Knollwood is individually listed on the National Register of Historic Places and protected by a landmark H overlay.

REPAIR SCOPES
2. The application includes a significant amount of repair which clearly meets the design guidelines, including: repair and restoration of existing windows; repair and replacement in-kind to wood lintels, sills, and detailing; repair to the wood cornice; masonry repointing; repair to the front portico columns; and repair to the front door, transom, and sidelights.

3. The proposed new shutters replace non-original, deteriorated wood louvered shutters on the façade. The application includes a flat-panel design and a smooth-finished, Boral (composite) material for ease of maintenance and longevity of materials. In the opinion of staff, the proposed alternative material can sufficiently mimic the visual qualities of wood if it's smooth-finished and painted. The Commission should discuss the flat panel design and cut-outs versus louvered panels, taking into account SOI Standard 6.

4. Repair to, and reconstruction of, the brick masonry chimneys is appropriate within the guidelines. The proposed additional corbels of brick at the top are simple in design and will not detract from the overall design of the house. Both options of copper chimney caps (flat or half-barrel) shown in the application would be appropriate for the style of the house.

5. The applicants have researched methods to remove the salmon-colored paint/stain from the exterior brick "using the gentlest means possible" (SOI Standard 7) and selected the dry ice blasting process. Removal of the patchy/irregular stain is appropriate. Masonry repointing and paint removal should meet the standards of NPS Preservation Brief 2.

6. The applicant notes that the roof originally featured a slate tile roof; removing the asphalt shingles and installing a new slate roof meet the design guidelines. While the lower-slope copper roofing elements, flashing, and gutters may not have existed on the building originally, copper is a compatible material with slate and brick and appropriate for the periods of the house. The copper elements will be minimally visible from the public right-of-way and will patina to blend with the brick and slate.

NEW ELEMENTS ON PRIMARY BUILDING
7. The proposed installation of one new window on the first-story, right side elevation will not be visible from the public right-of-way. The design features materials and placement to reflect the existing windows on that elevation, and is a relatively minimal change.

8. The proposed installation of a new entry door on the right side elevation, towards the rear, will also not be visible from the public right-of-way and will activate use of the site on all elevations. Other design guideline documents discourage modifying secondary entrances to make them appear to be more formal entrances by adding sidelights and transoms, and note that secondary entrances must be secondary in importance. Due to the substantial front portico and design of the house, the front entrance is clearly the primary entrance to the building. However, the Commission may choose to discuss the design of the side elevation door.

9. The application includes the reconstruction/opening of the right side sunroom - opening it back to an open air porch. The National Register nomination for the property notes that "one-story portico wings with balustraded deck roof were attached to the [side] elevations in 1919." Neither the nomination nor the design guidelines' architectural description attribute a date to the porch's enclosure. While the enclosed porch may have acquired significance in its own right, evaluations and investigatory demolition have shown the sunporch to be structurally unsound. Reconstructing the east sunroom as an open air porch will maintain the original design's transparency and use materials and details compatible with the original house.

10. The application also includes work on the rear sunroom. While the proposed repeating French doors and sidelights are distinct from the original design, the work is proposed for the rear elevation and will not be visible from the right-of-way. The design will retain the general amount of transparency, and the original wood posts, brackets, and roofline will be retained.

11. The proposed roofline balustrade for the "maintenance mezzanine" lacks a historic precedent from this house. While an iron railing is thin in profile and visually modest in design, the upper deck would be visible from the public right-of-way. The Commission should discuss the visual impact of the iron railing and if it meets SOI Standard 3.

12. The two dormers proposed for the façade roofline are conjectural features which do not meet the design guidelines, as there were never dormers installed on the front roof slope.

CARRIAGE HOUSE
13. The proposed carriage house meets the Knollwood Design Guidelines for placement, which encourage any new buildings built on the site maintain the visual connection between Knollwood and Kingston Pike, and be constructed to the rear of the house when possible to "frame the house and provide background texture for it." The carriage house will locate utilities and service functions outside of the primary house, allowing the main house to serve a function closer to its original use.

14. The proposed carriage house will be clearly secondary to the main house and feature complimentary materials and design. The accompanying fence and gate house are minor in size and will not be visible from the public right-of-way.

15. New construction to the rear "should be accompanied by tree plantings that shall further screen the buildings into the background." The landscaping plan includes the retention of numerous existing maple and crepe myrtle trees which will serve as screening for the carriage house.

16. The proposed site work elements, including the incorporation of new Tennessee marble terraces, garden walkways, and steps, are appropriate within the design guidelines and will further enhance the site.