Stonework Renovation

Transcription

1 Stonework Renovation Cathedral Church of the Advent Birmingham, Alabama Stonework Committee: Dr. Thomas A. S. Wilson John C. Carraway Lowell K. Christy Bryan F. Helm John Morse Matt Owen Rick Carpenter

2 Background The Church of the Advent was constructed between 1887 and 1895 of Scioto sandstone from southern Ohio laid with lime mortar.!! Exacerbating the questionable choice of stones, numerous mechanisms of deterioration have taken their toll over the ensuing century. Birmingham's sulfurous air accelerated the decay of the stone. Previous attempts to patch or seal cracks have caused additional damage. Failed copings and overflowing gutters have allowed water into the walls.!! After researching various proposals to re-seal or "consolidate" the stone surface, it was determined that the only sensible approach would be to restore the walls to their original "breathable" condition by replacing modern cement in the joints with lime-based mortar.!! At the same time, flashings and copings would be replaced with new material. Water-shedding elements would be restored to function properly, and damaged stone would be thoroughly examined for structural dangers and replaced where necessary.!! Aesthetic renovation was not considered necessary as part of this project and, for the most part the condition of the walls has been stabilized and restored to proper function without regard to appearance. By nature, newly exposed gray surfaces should weather to the more consistent honey-beige color seen on the older faces.

3 1. Garden & Columbarium: The church was planning to add a Columbarium and wheelchair-accessible entrance in the Rector's Garden. We used that opportunity to inspect the foundations of the church, modify the surface elevations, and install a new drainage system for the garden. The Columbarium niches are fabricated from stainless steel embedded in concrete below the granite curb stones.

4 2. South Transept: Initial attempts to survey the wall conditions without erecting scaffold were ineffective. Diagnosis requires the whole team's ability to take a close look at each condition. The South Transept was the first area where we could really test out the restoration processes specified. We discovered serious shortcomings in the first attempt to place lime mortar. New copings were fabricated of stone from the original quarry and anchored onto the walls with stainless steel angles. Copper flashings add a layer of protection for the walls below

5 3. Carillon Installation: The donation of a carillon of bells was included in the restoration of the Bell Tower. A new concrete floor was installed for the bell chamber and the existing wood louvers replaced with bronze screening to allow the instrument to be seen and heard. The new floor, unprotected by louvers, is clad in lead-coated copper like the roof and sloped to safely drain water that blows into the openings. All of the interior brickwork was examined and found in need of restoration. The same process of repointing with lime mortar was followed.

6 4. Tower Restoration: Examination of the existing Bell Tower parapet revealed layers of tar under the plaster and lath. The brick inside was completely saturated. A majority of the stone merlons were in a dangerous state of disrepair. The existing wood roof structure was also damaged. Iron crimps secured the original parapet blocks to the brickwork. These were replaced with stainless steel anchor straps to prevent damage from corrosion. The finished tower roof is flat seam 20 oz lead-coated copper on a reinforced concrete slab with two drains and two overflows. The parapet also has lead-coated copper through-wall flashing and the merlons were rebuilt with new stone backs and tops. The corner finials were also replaced.

7 5. East Wall & Chancel: 2004 The roof drainage at each end of the East gable was redesigned to help conduct water quickly off the roof. The unused chimney was lowered to below the height of the gable and re-roofed. Flashings and gutters were repaired and new protective glazing installed over the stained glass. This "back" wall was built of smaller, lesser stones than the tower and nave walls. The coping was also in very bad shape. In addition to mortar restoration and coping replacement, flashings and gutters were repaired and new protective glazing installed over the stained glass. The new chimney roof, wall coping, and flashings are visible in this photograph. The portion of wall above the chimney was re-laid with salvaged stones from the demolished section.

8 6. West Wall & Narthex: 2005 A significant proportion of the stones making up these "eyebrow" mouldings over the arches needed to be replaced to restore proper water-shedding. The entire front parapet was in serious disrepair and was replaced with new stone and flashings. The roof behind the parapet is scheduled to be replaced with lead-coated copper and a new overflow drain will be installed. The front columns at the entrance to the church have been treated over the years with various patches and coatings. We have removed what we could without causing further damage and plan a judicious reshaping to preserve the original moulded detail. The carved capitals of these columns, on the other hand, are in phenomenal condition.

9 7. North Wall Drainage: 2005 Excavation of the North planting bed revealed that the foundation walls and footings were in very good condition. Some repointing of deteriorated mortar was carried out and the areaways were reconstructed. Because there is no storm sewer on 6th Avenue, all of the surface water has to be drained to the curb, limiting the depth of plantings in this bed. This engineered fill is compacted to form a relatively impermeable layer which slopes away from the building.

10 Conclusion We have gone to great lengths and have every expectation that the work done in the last five years puts the church in excellent condition for the next 100-plus years. - Your Stonework Committee