Type: Single Family Housing
PROJECT OF THE YEAR: FIREPLACES
Architect: Vincent P. Guntlow Associates
Masonry Contractor: Deer Hill Masonry
General Contractor: Geary Builders
Masonry Supplier: American Granite
Stephen Bushway of Deer Hill Masonry was contacted by Geary Builders of Cheshire, MA to design stone fireplaces for a client’s timber frame addition in Williamstown, MA in the fall of 2007. Owner Jim Geary has a reputation for high end projects in North County and this was no exception.
Architect Morris Schope of Vincent P. Guntlow Associates in Williamstown, MA designed the ballroom addition with a 12 ft wide fireplace centered in the room, 7 ft in from the far end. The ceiling is 11 ft and graced with four massive octagonal Douglass Fir posts recycled from a closed quarry in Quincy, Mass. Several rendering sketches were done, and the team soon realized the large mass and space required an equally massive look for the stonework.
A four ft square firebox with flush hearth was chosen to give the visual appeal desired without risking undue challenges of a bigger firebox, for the HVAC contractors relative to make-up air requirements. The design also provided an air intake at the front of the firebox supplied by the basement. To ensure that the building would be able to supply enough air for proper venting, the stress skin clad building would be equipped with a self balancing air handler.
The fireplace face was to be a single lintel stone over post stones, which Bushway selected from a quarry in Warrensburg, NY. He was able to find enough split faced stones for the first floor fireplace, the wood box floor, and stock for the bedroom fireplace at 2/3 scale, which he later split to width with feathers and wedges. The rest of the 26 tons of veneer was mostly “square and rectangular” with a few ton each of “ledge stone,” “mosaic” and “thin wall.”
The building was closed in January when the pad was poured and access from outside was challenging. With the help of an on-site skid steer, masons were able to maneuver the lintel stone to a flat area just outside the building. There they trimmed the 1,300 lb stone to its final shape, located the post contact points and traced on cardboard the corresponding shape the tops of the post stones would need to conform to.
They then went about squaring and cutting the bottoms of the posts with a gas saw. They used the cardboard templates to mark straight cuts at the high spots: two for the left side and one for the right. After the posts were roughed out, they were brought in and set on the pad against 8 in. CMU block post backer supports, so the firebox opening was relatively plumb from the front and side. The lintel stone was then maneuvered to the door opening and set on a heavy duty dolly with inflatable wheels, built especially for the task.
Once rolled in and situated diagonally between the posts, the masons wrapped heavy cable around the center point of the stone with two U-clamps on each end. Another cable was clamped in similar fashion to a timber spanning the opening on the second floor above. A one ton chain fall was hung from this timber. They were then able to raise the massive lintel stone to clear the posts and rotated it to find the contact points they marked outside.
Once adjustments were made to find the balance point of the stone and the correct location on the posts, they began the repetitious process of lowering the lintel stone onto the posts, finding the contact points, raising and rotating the stone enough to expose the contact surface for chiseling/grinding away, either on the lintel or post stones to create a tight “dry look” fit that would characterize the project.
As they gained confidence that the lintel was securely held, masons could ignore working inches away from a very heavy stone. The chain fall was the perfect tool for raising and lowering the stone without fuss.
Joint width was kept to between 1/8 and 1/4 inch. On the left side of the mass, a built-in wood box was incorporated. The entire mass stepped back 5 in. to expose the top of the lintel stone creating a full length integral mantle. A gentle side taper of 5 in. took the work the remaining 5 ft to the ceiling and helped “ground” the mass.
The masons organized the space to efficiently work the stones. Nearest the door, they set a hydraulic stone splitter, so they could cull out large/odd stones for re-splitting. In the 7 ft space behind the ballroom fireplace, they installed an exhaust fan behind a grinding bench station. Beyond that, they had a wet saw on a 220 volt dedicated circuit next to a sand table for before/after trimming. Whatever couldn’t be done with hammers and carbide chisels was done with a mini grinder and shop vac for dust control.
While the fireplace downstairs was squat, symmetrical and massive, upstairs it was vertical and asymmetrical. The raised hearth wrapped around the left side and stepped in again at mantle height with a Goshen stone capped shelf. Hearth stones up and down and chimney caps are blue stone. Bushway invented “Ultimate Ridgehooks” mated with Vanguard chimney brackets, keeping the staging in place without any roof penetrations.
The challenge upstairs was replicating the post and lintel detail at 2/3 scale. Masons had to wedge split the stones to get the same proportions as those downstairs. The lack of mass made the “build against” technique employed downstairs tricky to employ.
The weathered face of American granite is more natural looking than a split face quarried stone. It is also softer than the back side, so site splitting had to be done thoughtfully to avoid losing the face. This look could have been achieved without diamond blades had many more tons of stones and skilled eyes been available to pick them.
Even though these are free-standing interior fireplaces, the firebox backs are insulated with cermaic wool to help them heat up and radiate heat into the room after the fire is out. Rigid lengths of 304L stainless steel flue liners were used: 14 in. diameter downstairs, 10 in. diameter upstairs.
Top sealing gasketed dampers were installed to prevent heat loss through leaky cast throat dampers and allow for a more aero-dynamic shape in the throat area. Following fluid dynamic principles of British engineer, Peter Rosin, the turbulence producing smoke shelf is also eliminated. To keep water out of the system, the stone rain cap is grooved ¼ in., 1 in. in on the underside as a drip edge.