The 1918 island house served three-season and vacation purposes for decades, but the years took their toll. Now, the house is getting a complete makeover, including comprehensive structural reinforcement and a thorough above-code energy upgrade. Board sheating visible here will be retained, covered with air-tight impervious membrane, and over-insulated with three inches of high-density polyurethane foam.
This perspective view of the house early in the project shows several aspects of the planned comprehensive makeover. The unreinforced block foundation at bottom will be undermined and supported from below with a new poured concrete footing, then insulated and frost-protected with below-grade wing insulation. The newly framed and sheathed corner was previously part of the wrap-around open porch, but will now become enclosed and conditioned living space. The complex framing of the second-story roof and dormers has been pulled back into shape after years of sagging and slumping, and will be deepened, reinforced, and heavily insulated. Another dormer will be added at the back of the house, and skylights will be included in the roof plane shown here.
Carpenter Shane Fenton excavates next to the block foundation with a mini-excavator. To place the new foundation under the existing block, the crew will dig down to the level of the lowest course with the excavator, then hand-dig under the wall in four-foot sections to form and place short sections of footing. It will take several days of step-by-step forming and pouring to insert the new continuous footing under the unreinforced block.
Fortunately, the existing soil under the block wall is consolidated sandy soil with a good bearing strength, allowing a 16-inch spread footing to easily do the work of supporting the existing block foundation as well as the new framing load to be installed above it.
Fenton digs along the base of the wall with the mini-excavator while another crew member hand-digs the last few inches. The ledge on the site is only a foot or two below the lowest course of block in most places, and rises to the base of the wall in several spots.
Mason Joe Martignetti hand-digs under the corner of the block foundation wall to start the underpinning work.
Martignetti sets a wooden footing form under the foundation. The plan is to dig and form up footings in short sections, pour a section of concrete footing and let it set, then excavate and underpin the next short section, and so on.
Snow, freezing rain, and frost are coming this month, so the crew has set up a temporary plastic shelter around the house perimeter to protect the foundation work.
The inside of the block wall is being re-pointed at joints, and and cracks in the block are being ground out to ½-Inch depth and grouted with mortar. Here, mason Joe Martignetti wets the crack with a brush before applying grout.
Martignetti works grout into the crack. The entire face of the block foundation will later receive a reinforcing parge of modified cement.
Thompson Johnson Woodworks lead carpenter Mark Pollard explains the re-worked sill detail for the house. The sill beam, which was found to be suffering from rot in a few limited areas, was jacked up and shimmed straight (if not level). The crew has isolated the sill beam from the block foundation with Grace membrane.
The first floor ceiling (second floor frame) of the old house was originally framed with sawn 2x8 boards more than 26 feet long, spanning the entire downstairs of the house. The floor joists had sagged four inches in the middle of the span. Thompson Johnson cut the joists and two mid-span locations and reframed the floor with two long beams built up with doubled 1.75-inch by 10-inch LVLs, and supported by Douglas Fir posts.
In the upper story, long temporary strongback posts topped with bottle jacks were used to lift the ridge of the complex hip roof, while comealongs were used to draw in the kneewalls of the house, which had splayed outward over the years.
Mark Pollard surveys the complex framing of the old house roof, which has to be pulled back into shape, reinforced, and deepened to allow above-code levels of insulation. At left rear is a set of come-alongs used to haul inward on the house’s balloon-framed kneewalls, which had deflected out severely over a century of service. Coastal Connection will take a closer look at the roof re-framing and envelope energy detailing in a future issue.