Insulated Foundation for an Urban Infill Site

Project manager, Steve Daly, and carpenter Greg Hunt carry a bundle of foam forms into the foundation hole on site. The lightweight foam forms eased the labor of construction for the project while improving the foundation’s energy performance.

Steve Daly sets a corner form section for the ICF foundation system. The recommended process is to start setting foam form blocks in the corners and work toward a point in the center of the wall.

Steve Daly sets a wall form block, working from the corner toward the center of the wall.

At the center of the wall, sections have to be trimmed with a handsaw to fit into the remaining gap.

Steve Daly slides a cut-down segment of foam form into the remaining gap in the wall line.

Steve Daly screws a 2x4 scab into the plastic ribs of the foam forms, to create a reinforcing scab at the point where the last segment of foam form has been cut and pieced into place. The ICF system supplier recommends making all the joints in the wall at a single point, which can then conveniently be reinforced with scabs and braces before concrete is poured.

The ICF system includes wire spring-ties, used to connect form segments and courses.

Steve Daly and Greg Hunt set a piece of rebar into the corner of the ICF formwork. The plastic ribs that connect and brace the ICF form blocks are designed to hold the steel reinforcing bars in place, eliminating the labor of tying rebar.

A closer look at the rebar in place in the form, held in place by the plastic ribs of the foam forms.

Steve Daly and Greg Hunt place another piece of rebar into the form.

Placing concrete into the form system.

Workers strike the concrete level and trowel it flat on the day of the wall pour.

After leveling and compacting the existing soil within the stemwall perimeter, Placetailor’s Evan Smith compacts a layer of engineered fill material containing stone dust along with graded crushed stone, in preparation for adding more gravel to the slab sub-base. Smith explains that without the engineered material, regular gravel would sink into the soft existing soil and be hard to compact, leaving the slab with insufficient support.

Evan Smith pulls a load of gravel into the foundation. The small skid-steer Smith is driving was the only piece of equipment that was practical for the small site, given the limited access from the street.

Project manager, Steve Daly, compacts gravel inside the foundation perimeter while coworker Scotland Willis excavates with a shovel for a small section of thickened slab intended as the footing for an interior wall by the stairs of the building.

After gravel is placed and compacted, foam insulation and a poly vapor barrier are placed on the sub-base in preparation for placing the interior concrete slab floor. Here, Scotland Willis tapes a seam in the vapor barrier plastic.

Scotland Willis installs guide boards for a concrete screed. The 2x10 boards are screwed to the plastic ribs in the ICF forms, then a level line is snapped on the boards and the boards are trimmed to create a level guide surface.

Scotland Willis and Placetailor project manager Laura Doyle set pieces of angle iron down onto the boards screwed to the ICFs, to serve as a hard straight-edge guide for the concrete screed that will be used to strike a level surface on the building’s first-floor concrete slab.

Laura Doyle holds the tape and Scotland Willis screws the angle-iron down to the wood for the screed guide, while Steve Daly sights with the transit to verify that the edge of the angle iron is level. The arrangement is intended to ensure that the slab to be placed will be level to within ? inch.

On the morning of the slab pour, three workers shovel and rake concrete while two operate the long screed to strike the concrete level, one handles the hose from the pump truck, and one bull-floats the concrete.

On the morning of the slab pour, three workers shovel and rake concrete while two operate the long screed to strike the concrete level, one handles the hose from the pump truck, and one bull-floats the concrete.

During an unexpected delay in the arrival of the third concrete truck, which got stuck in traffic, the concrete from the second truck began to harden. Here, workers roughen and work the concrete in hopes of preventing a cold joint.

During an unexpected delay in the arrival of the third concrete truck, which got stuck in traffic, the concrete from the second truck began to harden. Here, workers roughen and work the concrete in hopes of preventing a cold joint.

A few small parts of the slab couldn’t be reached by the long screed made of wood I-joists. Here, Evan Smith trowels a small area between two plumbing pipes.

A few small parts of the slab couldn’t be reached by the long screed made of wood I-joists. Here, Evan Smith trowels a small area between two plumbing pipes.

Towards the end of the pour, too much concrete piled up in front of the screed, and the screeding was tough going for the men on either end of the tool. Here, Steve Daly removes excess concrete from in front of the screed.

Towards the end of the pour, too much concrete piled up in front of the screed, and the screeding was tough going for the men on either end of the tool. Here, Steve Daly removes excess concrete from in front of the screed.

The holdup in the arrival of the last concrete truck meant that finishing of the early deliveries and placement of the final delivery had to happen simultaneously. Here, Evan Smith is almost done power-troweling the second segment of the slab while Steve Daly is still bull-floating the third segment.

The holdup in the arrival of the last concrete truck meant that finishing of the early deliveries and placement of the final delivery had to happen simultaneously. Here, Evan Smith is almost done power-troweling the second segment of the slab while Steve Daly is still bull-floating the third segment.

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