Description
How do you pour a foundation slab for a full room addition with an attached kitchen and bathroom? This Huntington Beach project shows every major step.
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David O’Dell and the crew remove part of the existing driveway, grass, roots, and debris before excavating down to native soil. The new addition will bring the front of the house closer to the garage while preserving a courtyard outside the existing front door and a passage between the addition and garage.
This is a complete room addition with an attached kitchen and bathroom—not simply a basic bonus room. That means the concrete foundation must accommodate plumbing penetrations, interior walls, structural anchor bolts, and a connection to the existing house.
The foundation uses a roughly 5½-inch concrete slab with a large perimeter footing that David estimates at approximately 15 inches wide and 20 inches deep. The setup includes 2×12 perimeter forms, #4 rebar at 12 inches on center throughout the slab, additional footing reinforcement, a 10-mil Visqueen vapor barrier, gravel underneath, and sand above the plastic.
The crew also prepares epoxy rebar dowels where the new foundation joins the existing house. David explains when this work may require a special inspection, why every form must be rechecked after the plumbers finish, and the advantages of wood stakes when forming a foundation.
During the pour, the first 10-yard load does not completely fill the slab and footing. A delayed cleanup load allows the first section to harden, creating a substantial cold joint. David explains how the dense reinforcement keeps both placements structurally connected before the crew finishes the surface and installs the interior-wall anchor bolts.
FEATURED TOOLS AND MATERIALS:
• Bobcat skid-steer loader
• Milwaukee cordless rotary hammer with clay spade
• Five-foot fiberglass bull float
• 2×12 foundation forms and wood stakes
• #4 reinforcing steel
• 10-mil Visqueen vapor barrier
• 5/8-inch galvanized anchor bolts
• Quarter-inch square plate washers
CHAPTERS:
00:00 Full room-addition foundation overview
01:05 Removing concrete, grass, and debris
01:45 Quick Bobcat flat-tire repair
02:00 Addition, courtyard, and passage layout
02:16 Digging the foundation footings
03:19 Crew and formwork setup
03:46 Footing, rebar, and vapor-barrier specifications
04:26 Epoxy dowels and special inspection
05:24 Plumbing installation and rechecking forms
06:19 Why wood stakes work for foundations
06:59 Underpinning the low areas
08:12 Screws versus duplex nails
09:12 Pouring the first 10 yards
09:49 Delayed cleanup load and cold joint
10:50 Interior-wall anchor bolts
11:32 Finishing the concrete surface
12:01 Galvanized bolt and washer requirements
12:57 Completed foundation slab
Visit Odell Complete Concrete:
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