Part 2 — The Foundation Plan | Sheet by Sheet

 

Every house sits on it. Most problems start beneath it.

The foundation plan is the first structural sheet in the set — and the one that has to be right before anything else can move forward. Get it wrong and you're not fixing a drawing. You're fixing concrete.

What it shows:

• Foundation type — slab, crawl space, or basement
• Footing locations, sizes, and depths
• Bearing wall locations above
• Step footings on sloped lots

• Anchor bolt and hold-down locations
• Thickened slab areas under load points

The three foundation types:

Slab on grade — most common in NC, SC, GA. Concrete poured directly on prepared ground. Fast, cost-effective, but zero tolerance for grading errors.

Crawl space — elevated foundation with ventilated space below. Common in flood zones and sloped sites. More complex to document — vents, access points, and vapor barriers all need to be shown.

Basement — least common in the Southeast but critical to get right when specified. Waterproofing, egress windows, and structural walls all add complexity to the foundation plan.

Where builders get burned:

Wrong foundation type for the lot. A slab specified on a lot with significant grade change means expensive cut-and-fill work — or worse, a redesign after permits are pulled. The foundation plan should always be read alongside the site plan and grading plan, not in isolation.