10/21/2026
🚧 BEFORE THE WALLS GO IN, GET THE GROUND RIGHT. 🧱
We’re at the Princeton project bringing in clean crushed stone for the Superior Walls system. Here’s how we figure out how deep to dig. 👇
📐 Start with the finished first-floor elevation and work down:
✔️ Subtract the full floor assembly above the foundation wall—16½ inches in this example, accounting for framing, sill plates, subfloor, and finishes.
✔️ Subtract the foundation wall height—we’re using nine feet here.
✔️ Subtract the specified stone depth—we’re using six inches.
📏 That gives you the planned subgrade elevation—the level of the ground underneath your stone, before any additional engineered undercut. These are example numbers. Your foundation wall heights, framing, and stone depth all vary according to your plans.
👷 Always refer back to the approved plans and your geotechnical engineer’s recommendations. Depending on the soil, you could be digging deeper to remove weak ground and building back up with three feet of stone—if that’s what the engineer specifies.
🪨 Properly prepared crushed stone helps spread the foundation’s weight onto the soil below and supports drainage. The ground underneath still needs to carry that weight.
🔎 Get a soil bearing capacity test done before the foundation goes in. I’ll touch more on why that matters in our next video.
💪 Know your elevations. Follow the plans. Build on proper support.
📍 Princeton, New Jersey
🏗️ CMG Contracting LLC
🔗 CMGContractingLLC.com