Traditionally, bottom plates for house framing are made of 2x4 or 2x6 lumber. However, structural engineers are increasingly specifying 3x4 and 3x6 bottom plates to provide additional structural support. This can be confusing for framers who are accustomed to using the traditional 2x4 or 2x6 sizes.
Key Points to Consider When Installing Bottom Plates
Engineer's Specifications: Always adhere to the specifications outlined by the structural engineer for your project. If the plans call for 3x4 or 3x6 bottom plates, it's crucial to use them.
Anchor Bolt Placement: When using 3x4 bottom plates, ensure that the anchor bolts are positioned correctly and protrude high enough to accommodate the thicker plate. Failing to do so can necessitate shaving down the anchor bolts, a solution that structural engineers are unlikely to approve. In the worst-case scenario, incorrect anchor bolt placement might require re-epoxying new anchor bolts into the thicker plate, which can be a time-consuming and frustrating process.
Existing Raised Floor Foundation: Particular challenges arise when working on existing raised floor foundations. If the engineer specifies 3x4 bottom plates, and the existing floor joists (typically 2x6) are sitting on 2x4 bottom plates, modifications are necessary. In this situation, you'll need to raise the building to install the 3x4 plate.
Bonus Tips
Double-Check Compatibility: Before installation, confirm that the specified bottom plate size works with the overall project design.
Prioritize Correct Installation: It's crucial to install the bottom plates correctly from the outset. Avoid the hassle of having to retrofit 2x4 plates with 3x4 plates later if shear panels and floor framing are already attached.
