Every window and door opening interrupts the vertical load path. Learn how headers bridge gravity loads, how many jack studs are required by code, and the standard 3-1/2" & 5-1/2" sandwich build.
Short vertical 2x4/2x6 studs directly above the header that transfer roof truss / floor joist loads straight into the header beam.
Double 2x6, 2x8, 2x10, or 2x12 lumber sandwiched with 1/2" OSB to bridge the opening without sagging under floor weight.
Cut to support the underside of the header directly, carrying 100% of the bearing weight down to the foundation.
Two pieces of 2x lumber (1-1/2" + 1-1/2" = 3") + one piece of 1/2" OSB or Plywood spacer in the middle. Total thickness = exactly 3-1/2", matching the 2x4 wall framing depth flush on both faces.
Two 2x pieces placed to the exterior face, with a 2" Rigid Foam insulation board (R-10) on the interior to eliminate thermal bridging through the header opening.
Nail the header plies together with 3" (10d or 16d) framing nails in pairs every 16 inches along both top and bottom edges. Nail king studs to jacks every 12" with 3" nails.
Enter your window/door rough opening width and wall load condition to determine code-compliant header depth and jack stud counts.