Overview
This lecture explains the key components of house framing, covering their names, locations, and structural functions from the foundation to the roof.
Foundation and Floor Framing
- The mud sill (sill) is pressure-treated lumber laid on the foundation to prevent rot and anchor the framing.
- Joists are edge-set lumber that span between supports to create floor or ceiling structures.
- Rim joist or band forms the outside edge of the floor structure.
- Girders or beams are large horizontal supports for joists, made from groups of lumber or engineered LVLs.
- Columns and posts (vertical supports) transfer loads from beams/girders to the foundation.
- Subfloor, made of plywood or strand board, is laid on top of joists for a stable surface.
Wall Framing Components
- Studs are vertical framing members (typically 2x4 or 2x6) spaced 16" or 24" apart.
- Plates are horizontal members; bottom plate at the base of the wall, double top plates at the top.
- Stud packs group multiple studs to carry heavy loads.
- Headers are horizontal beams above door/window openings, transferring weight to edges.
- Jack (trimmer) studs support ends of headers; king studs run full height beside them.
- Rough sill is the bottom framing in window openings; rough opening refers to the total framed area for doors/windows.
- Blocking (or nogging) are short horizontal pieces for bracing, fire stops, or mounting hardware.
Stairs, Floors, and Multi-Story Framing
- Staircases use stringers, treads (horizontal steps), and risers (vertical faces).
- Knee walls are short wall sections under three feet for support or partitioning.
- In floors/ceilings, headers also frame openings (different use from wall headers).
- Upper floors are framed similarly to the first, stacking joists, subfloor, and walls.
Roof Framing
- Rafters are diagonal members supporting the roof, meeting at a ridge board.
- Hip rafters run to outside corners, valley rafters to inside corners; jack rafters meet hips/valleys.
- Common rafters run from wall plate to ridge; barge rafter projects at gable ends; rafter tails form eaves.
- Roof trusses are pre-engineered frames replacing rafters in many modern homes, forming strong webs to span wide distances.
- Trusses can substitute for rafters and are also used for floors.
Sheathing
- Sheathing (plywood or strand board) covers exterior walls and roofs, adding strength and forming a substrate for siding.
Key Terms & Definitions
- Mud sill — Treated lumber separating foundation from framing.
- Joist — Horizontal floor or ceiling-supporting member.
- Beam/Girder — Large horizontal support for joists.
- Stud — Vertical wall framing member.
- Plate — Horizontal wall framing member (top or bottom).
- Header — Horizontal beam over openings.
- Jack Stud — Short vertical support under header.
- King Stud — Full-height stud beside an opening.
- Blocking/Nogging — Horizontal bracing within walls.
- Rafter — Angled roof framing member.
- Truss — Engineered roof or floor support.
- Sheathing — Panel covering for walls/roof.
Action Items / Next Steps
- Learn and review key framing terminology.
- Observe framing components in real buildings or diagrams for visual understanding.