Roof Framing & Trusses
Common, hip, and valley rafters, bird's mouth cuts, ridge boards, collar ties, trusses, and roof geometry.
- Identify roof types and their structural components
- Lay out and cut common rafters including bird's mouth, plumb, and tail cuts
- Explain the differences between hip, valley, and jack rafters
- Describe truss types, gusset plates, and engineered roofing systems
- Identify eave, soffit, and fascia components
Lección 1
Roof Types & Terminology
Roof Geometry Basics
Roof framing is where a carpenter's skill and knowledge are truly tested. Understanding roof geometry - pitch, rise, run, and span - is essential for laying out rafters and calculating materials.
Roof Pitch and Slope
Roof pitch is expressed as the ratio of rise to run. A 6:12 pitch means the roof rises 6 inches for every 12 inches of horizontal run. The typical slope of a standard residential roof is 4:12 to 8:12. The typical angle for most residential roof pitches is 15-45 degrees depending on pitch. A 1:12 slope is too flat for most roofing, and 12:12 (45 degrees) is very steep.
| Pitch | Rise per Foot | Angle | Classification |
|---|---|---|---|
| 2:12 | 2 inches | 9.5 degrees | Low slope |
| 4:12 | 4 inches | 18.4 degrees | Standard |
| 6:12 | 6 inches | 26.6 degrees | Standard |
| 8:12 | 8 inches | 33.7 degrees | Steep |
| 12:12 | 12 inches | 45 degrees | Very steep |
Common Roof Types
Gable Roof
Shape: Two slopes meeting at a ridge
Rafters: Common rafters only
Advantage: Simple to frame
Most common residential roof type
Hip Roof
Shape: Slopes on all four sides
Rafters: Common, hip, and jack rafters
Advantage: Better wind resistance
More complex to frame
Shed Roof
Shape: Single slope
Rafters: Common rafters only
Advantage: Simplest to build
Common for: Additions, porches
Roof Slope
The typical residential roof slope is 4:12 to 8:12. Slopes below 4:12 require special roofing materials. Slopes of 12:12 (45 degrees) are considered very steep and require extra safety measures.
Roof pitch is expressed as rise per 12 inches of run. The typical residential roof slope is 4:12 to 8:12. Gable roofs are simplest (two slopes), hip roofs have four slopes, and shed roofs have one slope.