Reference charts for the job site
Frame Sums
Carpentry charts with a calculator under each one: board feet by lumber size, stair rise and run, roof pitch to degrees and rafter length, deck boards, fence posts and pickets, baluster spacing, and wall studs. The numbers a framer keeps in a notebook, computed and cited.
Roof pitch, the chart everyone looks up
| Pitch | Degrees | Percent | Slope factor× run = rafter |
|---|---|---|---|
| 1:12 | 4.76° | 8.3% | 1.0035 |
| 2:12 | 9.46° | 16.7% | 1.0138 |
| 3:12 | 14.04° | 25% | 1.0308 |
| 4:12 | 18.43° | 33.3% | 1.0541 |
| 5:12 | 22.62° | 41.7% | 1.0833 |
| 6:12 | 26.57° | 50% | 1.1180 |
| 7:12 | 30.26° | 58.3% | 1.1577 |
| 8:12 | 33.69° | 66.7% | 1.2019 |
| 9:12 | 36.87° | 75% | 1.2500 |
| 10:12 | 39.81° | 83.3% | 1.3017 |
| 11:12 | 42.51° | 91.7% | 1.3566 |
| 12:12 | 45.00° | 100% | 1.4142 |
Full chart to 24:12 with hip and valley factors, and the converter, on the roof pitch page.
Questions
Why charts first?
Because that is how the numbers are used on site: a framer glances at a pitch chart or a riser table and cuts. Each page leads with the reference chart, computed from the formula stated beside it, and puts a calculator underneath for the dimensions that are not on the chart.
Where do the code figures come from?
The International Residential Code as adopted in most US states: R311.7 for stairs (7¾-inch maximum riser, 10-inch minimum tread, 6-foot-8 headroom), R312.1.3 for the 4-inch guard sphere, and standard framing practice for 16-inch stud spacing and three plates. Local amendments override all of it, so the inspector has the last word.
Are the material counts exact?
They are take-off numbers: the count you order, with the usual waste allowance stated on the page. Species, grade and span tables decide sizes for anything structural, and the charts do not replace them.