THOMSON Construction Master Pro

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Sample

60 Part C

■

Framing

■

EXAMPLE 6.1

A common rafter rises 5⬘-4⬙ in a run of 14⬘-2⬙. Find (a) the pitch of this

rafter in inches, (b) its pitch in degrees and (c) its slope.

Solution:

KEYSTROKE DISPLAY

(a) (b) (c) Following the procedures outlined in Chapter 2, enter the given

data as shown, and solve for the pitch:

5 f 4 i r

RISE 5 FEET 4 INCH

1 4 f 2 i R p PTCH 4-1/2 INCH

p PTCH 20.63°

p p SLP 0.376471

Your Construction Master Pro calculator can also provide the point-to-point

rafter length (excluding ridge adjustment or overhang) for common rafters, as

well as the angles, in degrees for making plumb (vertical) cuts, and level (hor-

izontal) cuts as shown in Figure 6-2. These angles may be used for fitting

rafter to ridge; cutting a bird’s mouth to seat a rafter on the top plate; or trim-

ming rafter tails to accept fascia and soffit boards.

■ EXAMPLE 6.2

For the rafter of Example 6.1, find the rafter length, and angular values for

plumb and level cuts.

Solution:

KEYSTROKE DISPLAY

Enter the data for rise and run as before:

5 f 4 i r RISE 5 FEET 4 INCH

1 4 f 2 i R RUN 14 FEET 2 INCH

d DIAG 15 FEET 1-5/8 INCH

d PLMB 20.63°

d LEVL 69.37°

Using the capabilities built into your Construction Master Pro calcu-

lator, it is possible to determine all information related to common rafters

for any specified framing conditions. Three of the situations most fre-

quently encountered by builders are these:

1. Given the rise and run, determine the pitch and rafter length.

2. Given the pitch and rise, find the run and rafter length.

3. Given the pitch and run, calculate the rise and rafter length.

Notes

Construction Master® Pro Workbook and Study Guide

and Thomson Delmar Learning

Calculator Tip

Pitch Display Order:

Order of answers

displayed varies

depending on last

format of pitch entered.

Continue pressing p

until desired format is

displayed.

Calculator Tip

Power User Tip:

Displayed pitch results

will start with the last

entered pitch format.

For example, if 7 i

p is entered, any

future pitch calculation

will begin with the pitch

in inch format, unless

calculator is reset.

THOMSON Construction Master Pro - Common Rafters