Page 38
IRREGULAR HIP/VALLEY AND JACK RAFTERS - ON-CENTER SPACING MAINTAINED
Example: You’re working with a 7/12 Pitch and half your overall span is 5 Feet. The irregular Pitch is
8/12, and 16-inch On-center spacing is maintained on both sides. Complete the following steps:
1. Find the length of the common rafter;
2. Reset calculator to 16-Inch On-center spacing;
3. Enter the Irregular Pitch; nd the length of the adjoining “Irregular” Hip (or Valley) and the cut
angles;
4. Find the incremental jack adjustment and the jack lengths on the “Irregular” Pitch side (16-Inch
On-center spacing);
5. Find the cut angles;
6. Find the incremental jack adjustment and the jack lengths on the “Regular” Pitch side (16-Inch
On-center spacing);
7. Find the cut angles.
KEY INPUT & DISPLAY
0
On/C On/C
PTCH 7
Inch
1. Find Common rafter length:
RUN 5
Feet
0
Inch
DIAG 5
Feet
9-7/16
Inch
OC 16
Inch
2. Enter On-center spacing:
IPCH 8
Inch
IH/V 7
Feet
3-1/16
Inch
3. Find Irregular Hip/Valley rafter length and cut angles:
PLMB 32.70˚
LEVL 66.30˚
CHK1 41.19˚
CHK2 48.81˚
IJOC 16
Inch
INCR 1
Feet
4-13/16
Inch
4. Find irregular incremental jack adjustmental jack adjustment and Irregular Jack lengths:
IJ1 3
Feet
10-1/4
Inch
IJ2 2
Feet
5-7/16
Inch
IJ3 1
Feet
0-5/8
Inch
Cont’d on page 40
STORED
STORED
IJ4 0
Feet
0
Inch
Jack
Pitch
Run
Diag
Feet
Inch
7
5
(o.c.)
Inch
Stor
5
6
1
Hip/V
Inch
Conv
8
(Ir/Pitch)
Hip/V
Hip/V
Hip/V
Hip/V
Hip/V
Conv Jack
Jack
Jack
Jack
Jack
(Ir/Jack)