Hip Rafter Length

Correct hip rafter length can easily be determined with the use of a Construction Master Calculator. If you enter the right information there is no need to shorten the rafter half the thickness of the ridge board.

If you deduct the thickness of the ridge board when you calculate the common rafter length then the hip length given by the calculator will be correct with no need to further shorten the hip.

Let us use as an example a building that is 24 feet by 28 feet. With a standard hip roof and a 6/12 pitch. Below is a snapshot of the paperless tape feature found on the calculator.

Paperless Tape

24. FEET -

1 1/2 INCH =

23-10 1/2 FEET INCH ÷

2. =

11-11 1/4 FEET INCH RUN

6. INCH PTCH

13- 4 3/16 FEET INCH DIAG

17-10 7/8 FEET INCH H/V

5-11 5/8 FEET INCH RISE

16. INCH JKOC

1- 5 7/8 FEET INCH INCR

11-10 1/4 FEET INCH JK 1

10- 4 3/8 FEET INCH JK 2
8-10 1/2 FEET INCH JK 3
7- 4 5/8 FEET INCH JK 4
5-10 11/16 FEET INCH JK 5
4- 4 13/16 FEET INCH JK 6
2-10 15/16 FEET INCH JK 7
1- 5 1/16 FEET INCH JK 8

Explanation

Building Width

Thickness of Ridge Board

Width Minus Ridge Board

Divided by 2

Run of Common Rafter

Pitch of Roof

Common Rafter Length

Hip Rafter Length

Peak of Roof Above Wall Plates

Jack Rafter Spacing

Difference in Jack Length

Longest Jack Rafter

The rest of the Jack Rafters


How to Measure Hip Rafters

Hip rafters should be measured along the top from the long point of the plumb cut.

I will often go ahead and make the plumb cuts on the hip rafter so its easier to measure and mark the seat cut and tail cut.

To find the amount to add for the tail just add the run of the overhang minus the thickness of the sub fascia. For a one foot eave with 2 x 6 fascia this would be 10 1/2 inches.

So you would add 15 3/4 inches for the tail cut.


6. INCH PTCH
10 1/2 INCH RUN
15 3/4 INCH H/V

Links to Related Carpentry Pro Framer Pages

Hip Rafter Length to Home

Hip Roof Framing

Cutting Hip Rafters

Ridge Board Length

Basic Roof Framing

Pyramid Roof

Dropping Hip Rafters

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