Equal pitch hip roof framing plans showing basic hip framing layout and placement of common rafters and hip roof rafters by custom house plan designer.
In this article we will try to show you how to build a simple "hip roof" and try and show the component parts that make up an "equal pitch hip roof" structure using the "double cheek cut hip rafter method" used by most framers today.
In this method of construction the center ridge board will grow by half the thickness of the ridge board material, usually 3/4" at each end of the structure.
In this example we are looking down on the right rear corner of a simple rectangular building. Using half the span distance of the building less half the ridge board thickness which is 3/4" in this example, mark your top plate and set ahead 1 1/2". That will be the location of the first common rafter front and rear on both ends of the building.
Your jack rafters will start from that position and layout on 16" centers toward the right rear corner. This is the hip and jack rafter measurements as shown in this example. You could actually cut all four hip sections from these measurements and they would complete your rafter construction perfectly.
But that would not work well for ceiling joist layout and being able to tie both rafters (common and Jacks) together to create a solid and well built home. So we would want to offset the common and jack rafters 1 1/2" to allow both to be able to lap beside each other and be nailed together forming a well built roof system.
This method will cause all of the rafters and jack rafters on the front side to maintain a 16" on center balance.
This makes cutting the roof sheathing much easier and quicker. In the event the ceiling joist are used as a attic flooring your plywood sheathing will work well also.
Note: This will force you to custom cut the front right corner as well as the front and rear sections on the left end of the building. I show this in figure #4 marked "Special Cut Jack Rafter Layout" near the bottom of the page.
Not to worry though its easy to do. The right front section jacks would simply be 1 1/2" shorter. The left end can be simply measured once your layout work is complete maintaining your 16" on center the entire width of the building. The remaining jack rafters in these two sections would simply decrease each one by a given number according to the roof pitch used.
Common Rafters:
Common rafters are the same on gable roofs as well as on hip roofs and can be figured exactly the same way.
Hip Corners:
Regular pitch hip roofs means that all four sides are on the same angle plane and will run at a 45 degree angle directly from the corner to the end of the center ridge board.
Hip Rafters:
Hip roof rafters are designed with a lower pitch so the corner can be made and roof sheathing can be applied to form the corner of the structure properly. It also carries the smaller jack rafters.
Plan View:
Our plan detail drawing shows all four corners of this simple hip roof structure with all common rafters, hips and jack rafters fitting together properly.
Equal Pitch Roof Rafter Layout:
Placing the ridge and common rafters should be the first thing to be laid out on your wall top plates. From this layout you can mark out all the rest of the common and jack rafter positions. It might be a good idea to draw a big X where the rafters will actually set.
Hip Rafter Side Cut Angles:
This side cut angle can be obtained the same way as the jack rafter cheek cut angle.
Jack Rafter Side Cut Angles:
Side cut angles or commonly called cheek cuts enable the jack rafter to connect properly with the side of the hip rafter.
Plywood Cut Angles:
Even though a equal pitch hip roof has hips running inward at a 45 degree angle the plywood sheathing cut angle is very different and on our 4x12 pitch roof example it turns out to be 46.53 degrees.
Jack Rafters:
Jack rafters start with the first common rafter and continue on to make up the complete corner. These must be calculated properly to fit in order for the sheathing to continue to the corner. When installing your jack rafters be sure to straighten the hip rafter and install the first two jack rafters some where in the middle to secure the hip. When you install one side install the other side of the hip as well. This will help keep the hip rafter nice and straight.
Typical Ceiling Joist Layout:
Ceiling joist layout if placed properly will enable you to set all rafters much quicker and finish with a very neat project.
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