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  • Writer's pictureJosh Lefebvre

How to Calculate Irregular Valley Rafters with the RedX Roof App


There are several ways to calculate irregular valley rafters and jack rafter lengths. I'll cover the most efficient method i've found, which uses the RedX Roof App. Here is what the app will automatically calculate for us:

• Full cut list.

• 3D model of the Valley Rafter and Jack Rafters

• Calculate all Jack Rafter Lengths

• Calculate the Valley Rafter and Jack Rafter saw bevel angles

• Calculate the Valley Rafter backing angles

• Show the wall height difference, or choose to keep both walls at the same height

Below is an example 3d model of open valley you will be creating



Measurements needed

The measurements we will need to to enter into the app are as follows, We will go into details on all of these later on.

  1. Roof Pitch (or roof angle) 1

  2. Roof Pitch (or roof angle) 2

  3. Facia overhang

  4. The Bottom Run of the common rafter of the main roof

  5. Jack rafter spacing

Optional Customization

There are many things we can customize like:

• Hip rafter thickness and depth

• Jack rafter thickness and depth

• Facia thickness and depth

• Different fascia overhangs

• Choosing to have different wall heights or keeping them both at the same height

• The depth of the birds mouth cut


3D Viewer

After the inputs, the magic begins. The Open Valley Builder will automatically generate an interactive 3D model of the corner valley, offering a detailed visualization that you can pan, zoom, and toggle between 3D and 2D.


Full Cut List

Scrolling down, you'll find a comprehensive cut list, which includes the quantity of required pieces, the material size, the length of the cut, and the use of each part.

Material List

Just below the cut list, there's a material list with all the required lumber.


Open valley roof cut list, irregular valley rafter

You'll notice in this list, every component has a Label that will correspond with the label on the top down view (plan view) of the 3d valley rafter, along with the quantity, material size, overall length of the component, and the component use.


Viewing Rafter Plans

Each component in the cut list is selectable, selecting one opens up the corresponding rafter plan. You'll notice i've selected the valley rafter in the list. You can choose to view the valley rafter with the rafter plan viewer inside the app or or you export or print the rafter PDF plan.


Valley Rafter Plan Viewer

With the plan viewer you can view all sides of the rafter along with all of its measurements. Below every rafter plan is a list of measurements like total rafter length, saw bevel angle, rafter angle, fascia overhang and more. Selecting any of these measurement will automatically zoom into that measurement on the rafter plan. This helps with understanding all of the measurements.


valley rafter plan for irregular valley rafter calculator


Valley Rafter Layout

For the valley rafter and fascia boards, you'll see a 'Show Layout' button when pressing it, it will show you where all the jack rafter intersects the main rafter, with the measurements for your layout.


Calculating the Valley Rafter Backing Angle

If you wanted to be fancy and bevel the top of your valley rafter In the list of measurements for the valley rafter, you can press the 'Show Backing Angle' button to view the backing angles for the valley rafter.


valley rafter backing angles how to calculate

Viewing the Jack Rafter Plans

To view all of the jack rafter plans, just select it from the cut list and you'll see the corresponding rafter plan will open up below.





Create a Rafter PDF Plan

If you want to create a pdf plan of the valley rafter or jack rafters it's supper simple, there are 2 main ways to do this.

Option 1 Export 1 Rafter Plan: Press the blue export button in the top right corner of the rafter plan, 3 options will come up, choose to either print, share or save the rafter pdf plan to your photos.

Option 2 Export All Rafter Plans: At the top of the cut list on the right, press the menu button, from here you chan choose to share all rafter plans, print all or save all to your photos.


hip rafter pdf plan


Lets Go Over The Details

Now that you’ve seen what the app can do let me show you all of the details.


The Measurements You Enter Into The App

View the rafter terminology section below for more information on these terms


Main Roof Inputs

- Roof Pitch or Rise From Wall for this first input you can enter either the roof pitch of the main roof side if you know it, or the common rafter rise from the top of the wall to the top of where you'r common rafter will finish.


- Main Roof Run This is the the horizontal distance from the outside of the wall to where your common rafter ends, this is the run for the main roof.


- Main Roof Overhang Here you enter the fascia overhang of the main roof, the horizontal distance from the outside of the wall to the inside of the rafter.


- Rafter Height Above Plate or Fascia Drop: Here you can enter either the Rafter Height Above Plate, Or the Fascia Drop Measurement of the main roof. (This will affect the height of the fascia)


- Main Roof First Rafter Center Here you enter the wall height of the main roof.


- Main Roof Wall Height Here you enter the the distance from the corner of the two fascias, to the centre of the first rafter on the main roof.


Valley Roof Inputs

- Roof Pitch or Rise From Wall for this first input you can enter either the roof pitch of the valley roof side if you know it, or the common rafter rise from the top of the wall to the top of where you'r common rafter will finish.


- Total Building Width Here you enter the the total building width of the valley roof, from the outside of the wall to the outside of the other wall. (Essentially the rafter run x 2 + ridge thickness)


- Valley Roof Overhang Here you enter the fascia overhang of the valley side, the horizontal distance from the outside of the wall to the inside of the rafter.


- Rafter Height Above Plate or Fascia Drop: Here you can enter either the Rafter Height Above Plate, Or the Fascia Drop Measurement of the valley roof. Tip: If you want to keep both fascias at the same height when the main roof and valley roof have different roof angles, Toggle over to use Fascia Drop for both the main roof and the valley roof side and make both fascia drop measurements the same. This will make both fascia be at the same height.


- Valley Roof Wall Height Here you enter the the distance from the corner of the two fascias, to the centre of the first rafter on the main roof.



Rafter Terminology

For more information on all the different rafter terminologies have a look at the in depth tutorial i made here Everything You Need to Know about Rafters: Key Concepts and Terms Explained


Save And Load Jobs

To learn more on how to save and load jobs on the RedX Apps view the in depth tutorial here Saving And Loading Jobs On RedX Apps


Print and Share The Plan

To learn more on how to print and share your jobs on the RedX Apps have a look at the in depth tutorial here Print and Share Plans with RedX Apps



Conclusion

As you can see the RedX Roof App makes it super easy to get every single measurement and rafter detail to build an irregular valley roof or a same pitch valley roof. There are lots of other great features like Hip Rafter Builder, Rafter Calculator, Turret Roof Builder, Plywood Angles, Dormer Builder and others...

Do you think this is something that you would use? Let me know in the comments.


Thanks to all of you who made it this far!



429 views1 comment

1 commento


Eddie Simpson
Eddie Simpson
29 nov 2023

The advice given is both practical and creative, making it appear easy to put into action. I particularly liked the emphasis on effectively organizing your space and adding personal touches to create a more enjoyable work environment.

On a different note, for those seeking to further improve their home office setup, I highly recommend exploring the offerings from Duplicator Sales. They provide a wide range of business solutions, including managed IT, document management, and managed print services, all of which can significantly enhance efficiency and streamline your work experience. Integrating their services alongside the DIY ideas shared in the article could elevate your home office to the next level!

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