Garage Roof Rafter Design

Rafter spans for southern yellow pine douglas fir and eastern spruce.

Garage roof rafter design.

The first step of the project is to install the bottom rafters to the frame of the garage. Then you can ensure adequate bearing points or add framing and install beams to carry the loads through the walls down to the foundation. Place the rafters every 24 on center if you want to get a professional result. Just as there are many types of roofs with many roof parts there are many different types of roof trusses this extensive article explains through a series of custom truss diagrams the different truss configurations you can use for various roofs.

Let s consider a basic gable wood roof framing design. Rafter span tables use these tables to determine lengths sizes and spacing of rafters based on a variety of factors such as species load grade spacing and pitch. Metal rafter ties make the installation of trusses easier and more secure. Offset rafter framing can be done on garage roof framing if you are building a garage from plans that are sealed by a professional architect or structural engineer licensed within the jurisdiction you are building a garage in if those designs specify rafter offset.

The image below shows a cross section of our simple 12 x 13 house from the joist span tables section of this tutorial. If your project had a rafter length of 8 or less a safe and strong method is to use 2x8 framed 16 on center. Many of the plans use manufactured roof trusses and others use conventional rafter and joist framing. Visit the roof framing page for more information on cutting roof rafters and visit the roof pitch calculator for determining rafter lengths based on rise and run.

There are certain situations where offset is more practical than opposed rafters which usually occurs on very complicated roof framing schemes. For our 4 x8 lean to example using a 2 4 rafter the depth of the birdsmouth is limited by the 1 3 depth of the rafter rule. A 2 4 wall with a 2 6 rafter can be notched for a 4 seat. As you can see in the image you need to cut them at the right size and secure them to the top plates with galvanized screws after drilling pilot holes.

As a general rule roofs that have a high human occupancy rate should be framed with rafters every 16 structures such as sheds or barns can be frames with rafters every 24 again make sure to consult local codes. If in your plans you have an overhang rake rafter on either end of the garage you will need to adjust the measurement to insure a sheet of plywood beginning at the edge of the overhang rake will end in the center of an interior truss. Our garage plans are to designed to irc building code conventional framing details. Our plans can be built in most us locations.

Continuing on from part 3. All behm design garage plans include foundation plans and details using industry standard materials and assemblies. While this article focuses on configurations we also have a very cool set of illustrations showcasing the different parts anatomy of roof trusses. Use a framing square to help lay out the notch based on the slope of the roof.