How to Construct Rafters

Rafter construction

Rafters are essential to any home construction. Without them, you can have no real functional roof, and with them, the roof can be transformed into a delightful hat for any home.

Things You'll Need

• 2-by-6 pine boards
• Carpenter's square
• 16 penny nails

Instructions

1. 

   Determine the rafter type. Rafters come in many different types and designs. Before you begin to construct your rafters, you will need to know what type, shape and angle. See the picture for rafter types.

2. 

   Begin the construction of the rafters. This article will present information on gabled end rafters.

3. 

   To determine the rafter lengths, divide the entire span by two (example: If the house span is 46 feet 6 inches, divided by 2 = 23 feet 3 inches). Now add the overhang (example: 12-inch overhang makes the length 24 feet 3 inches). Now, convert the 3 inches of the 24 feet 3 inches into a fraction. It happens to be 0.250. Thus 24 feet 3 inches is now 24.250 inches.
   Suppose you desire an 8/12 roof pitch, or for every 12 inches horizontally, you get 8 inches up and 12 inches vertically. Convert that number by using a rafter conversion chart. For the purpose of this article, the 8/12 roof pitch converts to 1.201850 on the rafter conversion chart found on any framing square.Therefore, 24.250 x 1.201850 = 29.1448625 feet is what the rafter length will be.

4. 

   Set the ridge board. To determine the length of the ridge board, take the length of the house, add the overhang distance, and multiply by two. Use 2-by-6s cut to the appropriate height and placed under each end of the ridge board and onto the top sill of the wall.

5. 

   Cut the appropriate angles that corresponds to the pitch. The builder will need to determine the angle based on the rise and run of the roof. Place one at the top of the rafter and one at the bottom but in reverse order. The angles can also be determined, based on the rise overrun of the roof, by the conversion chart found on the framing square. Nail the rafter into place with 16 penny nails. See the image for detail.

Tips & Warnings

• Always wear protective clothing. Be careful when cutting with a circular saw.

Resources

• Builder Bill DIY help
• Rafter conversion chart