Understanding the difference between them is essential for those working in the construction trades while basic knowledge is useful for homeowners if repair and maintenance issues arise.
Roof rafter and ceiling joist framing section.
Rafters attached to ceiling beams.
Where ceiling joists are not connected to the rafters at the top wall plate joists connected higher in the attic shall be installed as rafter ties or rafter ties shall be installed to provide a continuous tie.
Ceiling joists shall be continuous or securely joined where they meet over interior partitions and fastened to adjacent rafters in accordance with tables 2308 10 4 1 and 2304 9 1 to provide a continuous rafter tie across the building where such joists are parallel to the rafters.
Ceiling joists shall have a bearing surface of not less than 11 2 inches 38 mm on the top plate at each end.
2x4 connected to each rafter if no rafter tie ridge to be supported by engineered wall or girder.
Roof ceiling framing rafter exterior wall nailed to rafter ceiling joists parallel to rafters 2006 irc r802 3 1 joist or rafter tie which must be min.
A 2 4 wall with a 2 6 rafter can be notched for a 4 seat.
The international codes i codes are the widely accepted comprehensive set of model codes used in the us and abroad to help ensure the engineering of safe sustainable affordable and resilient structures.
Section r802 5 2 also states where the ceiling joists are installed above the bottom third of the rafter height the ridge shall be installed as a beam in other words to raise the ceiling joists more than one third of the ridge height a structural ridge would be required.
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.
Section r802 wood roof framing.
In order to maintain the triangle shape there are specific requirements for how to fasten the corners of the triangle together.
Where joists are located above the top of the wall the joists have to be nailed.
Meeting current irc roof framing requirements means builders are really constructing very simple triangles using the rafters and ceiling joists because triangles are known to be the most stable shape.
Use a framing square to help lay out the notch based on the slope of the roof.
The international code council icc is a non profit organization dedicated to developing model codes and standards used in the design build and compliance process.
Ceiling joists shall be continuous or securely joined in accordance with table r802 5 1 9 where they meet over interior partitions and are nailed to adjacent rafters to provide a continuous tie across the building when such joists are parallel to the rafters.
Joists and rafters are components used in the construction of buildings.
