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    Angelique H.
    US
    Angelique H.

    the text for the rafters portion is missing :(

    Angelique H.
    US
    Angelique H.

    Here is the text for the Rafters portion (please forgive me if i mispelled anything) The following is a list of terms related to laying out rafters. • Span The horizontal distance from the outside of one exterior wall to the outside of the other exterior wall. • Run The horizontal distance from the outside of the exterior wall to the outside of the top plate to the center line of the ridge board (usually equal to half of span). • Rise The total height of the rafter from the top plate to the ridge. This is stated in inches per foot of run. • Pitch The angle or degree of slope of the roof in relation to the span. Pitch is expressed as a fraction; e.g., if the total rise is 6’ and span is 24’, the pitch would be ¼ (6 over 24). • Slope The inclination of the roof surface is expressed as the relationship of the rise to the run. It is stated as a unit of rise to the number of horizontal units; e.g., a roof that has a rise of 5” for each foor of run is said to have 5 in. 12 slope. The roof slope is sometimes referred to as the roof cut. Laying out the framing for roof involves 4 tasks: 1. Mark off the rafter locations on the top plate. 2. Determine the length of each rafter. 3. Make a plumb cut at the ridge-end and tail-end of each rafter. 4. Make a bird’s mouth cut in each rafter. Determining the length of a common rafter The first step in determining the correct length of a rafter is to find the unit rise, which is usually shown on the building’s elevation drawing. The unit rise is the number of inches the rafter rises vertically for each foot of run. The greater the rise per foot of run, the greater the slope of the roof. A rafter framing square is a special carpenter’s square that is calibrated to show the length per foot of run, for each type of rafter. The steps for determining the required length of a rafter are: 1. Measure the building span. Divide that in half to determine the run 2. Determine the rise. (Calculate the total rise by multiplying the span by the pitch. For example, 40’ span x ¼ pitch = 10’ rise). Speed Square for Rafter Layout The speed square, also known as a super square or quick square, is a combination tool consisting of a protractor, try miter, and framing square. A standard speed square is a 7” – triangular tool with a large outer triangle and a smaller inner triangle. The large triangle has a 7” scale on one edge, a full 90-degree scale on another edge, and a T-bar on the third edge. The inner triangle has a 2” square on one side. A 12” speed square is used for stair layout. To use a square, you need to know the pitch of the roof. When you buy a speed square, it usually comes with an instruction booklet. This booklet normally contains (among other information) tables that show the required rafter length for every pitch. PROCEDURE FOR LAYING OUT AND CUTTING A COMMON RAFTER 1. Start with a piece of lumber a little longer than the required length of the rafter, including the tail. If the lumber has a crown or bow, it should be at the top of the rafter. Lay the rafter on sawhorses with the crown (if any) at the top. 2. Start by making the ridge plumb cut using the framing square. Be sure to subtract half the thickness of the ridge board. Make the cut. 3. Measure the length of the rafter from the plumb cut mark to the end (excluding the tail) and mark another plumb cut for the bird’s mouth. Reposition the framing square and mark the bird’s mouth seat. 4. Make the end plumb cut, and then cut out the bird’s mouth. Cut the bird’s mouth partway with circular saw; use a hand saw to finish the cuts. 5. Use the first rafter as a template for marking the remaining rafters. As the rafters are cut, stand them against the building at the joist locations.

    Yannai K.
    US
    Yannai K.

    The text for much of this module is missing.

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