# Determining slope/angle of roof joist inside attic

Discussion in 'Framing and Foundation' started by swindmill, May 5, 2010.

1. May 5, 2010

### swindmill

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This is a very elementary question, but rather than walk around Lowe's looking at tools, I figured I'd come here: What's the easiest way to determine the slope of the ceiling/roof joists in my attic? I'm building a knee wall and the top plate will be attached to the joists, so the studs will need to be cut at the angle of the ceiling. I assume there's a simple tool for this?

Last edited: May 5, 2010
2. May 5, 2010

### Wuzzat?

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If Rise over Run is 3 over 10, the angle is the arctan of 0.3; 16.7 degrees.
The angles have to add to 180 so one angle is 90 and the other must be 90-16.7.

3. May 5, 2010

### inspectorD

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Its called a level and a block of wood....trace the angle on the wood when it is perpendicular to the angle you need.

4. May 5, 2010

### swindmill

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Good call. Thank you.

5. May 5, 2010

### CraigFL

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