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View Full Version : "shim" or wedge for top of roof joist.



Stephen Tashiro
10-07-2010, 10:02 PM
The slightly sloped roof on my storage building (vintage 1941) was made by having each joist level and putting a board on top of it to create the slope. The board on top is like a long wedge, so it reminds me of a "shim". It seems to me that cutting such a wedge would be very labor intensive. What would the modern way be to accomplish the same effect if the joists are level?

Jamie Buxton
10-08-2010, 12:29 AM
How wide are the joists? Are they 2x8s or the like? That is, the wedge is only 1 1/2" thick. You could cut that on a tablesaw with a long taper jig. It wouldn't be particularly labor-intensive -- just one quick pass through the saw. Or if you don't want to handle that long a plank through the table saw, you could use a track saw -- y'know, a Festool thing if you're rich, and a circular saw with a straightedge if you're tighter with your pennies.

Stephen Tashiro
10-08-2010, 1:49 AM
The joists are 2x10's about 16 ft long. I'd guess the wedge was cut from a 2x6.

Jamie Buxton
10-08-2010, 9:56 AM
Or you could snap a chalk line and cut along it with a skillsaw. In the construction world, that would most likely how it was done.

Ben Franz
10-08-2010, 1:04 PM
The joists are 2x10's about 16 ft long. I'd guess the wedge was cut from a 2x6.

If you're looking for 1/4" per foot, the wedge will go from nothing to 4" and nailing the fat end is a problem. We did a similar thing to correct a truss design error (oversight? brain lock? general HUA?) and ended up using 4" screws to get adequate fastening. It was a PITA and slow but beats eating the truss cost. An alternative might be to "sister" a 2x6 to the 2x10 at an angle and face nail with a gun. Probably twice the material but much faster. There could be issues with the shear load transfer between the roof and wall diaphragms if you're in earthquake or high wind regions so take the suggestion with caution.