"ripping" deck joists
"ripping" deck joists
(OP)
In specifying deck joists where the client desires a flat ceiling I would typically specify ripping the joists so that they will slope to drain. For the first time I have a plan check comment telling me that this is not permitted by the code. Naturally, the plan checker did not site the code. Does anyone know anything about this?





RE: "ripping" deck joists
If you rip the joist - then you effectively have a less deep member - and any calculations should be based on this reduced depth across the entire span.
RE: "ripping" deck joists
RE: "ripping" deck joists
RE: "ripping" deck joists
RE: "ripping" deck joists
RE: "ripping" deck joists
The fastening method would have to resist the uplift forces.
RE: "ripping" deck joists
RE: "ripping" deck joists
Ripping a standard sawn lumber joists will not "compromise the lumber grade". Ripping the top flange of a engineered wood I-joists probably is not a good idea, and likely "illegal".
RE: "ripping" deck joists
RE: "ripping" deck joists
RE: "ripping" deck joists
I don't believe you could demonstrate that the joists comply with the code unless you had the joists regraded and then submitted an engineering analysis showing that stresses in the joists didn't exceed the allowable.
When you rip down a wood member you are voiding the grade, so unless you have it regraded you don't know what grade of material it is. Without knowing the grade you can't establish that it complyies with the code.
I have to go to a meeting so I will try to write a clearer explanation later.
RE: "ripping" deck joists
RE: "ripping" deck joists
Lumber at the mill is produced in certain standard sizes, such as 2x 10 & 2 x12, to be used for specific applications such as floor joists. Grade rules have been written to establish design values for lumber of certain sizes and specific end applications.
Generally floor joist material is produced as 2x8, 2x10 & 2x12 either in #2 grade or #1 & Better.When lumber is remanufacture or ripped the size is changed and as a result it may no longer make the same grade as it did before.
If we look at a 16' long 2x12 and saw in a taper of 1/8" per foot our section would go from 11 1/4" down to 9 1/4". Basically it is reduced from a 2x12 down to a 2x10. If the 2x12 was of #2 grade material it would be allowed to have a 4 3/4" knot on the wide face centerline. Now if there was a knot of that size near the 9 1/4" end of the joist it would no longer be on the section centerline and also would exceed the maximum knot size allowed for a 2x10.
Summarizing the above, the reason you can't rip lumber down is that you are changing the location of the strength reducing characteristics, such as knots, in relation to the centerline of the section. Also the larger section allows for larger knots than are allowed in the smaller section.
RE: "ripping" deck joists
RARSWC is correct.
Check out this document:
"American Softwoods Standard" DOC PS 20-99
Section 7.3.7:
"Remanufacture (ripped, resawn, or surfaced) of graded or grade marked lumber negates the grade or grade mark and the design values of the original product"
browntrout
RE: "ripping" deck joists
You are correct.