![]() but wood is normally stronger by increasing depth rather than width, so I'm not sure if making that a 4x10 will get you double the spacing. ![]() In any case, we used #2 rough 2x12 Spruce, 16" oc on a 15' span with 60# LL (wood stove & water tank) and 10# DL and we passed structural checks with L/360 deflection (minimal bounce).Īccording to the calculators, you should be able to make 17'3" with #2 SPF 2x10, 12" oc. Joists, rafters and studs get some funky load offsets since they're repetitive members, but that's always in your favor if you did the load calcs based on single beam ratings. If you know the total load calculations, you can also find beam calculators on the Forestry Forum. You can also download their Post Frame Building guide. They also have span tables for joists and rafters and structural design date for beams and timber available for PDF download (I think you only have to pay if you get a hardcopy). ![]() Lodgepole Pine falls into the "Spruce - Pine - Fir" category. You can try the AWC Calculator for joists and rafters, but all calcs and tables for joists and rafters are geared toward 2x dimensional lumber. I'd be cutting pockets in the existing logs for joist bearing points. It will have 2圆 T&G subfloor (and as exposed ceiling in the lower room) with hickory for the finished floor above that. I'm wanting to use Lodgepole Pine rough cut 4x10's as floor joists, with a span of 17'4" max, 24" centers for an interior floor in an existing house. All I can find is related to using that size lumber as deck beams, which have different load characteristics. I've been looking for an applicable span rating chart that deals with 4x10's as floor joists. Small Cabin Forum / Cabin Construction / Span rating for 4x10'? In constructing a deck, I think it would be highly unlikely that going to 4x lumber for floor joists would make any sense at all rather than following conventional construction practice that meets applicable codes and industry standard construction practices.- Forums - Register/Sign Up - Reply - Search - Statistics. This is due to the increase in the moment of inertia by an extra 2 inches of nominal width size. If you examine the tables provided by Dupe, you will determine that going up to the next size 2x increases allowable span much more than use the same 2x at the next closer standard spacing. If your solution is to go to 4x lumber to attempt to fix the problem of an inadequate floor joist, then you probably need to step back and reevaluate your design or question your understanding of the concept of moment of inertia as it relates to supporting floor loads.Ģx lumber works well for standard construction techniques, including the ability to fasten it in a structurally sound method as well as being able to handle it and fabricate with it using common tools. The various organizations providing span tables for 2x construction did so for well thought out and time honored reasons.īasically, if a floor joist is determined to be inadequate to support a given load at a given span, then you must either reduce the span to a safe one for the desired floor joist size, reduce the spacing between floor joists to a lesser but still practical standard spacing, or go to a larger 2x lumber size of sufficient width to safely support the load at the required span under the given load. The lumber yard you called asked a very pertinent question. The following is posted soley in service to public safety.ĭupe posted important information relating to allowable spans for various sizes of standard 2x lumber. I don't know what code covers post and beam construction, but that's probably where you need to head. I think regular code doesn't list them because it's cover light wood framing, not heavy timber framing (post and beam). Also if these are sawn beams with no stampings on them, now that's a whole other issue. I would direct you to local building department. Engineered beams take this to an extreme and thus why something of the same dimensions has much higher ratings, they know what they got in that beam, so you can't use their numbers and apply to a sawn beam. ![]() The conservative nature makes sense both from simplicity but also when laminating multiple members you have a lower statistical chance of a bad flaw being in the same spot of the beam (one board could have a crack, the other doesn't vs one crack thru it all). So that is one place that touches on this. Now I would assume a 3圆 to be 2.5" thick vs 2 2byes which would be 3", so maybe some conservative nature. It list the same span values for the solid verses the build up. It has a few rows that call out 3圆 or 2 -2圆, 3x10 or 2 - 2x10, etc. There is an interesting table for deck beam spans. So in IRC 2015, most tables for headers and such have a note below them saying to can interpolate for values between those listed.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |