Log rafter span calculator3/19/2024 ![]() ![]() I've suggested (2) 8x8"x24' cants coupled together with 6圆x8" blocking on 24" centers which would make a 24" tall truss. I have plenty of trees to choose from, so getting good straight wood shouldn't be difficult. I'd rather create a truss out of heavy timber to carry the load instead, but I'm not finding any way to run the numbers. Putting a steel I-beam in (I need two such members to support this floor) seems sacrilegious. The other truss will hold joists on both sides and it's opposite side will be the outer wall of the building. One of these trusses will only support floor on one side, and the other side will be open to the center of the building. ![]() I want to put two trusses across 24' on 10' centers and then string joists between them for holding the floor sheathing (or boards). 2x12" oak maxes out at 19'6" for a joist. But since it's cold outside and I have 3 months of winter remaining, I figured I'd start working out the new monitor barn's design.Īre there resources out there I've failed to dig up with google searching? Some kind of calculator that'll give me data I can plug into another software program for double chord truss design? Everything I've found, or has been suggested to me, is for 2x and maxes out at 12" widths. ![]() I don't have any books on the subject yet, since I don't even have my mill built right now. The problem I'm encountering is no one has any engineering data for this stuff, or at least none they're willing to share publicly. The frame will be traditional heavy timber (8x8"), so I'd like to stick with timber instead of doing stick trusses. If you add an eaves overhang dimension, then the calculator will add the amount the rafter sticks passed the wall to the rafter length. The calculation includes results for hip/valley factor, slope factor and the roof slope in degrees. I could also argue that the structure in question is `unregulated’, so why the worry? I’ll tell you the worry! … I’m gonna be up there building the thing, and at times I will be sitting, or standing on, a single rafter!!! I’ll snoop around and find some other (independent, and free, online, for kicks and giggles) means of checking the concentrated load condition (other post).I'm trying to figure out how to support a 24' wide floor in my new shop. Calculate the length of a rafter from the roof slope ratio of inches per foot and a building width measurement. It could be argued that the 300-lb load need not be entirely carried by a single rafter. NOTE: it does not appear that the Span Calculator took into account the 300-lb concentrated load, which, we showed earlier, `governs’ the design. 2 are relatively high grades, which is what I (we) expected with the dim lum sections. That’s what I (we) came up with earlier … the Select Structural (SS), No. I’m used to using the `2012 Version’ (the one on the left) …ĭeflection Limit: L/180 … we haven’t talked about deflection yet … I will set it to the least stringent condition … L/180 means that the calculator will select a rafter size/grade that deflects (bends, bows) not more than the length/180 under the design roof load … (L/180 = 12 ft x 12 in./ft / 180 = … in this case … 0.80 in.) I also like the AWC `stuff’ … (use it all the time). I know a bunch of the folks at the AWC, and they are some of my favorite people. Use ForteWEB to determine solutions for conditions beyond the scope of this table. For Canada switch to Canada Sizing Table Lookup. The American Wood Council (AWC) has put together a free, online, span calculator. Use the drop downs below to select your loading, house width, and material to calculate the appropriate size of TimberStrand or Parallam ridge beam. If I was to run rafters every 2ft OC there would be 16 rafters in that span. ft x 75lbs (snow and dead load combined) 27,000lbs total on the roof. I was figuring it as 12ftx30ft 360sqft of roof. Recall that we (I) came up with 2×6 rough sawn (actual dims) stressed to 900 psi, which is probably doable in SP lumber, and likewise doable with 2×6 dimension lumber, but because the dim lum has less section, it will be stressed to 1428 psi, which is still likely doable, but using a higher `grade’ of lumber. The rafter span is 12 ft and the run is 30ft. ![]()
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