When supporting joists that span 12 feet with no overhang beyond the beam, a double ply beam can span in feet a value equal to its depth in inches. A double 2x12 beam can span 12 feet; a (2) 2x10 can span 10 feet and so on. Spans in excess of 20 m can be achieved (for the purposes of this article the definition of long span is taken as anything in excess of 12 m). Generally long spans result in flexible, column-free internal spaces, reduce substructure costs, and reduce steel erection times. Obviously, the larger the beam, the greater the distance it can span between posts. A Redwood 4x6 beam should span no more than 6' between supporting posts. Re: 20 foot clearspan beam size In that case, you need something like a 12-16" GLULAM or LVL to span the 20' and can use simple 2x8-10 dimensional lumber 16"OC as floor joists. In general terms, joists spaced 16 inches on center can span 1. 5 times in feet their depth in inches. A 2x8 up to 12 feet; 2x10 to 15 feet and 2x12 to 18 feet.
Max. Live Load 30 lbs/ft2 (1436 N/m2) Maximum Span (ft - in) Nominal Size (inches) Joist Spacing Center to Center (inches) Lumber Grade 2 x 10 12 20' - 3" 16 18' - 5" 24 15' - 0"
An H-beam has a thicker center web, which means it is often stronger. An I-beam often has a thinner center web, which means it is often not able to take as much force as a H-beam. The H-beam is often a lot heavier than the I-beam, which means it can take more force.
When supporting joists that span 12 feet with no overhang beyond the beam, a double ply beam can span in feet a value equal to its depth in inches. A double 2x12 beam can span 12 feet; a (2) 2x10 can span 10 feet and so on.
Table 2 - Size of steel beam supporting partition Partition load (from Table 1) [kN/m run] Clear span of beam [m] Smallest suitable Universal Beam size [mm x mm x kg/m] 5 to 7 up to 2. 5 2. 5 to 3 3 to 4 over 4 127 x 76 x 13 152 x 89 x 16 178 x 102 x 19 see Note 2
If you have a beam of steel which has a basic permissible bending stress of about 23000 lbs per square inch, by the time you make allowances for the span and the lack of restraint, the actual bending stress that the beam can handle is down to about 6100 lbs per square inch under these conditions.
In fact, each 2x10 will support 1, 200 lbs.
Structural Support Any new beam should normally have at least 150mm bearing (overlap onto the existing wall) on each side of the opening and the existing wall beneath the bearings are likely to need to be strengthened to prevent crushing of them.
Max. Live Load 20 lbs/ft2 (956 N/m2) Maximum Span (ft - in) Nominal Size (inches) Rafter Spacing, Center to Center (inches) Lumber Grade 2 x 10 12 27' - 6'' 16 25' 24 20' - 9''
per square foot for northern areas of the U. S. For rooms which are heavily frequented, it may be 50 lbs. per square foot. Multiply the loading per square foot by the area in square feet of the surface which the beams will be supporting. Divide by the number of beams which will be installed to get the loading per beam.
of 14 feet for a triple 2x12.
One 2x12 can support about 180 lbs. per foot or about 2, 100 lbs.
some of it gets pretty technical in nature, and mostly relates to pounds / square foot of loading. 2x6s are generally used for ceiling joists, esp since you said 24" oc and reallllly short spans only (5 or 6 feet ). Most floor loads would be a minimum of 2x8 @ 16" oc and most preferbaly 2x10.
A triple 2x6 beam over a span of 10' feet should be more than sufficient for normal deck loads.