Use the span tables below to determine allowable lengths of joists and rafters based on size and standard design loads.
Residential wood floor joist span table.
Joists rafters simplified maximum span tables for selected visual and mechanical grades of southern pine lumber in sizes 2 4 thru 2 12.
Straight line interpolation shall be permitted for intermediate spans and design values.
So our house would look like the picture below with all floor joists 2 x 8.
The maximum span is measured o c.
Floor joist span tables for various sizes and species of wood joist span table use these tables to determine floor joist spans based on grade of lumber size of joist floor joist spacing and a live load of 30 lbs ft 2 or 40 lbs ft 2.
Lp solidstart i joists technical guide for residential construction lpi.
You can also use the wood beam calculator from the american wood council website to determine maximum rafter and joist lengths.
Listed are 46 tables based on common loading conditions for floor joists ceiling joists and rafters.
This sample table gives minimum floor joist sizes for joists spaced at 16 inches and 24 inches on center o c for 2 grade lumber with 10 pounds per square foot of dead load and 40 pounds of live load which is typical of normal residential construction.
Reading the table you ll see that 2 x 8s installed 16 apart on center can span 12 4.
Dead load deflection is limited to l 360 and total load deflection is limited to l 240.
These span tables assume installation of at least three joists or rafters that are spaced not more than 24 on center.
Of bearings and is based on uniformly loaded joists.
This performance standard provides an easy to use table of allowable spans for applications in residential floor construction allowing designers and builders to select and use i joists from various member manufacturers using just one set of span tables.
High pitch 6 12 to 12 12 16 17 load bearing cantilever tables 18 21.
This means that some values are slightly more conservative than span tables from other sources if those do not include the amended guidance.
Low pitch 6 12 or less 14 15 roof span tables.
Our floor joist span tables are based on loadings given in the newer amended version of bs 6399 1.
The spans are based on simple span joists.
The calculated spans assume fully supported members properly sheathed and nailed on the top edge of the joist or rafter.
Span tables for domestic floor joists to bs 5268 7 1 note.
The minimum bearing length is 1 spans values in bold indicate that web stiffeners are required at the osb end panel.
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View joist rafter tables.
Since the example house we are designing for is 12 feet wide we need to find in the floor joist span table a joist size and centering that can span 12 or wider.
True floor joist span calculations can only be made by a structural engineer or contractor.
