This a rough guideline.
2x4 rafters to 2x8 floor joists.
The rule of thumb is 6 foot span with a 2 6 on 16 centers.
Pictured at left is a diagram of some recommend prescriptive repair techniques for floor joists.
For example in the rafter span table below the highlighted cell in the 40 live load table indicates that 2 x 8 southern yellow pine joists that have a grade of 2 that are spaced 24 apart can have a maximum span of 10 feet 3 inches 10 3 if designing for a live load of 40 lbs ft 2.
While every effort has been made to insure the accuracy of the information presented and special effort has been made to assure that the information reflects the state of the art neither the west coast lumber inspection bureau the american wood council nor its members assume any responsibility for any particular design prepared from this online span calculator.
Also available for the android os.
In this case the framer just needed a longer rafter.
In this case the framer used 9 8d nails on each side of splice which is adequate in this case.
The heavier the load the closer together the.
Get free shipping on qualified 2x4 joist hangers or buy online pick up in store today in the building materials department.
Purchase the type of lumber that matches the width of the existing joist.
When building a house or even a deck it is important to confirm you have the correct joist sizes spans and spacing before you get started.
Span calculator for wood joists and rafters also available for the android os.
Floor joist table joist size joist spacing maximum span 2 x 6.
Splitting the wood does no good.
Sistering 2x6 joists next to your current 2x4 joists will simply give you a new floor height of 5 1 2 inches as opposed to the current 3 1 2 inches.
Joist span and spacing is set by your local building code.
However when running spf 2 6 floor joists into the floor joist calculator referenced above you get a maximum span of 9 feet 8 inches with a minimum bearing length of 3 inches at each end on 12 centers.
While most residential construction uses 2x8 joists with 16 inch spacing there are many other factors you need to consider when determining the proper joist span length.
If you want to put down flooring in your attic and want more insulation underneath that floor then you need to increase your joist size.
Floor beam table.
Measure the width and length of the existing joist.
Hem fir 2 joists with a live dead load of 40 10 psf.