2x4 Rafters To 2x8 Floor Joists

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.

2x4 rafters to 2x8 floor joists.

Use your common sense when deciding how many fasteners are needed. Purchase the type of lumber that matches the width of the existing joist. This a rough guideline. Span calculator for wood joists and rafters also available for the android os.

Pictured at left is a diagram of some recommend prescriptive repair techniques for floor joists. Joist span and spacing is set by your local building code. 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. Also available for the android os.

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. Floor beam table. 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.

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. Most new construction uses 2 by 8 lumber for joists although 2 by 6. The heavier the load the closer together the. In this case the framer used 9 8d nails on each side of splice which is adequate in this case.

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. The rule of thumb is 6 foot span with a 2 6 on 16 centers. Measure the width and length of the existing joist. Hem fir 2 joists with a live dead load of 40 10 psf.

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. A 9 2 2x4 2 2x6 2 2x6 2 2x6 2 2x8 2 2x10 2 2x10 2 2x12 2 2x12 n 10.