Porch Floor Joist Size

As a critical part to a deck that will last you for years to come it s important to find out just how many joists you ll need to safely support your decking and that depends on the size of your deck and approved building permit plans.

Porch floor joist size. So for an 8 foot long 2 44 m deck a redwood joist of grade 2 lumber would need to be 2 x 6 50 8 x 152 4 mm. 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. 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. Joist span and spacing is set by your local building code.

For best results refer to our wood and composite deck joist span table. Although building a deck seems straightforward there are a few important design factors to keep in mind. 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. In typical deck construction with a ledger on one side of the joist and beam on the other the size of the joists is driven by the size of the deck and based on the general maximum spans mentioned above.

True floor joist span calculations can only be made by a structural engineer or contractor. Your maximum joist span will depend on the wood species joist spacing size and whether the joists will be cantilevered. A larger joist size would be perfectly acceptable whereas a smaller size would not. Determining the correct deck joist spacing and span is actually more complicated than you may think.

In this example there will be a greater number of joists supporting the weight of the deck or flooring.