But I would tell you that using 2x4s as joist is problematic. They are much weaker than 2x6s so you will have to have a much tighter joist spacing, certainly no more than 12" from center to center. Secondly you will have to have many, many deck blocks along the length of each 2x4.
IF you are allowed to use 2X4's for the joists, it'll cost you more money than using 2X6's would. The 2X4's won't span as far, so you would need more beams and more footings to support them. The 2X4's won't span as far, so you would need more beams and more footings to support them.
Hi. I'm just about to order the lumber for my deck project. While I'm determined to buy cedar decking, I thought I had settled on the idea of using
"Sunset Decks" right here as I read it, it says that for Western Cedar, recommended max joist spans are 8'7" for 2x6, 11'4" for 2x8 and 14'6" for 2x10, all for 16" spacings.
Framing for deck on grade Tags: Tools and Workshop I am planning to build a deck on grade by laying 2x4s on the flat to act as 'beams' and then running joists over these.
Low Profile Deck Using 2x4 Joists by: Editor - Rich Bergman 2x4 joists would be sufficient depending on close they are spaced no further than 12" on center, maybe even a bit closer and how long the 2x4s will span from one support beam to the next. 2x4s can not span a very long distance without starting to bend.
In other words, when you put weight on the deck, the joist won't bend. The usual solution for dealing with undersized joists is to use more of them, spaced closer together. So, for example, instead of 16" spacing with 6" joist, you may have to go to 12" spacing with a 4" joist.
The size of joists, beams and most other standard framing elements are usually dictated by code. If you have a custom designed house, the architect will typically specify the required size of the framing elements, usually assisted by a structural engineer.
The problem you'll have with trying to use 2x4's as floor joists is that most span tables don't include 2x4's. This means that it will be hard for you to convince your planning department to approve your plans without some sort of proof that the 2x4's are adequate.
The 2x4 also wouldn't make for a sufficient floor joist, so you'd have to use new structural lumber for that anyways. If it's old lumber, I'd consider saving it for another construction project, or donate it to your local re-use center or habitat for humanity.
Well, my 2x6 joists are spaced the maximum recommended 16 inches on-center on the new deck and 12 inches on-center on the refurbished one. Although the joists span about 6 inches farther on the former than on the latter and add a cantilever, this still sets up an easy, if unscientific, comparison.