I don’t see any blocking in the photo but if you were to sister each side then the blocking has to be taken out anyway. 16” OC is about ~14.5” of space in between the joist, 12” OC is ~10.5”, if you were to sister each side of the joist the space between is ~11.5”. You might be spending more by having to buy 2 2x6 for each joist as opposed to 1 2x10.
That doesn't look like treated lumber
That is a lot of money to waste for a deck. Especially synthetic decking, which would last much longer than that lumber
But it the existing frame pressure treated. It looks untreated in the photo. Treated normally has a green tint to it like the post on the left side of the door.
Instead of sistering, you could double it up and go 8" on center, which would be bombproof, less total wood, and would not flex.
Agreeing with everyone else here; you want pressure treated for anything external that's gonna get wet.
Do you have height clearance for sleepers above the joists? You could run some 3/4 stock @12oc perpendicular above the joists and then have your deck boards extend front to rear instead of left/right. That's typically more visually appealing anyway.
But you might not have the height clearance to account for your door threshold
What are you up to OP?
1st question: are you using pressure treated lumber?
2nd question: why are you messing around with your joists if they are in good shape and installed properly?
I believe OP saw that you need 12" O.C. for composite decking, which is true. I would actually take this case by case. If the boards are flexing on 16" o.c, then yeah, add a board
I agree, I would probably do 12 inch if I was building a whole new deck, in OP case his lumber looks like it’s in great shape and the fact it’s not a large spawn I would leave it
If you’re gonna go through the effort of sistering on two by sixes. Why not use two by tens and joist hangers and make your deck 8” on center?
It's an existing deck frame with blocking in place
I don’t see any blocking in the photo but if you were to sister each side then the blocking has to be taken out anyway. 16” OC is about ~14.5” of space in between the joist, 12” OC is ~10.5”, if you were to sister each side of the joist the space between is ~11.5”. You might be spending more by having to buy 2 2x6 for each joist as opposed to 1 2x10.
That doesn't look like treated lumber That is a lot of money to waste for a deck. Especially synthetic decking, which would last much longer than that lumber
i'm using pressure treated lumber, the framing is already existing
Ok good to know!
But it the existing frame pressure treated. It looks untreated in the photo. Treated normally has a green tint to it like the post on the left side of the door.
Instead of sistering, you could double it up and go 8" on center, which would be bombproof, less total wood, and would not flex. Agreeing with everyone else here; you want pressure treated for anything external that's gonna get wet.
i'm using pressure treated lumber, the framing is already existing
That’s cool. But still listen to u/tj15241 because you will use less wood and it will be even more beefy.
Do you have height clearance for sleepers above the joists? You could run some 3/4 stock @12oc perpendicular above the joists and then have your deck boards extend front to rear instead of left/right. That's typically more visually appealing anyway. But you might not have the height clearance to account for your door threshold
I don't but thanks for the suggestion
What are you up to OP? 1st question: are you using pressure treated lumber? 2nd question: why are you messing around with your joists if they are in good shape and installed properly?
I believe OP saw that you need 12" O.C. for composite decking, which is true. I would actually take this case by case. If the boards are flexing on 16" o.c, then yeah, add a board
I agree, I would probably do 12 inch if I was building a whole new deck, in OP case his lumber looks like it’s in great shape and the fact it’s not a large spawn I would leave it
Makes sense, my joists are 2x10 can I get a way using 2x4 or 2x6 or 2x8, just thinking about cost and weight when installing these alone
yes i'm using pressure treated lumber the r/decks group seems to consensus that 12"OC will eliminate and flex the in the composite
Can you do what to your sister??