Adding mini-joists between full joists for parallel decking/flooring
What do you guys think of this technique of putting 16″ OC blocking between each joist, secured with joist hangers, in order to lay deck boards parallel to the joists? In the case of 2×8 joists that span 11ft, I wonder if this weakens the structure, or if the load still gets distributed the same.
It’s more work and hardware, but it would be great for me on my current project since the joists are parallel to the house, and I’d like to avoid laying the decking perpendicular to the house.
I’m also wondering if in this case the full-length joists really need to be 16″ OC with the structural blocking also 16″ OC, or if making the joists into 2 or 3-ply beams would allow for more space between them, ie longer mini-joists (still spaced at 16″) and less hardware. Any suggestions?
Replies
Make your joists heavier and they become beams and can be farther apart. Then the "blocking" becomes "joists". No magic required.
Dan, I was thinking the same thing, but my joists can't be taller than 2x8s (beams are mated to house, can't go lower). So I can only make them heavier with multi plies but I'm not sure what acceptable spacing that gives me for the 11ft span. I know spacing 1-ply joists at 16" OC over 11ft span is okay, but I wonder if that means 2-ply joists can be 32" OC, and 3-ply joists can be 64" OC, and so on... or what
Hi there,
If your reason for wanting to run the decking parallel to the house is purely aesthetic then I would recommend an alternative that looks good and is much less work. Add blocking only at the outer joist bay and run one or two courses parallel to the house/joists, then run the other deck boards into those. You won't have any ends to look at from the yard side and the decking lengths will be one piece per course with no butt joints.
that's an interesting suggestion. I'll definitely consider it, thanks
Your plan would be a lot of extra work, would cost a fortune and take a lot of time. The blocking will work without the joist hangers or, if you are still planning, drop the deck framing down 1 1/2" and put 2 X 4" strapping across the joist for your decking to attach to.