Sistering short joist for composite deck edge?
Tony_M3
| Posted in General Discussion on
I’m replacing old deck boards with composite ones. Where two boards butt up against each other I don’t want to try to screw them both to the same 1.5″ thick joist. I’d like to attach a short (8 inch?) 2×6 flush at the top so the end of one board can attach to the joist and the end of the other board can attach to the small sistered piece. Are there any problems with this? Any particular size of the sistered piece, or fastener type to avoid code violation? I realize codes can vary by location, I’m just looking for any insight on this methodology if anyone knows any do’s/dont’s. Thanks!
Replies
I'm not qualified to answer this question but isn't there an issue with replacing wood decking with composite considering the fact (I think) that most wood decking is fastened to joists that are 16" on center while composite requires 12" on center?
I'm interested in doing the same thing you are wanting to do but thinking I need to rip out my entire deck and start over with an increased number of joists.
For most composite the manufacturers state 16" is max acceptable spacing unless you're doing a diagonal pattern, in which case 12" is the max spacing.
If anyone has insight on my original question please chime in!
What you are describing is called a scab board (lingo in my area anyway), it’s not really sistering a joist. You simply want a nailer for single piece of decking. Can install a scab board just fine and it will pass inspection, but to a trained inspector and carpenter eye it will look a bit cobbled up, not as clean as a pro install. Will need to use corrosion resistant nails or screws like the rest of the deck to attach it. It can be a 2x4 as well. For butt seams on decks a lot of guys including myself place a board in the middle of the deck perpendicular to the decking to create an effect of two picture framed areas. It looks a lot better than having butt seams everywhere. You can usually order composite decking in up to 20’ lengths, so might not need any butt seams at all.
i am planning on building a 20'x16' ground level deck, composed of only 2''x6'' ground contact pressure treated douglas fir #2, and trex decking boards. the side that is house and backdoor adjacent will be framed using a 2''x6''x20' ledger board. I plan on running 2''x6''x16' joists, around 14'' O.C, perpendicular to the house from the ledger board to a (2)2''x6''x20' flush beam. the flush beam will comply with deck beam span lengths and will have support every 4'. now obviously the joist are overspanned, so my question is:
•Considering that the allowable joist span for a #2 douglas fir 2"x6" spaced 16'' O.C. is 8'8'', if i use pre cast decking blocks at the middle of each 16' Joist, would this alleviate the issue with the overspanning? i understand that this is nowhere ideal, i just want to know if its in the ball park of reasonable. also I am in socal so no concern of snow, no frost line, and very little concern of rain or wind.
Check with you local code authority, but ground level decks usually do not require a permit in most cities. If you exceed 200 sq ft and/or deck is being used as a form of egress you may need a permit. Assuming no permit is required and no frost line concerns, using blocks as you described is fine. Your deck is basically acting like wood pavement, so safety isn’t really a concern. No risk of collapse etc. I would compact the dirt well below the blocks.
Thank you jlyda!