Rebar Placement, Splicing and Tying for Monolithic Slab

[Danno]

Hello :-)

I just finished bending and laying #4 rebar to go in my 1' x1' footings, 2 lines ~3" off the bottom, another above the outer bottom line ~2" below the top of the 4" slab. See http://www.construction-resource.com/forum/ftopic4131.html&highlight= for background detail. Here's some questions:

Splice PlacementI used 16-20" overlap for splicing. Some of the splicing occurs near the corners. There are a few areas where the 3 lines have splices in the same places, i.e. the bottom outer line has a splice right under the top line splice and next to the bottom inner splice. You can see this in the pic posted. Are both of these splice situations (splices at corners and splices same place as neighboring splices) okay?

CornersIn the straight sections, my rebar is as per plans about 3.5" away from the outside forms. After bending the rebar is ~6-8" away from the form at the corner, due to the bend radius. Is this okay? There will be SSTB's about 7" from the corner, so it looks like they could be easily tied as it is now.

#3 mesh and #4 toplineI used 1' pieces of rebar nailed in place with a couple poultry staples to support the topline #4 rebar 3.5" away from the forms shown in the pic. This is a temporary position, just for bending and cutting. I plan to hang them 2" lower so they will be 2" below the top of the slab. Then I will run #3 along both the length and width of the slab about every 3', turning the ends down into the trench. They could bend around the upper #4 rebar, which would support that section. I could also tie the bottom of the turned down #3's to the outer #4 rebar line in the bottom of the trench, but I'm not sure that is needed.

Tying: Splices and DobiesI've got a roll of tie wire and locking and non-locking pliers. How do I tie the splices? Do I need to tie the dobies to the rebar? There are 2 chunks of pavers supporting the footing rebar, 1 chunk supporting the #3 mesh in the slab.

Anything else I need to do before calling for a pre-pour inspection?

Thanks :-)

[Rich]

I think you're just fine. You do need to tie the splices together - 2 per splice. Wrap around both pieces of rebar (once or twice as you prefer) and then twist until tight. You do not need to tie the rebar to the dobie's - unless you feel so inclined to do so.

[Danno]

Thanks, Rich :-)

Couple more questions:

Is it okay to butt 2 ends of rebar together, then use a 3rd short section and tie all 3 together? With #3 rebar, 12" is a rule of thumb splice length (I think), so using a 24" 3rd piece would give me 12" tied to each longer section, which is the same amount of overlap for a conventional splice.

Another way to deal with this problem is to turn down only 6" into the trench instead of 12". That would allow for a 2-piece splice instead of the 3-piece one.

Are either of these okay? :-)

[Danno]

Okay. Just went out and bent the rest of my #3. I could have managed materials better so here's what I got:

For the 28' length of the slab, I've bent down into the trench 12" of a 20' #3. I've got 4 spaced equally across the 14' width. Each one ends 19' down the 28' length. If I had 4 more sections of 20' it would be a no brainer. But I have only 4' sections. With my existing rebar, I'd have to use 3 separate 4' sections with 1' overlaps for splicing. Is this okay?

Thanks! :-)

[Rich]

Shorter pieces are definately not as good as a long piece - but IMO it's just fine. In your prior post: I think either would be fine also.

[Danno]

Thanks, Rich. I ended up splicing 3 smaller pieces at the end. They were 4-6' lengths.