paulsharvey
Elite Member
Maybe in areas where they brine/salt roads? It isn't here.
Concrete Chairs
- Thread starter EddieWalker
- Start date
paulsharvey
Elite Member
Does the foam retain its shape/structure/insulating properties with that much weight on top of it? I've seen it used only in videos from eastern Europe, and typically with those radian heat floor tubes.
I used high density 1.5- 2" foam very minimal distortion, with wwf over it graded and compacted extensively before placing sheets even taped all joints. first time I used foam forgot to adjust for foam thickness lol needles to say I had a large pile of sand afterwords cuz of my f-up and should be in stupid thread. Btw I've had great results using compacted sand using a bit of water to help. I'll say I burn wood at my cabin the stoves on slab once that slab heats up it maintains heat for awhile. if I burn continuously for several days over 90% of the slab can be comfortably walked on barefoot and it's below zero outside.
jfsawatzky
Bronze Member
What distance between chairs would accomplish that?
ponytug
Super Member
I think that depends on the size of rebar in use and the spacing of the grid, doesn't it? Small diameter (number) rebar needs more supports, and larger rebar needs less. I believe that there are tables, like this one; https://www.lotel.com/sites/default/files/user/Rebar-ups spacing chart B.jpg
However, I think the bottom line is "Is the rebar staying at the desired height off the base?", and "is it not deforming if the crew walks around on it?".
All the best,
Peter
I'm stubborn and follow how I was taught commercially over 20,yrs ago pull wwf and or rebar as the concrete is placed. Only time I've used chairs is when a rotating laser retractable boom screed was used probably because they didn't want excessive crew members in between the rather large machine and screed board it was pulling so they gave me the job to put in chairs as the machine did its job. A machine that big moving around a grid will crush plastic chairs and deflect rebar no matter how well it's supported. Perhaps times have changed in over 20 years? From non commercial personal experiences I'd rather spend the money from not using chairs to put fibers plus wwf in the concrete so I'm for pulling as you place, and am far more concerned of wwf or rebar shifting to the edges of a form and being exposed, however I am not a concrete expert like a few on here, I also feel somewhat experienced building inspectors make the call if they want you to put in chairs based on getting a feel for your experience and or the reputation of the company. you hired, a rock bottom priced fly by night concrete contractor from previous problems the inspector might request they use chairs. Just my opinion.
JJT
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My last large pour, (40 yards, 15+ years ago), I used chairs made from concrete with a built in wire tie. Very handy. I searched and cannot find them now. It seems like plastic or wire are the only choices. I used #4 rebar, 24" on center in a grid format. I have no cracks, I did not use fiber in the small aggregate 4000 psi concrete.
MossRoad
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When I did my garage addition in 2020, I used these little plastic chairs. Pretty easy addition, cheap, and I know the rebar isn't laying on the bottom or 1/4" from the top. They are currently .29 each. Not sure what they were 4 years ago.
EDIT: They were .17 each in 2020.
Nice thing about Menards... they keep your receipts on-line for quite a while.
www.menards.com
(click to enlarge).
EDIT: They were .17 each in 2020.
Nice thing about Menards... they keep your receipts on-line for quite a while.
Plastic Rebar Chair
The 2-1/4in plastic rebar chair is a durable plastic rebar support system that is ideal for concrete applications. The chair is designed so that the rebar snaps securely into place allowing the rebar to sit above the ground while concrete is poured. The chairs are easy to work with and...
www.menards.com
(click to enlarge).
ponytug
Super Member
You might try searching for "wire dobie" or just "rebar support", or "rebar concrete block".
FWIW: They are in my local Home Depots, but not the few I checked in Michigan. In the Michigan Lowe's that I checked, it was called a "rebar concrete block", but clearly had wires on it.
Search Results for Rebar block at The Home Depot
Search Results for Rebar block at The Home Depot
www.homedepot.com
All the best, Peter