timberwolf78
New Member
Posts:43
|
16 Jul 2014 10:47 AM |
|
I am looking at the prescriptive method for ICF and am coming up with #4 rebar(I will be using #4 since that's what I have) every 6" OC for vertical reinforcement. My basement ceiling height will be 9' and backfill height on 2 sides will be 8'. The soil is clay.
Does this sound right? Any pouring issues with this much rebar?
Thanks |
|
|
|
|
|
ICFBdr
Basic Member
Posts:232
|
16 Jul 2014 11:57 AM |
|
There are a few other factors to consider. Where are you getting the reinforcing info (eg, Building Code, CCMC, Product Engineering, Site-specific engineering, etc)? Each of these areas may consider seismic zones among other considerations (and each one may offer different reinforcing schedules). Also, concrete thickness is a major piece of info that is missing. Sounds like you are in the ballpark with an 8" thick concrete, assuming no seismic zone and no unusual soil conditions at site (eg, expanding clay, etc). However, your best bet it to check with your ICF supplier, since they should be able to help with these types of technical questions (if not, I suggest searching for a new supplier) or your local building official. |
|
|
|
|
smartwall
Veteran Member
Posts:1194
|
16 Jul 2014 01:54 PM |
|
When you run your horizontal rebar use the inner most rebar fingers on alternate courses. This will hold the verts in towards the tension side and give you a clearer space to the outside for your pour. |
|
|
|
|
Lbear
Veteran Member
Posts:2740
|
16 Jul 2014 02:10 PM |
|
As a frame of reference my engineer called for #4 bar at 16" oc (horizontal) and 24" oc (vertical) for a 2-story wall in a Seismic Design Category "C" area with a 6" concrete core (3,000 psi mix).
|
|
|
|
|
ICFBdr
Basic Member
Posts:232
|
16 Jul 2014 04:33 PM |
|
Posted By smartwall on 16 Jul 2014 01:54 PM
When you run your horizontal rebar use the inner most rebar fingers on alternate courses. This will hold the verts in towards the tension side and give you a clearer space to the outside for your pour.
This is a good rule of thumb for a foundation wall that is laterally supported. Above grade walls often required rebar at the center of the wall, non-laterally supported foundation walls have tension side to the exterior, engineered walls can follow different rules. What I am getting at is to make sure you place rebar where is it required as per YOUR plans. Location of rebar is almost as important as amount/size of rebar to get full design-strength of the wall. |
|
|
|
|
Chris Johnson
Advanced Member
Posts:877
|
16 Jul 2014 06:28 PM |
|
You will be shocked when I tell you that you are probably too heavy on rebar Now that I got your attention Prescriptive method is a blanket, covers a multitude of areas (excl. California of course) and as long as you fit within the perimeters of what it allows, you will be fine. Hiring an ICF friendly engineer who actually understands the concrete code, concrete curing in ICF forms (yes this is important), exact site conditions, building configuration, etc, can usually reduce the amount of rebar needed as a project specific specification (that was a mouthful) Cost is always a factor, if this particular engineer can do other things needed on the project, in other words a multitude of engineering needs to be done, the fees he charges are generally a savings as what he can reduce in materials and labour in the actual construction. Time is also a factor, many times the engineer is rushed as contractors call them at the 11th hour looking for an answer and they need it now, so the engineer rather then work it to maximum cost savings, throws out calcs he knows work and doesn't give it a second thought to really push the envelope to create greater savings. But the blanket (prescriptive) method is always there, use as needed. Most of us do when plans arrive without engineering attached, it is our safety net too |
|
Chris Johnson - Pro ICF<br>North of 49 |
|
|
smartwall
Veteran Member
Posts:1194
|
16 Jul 2014 09:51 PM |
|
16" horizontal comes from the dark ages when that was the only spec available for icf. Pre prescriptive method |
|
|
|
|
Lbear
Veteran Member
Posts:2740
|
16 Jul 2014 10:35 PM |
|
Posted By smartwall on 16 Jul 2014 09:51 PM
16" horizontal comes from the dark ages when that was the only spec available for icf. Pre prescriptive method
ACI 318 dictates the horizontal spacing. It states a maximum of 18" oc vertical for walls. What do you do for your horizontal bars? |
|
|
|
|
Chris Johnson
Advanced Member
Posts:877
|
17 Jul 2014 08:01 AM |
|
Lbear The correct answer is 2% of the wall
|
|
Chris Johnson - Pro ICF<br>North of 49 |
|
|
ICFHybrid
Veteran Member
Posts:3039
|
17 Jul 2014 09:55 AM |
|
Is that for Grade 40 or Grade 60 bar? |
|
|
|
|
Chris Johnson
Advanced Member
Posts:877
|
17 Jul 2014 01:03 PM |
|
We only have access to Grade 60 in Canada as normally stocked rebar, actually its in Metric, converting it comes out to Grade 59 or something like that |
|
Chris Johnson - Pro ICF<br>North of 49 |
|
|
Lbear
Veteran Member
Posts:2740
|
17 Jul 2014 01:14 PM |
|
Posted By ICFHybrid on 17 Jul 2014 09:55 AM
Is that for Grade 40 or Grade 60 bar?
Grade 40 is junk. Most places won't even stock it because it's so bad. Grade 60 is at least 50% stronger than Grade 40. I've seen Grade 40 #5 bar snap in pieces when dropped from 5 feet. It was that brittle. It would prove useless inside a concrete wall that needs tension. |
|
|
|
|
Chris Johnson
Advanced Member
Posts:877
|
17 Jul 2014 01:26 PM |
|
I've bent grade 60 bar on a Hitachi bender and had it shatter in the process |
|
Chris Johnson - Pro ICF<br>North of 49 |
|
|
Lbear
Veteran Member
Posts:2740
|
17 Jul 2014 04:27 PM |
|
Posted By Chris Johnson on 17 Jul 2014 01:26 PM
I've bent grade 60 bar on a Hitachi bender and had it shatter in the process
Must have been some bad steel or it was heavily stressed from repeated bending? There was a batch of Chinese made steel that caused a lot of problems here in the USA. The steel had a lot of impurities in it and some was actually hollow in spots. Like the Chinese drywall debacle that cost Lowes millions of dollars. Grade 60 steel is the absolute minimum one should go with for a residential build. Grade 40 is guaranteed to be junk because it's rated a ridiculously low standards. |
|
|
|
|
Chris Johnson
Advanced Member
Posts:877
|
17 Jul 2014 05:10 PM |
|
Can you get #3 bar in Grade 60? I never saw it, or was able to get it. Unless you specify USA made rebar, chances are you are getting rebar from Mexico, Indonesia, Etc, Etc. And specifying USA made steel use to cost a hell of a lot more then whatever the supply house had in stock. And again I point out Prescriptive Method is a blanket, it is made to cover a lot of areas and allows for somethings to be missed and still works, so even if you have poor quality steel, the Prescriptive Method is overkill, the blanket, so most likely you are more then covered. As a rule of thumb, grab the tags from the steel and keep them on file...just in case there is a problem, the steel you are installing is stamped by an engineer who is taking responsibility for it's quality and meeting the minimum standard for grading. |
|
Chris Johnson - Pro ICF<br>North of 49 |
|
|
Lbear
Veteran Member
Posts:2740
|
18 Jul 2014 02:52 PM |
|
Posted By Chris Johnson on 17 Jul 2014 05:10 PM
Can you get #3 bar in Grade 60? I never saw it, or was able to get it. Unless you specify USA made rebar, chances are you are getting rebar from Mexico, Indonesia, Etc, Etc. And specifying USA made steel use to cost a hell of a lot more then whatever the supply house had in stock. And again I point out Prescriptive Method is a blanket, it is made to cover a lot of areas and allows for somethings to be missed and still works, so even if you have poor quality steel, the Prescriptive Method is overkill, the blanket, so most likely you are more then covered. As a rule of thumb, grab the tags from the steel and keep them on file...just in case there is a problem, the steel you are installing is stamped by an engineer who is taking responsibility for it's quality and meeting the minimum standard for grading.
Out here I can get #3 bar in Grade 60. All the rebar out here in my area is US Made unless you specify Mexican Made bar, which saves you maybe 3% on the total costs. The steel company I am dealing with sells US Made rebar and they go out of their way to make sure they sell only US Made rebar. A lot of it is regional dependent. In my opinion, Mexican-made Grade 40 rebar is a recipe for disaster. |
|
|
|
|