I read post after post on this forum where people criticize a well engineered plan as too much of this or that. Once again, as stated numerous times by others, ICF is is a concrete forming product ONLY - it has no special powers or qualities that alter the need for proper engineering. My 3500 sq ft, 3 level 100% ICF wall and floor, 100% DIY house is in a high seismic zone and in the tropics where high DPs are required. Look this plan and detail sheet over for how the Insul Deck is reinforced. 4 x #5 in each T Beam and a grid of #3 in the 3" cover slab for T&S. Basically zero shrinkage cracks. Cover the slab after tooling with a spray on chemical that inhibits evaporation and eliminate all of the watering others mention. Insul Deck mix is 4000 psi with fiber, aggregate 3/8 maximum. LBear, look in lower left corner of plan for detail on cistern access hatches that are similar to the access you wrote about. Files HERE

Posted By vitempest on 25 May 2014 01:30 PM
 My 3500 sq ft, 3 level 100% ICF wall and floor, 100% DIY house is in a high seismic zone and in the tropics where high DPs are required. Look this plan and detail sheet over for how the Insul Deck is reinforced. 4 x #5 in each T Beam and a grid of #3 in the 3" cover slab for T&S. Basically zero shrinkage cracks. Cover the slab after tooling with a spray on chemical that inhibits evaporation and eliminate all of the watering others mention. Insul Deck mix is 4000 psi with fiber, aggregate 3/8 maximum. LBear, look in lower left corner of plan for detail on cistern access hatches that are similar to the access you wrote about. Files HERE

Thanks for the details!

So this entire home was a DIY project?

What seismic area did you build in (C, D)?

Do you have any pics of the InsulDeck build?

Posted By vitempest on 25 May 2014 01:30 PM
ICF is is a concrete forming product ONLY - it has no special powers or qualities that alter the need for proper engineering.

This is where the mis-interpretation takes place.

It does have 'special powers', it is a stay in place form, insulated.

Calculating rebar is relatively easy for the stress limits, then you also have to take into account crack control, because that is what you are also trying to prevent.

On a typical cast in place wall, the forms are usually stripped within a day or so of the pour, this has the moisture escaping, causing a rapid cure and exposed cracks.

The ICF form is the perfect cure environment, not only does it stay in place, its foam, trapping the moisture and prolonging the cure time.

Do cracks happen in ICF, you bet, minor ones do. It becomes a non-issue since anything you are attaching to the surface is attached to the ICF, not the concrete, so these minor cracks do not effect your finish product on the wall

See CSA A23.3-04 sections 11 and 14

And because of this, it is why I say check and question the engineer, it is not that he is doing a bad job, I believe he is doing a job he is not familiar with, ICF. Unless he understands how it works, he treats it as a regular cast in place wall...which is it wrong? No, but it is costing the end user more then necessary, which can price ICF too high for people, hence the reputation that ICF costs too much.

And this is only one factor of several that can cause ICF to cost too much

All good points Chris Johnson. The special powers you cite are true positive features of ICF, but at the end of the day it does not have any of the other special powers some wish it had. It is not structural, it does not make your wall stronger (except for its contribution to slow cure), it does not require more or less steel than a properly engineered "traditional" concrete structure, it does not allow smaller walls than would other wise be engineered for a concrete structure formed traditionally. It does save $$ for heating and cooling over time, often it allows for smaller HVAC systems as the thermal loads are smaller, provide excellent sound and thermal insulation, offer multiple options for installation of plumbing and heating, attachment of interior and exterior sheathing and so forth. It is not a short cut to a well built house. It is a tool for use by thoughtful owners and contractors looking for exceptional long term results.

Actually it can allow for reduced rebar, based on the crack control of the slow cure, and because of the slow cure, strengths are generally a lot high then mix design for the concrete and reducing cracks.

This is the part I am referring too when I say check and question the engineer, as ICF forms being used for the project have results that conventional forms do not, most engineers default to conventional form construction when designing for ICF. To this day, I still get drawings showing 12x12 10m (#4) grid for ICF. Most blocks are designed to spread it out more for a reason, they have examined and tested extensively to allow this.

Our engineer said he was not familiar with ICF. After reading what rebar everyone else is using in their wall, ours might be slightly over kill. 12"x12" #6 vertical #4 horizontal. But than again maybe he designed it to withstand earthquakes, Doesn't really bother me.

#6 for verts is pretty heavy duty, even for earthquake zones.

Rebar is sold by the ton, most is within a few bucks of each other per ton, but the quantity per ton changes a lot.

So lets say your paying $ 800 per ton, with #5 you get 96 sticks @ 20', with #6 you get 67 sticks at 20'

Do the math and get back to me for your project, then we can look at your horizontals

I used 3245 ft. of #6 in the wall cost $2000. for #5 it would have been $1450, #4 $932. When I was pricing rebar (20,000lb) for the whole house I got quotes that varied $1500. I wasn't sure if they called for the heavy rebar because of the concrete 1st floor and concrete roof.

vitempest
could you please contact me at
insuldeckflorida at aol dot com

LBear,

Do you have any updates on this project?

Thanks.

tom12ga, lbear...
if you dont hear from vitempest directly i can send you his pictures
just email me at insuldeckflorida at aol dot com

Lbear,

I just ran some quick and dirty calcs with the t-beam concrete software.
Your rebar setup will not work and of this I am pretty certain. I think your engineer made an error and meant to say 2-#5 at bottom (at least).
Talk again with your engineer. I would not fire them unless they are not willing to learn/communicate.
Also - the top rebar really does not do much for you. It is only needed for cases when you heave shear issues (or negative, for example, wind pressure pulling the roof up). Shear stirrups need to loop around it.
If you have no shear stirrups - ask your engineer to eliminate the top bar. Also #3 @ 12" o/c each way is too much. This is needed for punching shear for garage floors. WWM 6x6 2.1 gauge will do the job. However WWM is hard to keep centered in the slab so you may want to stick to the rebar grid.
3000 psi concrete is OK. 3/8" gravel and 5-6" slump.
This will be either 11" or 12" Insuldeck form. 3" Slab thickness works best.
For a 40psf LIve Load you will not need shear stirrups for this span. I really feel your EOR should go back to recheck his work.

Posted By Baldwin2014 on 26 May 2015 08:05 PM
Lbear,

I just ran some quick and dirty calcs with the t-beam concrete software.
Your rebar setup will not work and of this I am pretty certain. I think your engineer made an error and meant to say 2-#5 at bottom (at least).
Talk again with your engineer. I would not fire them unless they are not willing to learn/communicate.
Also - the top rebar really does not do much for you. It is only needed for cases when you heave shear issues (or negative, for example, wind pressure pulling the roof up). Shear stirrups need to loop around it.
If you have no shear stirrups - ask your engineer to eliminate the top bar. Also #3 @ 12" o/c each way is too much. This is needed for punching shear for garage floors. WWM 6x6 2.1 gauge will do the job. However WWM is hard to keep centered in the slab so you may want to stick to the rebar grid.
3000 psi concrete is OK. 3/8" gravel and 5-6" slump.
This will be either 11" or 12" Insuldeck form. 3" Slab thickness works best.
For a 40psf LIve Load you will not need shear stirrups for this span. I really feel your EOR should go back to recheck his work.

The EOR who did my InsulDeck engineering calcs is actually the same engineer that does the engineering for InsulDeck. He is the engineer for InsulDeck. In other words, he developed the calcs for the InsulDeck product and when InsulDeck publishes its span tables they use his calcs.

With that being said. Are you an engineer? I assume so since you have the T-Beam software.

In regards to, "3" slab thickness works best". I was told that minimum concrete thickness for anything structural is 4". That is why slabs are always 4". InsulDeck will span further with a 4" slab than it would with a 3".

We have complete confidence in the InsulDeck engineering. They are pros and know what they're doing.

Lbear... I see your ends are fixed... That makes a lot of difference and the top bar is warranted. You mention that down in one of your posts... I ran the calcs again on enercalc and am still having trouble with maximum bending stress ratio.... It will not hurt you nor your pride to go back and double check... Nor should he charge you more... Maybe your Live Load is really small... Theres tons of other possibilities...

Posted By Baldwin2014 on 27 May 2015 11:38 AM
Lbear... I see your ends are fixed... That makes a lot of difference and the top bar is warranted. You mention that down in one of your posts... I ran the calcs again on enercalc and am still having trouble with maximum bending stress ratio.... It will not hurt you nor your pride to go back and double check... Nor should he charge you more... Maybe your Live Load is really small... Theres tons of other possibilities...

Here is the JOIST info from the engineering plans:

Beam Width = 4 1/4"
Beam Height = 8"
Slab = 4"

J1- J2- J3 InsulDeck Conditions

J1 = Top Reinforcing - Continuous Bars = (1) #5
Bottom Reinforcing - Continuous Bars = (1) #5
Add Bars = (1) #5

J2 = Top Reinforcing - Continuous Bars = (1) #5
Bottom Reinforcing - Continuous Bars = (1) #5
Add Bars = NONE

J3 = Top Reinforcing - Continuous Bars = (1) #6
Bottom Reinforcing - Continuous Bars = (1) #6
Add Bars = (1) #6



Stirrups = NONE

Extend and Hook the Bottom is noted at both ends of the InsulDeck spans

We finally poured the last 28 yards on our little DIY project. Now it is on to the finish work! Pictures Here

Lbear... It looks like the J1 and J2 setup is for shorter spans - probably 18 feet (rough guess) and J3 being for the 25 span? J3 has #6 top and bot. rebar - this makes a big difference....