Jack,

ICF construction is a VERY well-known and widely used construction technology in many areas. It has been used successfully (and cost-effectively) on countless projects by numerous people (commercial contractors, residential builders, and even DIYers). The fact that your area seems to be behind the times is an indication that your local market has not yet been properly exposed to ICF construction. To me, this does not indicate that there is a problem with the entire ICF industry, rather a lack of education, availability, etc. in your particular area. The fact that ICF is not known by your local inspectors is alarming, as you said it is mentioned in your local building code, with regards to earthquakes.

Seems to me that you are in the perfect situation to set yourself up as an ICF distributor. You can stock the blocks nearby so customers don't need to pay the excessive freight. You can also supply only EXACT quantities of product so there is no need to order full pallets and try to sell left over pieces. This will give you the opportunity to work with architects, builders, etc. to ensure nobody goes through the headaches you seem to have encountered. Get ahead of the curve and make yourself some money!!!

I looked at the link provided.

http://www.buildblock.com/pdfFiles/prescriptivemethodforicf_2ed.pdf

I found nothing conclusive about core sizes.

In section 4.1 there is something about using #5 rebar every 24 or 18 inches, depending on seismic zone.

jack,

On page I - 49 of that document, it does say the following...

Base percentages are applicable for maximum unsupported wall height of 10-feet (3.0-m), light-frame gable construction, all ICF wall types
in Seismic Design Category C, and all ICF wall types with a nominal thickness greater than 5.5 inches (140 mm) for Seismic Design
Category D1 and D2.

I don't know what your seismic design category is in your region, but I'm going to guess in the D range. I personally would save the money (and headache) and go with the 6" and possibly loss the 2" inside. Perhaps you can get the County to allow you to bump out the footer and exterior of the house to make up the difference? I personally would feel better in a 6". If you go with 4" use very small stone and perhaps a plasticizer.

Wall thickness is not the same as core size and vice-versa.   A 4" core usually gives you a 9" wall thickness.   Not that it matters because I didn't see anything in that document that specifically stated that in a seismic zone c, d1, or d2 a specific minimum ICF core size or wall thickness is required.   That snippet that you refer to deals with wall length, not core width.   They don't want you to have extremely short wall lengths, and if you do have to have a short wall length you need to reinforce it.   That's what that text you are talking about refers to.

On here, if we say 6" or 8" ICF wall, that is the core thickness, not the thickness with the foam. The foam is normally left out of the discussion. Perhap I am wrong, but the way I interpert what is said, they recommend a wall of 5.5" thick (of concrete) or greater.

I just tried to get to the bottom of the question of which seismic zone I am in.  C, D1, D2?    My conclusion is that it is impossible to determine that designation without hiring a geologist and soils specialist.   Even if you hire the experts you're not going to get an answer.   They will just provide you with mountains and mountains of data and dump it on you.    Trying to get a decision out of these guys is like pulling teeth.  Nobody wants to commit to anything because they don't want to be the ones responsible for anything when the big one comes.  So, you can hire a geologist and he'll tell you it depends on the soil.  The soils specialist will tell you what type of soil you have in very scientific terms but he'll say the final designation depends on the geologist.   Both will be smiling when they get their balance check for providing you with mountains and mountains of raw data, which will let you the dummy decide for yourself what seismic zone you are in.    Now wouldn't it have been easier to roll the dice and divide by two then add seven?

Here's a follow up question to the experts.   Let's say you have #4 rebar sticking out of an already made concrete foundation every 14" vertically.    It's a done deal.  Cannot be undone.  Earthquake specs say that you should have used #5 rebar.   I have a concrete drill.   It's about 6-8" long.   What would be better in your opinion?   To drill holes in the concrete right smack next to the #4 rebars and use tie wire to connect them vertically?    Or to just tie the #5 rebars together above grade using tie wire?

Jack, When in doubt, overbuild.

Jack,

If I were you, I would recommend calling Advanced Building Technologies (661) 245-2005 (they are an ICF distributer) in Frazier Park, CA. While I don't know anything about them, I would have to think that they have a better understanding of the seismic conditions, could perhaps consult on the ICF pour (even if its not their product), provide brace rental, etc. Its worth a call to get their impression of the situation and determine what's your next best move.

Or call

Eco Hammer Design DEALER
Contact: Joseph Recht
Address: Kensington, CA
Phone: 510-867-5573


L'abri Architectural Products DEALER
Contact: Darrell Smith
Address: 864 Liam Way
Beaumont, CA 92223
Phone: 951-712-0170
E-Mail: [email protected]
Web site: www.labriarchitectural.com

Jack,

I just got off the phone with Darrell, he should be chiming in here soon and he feels that he can help you.

Best of luck!

OK, I'll overbuild.   I'm convinced I need to use #5 rebar.   The ICF's haven't gone up yet because I'm waiting for the rain to stop.   We have an unusually long and drawn out rainy season this year in Southern California.   Also I'm working DIY on weekends and that takes longer.     So... back to the issue.

If the rebar going into the foundations is #4 how does one best connect #5 going up vertically?    Do you drill a hole next to the existing #4 rebar or just tie wrap the #5 to the #4 going into the foundation?

I would use 6" core ICF's but...  architect wants $600 to change the plans, county wants $200 to approve the change, cement mixer wants $600 for 6 cubic yards extra of concrete = $1400 total.   Until I find a definite specification somewhere that says that 4" core ICF's cannot be used in Seismic zones C, D1, D2 I'll stick with the plan.

Jack,

How are you going to attach your roof to your ICF walls?

Haven't looked at the plans for the roof yet, but I would guess J-bolts.   It's a wood frame roof with metal covering, so it won't be too heavy.

I have not followed the complete thread so let me ask this:  jacktca, are you planning on using any ledgers on the 4" walls to support a second floor or roof?  And have your plans been approved by the local code official for 4" walls for your area?  Just curious.  No judgments being made here.  Just asking.

Have you had a look at the 5'' core size that Integraspec offers?
I know I'm late in the discussion but to me 4'' isn't quit enough. If adding 15mm bars not much space left for concrete.
What are the wind loads in CO?

He can't meet the minimum spacing of 2.5" from the edge of the concrete to the side of the J-bolt anchoring his top plate on with 5" core size ICF unless he uses a taper top block.

In answer to Alton's question.  The plans have been approved.    It's a one story structure with a very light metal roof.   I'm not worried about the roof.  I'm not worried about the 4" core size.   I can use #5 rebar instead of #4 rebar if that's what the specs require.  What I am most worried about is the 40 minute rule.   There's an old saying, "when a man rushes the devil is happy".    A barrel truck drives up.   You have 40 minutes to dump that load into those ICF's.   To top things off, a 4 foot high layer of ICF's, which is the requirement for max wall height to be poured at once in the county, comes out to 5 cubic yards.   So 40 minutes will have to cover the time spent to dump the rest of the load somewhere else as well.   The subject is challenges.   I mentioned this challenge before but I am repeating it.   Concrete trucks and the 10 cubic yard minimum and 40 minute rule is madness!!!

As for 6" ICF's being better than 4" ICF's during earthquakes.   The best building product for earthquakes is a 2x4 wood frame structure.   I have been in quite a few earthquakes, big shakers as well as small swayers.    Believe you me, when it starts jostling, you want less rock to fall on you and crush you.   It's best to have no concrete when that happens, and if you must, make it 4" rather than 6".

jacktca.

Thanks.

Jack, if you are so concerned about every penny spent on your house, why are you building with ICFs? Your structure is small and I assume your climate is pretty mild - why not just build with conventional materials that you can obtain locally? Say 2x4 or 2x6 walls with full OSB sheathing glued and screwed to the studs for strength then covered with 1" or more exterior foam for thermal break combined with wet blown cellulose in the stud cavities. At 800 sq ft that is a relatively low cost easy DIY project that would still provide good performance.

And frankly, your idea that 4" concrete walls would be better than 6" walls in an earthquake is just dumb in my opinion. If you are going to build with concrete you have to build the structure strong enough to withstand the forces it might experience. The roof you propose with 4" walls will kill you and your family just as fast as 6" walls if they collapse and fall on you. The difference is that the 4" walls are much more likely to collapse. The roof helps to keep the walls from collapsing. If you are in a strong quake and that connection between the roof and top of ICF wall fails, building collapse is quite likely.