Andy,

That is a pretty healthy amount of hillside, I would be inclined to agree with him. We did a retaining wall that had 12' of hillside directly on the wall and more above it (including a road). The wall was 12' x 120' with a radius in it. We used 10" ICF block with #6 rebar every 6" and 2 #4 rebar on every coarse, tied together per the engineer. As the builder put it said, "That wall is stout!". It worked very well.

I don't know about the soil there, but I would be inclined to agree with the engineer.

renangle

10" is pretty standard in that area for below grade, 12's probably pushing more then really needed.

Good chance you will need a double cage #5 rebar pattern because of the mass of concrete, also a good chance you will need piers as well

If your engineer needs a detail disc let me know

Hi Chris. I just moved to the Charlotte area from California, so I am familiar with what you are having to deal with. I have worked on several basements in California that were retaining with 6" and 8" block. The closest thing I have done that I think can compare with what you are doing is a basement in Quartz Hill that had a back wall spanning around 80' that was 14' tall that retained about 13' of hill side. We started the first two courses with 10" block and then converted to 8" block, and then at 14', converted to 6" block for the main level. We tried to get the engineer (who also was slightly experienced with ICF's) to switch to making all the basement walls 8" because we felt it would be enough, but he wouldn't go for it.

(When I say this I'm assuming that you probably have more experience than me), I believe one of the ideas with ICF's is that they are stronger than normal concrete walls since they are covered with the foam and are able to keep curing over time without being broken down by the elements. So in essence, you have a wall that keeps getting stronger and stronger over the years rather than weakening, which makes the ICF' superior and able to handle more than a regular concrete wall. If you have any comments on that ( or anyone else), I would like to hear them.

On the practical side of where you are with your project, the man that trained me in the ICF's in California is a great resource that may be able to help you find a better solution. His name is Jim Deering. His phone is (661) 714-3844. He would more than likely be willing to help you either see something that you might not have thought about yet, or know someone who can help. Either way, I hope it works out for you.

Andy,

There is a lot that goes into a design and many details are left out of your post. You may have a better chance using 8" walls if you have several interior ICF "T" walls along the wall. Also, 100%  back fill of drainage gravel.

On the other hand it maybe a California thing, seismic. Soil liquidification?

Patrick T.

 

Hey guys - thanks for the responses! I appreciate the info. So next question..I was looking at fox blocks or buildblock and they dont seem to offer a 10" block. So If at the end of the day the solution ends up being a 10" wall what block would you guys recommend?

andy

PolySteel offers two solutions for your situation a 10 inch waffle grid block and the PolyPro which comes broken down and can be adjusted to a core depth of 4 inches up in 2 inch increments.  The benifit of the waffle grid is that if it will work for your situation you will save about 25 percent on concrete over a 10 inch flatwall core.  The PolyPro is a flatwall core and you would install a 4 and 6 inch spacer in the forms to give you a 10 inch core.  I built a 60 foot long, 10 foot tall curved retaining wall out the PolyPro with a 10 inch core, pictures at www.sonomapolysteel.com.  If you want more information please feel free to contact me at [email protected]. 

I don't want to disagree with glzman, but I believe that I don't have much of a choice. I seriously recommend that you contact your engineer if you consider doing a waffle grid for your 12' of backfill. I won't knock a waffle grid above grade, but below grade would be more questionable imho.

There are block out there that are 10", 12", and more if you search. Amvic and Reward are two that I know of that sell them. Depending on where they come from (i.e., freight) I would probably look at Amvic simply because their larger block are 4' x 2', thus 8 sq.ft. and they are easier to stack.

I would have to agree with renangle, if my main concern was the strength of wall due to backfil height I would not want to use a block that used 25% LESS concrete!!!
I would recomend that you go consult an engineer first, then come back here, tell us what he/she said, and go from there.
As for the block to use. I would decide if you are going to install yourself or have a contractor install. If you are going to get someone else to do it, find out which block they are most comfortable using. That way you will probably get the best job possible. Just picking a block and having someone install it isn't always the best way to go.

Just a thought - The vertical TF system goes from 4 - 10" in the plastic web and up to 24" in steel.

steve

1) yes I'll be stacking as an owner builder so it's really a blank canvass. I'm currently looking at fox and buildblocks because they advertise thier prices front and center. That says alot in my book. Not to mention the blocks appear to be engineered well and I havent heard anything bad about either. I know on this board everyone seems very polite about referencing other blocks by name when theres a complaint,  so any one have anything positive to say about these 2 ; ) ?
2) I will definately get back to you guys when I get get my soils reports and my engineer's recomendation. Always better to have all the onformation ; )
3) I would have a tendancy to agree about the waffle walls.  Aside from less concrete here's another anecdote - We just had a pretty substantial fire up here. I think 20+ homes were lost.
There was one pic on the Merc website (local paper) with the caption "concrete home with metal roof  burns."  Looking a bit carefully They were waffle walls and all the insulation had burnt out...Doesnt seem like you'de be able to rebuild those the same you could the solid walls that would be left behind with solid forms...but maybe so .. Any body have any thoughts?
4) with the price of concrete SO friggin expensive here I love the idea of saving on some - Does anyone have any experience or comments on the waffle walls?

Thanks Again!
Andy

Haven't used either but I know someone who has used Buildblocks, I respect his opinion and he felt that it was a good, solid block! Hope that helps.
Have you looked into there shipping costs?? depending on where they are coming from could really affect the square foot price of the block. Logix has just opened up a manufacturing plant in Cali. Try them (excellent block) may be cheaper for delivery.

hmm - didnt even occur to me to factor shipping in - duh.
Will look into Logix too when the time is right.
Thanks

6 and 8" most every manufacturer is open to you, 10" limits your supply and 12" leaves you with very few to choose from.

Waffle walls are the past, they were the way many years ago, times have changed and flatwall is the new or next generation and so as not to upset anyone, all cars were DC till the mid 60's and switched to AC, same idea, both work but the world went with the new technology.

Also as a DIY builder Waffle are a little tricky to pour, you will have a better chance of success with a flatwall.

If you are in the South Bay area concrete will be a premium (expect $ 130+ per yard), same as the North Bay, all aggregate is imported since they stopped mining in the local river (Do you think that has anything to do with the cancellation of Salmon fishing?)

And not to be smart, but companies that advertise their price and sell direct to you, be careful, it's not a scam, but without buying local from a local distributor...where's your on site tech support coming from? How do you propose an alignment system rental? Just some food for thought in your journey.

gotchya on the waffle - thanks.

Chris - where are you located? Sounds like you're in the area?? Are you a GC or a Distributor (both)?

So BuildBlock and Fox seem to be spoken of fairly well -  but yes I will do some more research when I have real numbers. My engineer is expecting my drawings in August so thats when I'll be really digging in.
As far as support...Well Im a pretty detail oriented DIYer with alot of exposure to the trades  - and had figured that I'd educate myself well and take my time. But, that being said - You're right - would be re-assuring to have someone available if I get in a bind. Is this the type of service that local distributers provide? And at what cost? Is it a premium price for the blocks, an added support package, or just an assumed service that goes along with buying from them?

So  - the bracing....well - I wanted to shy away from renting becasue I didnt want to be 'on the clock' paying rental fees while Im at work during the week. And certainly dont want to be rushed with this part of the job. Beyond that thought tho I have nothing ; ) I do have a nieghbor - guy I bought my backhoe from - that poured polysteel and braced it up with 2x4s...

Your thoughts?

and BTW - thanks for humouring the never ending post ; )

Cheers
Andy

Andy
You are going to want to use the proper bracing system to get the best result. It is possible to do it with 2x4's but involves a lot more work. You will be able to build all of your walls without the proper bracing by using ladders, scaffolding, etc. then when it comes time to pour have your bracing brought in, set it up, pour, then give it back. you will maybe have to pay rental for about 4 days. That should save you some money on rental if you are going to be working on it on the weekends. I know some distributors like to charge for their bracing by the day which can get quite expensive, mine charges by the pour which is nice!!
Good luck
Paul

Andy...

I am in the North Bay area and I am merely a lowly ICF installer who frequently visits this site to help people with thier ICF queries and to promote the good use and execute the proper installation of ICF's...no matter what brand

Premium is a harse word to use for buying from a supplier as opposed to buying direct, there is a cost value added to the advertised price online and this generally covers the suppliers support of your project...meaning they visit before, during and after the build (Hell, half of them will hang out with you for part of a day and stack block) to advise and review any problematic areas of concern.

I don't know of any supplier who will rent you bracing without the block purchase....kinda like kicking a guy and then asking for forgiveness, 2x4's are possible but are old school, difficult to adjust while pouring, but feasible.

drewsteele,

I saw one of the responders mention the TF System. Great ICF system. I've built with almost every type of block system and the ease of TF out shines blocks in my opinion. Go to either
tfsystem.com to check it out or our website - ebuildingsystems.com which has links and information about TF. As the other person stated you can get TF in sizes from 4 inch to 12 inch.

Don't get me started about engineers. Hopefully, you're not working with one that is afraid of his own shadow, or more accuartely put doesn't want to pay for errors and ommissions insurance, so they over engineer everything by a factor of three just to cover their ass. One guy posted that his engineer had him put #6 bar 6 inches on center. That engineer must have been the grandfather of chicken little.

I've install many an 8 inch retaining wall inside cuts of 12 foot and higher. I'm no engineer, but I play one on TV. Your soil is definately the determining factor as to how your retaining wall needs to be engineered.

The Panel Guy

Take a look at Quadlock, I just put in a foundation using Quadlock and am now switching to Quadlock for all of our foundations. They have regular ties that allow for both 10" and 12" cavaties. You can utilize their extender ties to achieve up to a 24" cavity (although I assume you would only use this to create pilasters). I can't tell you how happy I am with the finished product, it worked great.

I'll second what congacox and the Panel Guy said: check out the TF System ( tfsystem.com ). Easisest, if not the most versatile ICF system to use. I know a contractor that needed 4 different block systems to do his project. Could have done it all in the Vertical ICF system. Faster to install to boot. Plus you then have the advantage of continuous fastening locations (every foot on center, where there is a vertical I-beam).
Our finishers have an easier time as they alway know where they can screw. Sometimes a bit of hit-and-miss if you can't see the web locations of the block based stuff.