I am having an ICF house built in Colorado. It is a ranch with a walkout basement. One side of the basement will be about 10-11 feet below grade. We were planning on using Tech Block ICF's for the foundation and the main floor. Just found out that they are only useable to 8' below grade. Anyone know of a similar system as Tech Block that can go deeper?

At the risk of making the good people at Tech Block upset, but why not consider another block as an option? Tech Block is essentially a waffle grid ICF and I would argue that many on here would advise staying away from a waffle grid type system. I feel that a waffle grid block are more suseptable to having a structural problem then a monolithic block. I would not ever considered doing a waffle system below grade, not at 4 feet.

Any of the blocks listed as sponsors should be able to go beyond 8' of backfill. It may require a 8" or 10" or 12" block, but a traditional eps block should work fine for you. Also, performance wise, I personally believe that a traditional eps ICF block will be more energy efficient and tighter.

Each Tech Block weights 47 lbs...I would have to believe that you could build with ICF for the close to the same price as Tech Block. I think that you may be wise to discuss your options with someone who has experience there building with ICF...what do you have to lose? Apparently, you already have a problem with the 8' of backfill, so you must start thinking out of the box.

best of luck. renangle

Thanks for the feedback. I forgot to mention that the house is being built to Passivehaus standards. Tightness is important - so your point of traditional EPS being tighter could be important for what we are trying to accomplish. Are any of the traditional EPS systems tighter than others?

I am definitely a fan of composite ICFs like Tech block. That being said, everything has it's applications. Yours is better suited for one of many of the flat-wall traditional virgin EPS ICFs in 8" or more.

If you are going to build to Passivehaus standards a traditional flat-wall ICF block should serve you well. As to the question if any ICFs are tighter than others, technically I think you could say yes, but the differences would be so incredibly small it would be difficult to measure.

I would advise you to locate a contractor in your area that is experienced in building with ICFs. They should be able to explain to you the benefits of a flat-wall system and they one that the prefer usings (and why). If you are comfortable with the contractor, use the ICF block that he is comfortable using. The difference in price between block really shouldn't be that huge.

renangle

I'm not so sure it is a block limitation as opposed to an engineering limitation.  I have seen waffle grid ICFs 2 storeys below grade in an underground parking structure with 20+  storeys above (Durisol).  I have completed numerous projects that have 9, 10 and 12 foot clear heights below grade.  Again, perhaps question the engineering.  I am not familiar with the Tech Block so I cannot comment.  There are many ICFs available that can quite easily achieve what you are trying to do.  I don't think you'll have to look too far!

a 12' basement with waffle grid systems are no problem (I have done them). Structural requirements are met, less concrete is used, you don't use any polystyrene, you can leave the interior exposed/unfinished if you want as well.

With the Passivehaus std - it looks like the best option is an ICF that has the majority (if not all) of the insulation on the outside of the house. This allowing us to benefit from the thermal mass of the wall. It seems that many ICF systems have equal insulation inside and out. Durisol, Faswall, Quadlock are some that have more if not most on the outside. Durisol and Faswall use the recycled wood/cement for the actual block and rockwool inserts for insulation. It would be great to hear any comments or experiences with these brands or other options that may offer the majority of insulation on the outside. The big concern with the Passivehaus is air leaks. Will any of these systems be easier to seal.

I did a Faswall system for a friend a while back.  There wasn't a square block in the batch.  Most were out 1/4" or more.  Tuff to seal tight.  Maybe we just got a bad batch but my experience with them won't be repeated. 

Icf's in general when consolidated properly won't have air leaks in them and are very tight. I'm here in Colorado and would like to help you with your project. Drop me a message.

Dave

It has been backed up by testing that a flat wall ICF will out perform a waffle grid or post and beam wall on energy efficiency and strength. I would seriously consider using a flat wall system. We have done a 20' elevator shaft below grade with the flat wall system that we use.

--- Just a little rant---- I think it is quite interesting that many of the waffle grid and post & beam manufacturers that have preached how much better it was are now manufacturing flat wall.

I believe we had a similar situation with our house.

The house is one storey with a walk-out basement, built into the side of a ridge. As a result, one side of our garage wall, next to our front entrance had to be backfilled to approximately 9 feet. After looking at the options, we agreed with our builder to extend the Nudura wall using a T block at the front and made one side of the garage completely out of Nudura blocks.

Of course we had to install the necessary additional steel rebar to make it a properly engineered wall for the application.

hoog33, If you haven't made your decision as to which ICF system will work best for you, take a look at TF (The "vertical" system) You can evaluate the features of this system for yourself, and determine the benefits, however, one particular feature that you may want to look closely at is that you can get the EPS foam "Planks" at exact plate heights up to 12' which should work well for your 10' to 11' below grade wall (as well as for the rest of your ICF walls.)

Whatever your material choice, good luck with your project!

When it comes to cement bonded wood fiber, Durisol has been infinitely better with respect to tolerances, strength and service. I saw the Faswall blocks and I'm not sure what type of equipment they are using for cutting the unit heights. You should ask for an actual block from each of them and see the difference.

Hello: How long ago did you build with Faswall? Their new blocks out of Oregon are excellent. TomVD

James: How long ago did you use the Faswall blocks? Their new blocks out of Oregon since spring, 2007 are excellent quality. TomVD

hoog33
Another system to look into is www.hobbsbuildingsystems. They engineer each project to your site specs. Its a vertical system made to your specifications.

A lot of responses on that one! I'll address your original question, hoog. When you say it's "useable" to only 8 feet, that limited only prescriptively, that is, "designing" from tables. Get a structural engineer, and he'll be able to provide the design you need, to whatever depth you need. An engineer on a project involving concrete is always a sound idea.
Without getting into a discussion on the merits of waffle versus flat (they're all monolithic) wall systems, a waffle system has no inherent issues that make it more susceptible to structural problems than any other. They simply have to be designed differently.

Thanks.