My wife and I have just started an Arts and Crafts ICF home in SW MT. Given the architectural style, we have one bump in entry and 3 bump outs, originating 9 feet below grade and ranging from 2 feet to 10 feet out, away from the structure. The length of these "bumps" range from 7ft to 21ft. With a desire to keep these entrys open, I've been debating with myself as to the best method(s) of supporting the returning ICF wall, both short term and long term. I realize this is largely a question for a structural engineer and not for us low life contractors. I also realize a properly supported opening (possible 2 X 12 one ft on center) with adequate rebar within the header block would provide considerable strength during the pour. This home, by the way, has a full basement, main level and an upstairs, all ICF. Below grade will be 8" ICF and above grade will be 6" ICF. I'm seriously considering framing the openings with steel ibeams. Suggestions? Thank You. sucecreek

Depending on the standard width of opening, core size of ICF, depth of lintel, loads above all generally require an Engineer, some ICF manufacturers create lintel specs, depending on your area you may be able to spec this your self. As an example, when I lived in Ontario provided I had all my ducks in a row and could show the Building Department how I calc'd my lintels with all information I could use a manufacturers recommended spec's, Now I moved to earthquake friendly California and throw my manufacturers lintle spec's away as everything must be individually calc'd. Using the steel I-Beams for lintles usually requires some form of attachement detail to the concrete in the ICF wall and I would wager (even though it is a fairly simple connection detail) the inspector will want an engineer detail for clarification. When ever possible I try to stay consistent and use concrete beams/lintles

Chris

Suce,

Hows the browns and the brookies doing there. If I am understanding you correctly you want to cantilever your concrete out from your building 2 to 10 feet from your structure without any supporting columns. And the lengths of these cantilevered portions will range from 7 to 21 feet in length. At what angle will these come off of the builging?

ICF Contractor

Chris & ICF,

Thank you for your replys. I realize I'm being rather vague, in part because I'm looking for some generalities
when supporting ICF walls over openings and the necessary reinforcement.
Maybe the best way to imagine what I MAY BE doing, in one case, is a
main floor sun room with a framed roof, OVER a below grade wine cellar that is open (approx. 10 feet) to the
existing basement. Generally, I think Chris is right, "it's all in the lintle tables." Has any one had experience
removing a supporting wall from a 10 ft opening with 20 ft of ICF wall above....... just sounds a bit frightening.

sucecreek

Okay, so what you are asking is sorta like this

the ICF wall is poured and you for the sake of this conversation 'Forgot, or wish to add' an opening, you now want to cut in the opening and want to know if there is sufficient strength in the concrete left above and around the 'New' cut out opening. This is a tough question, depending on all the items I talked about above, depth of lintle, width, etc. will give you a basic answer before you need to do the final item. The final item is have it reviewed and signed off by an engineer, but before spending your money doing this, you can do the basic calc's yourself to know what you may be getting into. Who manufactured the ICF? do they provide lintle tables as guide for you to work with? can you review this yourself to give yourself an idea as to which way this is going? A lot depends on your area, as an example, I currently live in CA, siesmic 4, your idea would not work here, period, engineer would be required and yes a steel beam and legs would be required, I use to live in ON and based on the info you provided, I could make this opening without a problem, need a few extra details but in general it would fly there, engineer may be required to look at it and sign off, but the fee would be minimal. I know this answer does not really help you a lot, but who helped you build this orignally and are they still available to help or even consult on this?

Chris

Suce,

Openings in a wall are rather simple to make in concrete construction. There are a few things that govern your opening and the "LINTEL" tables are a product of these factors. First off siesmic zone, I don't know if they consider SW Montana a siesmic zone but I do know one of the largest earthquakes to hit the continental US was in the Quake Lake area. Secondly, size of opening, depth of concrete above the opening, the load above, width of concrete, the compsessive strength of your concrete, and the size and grade of your rebar. All of these factors come together to produce your lintel design. Then if you shore that lintel properly underneath you should allow the concrete to reach design strength before oyu remove the shoring. This is not a scary concept since your lintel is designed to have less than a 1/360 th of a deflection. Your concrete is way more stable than a wood beam ever would be.

ICF Contractor

Thanks again for the good info.
For any one else whose interested, I came across a good, but short, article in the Reward Wall Newsletter dated Winter 2006 entitled "Lintel Design and Reinforcement Tables" that shed some light on the subject. The article touches nicely on lintel height, loads, shear strength and more. Tibits like the horizontal rebar "should not be more than 3" from the top or bottom of the opening," and "horizontal bars in between the top and bottom does not add strength to the lintel," seemed wise to keep in mind.

JC
sucecreek

"provide considerable strength during the pour"

For eight inch concrete core, we space 2 by 4 temporary bracing at 30" O.C. for temporary support during the pour. We double the verticals, and run single horizontal bracing between them. For six inch concrete core, we space 2 by 4's 36 inches on center... Check out the image gallery on www.icfresource.com for excellent installation photos and options....

"considering framing the openings with steel I-beams"
We have used steel I-beams for headers, and continued ICF walls above them as per engineers specs. We have also used low profile steel posts for intermediate support on wide openings, as another option.

Who is selling you block? You have great questions, ones which should really be available to be answered by your local distributor...? Are they helping you?

Kevin

Kevin

Questions like these are best answered by an engineer.  If, heaven forbid there was a failure, the person furnishing the advice could certainly be caught up in the litigation that would surely follow.  To stay out of that kind of situation no distributor, builder, or block company will supply you with an answer. 

We have recently received drawings back from a local structural engineer via the architect for our Reward Wall full basement plus 2 story home which I will be building. Assuming I understand things correctly, with adequate #5 rebar and no less than a 3 foot tall ledger (with no openings) we are able to span (with proper bracing during the pour), up to twenty feet....... a sizable opening fer sure. Given the 9 foot basement ceiling height, the "door" height is reduced to approximately 6 feet. I suspect I will build a 2 X 12 wall to support the ledger during construction.

sucecreek

Hi sucecreek:

So, now that you have a Structural Engineer come up with the need for a 3 ft deep beam/lintel over 20 ft span ... but you say that does not give you enought heigh for your door openings. I hope you have provided all the details to your Architect  and the Structural Engineer of the overall layout where the 20 ft opening is, and all that sort of information.

I am not clear on what exactly your situation is ... but if you talk to your Architect and the Structural Engineer, perhaps the lintel can be redeigned to meet your depth/height requirements by using more rebars and/or using structural steel reinforcement, ... 

Please keep us posted with how you make out. By the way, how about posting picture(s) of the wall in question, the associated beam/lintel and the door openings you talked about.