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ICF design considerations for lower cost

Last Post 06 Nov 2012 10:11 PM by Lbear. 12 Replies.

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eugenep

Basic Member

Posts:144

05 Nov 2012 07:21 PM
Hi, I am planning on building an ICF home. Single story with a basement, and I am wondering what types of things should I consider to make my home less costly. For example, I was thinking that making the window openings at either 32" or 48", and then to make them a multiple of 16" tall would cut down on ICF block cutting, also, if making a bay window, make it exactly 2 90 degree deep, and then make it exactly 1 or 2 blocks wide. I also thought that making the basement either 9'4" or 10'8" to the top of the finished first floor, so again, no block cutting. Does that much of a difference? thanks, eugene

angelicareid User is Offline

New Member

Posts:6

05 Nov 2012 11:52 PM
You can consult expert contractors. We need not just low cost materials but also a high quality and durable materials that can last long. You need not to consider sub-standard materials which can cause accidents in the near future.

Lbear

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Posts:2740
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06 Nov 2012 12:52 AM
ICF costs are generally calculated by totaling the wall square footage INCLUDING windows. So it really does not matter about the window sizing, as it is calculated in the same square footage costs. So if you have 2,000 square feet of wall space and 300 square feet of window space, you have 2,300 square feet that is then calculated by the cost of ICF multiplier which is usually $11-$14 per square foot.

eugenep

Basic Member

Posts:144

06 Nov 2012 01:09 AM
So, you don't feel that the labor will be reduced if you design things strategically, or that the savings will only translate to more profit for the contractor.

Lbear

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06 Nov 2012 03:31 AM
Posted By eugenep on 06 Nov 2012 01:09 AM So, you don't feel that the labor will be reduced if you design things strategically, or that the savings will only translate to more profit for the contractor. The problem is that you are approaching the project like a DIY builder or in others words, as if you were going to be your own GC. Contractors will not sit there and dissect the project like a DIY builder would. A GC will look at a project like your home, they will measure the wall square footage, including windows, then give you a baseline cost per wall square footage. The costs are fixed for many things like concrete & rebar. The ICF and labor is also basically a fixed cost by the size of the structure and complexity. If you are building a basic rectangular home, measuring out window sizes to the exact inch in order to save a row of ICF is NOT going to save you money. You should design the home because of your needs, energy efficiency and aesthetics. Generally speaking, the ICF costs will not change unless you get really complex and introduce curves, tough lintel designs, complex shapes, etc. So let's say the GC runs around $12 per sq.ft. of wall space to do residential builds. Then you approach him with your design and everything you did was based on making it super easy for the contractor to complete the job, you will NOT see a drop in his fees. He is not going to drop it down to $11 or $10 because you made it easier for him by not needing him to cut a row of block. That's just the way business and bids work. Now if you get really complicated and introduce curves and other complex design shapes, then your cost per sqft will rise.

jdebree

Basic Member

Posts:497

06 Nov 2012 06:55 AM
Good luck finding windows and doors that fit ICF dimensions exactly. The other problem is that doors and windows may end up in places that don't work well on your interior layout. I planned my DIY ICF project very carefully, but the actual savings weren't significant. I drew each wall and each form, but what it mostly helped with was planning out things so that I could keep the fastening strips in line. I made a mistake in the basement, so I have one small area where they don't line up. It's going to make hanging drywall harder, as I have to map out the locations. Lesson learned- I had no such problems on the main floor. I think my contractor was amused at the pains I took trying to get everything to work out right. The time I spent planning would cost more than the materials wasted. That being said- A simple shape, and an envelope size that works well for your form system will save a bit. One thing I was disappointed with using Fox Blocks was that the different thickness blocks are somewhat incompatible. I went 8" on the basement, and 6" on the main floor- a reasonable plan. But the difference in the forms required trimming either the basement or the main floor. Otherwise, I would have had a step on the outside, rather than the inside of the walls. I had to trim the basement walls 4", IIRC, so that the main floor would line up. The problem is that the 6" corners are shorter than the 8" forms. So- good luck trying to save much.

Alton

Veteran Member

Posts:2164

06 Nov 2012 10:21 AM
Eugenep, I agree with the posted comments above. Where will you be building? Other building technologies may be available.

Residential Designer & Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period . 334 826-3979

eugenep

Basic Member

Posts:144

06 Nov 2012 10:56 AM
Posted By Alton on 06 Nov 2012 10:21 AM Eugenep, I agree with the posted comments above. Where will you be building? Other building technologies may be available. I live in Santa Clara county in Northern California. Are there many new technology or ICF builders contractors in the area? I haven't seen much when I try to do searches. It seems strange that such a high tech region seems relatively devoid of high tech builders. Also, with such high land cost, it is very strange that people, i.e. friends and coworkers, consider basements extremely odd and unnecessary. Yet, at the same time, they complain that the building area limit is very restrictive.

Roundeye

New Member

Posts:44

06 Nov 2012 11:10 AM
Santa Clara, depending on where you're planning on building has a very high water table. 4 or 5 feet below the surface in the Camden area. Basements were always considered a place to hide from tornadoes. So yes it's odd but I like basements. I can steer you to 3 contractors that use ICF's in your area. PM me or shoot me an email. [email protected]

I love any new challenges and ideas. Briing it!

eugenep

Basic Member

Posts:144

06 Nov 2012 01:21 PM
Okay, what about the garage? We plan on having an attached garage, and so two walls will go straight up from the basement. For the two remaining walls, I plan on using ICFs. So is it more economical to do ICFs straight up from the basement footings everywhere, and then have the garage floor over basement, or is it cheaper to have some kind of step-up footings from the basement to grade, and then have the ICFs align with the other walls? Because I don't understand how to go from basement floor to grade, it seems cheaper to make everything uniform. However, I presume the concrete floor over joists is much more expensive then a slab on grade.

Alton

Veteran Member

Posts:2164

06 Nov 2012 02:58 PM
If you have at least one basement wall above grade, then with proper design and installation, you can have a dry basement that is quality space. If all walls are below ground level, then you may need a sump pit and pump. Basements with all walls being concrete can easily support a concrete ceiling/floor. See Lite-Deck, Insul-Deck, etc. for EPS forms for concrete slabs. Structural Concrete Insulated Panels are available in the Southern part of California. See http://www.tridipanel.com/contact-us.php and http://www.tridipanel.org/ This panel manufacturer may know of an installer for your area. I have used this panel when it was called Insteel. SCIP panels are also available from Gulf Concrete Technology in Long Beach, Mississippi but the freight might be expensive to CA.

Residential Designer & Construction Technology Consultant -- E-mail: Alton at Auburn dot Edu Use email format with @ and period . 334 826-3979

eugenep

Basic Member

Posts:144

06 Nov 2012 03:22 PM
Posted By Lbear on 06 Nov 2012 03:31 AM Posted By eugenep on 06 Nov 2012 01:09 AM So, you don't feel that the labor will be reduced if you design things strategically, or that the savings will only translate to more profit for the contractor. The problem is that you are approaching the project like a DIY builder or in others words, as if you were going to be your own GC. Contractors will not sit there and dissect the project like a DIY builder would. A GC will look at a project like your home, they will measure the wall square footage, including windows, then give you a baseline cost per wall square footage. The costs are fixed for many things like concrete & rebar. The ICF and labor is also basically a fixed cost by the size of the structure and complexity. If you are building a basic rectangular home, measuring out window sizes to the exact inch in order to save a row of ICF is NOT going to save you money. You should design the home because of your needs, energy efficiency and aesthetics. Generally speaking, the ICF costs will not change unless you get really complex and introduce curves, tough lintel designs, complex shapes, etc. So let's say the GC runs around $12 per sq.ft. of wall space to do residential builds. Then you approach him with your design and everything you did was based on making it super easy for the contractor to complete the job, you will NOT see a drop in his fees. He is not going to drop it down to $11 or $10 because you made it easier for him by not needing him to cut a row of block. That's just the way business and bids work. Now if you get really complicated and introduce curves and other complex design shapes, then your cost per sqft will rise. I see your point. If it isn't necessarily cheaper, do you think it might be easier for them to install if I make certain design choices, and therefore more likely that the finished home will be tighter, or is that really a non-issue.

Lbear

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Posts:2740
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06 Nov 2012 10:11 PM
Posted By eugenep on 06 Nov 2012 03:22 PM I see your point. If it isn't necessarily cheaper, do you think it might be easier for them to install if I make certain design choices, and therefore more likely that the finished home will be tighter, or is that really a non-issue. I think it is a non-issue. It all depends on the experience of the ICF contractor. Typical air leakage in an ICF home is the windows, door and roof areas. The wall areas are pretty much bullet-proof but keep an eye on penetrations like dryer vents.