ICF Forms - Question 3

[SJLGlobal]

Is it possible to use sand or earth to fill the cavities in ICF forms in lieu of concrete for the construction of a simple single story building? I am assuming we could devise a way to keep the sand/earth in the forsm without leaking (vapor barrier?). Thnk you.

 

[JedClampett]

Sounds like a bad idea to me. What's supporting the roof? Sand and styrofoam? What's providing the shear resistance?
This is a structural engineers forum. Advice obtained from its contributors will result in permanent structures following good engineering practice, not something that will blow away in a stiff breeze.

 

[SJLGlobal]

The structure is a simple single slope roof. We are considering using ICF forms for the exterior walls of a single family house to be built on a mission trip to nicarauga later this year.

 

[msquared48]

I can think of a lot of reasons not to do this, and very few to do it.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Ron]

Absolutely not!

 

[JAE]

I would say no - but if you insist on trying - suggest you do a mock-up and load test - then video the test - then post it on YouTube for a good laugh.

 

[dik]

I would have a geotekkie dissuade you... sand will not likely provide a consistent shear resistance with moisture changes, leaks, etc. With reduced shear resistance, the bearing capacity of it may diminish. Also, the plastic form, may deform plastically over a sustained period of time...

Dik

 

[Ron]

SJLGlobal....some of our answers have been a bit "tongue-in-cheek", but nonetheless meant as a warning. ICF means "Insulated CONCRETE Form". The polystyrene is just a form that provides additional insulation that aids in energy conservation in the structure and serves to assist in the curing of concrete by holding moisture in the concrete. The form has NO inherent strength. It simply creates a cavity gridwork of reinforced concrete.

You are planning to build structures in a potentially high wind zone. Even though they might be small and single story, they still must withstand imposed loads.

Thinking outside the box to build inexpensive, viable structures is commendable, but as others have noted, this is not a process that has much capability to achieve your goal.

Since concrete is expensive, you might consider combining your intended process with some cement to produce a low strength, but competent material, that could be site-mixed. Even this would require testing and analysis to determine its efficacy.

Good luck.

 

[SJLGlobal]

Thank you all for your input on this subject. More than likely in the regions of the world we are looking at sending this structure materials for making even a crude concrete mixture are available (we send portland cement with the mission teams).

 

[concretemasonry]

Shipping ICFs can be a real problem because of the volume required in addition the the material cost. Is insulation really a problem or goal?

Look a little closer the the traditional building materials that have a history of use and developed practices. No sense in reinventing the wheel using most costly materials that no one is familiar with in place of locally available materials. - especially for a one story home system. There many many different systems that are used in a wide range of countries. Even rammed earth is very usable in some primitive areas for 1 or 2 story structures.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[hawkaz]

As concretemasonry noted,
If you are looking for something that can be constructed in areas with minimal access- consider rammed earth. You still need to reinforce these walls, but more along the lines of masonry reinforcing instead of concrete reinforcing.

The mix is very important- so you do need to know the soil types to determine if local soils are acceptable.

 

[spats]

This is one for the books... and in one of the most eathquake-prone regions of the world... go figure! How about adobe? I'm not familiar with it, but it's actually allowed by some codes. Probably not too great for an earthquake either, though.

 

[msquared48]

If you are thinking using the forms to make a rammed earth structure, I would think again. I don't think the forms could take the stress, and I would also be worried about rodents chewing on the forms too.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[southard2]

Just the pressure from the soils will likely cause them to blowout as you fill them higher and higher. Nope don't do this

John Southard, M.S., P.E.

http://www.pdhlibrary.com

 

[concretemasonry]

msquared48 -

You are right about the ICF not being adequate for anything to "rammed" into the cavities or voids (depending on the type). The forms are not rigid enough for compaction and some systems (not the flat plate systems) can be penetrated by vermin and insects.

I assume this is for residential construction.

Rammed earth usually is just damp soil and some cement that is rammed into a confined space/form and is a very basic, rudimentary material below adobe on the pecking order, but is used if there is not the right type of soil/clay. It minimizes the amount of materials (cement) that must be brought into remote areas.

In most of the developing countries brick (if suitable materials are available) have been used for centuries and can be reinforced. A step up from adobe and partially fired brick, concrete block are commonly used in many countries because of the availability of local aggregates and ability to make stronger units and be easier to reinforce, if necessary.

In some of the more rapidly areas of Africa concrete block are common since 6" block walls can use local labor, local materials (except possibly some cement) and easily be reinforced for 1 and 2 story homes. There are many "portable" block machines in these countries, with permanent ones in the larger, more developed markets.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.