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ICF (Insulated Concrete Forms)


ICF is a sensible choice for walls

General info on ICF can be found here .  It lists the various benefits associated with ICF construction.

This page (that you're on now) concentrates on the specific ICF purchasing details.

Even better than using ICF is to use the IFC (Insulation Formed Concrete) method of wall building.  I refer to this as Carnation Walling and you can see the implementation steps here .


Choosing an ICF supplier

Each supplier of ICF blocks will naturally talk about the benefits of their block design relative to other ICF suppliers.  Certainly there are different features, but really at the end of the day they pretty much perform the same function.  A higher order bit in making the decision on which block to use is the price.  When I say price I also mean shipping price.  That tends to mean you want blocks that are manufactured within driving distance of your location.

Typically different companies that own ICF block designs and the associated marketing subcontract the manufacture of the blocks to companies that produce expanded polystyrene.  The ICF brand companies lend a mold to the expanded polystyrene companies.  Typically the expanded polystyrene company manufactures ICF blocks for about 5 different ICF brand companies.

In many ways, picking the expanded polystyrene manufacturer (primarily based on location) is more important than picking the brand of ICF.  After you have selected the polystyrene manufacturer, ask them which brands they manufacture and then contact the brand companies to see who can give you the best price.

In my case there is a good expanded polystyrene company in Post Falls Idaho which is about a 6 hour drive from me.  They are called FMI-EPS.  They manufacture ICF blocks for many of the well known ICF brands.  I would be equally happy with any of those brands.  In my last purchase I chose GreenBlock ICF blocks, but if another brand is prepared to give me a better price then I will chose them in the future instead.

Even though I don't care about which brand, I have been very happy with the GreenBlock blocks.  They are 12" high, whereas many of the others are higher.  The height of the block does affect rebar placement and some people think that being only 12" high pushes you into using more rebar, but that's a myth.

Having thick and dense polystyrene to avoid blowouts is good.

If the blocks are not reversible then need both left and right corner types, but a pallet has equal numbers of each.

In my house design, all the walls are straight so there is no need for curved or fancy ICF shapes.

T pieces are not needed as it can be done by cutting a cavity sized hole as needed.

Having a large wall thickness is not a problem and is in fact preferred because of the greater strength and better insulation.  Assuming only a small cost increment over thinner (obviously more concrete too) then 8" cavity ICF is the best choice.  8" cavity blocks are easier to tie rebar inside.  For critical areas it's good to even go to a 12" cavity.

It is most convenient if you can arrange to place internet orders for the ICF bricks.  This makes it easier to order the various batches that you will need at the different stages of construction.

Greenblock ICF - two blocks 


Transportation and batching

If you are going to pickup the ICF blocks yourself straight from the polystyrene manufacturer you will need to hire the biggest possible removals truck (eg a 26 footer from Penske).  You will want to order the ICF blocks in batches that are multiples of the number that will fit in the truck.  You may also want to coordinate this with any other items that are being manufactured by the same company such as EPS sheets and EPS flooring sections.  You should aim to order everything for the basement and then place separate orders for each of the floors after that.  When calculating ICF quantities don't forget about the internal ICF walls.


Storing ICF

ICF is just EPS and plastic webbing so is not damaged by water.  It is though damaged by long term (6 month) exposure to UV (sunlight).  It is ok to store it outside, but it is best to find a shady location.  In my case I store it in the forest where the trees help keep the sun off it.

ICF in forest  

If it does get left in the sun for months on end then it will develop a yellow dust on the surface.  This can be brushed off and the ICF blocks are still perfectly ok to use.



GreenBlock is the brand I used on the evaluation building and I found it to be good.


Order from "Doug Eltze" <deltze@greenblock.com>

An 8" cavity has a polystyrene outside dimension of 13.25".  The actual polystyrene on a form is 2-5/8 inches thick on each side.

GreenBlock corners are 1'4" length on one side and 2'4" length on the other.

Standard bricks in bundles of 12.  Corner bricks in bundles of 16.

Each pallet is about 4'x4'x4'.  In a van you can stack 2 across and two high, so a 24 ft van can hold 24 pallets (if you are lucky and there are no protrusions in the van).