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Able Spaces Inc
ICF Insulated Concrete Forms
Planning an ICF project from the ground up


In this case the excavating has been done for a slab on grade application.  The forms shown are Form-a-Drain. This product has built-in drainage system for both water and radon. It does require some special care when installing stakes.

Normally the stakes primarily provide support to prevent the concrete from pushing the forms outward. In this case the radon rock is blown or shoveled into place prior to the concrete being poured. The slim metal stakes are held in place with drywall screws, with the support of the rock they do a good job of holding the concrete in.

The problem arises when the concrete is poured and people jump across the trench with a hose load of concrete. The drywall screws pop and the form is forced inward. This causes bows in the form at a time it is difficult to correct.

The best approach is to add extra flat metal stakes on the inside of the form to prevent it from bowing inside the area for concrete. 

Spacers from Form-a-Drain are used to keep the forms straight prior to installing your rebar.

Order at least one extra length of the form in case someone later in the project breaks or cracks a section, repairs can be made without delays.

A Theodolite will send out a beam to a rod from a central point and aid in finding the low point.  Now dig every thing down to that level within accuracy of 1/8".  

To get there, set up the Theodolite when you have time to go through all the points to be checked at once. Getting the Theodolite set up exactly the same a second time is very unlikely.  

Once corners are at the same grade, use a laser level to connect the dots. Without special glasses to see the beam this is best done early or late in the day when the sun is not as bright. 

A laser can be used to determine if the building is square. We went the old fashioned route with landscaping tapes and poles. The building has ten corners and the result was 2" overall out of square.
The building was engineered and therefore required sign-off from the engineer on all rebar layouts. Both plans and elevations were submitted for all rebar from the footings to the lintels.

To ensure all of the rebar was installed as specified, it was pre-cut/pre-bent and labeled for each application. This saved time and energy and added little cost.

Note: Two sections of vertical rebar bent to extend into the building are required to act as the electrical ground. One of these should be located close to the main electrical panel.


Follow the manufacturers guidelines for stacking the block. Each system has its own intricacies and forcing the blocks can cause damage to the interlocking teeth.  

The first layer of blocks should be laid out on the footings. If your layout does not fit the block increments exactly you need to decide where you will cut the block creating a vertical seam. That location should not be near a corner or where openings will occur along the seam such as doors or windows.

Once the first tier is completed the blocks can be attached to one another with large zip ties. Then the block is attached to the footing with special spray foam. Without the spray foam a short wall can start floating above the concrete as it is being poured. 

Block is set in courses one complete layer or tier before another complete tier is started.

​If Form-a-Drain system is used, ensure drains and the radon vent (if required) are in place prior to the pour.  
ICF block stacked first four courses

Steel fire door frames with custom flanges set into ICF block

ICF bracing installed ​before catwalk installation
Catwalk and window buck bracing
If improved fire resistance is desirable steel bucks/frames can be used for fire door installation.

The frames are installed as the stacked block height reaches the threshold. The frames must be braced while block is stacked around them.
The height of the braces should extend above the overall height planned for the blocks.

Bracing for the block should be installed between the 3rd and 5th tier of block. If you are in a location where wind conditions may be a concern put the bracing up closer to the 3rd tier.

The most common installation for bracing is on the interior of the building. In this case below grade mechanical interfered with bracing placement.  Interior ICF walls were braced on the interior of the building, while exterior walls were braced from the exterior.  

All the corners were braced from both sides inboard of the shorter end of the corner blocks. Braces were also placed at the outside of all "T" wall intersections.  

The bow set up for the pour in the outer walls was 1 inch at the center of the span.
The catwalk will assist in stacking block on higher tiers, but its primary function is as a platform for the person doing your pour to stand on while pouring the concrete into the wall cavity.

It is commonly thought the biggest risk to an ICF project is a blowout during the pour. A far more common occurrence is serious injury resulting from a poorly constructed catwalk. The catwalk should include the walk platform and a hand rail.
Catwalk installed with hand rails

In a slab application the mechanical systems such as water, sewer, and gas lines are put in below grade. The foam forms can be cut out for installation of pipes, however this is also removing part of your insulation.  

If mechanical is centrally located putting in a stud wall leaving space for the mechanical preserves the insulation and makes installation of the mechanical easier.

NOTE: Locating your propane tank and lines below ground reduces your risk of explosion in a wildfire by 80%. Gas lines can be sleeved and installed below the slab keeping the gas line away from electrical in the ceiling.​

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