How To – Foam Concrete Forms

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    A growing trend in form building for residential and commercial concrete foundation and above grade walls is the use of polystyrene or foam forms.

    The products are simple to use and install and because they are light weight there is no need for boom trucks or breaking your back lifting heavy aluminum panels when building your foundation forms.

    An added benefit is that the Foam panels that are used to create the form for your concrete stay in place and add insulation.

    Each manufacturer will have their own system for designing Foam Foundation forms.

    Some companies have single wall supports that are as high as you order the wall to be. They come with separators and ties already in the foam form with both sides attached and spaced to the appropriate width of the completed wall.

    Other manufacturers provide 1 foot tall 8 foot long boards that you build up similar to building up a block wall. You use as much as you need and add the ties on the top of each course as you go.

    Normally 2×4 bracing is installed vertically every 8 feet. attached with screws into the form and into the top of the form that was used to pour the footing. At the top of the styrofoam form you use 2x4s to wrap the top edge this will allow you to align and straighten the form incase there is a bow.

    Standard footings are used with a foam form install and will need to be designed by your architect.

    Other benefits include pre-installed furring strips for siding and stucco.

    Depending on which manufacture and product you select you can install rebar easily by fastening it to the ties that separate the the outside foam walls.

    Once you have completed the install of your foundation you will want to cut holes for waste pipe and other services. There are a variety of specialized tools that will make cutting the foam quick and easy or you can resort to a keyhole saw or hole saw on your drill.

    Hot wire cutters are used to shape the forms to provide access for windows and doors.
    Common soldering irons can be used to cut holes for electrical and plumbing access.

    Use a foam in a can to make sure that the holes you cut are sealed.

    Concrete should be poured at the manufacturer’s recommended rate which is usually 4 feet an hour. A pumper truck is recommended as you will want to fill the forms gradually building up the level of concrete evenly throughout the forms.

    You will need to tell your mix company exactly what slump you need because forms of this type will require a thinner mix with smaller aggregate to fill the voids.

    If you want to go higher then a single story or 8 to 10 feet you will need to allow the wall to cure before continuing.

    Some local inspectors are knowledgeable about this product but you should specify the use of foam forms in case they want to send an inspector to view not only the prep but the total pour of the foundation.

    The total cost to install a foundation using this type of solution should be taken into consideration.

    In remote settings where delivery of concrete can be more expensive or less available by pump truck you may find that a block wall solution is your best value but then again this would also mean conventional aluminum forms would also not be used for your project.

    PolySteel is a manufacturer of Foam Concrete forms
    For more information contact their website

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