How to Finish an ICF Basement

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Things You'll Need

  • Exterior waterproofing membrane

  • Chainsaw, router or circular saw

  • Electrical wire, connectors and boxes

  • Concrete drill and bits

  • Metal or plastic sleeves

  • Interior finishing materials (most likely drywall)

  • Nails and screws

  • Adhesive

  • Pens and markers

Creating a great basement

Insulated Concrete Form (ICF) basements are becoming popular in new construction, and for good reason. They provide excellent insulation values, great structural rigidity, are cost-effective and can simplify development of the interior. ICF walls are constructed using styrofoam blocks, which are then poured full of concrete, with steel bars (rebar) inserted in the concrete. The result is a reinforced concrete wall with styrofoam insulation on both the interior and exterior sides. Finishing of interior walls is possible for anyone with basic knowledge of tools and construction.


Installation of Infrastructure in ICF Walls

Step 1

Install waterproofing membrane on the exterior of the ICF wall, below grade, before backfilling.

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Step 2

Drill the wall and install sleeves for required penetrations--(electrical wire, vacuum system, etc.--if these were not installed when the wall was poured


Step 3

Plan routing of electric wire and locations of boxes, and mark these on the Styrofoam.

Step 4

Use the chainsaw, router or circular saw to cut the Styrofoam where the electrical materials will be located.


Step 5

Press the boxes and wire into the Styrofoam, and wire as required.

Step 6

Follow the same procedure for other items, such as computer wiring, vacuum systems and security wiring.

Finishing the Walls

Step 1

Locate the plastic ties in the styrofoam blocks--these are generally identified by a series of Xs. Mark the locations of these onto the drywall.


Step 2

Apply adhesive--desirable, but not mandatory--to the Styrofoam.

Step 3

Place drywall onto the Styrofoam, lining the marks up with the plastic tie locations (refer to Step 1).

Step 4

Insert drywall screws into the drywall as marked. These will go into the plastic ties for a solid fit.

Step 5

Complete this process for all ICF walls. Finish the drywall as required.


Check detailed information on the company website for the brand of ICF blocks you will be using. Printed materials supplied are often brief and lack the detail contained on the website.

When using adhesive, do a test to ensure that it does not “eat” the foam insulation.


Although ICF is gaining in popularity, many building inspectors are not familiar with this method of construction. Check with your local building inspector first to ensure that he has current information on ICF. You may have to educate him on this building method.


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