Insulated Concrete Forms

Topic 4 – Insulated Concrete Forms

Insulating Concrete Form (ICF) systems differ from panel form systems in their composition and assembly. Unlike conventional formwork, ICFs are not removed after the concrete has set. The form’s main component is expanded polystyrene blocks, planks or panels for predetermined wall thicknesses. Both sides of the form are held together with a plastic or metal web. The webs will allow for the proper placement of rebar.

Source: https://upload.wikimedia.org/wikipedia/commons/7/79/Insulating_Concrete_Forms_ICF_Interior_Block.JPG

Each manufacturer’s specifications will include assembly instructions. The ICF is set on a footing or slab usually starting from the building corners. Most products will require an adhesive to “glue” the form to the footing and at set intervals. Intermediate bracing is done with a strongback and adjustable brace. Unlike conventional wall form systems, ICFs have the wall leaning slightly inwards prior to placement. During placement pressure on the brace will tighten and the wall will lean outward at the top.

For additional reading refer to

• Carpentry Chapter 31 Insulated Concrete forms

For Code Requirements for Insulated Concrete Forms refer to the

1. National Building Code of Canada, 9.15.4.1 to 9:15.45C, and 9.20.17 also study Tables 9.20.17.4-A, 9.20.17.4.-B, 9.20.17.4-C

Review Instruction Sheet (IS) on Brightspace:

FNDT 100 (p. 168 – 182):

• IS 3.2 Insulated Concrete Forms (ICF):

Review Questions

1. ICF forming starts at the ____ and moves toward the _____.
2. Describe bracing required at the corner blocks.
3. How are blocks braced along the rest of the wall?
4. Where are bucks required in an ICF foundation?
5. What is the minimum thickness of an ICF Foundation?
6. When is an ICF foundation considered to be laterally supported at the top?
7. When is an ICF foundation considered to be laterally supported at the bottom?
8. Describe the reinforcement requirements of ICF foundations in the NBC.
9. If the height of the finished ground above the basement floor is 1.6 m and the maximum unsupported basement wall is 2.44 m, what size bar and what spacing would be called for?
10. How would a cold joint be reinforced in an ICF foundation?
11. How should floor joists be supported on an ICF foundation wall?