Step Footings Using the Advantage ICF System
Prior to starting any building project it is strongly advised to consult the local building authorities to confirm the requirements are for building in your area. In some cases there may be municipal regulations that add requirements beyond Provincial Building Codes.
Footings are the base on which you erect the foundation walls of your building. The footings ensure the load from the walls are spread evenly to the soil below. A level and square footing is always best to start with. If your footings are not square and level, this will potentially slow the installation of your ICF walls. It is recommended that the maximum variance in elevation on a footing not be greater than ¼” in height. If there is a variance in level greater than ¼” in your footing elevation it will require shimming or trimming the bottom edge of the first course of ICF blocks to ensure that the start of your build is kept level.
In general, the width of your footing should be no less than 24”, but wider footings may be required dependent upon the design requirements for your application. A 24” width will ensure that you have sufficient room to place either the 6” or 8” Advantage ICF blocks. On the 6” Advantage ICF the total width of the form is 11.25” which leaves you with 6.375” of the footing on either side of the block. The 8” ICF has a total width of 13.25” thus giving you 4.375” on each side of the Advantage ICF block. In both instances, this is using the centerline of the footing as the centerline of your wall.
STEP FOOTINGS USING THE ADVANTAGE ICF SYSTEM
If you are doing a walkout basement you will require step footings to accommodate the frost wall. The Advantage ICF blocks have a height of 16.5” on both the 6” and 8” product line. The NBC (National Building Code) states that the maximum rise or height for step footings shall be no greater than 24”. You have two options when making your step footings when using the Advantage ICF system. Firstly, you can use 3 – 2”x6” pieces of lumber stacked on their edge which equals a total height of 16.5” matching the height of the Advantage block. If doing a 4’ frost wall this is the best way to do your step footings as 3 steps at 16.5” equals 49.5” (3 courses of Advantage ICF). Refer to the diagram & photograph below which illustrates how this is achieved.
Second option if you do your step footings at a height of 2 feet you can use the Advantage Height Adjuster ICF block (7.5”) on top of a full standard block (16.5”) to achieve the 24” height.
Rebar dowels should be placed to match the vertical reinforcement size as per the rebar tables in the Advantage Technical Manual or the blueprints that are engineer approved. Using 10M rebar dowels spaced at no greater than 24” on center provides meets NBC requirements. The dowels must be placed with a minimum of 8” embedded into the footing and 3” concrete coverage to the bottom of the footing. Extending the dowels vertically above the footing is required so that they can be tied into the foundation wall rebar. If using 10M rebar, the dowels should extend a minimum of 18” vertically above the surface of the footing and 26” vertically for 15M rebar. This will ensure that the bottom course of your wall has sufficient lateral support from the footing to wall connection. The diagram below further explains how to achieve this.
Wall to Footing Connection Detail
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Coming soon: Insulbuck How-to video by Greg Doren, Advantage Brand Manager