J Form Training with Rob Leonard of Build SMART Institute

J-Form Insulated Foundation System
The Build SMART System is a series of mutually supportive elements and construction techniques that achieve a highly energy and labor efficient residential and non-residential building foundation system for slab on grade.
The J-Form Foundation System is a permanent part of the foundation structure. It includes:
• J-Form is fabricated per project drawings insulates the exposed vertical face and bottom of the turndown slab edge.
• Underslab insulation significantly reduces heat loss through the slab on grade.
• Horizontal wing insulation (if required)
• Underslab vapor barrier membrane provides for a warm, dry slab and prevents intrusion of soil gas such as radon.
Frost Protected Shallow Foundations
Since antiquity builders have recognized that, if freezing occurred beneath building foundations, ice in the foundation soils can cause an upward movement of foundations (wall footings, column footings, etc.). Water’s somewhat unique property is that it expands approximately 9% as it freezes. As water rises by capillary action, it forms ice lenses at the “freeze front” and accumulates through the freezing season. This upward movement at the freeze front is commonly referred to as “frost heave” and it is a potential to cause of significant damage. The time proven method of preventing frost heave is to place foundation structures below “frost depth” - deep enough below the ground surface that freezing does not take place beneath them - where water saturated soils do not freeze even when air temperatures are well below freezing. Of course, the colder the climate the deeper the frost depth. Every location in the United States and Canada has established the local frost depth. The recognized frost depth in North Dakota is much deeper than in North Carolina. In Florida, frost depth is zero. I.e. the soil does not freeze in Florida.
Frost heave protection can be achieved by construction foundations on bedrock, constructing foundations so the bottom of footing is below the frost depth, or by protecting the foundation per ASCE 32. There are three requirements that must all be present for soils to heave: frost susceptible soils, water, and freezing temperatures. Foundations on bedrock are not susceptible to frost heave.
For frost susceptible soils to obtain the quantity of water necessary for the growth of large ice lenses, causing frost heave, soils must be both permeable and have voids small enough to support capillary rise. Coarse sand has very poor capillary rise, but very good permeability. Clays have very good capillary rise, but poor permeability. Silts have both good capillary rise and good permeability which is why silts are generally considered frost susceptible. Classification of frost susceptibility of soil is determined by a soils or Geotechnical Engineer.

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