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Frost Protected Shallow Foundations, Incorporating Frost Protected Footings Design and Installation

Frost Protected Shallow Foundations, incorporating Frost Protected Footings Design and InstallationFrost Protected Shallow Foundations, or FPSF’s, are a tried and tested alternative to more costly deeper conventional foundation designs used in colder regions subject to seasonal ground freezing. GEO-Slab Frost protected slab on grade systems by Legalett provide complete protection from frost heave in both heated and unheated slab designs. FPSF design allows footings to be placed above the traditional design frost depth, by insulating the foundation and ground to prevent the earth freezing below the foundation.

The earliest documented use of the FPSF concept in the United States was by Frank Lloyd Wright in the 1930’s. In 1994, the US Department of Housing and Urban Development conducted several demonstration and monitoring projects, to verify the performance of existing European design practices. As a result an FPSF Design Guide was developed, to serve as a basis for building code acceptance and standardization in the States by the National American Home Builders Research Center.

In Nordic countries also, well over a million FPSF’s have been constructed successfully over the last 45 years. In Scandinavia, for example, the Frost protected shallow foundation systems are commonly used on both residential and commercial buildings, such as houses, townhouses, apartments, shopping malls, schools, low-rise office buildings, restaurants, gas stations, etc. FPSF’s have been the preferred method for frost protection of foundations and slabs since the 1970’s.


Traditional FPSF’s are slow and complicated to build with their thickened edges and skirting details, and require careful attention to design detail to ensure satisfactory performance. Traditional FPSF’s generally require their extensive skirting because they are only designed as unheated floor slabs.

GEO-Slab by Legalett is a unique approach in designing an FPSF by incorporating a forced air heating system specifically designed to be part of the Frost protected structure. By combining a frost protected foundation and the heating system, GEO-Slab shifts the bulk of the concrete away from the edge, and spreads it evenly through the insulated slab, maximizing the thermal mass of the slab for heating, and spreading out the load applied to the soil. This simplifies the installation of the GEO-Slab system, compared to other FPSF’s, in two ways - the GEO-Slab is the same thickness from one side of the building to the other, reducing installation time and cost by eliminating thickened edges and multiple concrete pours, and secondly, by reducing or eliminating the need for exterior frost skirting. A frost protected shallow foundation pour in Canada can be seen here...

The GEO-Slab is simpler to install, quicker and hence cheaper and more energy efficient than traditional FPSF’s.


Get things moving -find out how great, easy and cost effective it is to utilize Frost Protected Shallow Foundations in your next project - Contact Core in under a minute here and Get an initial Free Consultation or Quote. 

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State of the Art Frost Line Behaviour Modeling

Legalett engineers use state of the art Finite Element Modeling for heat transfer to predict the frost line.


  • Saves time, materials and money. No more limitation to building below the local frost depth to protect from frost heave.
  • Save on excavation, no more guessing about soil problems or hidden rocks, because GEO-Slab Frost Protected Shallow Foundations sit on grade.
  • No more crawl space issues.
  • All concrete pouring is completed at once with the Legalett structural insulated slab - Reducing construction time and costs.

The GEO-Slab frost protected structural foundation by Legalett is ideal for back walk-outs, poor soil conditions, lots with high water tables. NOTE: It is recommended that the top of the slab be a minimum of 20” above the ground water table.

From a slab on grade to fully buried structures and foundations - Core Construction Products supplies GEO-Slab heated and non-heated structural slabs from Legalett for both heated and non-heated buildings.


Get a free quotation for GEO-Slab Frost Protected Shallow Foundation System by Legalett quickly here Contact Core in under a minute here and Get an initial Free Consultation or Quote. 

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Frost Protected Shallow Foundation On Grade Below Grade Basement


The Advantages of Frost Protection using Air-Heated Floors from Core Construction Products
  • Air is a safe and reliable heating medium 
  • Save on construction costs
  • Save on energy costs every year
  • Extend the building  eason in cold climates
  • Eliminate the risk of moisture damage and leaks from water filled heating pipes 
  • GEO-Slab by Legalett is the foundation for a healthy, durable and cost effective Green Home Construction.

Unique Advantages

Warm air is recirculated through a closed loop piping system from a heater cast in the floor slab. The building envelope is completely insulated. GEO-Slab uses expanded polystyrene as stay-in-place formwork and under-floor insulation in a single operation. The slab-on-grade GEO-Slab system by Legalett costs less than conventional construction. The air you breathe is separate from the air used for heating so household odours are reduced and moisture, mould and mildew are eliminated. The heater box is insulated for quiet operation.

Very cost effective and reassuringly simple...  The GEO-Slab system is both healthy, affordable and ecologically sustainable.

With GEO-Slab, the heat comes from the floor eliminating drafts - feet are warm and any moisture is quickly and easily evaporated from the flooring surface. Even the bath mat dries quickly after showering avoiding that musty smell we all know in the bathroom!

GEO-Slab by Legalett is a PATENTED SYSTEM

Hot water and electric floor heaters have been available and accepted in North America for many years. Legalett have improved on traditional home heating, for example in the hot water floor heater, water is heated by the building hot water system and circulated to the GEO-Slab heater where the efficient exchanger system heats the circulated air system.  The alternative electric heater takes advantage of tiered electricity rates.  

The GEO-Slab system can:
  • be used for any building
  • be adapted to any energy source
  • regulate heat in different zones 
  • accommodate all floor coverings - ceramic, hardwood, carpet, linoleum
  • provide for barrier-free buildings (handicapped access)
  • be used below, on and above grade

Core Construction Products helps provide the design and supplies all components, for simple and cost effective installation, following the building process from concept to move-in.

Legalett's GEO-Slab slab-on-grade foundations eliminate footings and frost walls.

When working in a cold climate as found in central and Northern America, or central Canada, use of GEO-Slab's construction heater extends the building season, cast in place with a removable cover for easy access. CCP supplies GEO-Slab by Legalett air-heated floors for residential homes, retirement homes, schools & daycare facilities, churches, commercial & industrial buildings.

There is always a GEO-Slab frost protected shallow foundation design that works!  - Contact Core in under a minute here and Get an initial Free Consultation or Quote. 

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To watch a video of a Heated Frost Protected Shallow Foundation construction pour in Canada, click here.

To find out more about Frost Protected slab on grade construction systems in Colorado or the Western US, click here

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