Friday, January 4, 2013

Building with Insulated Concrete Foundations

By Nathan Pile


Insulated Concrete Foundations "ICF" have interlocking forms that are dry stacked and then they are filled with concrete. These forms lock together much like a Lego brick and can be used to form the structural walls and/or floors of a building.

What is the best ICF system? There is no front runner in design when it comes to choosing a ICF system. Consumers typically look for the number one rated product when looking to make a purchase . The buying public strives to have the best product at the best price. As for ICFs, it is obvious that each individual ICF building system has different properties that deliver different benefits to the consumer. Some have thicker insulation than others. Some are connected with metal ties, others with plastic ties. Some systems are stacked like building blocks, others require assembly. Any correctly installed ICF product will ensure that the customer is happy with his choice.

The most common ICF are manufactured out of Polystyrene Foam but they can also be manufactured out of Polyurethane Foam ,Cement-bonded wood fibre or Cement-bonded polystyrene beads. Once the forms are formed together, re-bar is usually added to give the concrete flexural strength and then the concrete is pumped into the cavity to form the structural element of the walls. The forms are filled in 1-12 foot "lifts" to manage the concrete pressure and reduce the risk of blowout . Once the concrete has cured , the forms are left in place permanently.

Here are some of the benefits in building with ICF:

ICF building are much more energy efficient and will continue to payback cost of original construction.

The form material can easily accommodate electrical and plumbing installations

Unlike framed walls, ICF has high sound absorption which helps produce peace and quiet

The longevity of ICF products provides a higher re-sale value in most Real Estate markets.

When wet , concrete and polystyrene do not rot

There are no problems with insect infestation or termites using ICF products.

Using ICF building products has shown to reduce heating and air conditioning costs by 50-70%

ICF creates a structural concrete wall that is up to 10 times stronger the a wood framed structure

Unfortunately, ICF has a few disadvantages as well

Adding widows,doors or utilities after the building is complete requires concrete cutting tools which makes it harder to do although it does not require the traditional steel lintels to support the new opening

Depending on the design , an average home can costs 2-3% more than a conventional wood built home

Minor problems with interior humidity have been know to happen during the first couple weeks as the concrete is curing. Residential dehumidifiers are an easy solution to the problem.

The exterior foam insulation provides easy access for groundwater and insects in polystyrene based forms. To help prevent these problems, some manufacturers make insecticide treated foam forms and promote methods for waterproofing them

Building with ICF can sometimes add 3-5% in construction cost compared to using wood frame, however the energy savings will usually result in much lower utility costs. Building with ICF below grade for typical basement forming should come in at about 40% less due to the labour savings from combining multiple steps into one. Above grade construction is a little more expensive but it becomes cost effective when adding large openings. In wood frame buildings, large openings require large headers and support posts but in ICF additional re-bar is all that is typically needed.




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