Foundation Insulation

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How to Insulate a Wood Foundation

A homeowner wonders whether exterior insulation is his best choice, and if so how it could be detailed on a log home

Posted on Dec 11 2017 by Scott Gibson

Jeepasaurus, a GBAGreenBuildingAdvisor.com reader from Eau Claire, Wisconsin, recently bought a log house sitting atop a permanent wood foundation (PWF). Although initially reluctant to buy the house because of this detail, Jeep did enough research to convince him there's nothing inherently wrong with a wood foundation. The problem is how to insulate it.


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Image Credits:

  1. American Wood Council

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Foamglas Exits U.S. Residential Market

Pittsburgh Corning pursues opportunities elsewhere, but says it may be back in the next several years

Posted on Apr 26 2016 by Scott Gibson

Pittsburgh Corning has pulled the plug on Foamglas sales in the North American residential market as it concentrates on developing business elsewhere.

Foamglas, a cellular glass material developed by Pittsburgh Corning in the 1930s, has a lower environmental impact than rigid foam insulation, making it an appealing alternative. Made entirely of glass, the material didn't need dangerous fire retardants, can be manufactured without the blowing agents that cause global warming and ozone depletion, and had a number of attractive performance characteristics.


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Image Credits:

  1. Alex Wilson

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The Best Way to Insulate a Foundation

A builder in Idaho works out the details for adding foam insulation to both sides of his basement walls

Posted on Oct 26 2015 by Scott Gibson

Nethaniel Ealy, a builder in Idaho who's about to pour a concrete basement foundation, is trying to come up with insulation and waterproofing details that will be effective and within the budget.

The current plan is to place 2 inches of extruded polystyrene (XPSExtruded polystyrene. Highly insulating, water-resistant rigid foam insulation that is widely used above and below grade, such as on exterior walls and underneath concrete floor slabs. In North America, XPS is made with ozone-depleting HCFC-142b. XPS has higher density and R-value and lower vapor permeability than EPS rigid insulation.) on the outside of the foundation walls. At some point in the future, the homeowners would place another 2 inches of foam on the inside of the foundation walls between 2x2 studs, and then apply drywall over the studs.


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Image Credits:

  1. Nethaniel Ealy

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How to Insulate a Foundation

Choosing the right material and the right technique for a house with a walkout basement

Posted on Jun 8 2015 by Scott Gibson

About to start a new house in Climate Zone 5, Nicholas C is working out the details of how to insulate the basement slab and foundation walls. There is more than one type of rigid foam insulation he could use, and it could be applied on either the inside or outside of the foundation.

For a couple of reasons, he's planning on 2 inches of extruded polystyrene (XPSExtruded polystyrene. Highly insulating, water-resistant rigid foam insulation that is widely used above and below grade, such as on exterior walls and underneath concrete floor slabs. In North America, XPS is made with ozone-depleting HCFC-142b. XPS has higher density and R-value and lower vapor permeability than EPS rigid insulation.) beneath the slab rather than expanded polystyrene (EPSExpanded polystyrene. Type of rigid foam insulation that, unlike extruded polystyrene (XPS), does not contain ozone-depleting HCFCs. EPS frequently has a high recycled content. Its vapor permeability is higher and its R-value lower than XPS insulation. EPS insulation is classified by type: Type I is lowest in density and strength and Type X is highest.). The XPS would perform better in a wet environment, Nicholas says, and Owens-Corning, one insulation manufacturer, claims it no longer uses a "bad" blowing agent.


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Image Credits:

  1. Scott Gibson
  2. Peter Yost

Passive House video — Episode 3

In “Superinsulated Slab,” the third episode in a series of videos on Passivhaus construction, the crew installs 10 inches of rigid foam.

After the concrete was placed, more rigid foam was installed above the slab. The finished floor assembly is rated at R-50.

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On the Jobsite with Foamglas

What we learned using Foamglas instead of polystyrene to insulate our basement slab and foundation walls

Posted on Nov 29 2012 by Alex Wilson

In my role with Environmental Building News and our GreenSpec Product Database, I get plenty of opportunities to research and write about innovative building products. That’s one of the really fun aspects of my job.


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Image Credits:

  1. Alex Wilson

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How to Finish Exterior Foundation Insulation

Options abound for covering up above-grade rigid foam insulation, including one that may surprise you

Posted on Nov 15 2010 by Scott Gibson

Energy gurus and building codes routinely recommend these days that foundation walls be insulated. One way of accomplishing that is by adding a layer of rigid foam insulation on the outside of the foundation.

And that's exactly what William Poole is planning to do.

Most of the rigid foam insulation will be underground and out of sight. But what do you do with that stretch of exposed insulation above grade?


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Image Credits:

  1. Green Building Advisor

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