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This article discusses the question: which is the best foundation insulation to use below-ground. Accompanying text is reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss. Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman. Underground use of Polystyrene Foam Insulating Board
The question-and-answer article about the below-grade use of expanded versus extruded polystyrene insulating foam boards, found just board, below paraphrases, quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss. Is Expanded or Extruded Polystyrene Foam Insulation Better to Use for Underground Foundation Insulation?
Answer:
Interestingly, the foam board insulation testing found that the most common expanded EPS - 2-inch thick, low density (1 lb./ft3), material - held up about as well as extruded stock in both vertical and horizontal insulation board applications. Both showed 2- to 13- percent increases in temperature conductivity after 6- and 18- month exposures. Dow speculates that the poor performance of the high-density DPS was due to high void content and poor bead fusion. EPS manufacturers agree that good bead fusion is harder to achieve in high-density foam insulating board stock. Here is a simple test of foam insulating board quality:EPS should break through the beads, not around them. Because over 175 small companies make EPS foam insulating board products, quality varies considerably. Our photograph of white polystyrene foam board insulation (below) shows broken foam boards at an indoor foam board insulation retrofit project.
See BASEMENT HEAT LOSS for a discussion of foundation and basement insulation methods. Readers should also see POLYISOCYANURATE FOAM INSULATION, INSULATION LOCATION for PASSIVE SOLAR FLOOR SLAB and also RIGID FOAM USE INDOORS. Readers should also see FLOOR, CONCRETE SLAB CHOICES for a discussion of choice of finish floor materials to preserve use of thermal mass of a concrete floor slab. Readers interested in basement insulation improvements should also see INSULATION LOCATION for BASEMENT WALLS and BASEMENT HEAT LOSS. For more general energy savings advice see ENERGY SAVINGS PRIORITIES, and our insulation home page at INSULATION INSPECTION & IMPROVEMENT. If you are going to insulate under a basement or grade-level concrete slab floor, be sure to read SLAB INSULATION, PASSIVE SOLAR. Finally, readers considering adding insulation inside or outside a basement foundation wall should see POLYSTYRENE FOAM INSULATION as well as BUCKLED FOUNDATIONS due to INSULATION? Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution. Foundation Foam Insulation Protection Methods & Advice
Question: What finishes are available to protect Styrofoam insulating board used for foundation insulation?I will be insulating a foundation with Styrofoam. I understand there are masonry finishes available that can be applied directly to the foam or to an intermediate mesh, and that such a surface will hold up to weather exposure. What finishes are available to protect my foundation insulation? - Thomas F. Harter, Oakland CA Reply: Several Ways to Protect Rigid Foam Foundation BoardsThere are several ways to protect rigid foam foundation insulation boards, ranging from pressure-treated plywood to factory-applied stucco finishes. One pre-finished foundation insulation panel is Thermboard, a 3/4-inch Styrofoam panel coated with a fiber-resin compound that has a stucco-like appearance. It costs [1980's prices] around $`.47 per square foot in the Wisconsin area where it is made. Thermboard is distributed by Georgia Pacific Corp. Another pre-finished foundation insulation product is Styrofoam FP Panels, distributed by Dow Chemical and available at many lumber yards. The finish is a cementious coating that looks something like concrete. For a field-applied finish to protect foundation insulation boards, you can trowel on your own stucco to the foam over expanded metal lath, or brush on a finish designed for this purpose, such as Styrofoam Foundation Brush-on Coating (also available from Dow Chemical). It comes in a kit consisting of a dry polymer cement mixture, liquid additive, and fiberglass reinforcing tape [use at seams between foundation insulation boards]. You mix the components with water and apply directly to the foam foundation insulating board. The insulating board is scratched-up to promote good adhesion. It dries to resemble concrete. The cost of this foundation insulation board coating is around 40 cents per square foot. [1986 prices]. [Solar Age 8/86] Here we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss. Frequently Asked Questions (FAQs)... Ask a Question or Search InspectApediaQuestions & answers or comments about how to insulate building foundations & about using polystytrene insulating board products. Ask a Question or Enter Search Terms in the InspectApedia search box just below. Technical Reviewers & ReferencesUse links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.
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