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A Builder’s Guideto
ResidentialFoundation
Insulation
111,000 Btu
Northwest Kansas(Goodland)
97,000 Btu
Central Kansas(Liberal to Kansas City)
76,000 Btu
Southeast Kansas(Parsons)
Heat Loss/Lineal Foot/Year(conditioned basement)
3%
3%
4%
5%
7%
9%
16%
54%
8 ft.
7 ft.
6 ft.
5 ft.
4 ft.
3 ft.
2 ft.
1 ft.
10%
20%
30%
40%
50%
60%
Basement Heat Loss
Uninsulated Foundations Loose a Lot of Energy
Slab-on-Grade
Foundation InsulationAnnual Energy Costs Savings
$0.00 $0.50 $1.00 $1.50 $2.00 $2.50 $3.00
3
2
1
3
2
1
3
2
1
Cli
ma
teZ
on
e
$/Lineal Foot/Year
Minimum R-value Preferred R-value
Crawl Space
Basement
Foundation Insulation Heating Cost Savings
Uninsulated Basement
Wall Condensation
484950
51525354
55565758
5960
64 66 68 70 72 74
Basement Air Temperature,oF
Gro
un
dT
emp
eratu
re,
oF
70 % Rh 80 % Rh
As little as R-2 insulation
can essentially eliminate
the risk of condensation
Foundations Insulation Cuts Moisture Problems
Basement air humidityincreases as a result humidoutdoor air and soilmoisture migration
Basement Condensation
Warm moist late Springand Summer air
67o
o63
o59
o56
Deeper soils remain coldfrom winter, coolinguninsulated basementwalls
Warm air flowing overcool wall condensesmoisture producingdamp basement
Water vapor in soilmigrates to warmer airif damp proofing orvapor retarder fail
Uninsulated Foundations Cause Condensation
A Builder’s Guide to
Residential Foundation Insulation
Prepared for:Kansas Corporation CommissionEnergy ProgramsSW Arrowhead RoadTopeka, Kansas 66604785-271-3349
Jim Ploger, Energy Program Manager
Prepared by:
Joseph E. King, AIACoriolis architecture energy
123 West 8th
StreetLawrence, Kansas 66044785-841-1906
Gene Meyer, PEEngineering Extension ServiceKansas State UniversityWard HallManhattan, Kansas 66506785-532-4994
Fall 1999
Disclaimer:This report was prepared by Coriolis and Kansas State University (KSU) as an
account of work sponsored by the Kansas Corporation Commission (KCC).
Neither the KCC, Coriolis, nor KSU, nor any person acting on their behalf: a)
makes any warranty, express or implied, with respect to the use of any
information, apparatus, method, or process disclosed in this report or that such
use may not infringe privately owned rights; or b) assumes any liabilities with
respect to the use of, or damages resulting from the use of, any information,
apparatus, method, or process disclosed in this report or its appendices.
This material was prepared with the support of the U. S. Department of Energy
(DOE) Grant No. DE-FG48-97R802102. However, any opinions, findings,
conclusions, or recommendations expressed herein are those of the author(s)
and do not necessarily reflect the views of DOE.
Acknowlegements:
We greatly appreciate the support and encouragement of Jim Ploger, Director
of Energy Programs at the Kansas Corporation Commission, and Steve
Palomo of the U. S. Department of Energy’s Denver Regional Office.
Blown cellulose between furingstrips.
A wide variety of foam boards arewell suited to foundation insulation.
Glass and mineral fiber batts ofmany configurations can be usedon the interior of basement andcrawl space walls.
Foundation Insulation
Polystyrene foam held in place withduct tape and cap flashing untilbackfill is complete.
Fiberglass batts stapled to furringstuds.
Installation Methods
Wrapped batts are easily installedin crawl spaces.
P
CPrepainted sheet metal roll stockmatches siding, serves as termiteshield, and protects exterior foamfrom damage.
Stucco over rigid foam board.
Insulation Protection
Cement board nailed to plate
protects exterior foam from damage.
The Purpose of a Building’sFoundation
Vitruvius set forth building designguidelines in 1
stcentury B.C. Greece,
stating that “Durability will be assuredwhen foundations are carried down tothe solid ground and materials wiselyand liberally selected...,” a concept thatremains just as valid as we enter the 21
st
century.
Foundations connect a building to theground structurally, transferring theweight of the building to stable soil. Aproperly designed and constructedfoundation insures a building enduresseasonal changes in temperature andmoisture with little movement.Foundations also connect a building tothe ground thermally.
< The common statement that “soiltemperatures are constant and thereforebelow grade insulation is of little value”is not correct.
< Unless geothermal heat is present, theheat that comes from deep in the earth isinsignificant compared to the flow ofsolar energy at the junction of the air andthe ground.
< While the earth is often thought of as astable temperature mass, soiltemperatures at depths less than eightfeet vary considerably during the year.The graph above shows how soiltemperature varies with depth and seasonfrom both ground water and mean airtemperature which ranges from 56o innorthwest Kansas to 62o in the southeast.
A team of building scientists at OakRidge National Laboratory conducted acomprehensive investigation of theimpact of residential foundationinsulation practices. In The Building
Foundation Design Handbook thatresulted, they concluded, “anuninsulated basement may represent upto 50% of the heat loss in atightly-sealed house that is wellinsulated above grade.”
Kansas Residential EnergyDisclosure and the ModelEnergy Code
The Energy Policy Act of 1992 stronglyencouraged states to upgrade theirresidential building energy standards torequire efficiency levels at least equal tothe Model Energy Code. In response,the 1997 Kansas legislature required allnew homes have a disclosure formitemizing their energy performancefeatures, or stating the home complieswith the Model Energy Code (MEC).Compliance with MEC provides ahome buyer with assurance that thehome has an integrated set of energy
features meetingminimum stand-ards, and it almostalways requiresfoundation insula-tion. This guide isintended to providehome builders andhome buyers withconcise informationon available foun-dation insulationmaterials, installa-tion details andmethods, installa-tion costs, andbenefits.
FoundationBuilding Code Requirements
Several requirements of the widelyadopted CABO One and Two Family
Dwelling Code affect foundationinsulation:
< drains are required around all concreteand masonry foundations enclosinghabitable or usable space below grade,
< concrete foundation walls enclosingbasements must be dampproofed with abituminous material from the footing tograde,
< masonry foundation walls enclosingbasements must be parged with portlandcement prior to dampproofing,
< foundation walls of habitable roomsbelow grade must be waterproofed,
< exterior foundation insulation must beprotected from weathering, sunlight, andphysical abuse,
< all foam plastic exposed to the interiormust have a maximum flame spreadrating of 75 and a maximum smoke-developed rating of 450 (ASTM E-84)and shall be covered with a ½” gypsumwall board or equivalent thermal barrier.
These requirements and all other healthand safety requirements of codesadopted by local jurisdictions prevailover the MEC and any suggestions inthis guide.
Benefits of FoundationInsulation
Insulating a home’s foundation offersmany benefits.
< Foundation heat loss can be reducedsignificantly and space heating costs canbe reduced as much as 50% in anotherwise well insulated home.
< Insulation improves foundation moisturecontrol and indoor air quality. Insulationon either side of the wall results in awarmer interior surface, reducing thepotential for condensation and associatedmold growth that reduces indoor airquality and can cause material damage.
< Thewarmer surface also results in amorecomfortable space, not only in thebasement, but also the floor above.
< Exterior insulation provides protectionfor dampproofing or waterproofing,extending their life.
These benefits are evaluated in detail inthe following sections.
Foundation Heat Loss
Soil can hold a great deal of thermalenergy, particularly if damp, but it is nota good insulator. Depending on soiltype, 7 - 11 feet of soil would berequired to provide the same insulationas two inches of foam or three inches offiberglass insulation. Uninsulated
1
Residential Foundation Insulation
Soil Temperature Change with Depth and Season
basement walls loose the most heatwhere exposed to winter air abovegrade and at shallow depths where theground isoften frozen.
Floors abovecrawl spacescan beinsulated butare often notto preventpipes in thecrawl spacefrom freezing. Heat passing from thefloor into the crawl space is lost throughthe foundation wall similar to base-ments.
Slab-on-grade floorswick con-siderableheat to theexposedslab edgeoften result-ing in a coldfloor. Add-itional heatflows
through the soil beneath the slab andout the perimeter foundation. Actualfoundationheat lossvaries byclimatezone, soiltype andmoisturecontent, thetempera-ture maintained in the house and a hostof other subtle variables. The map
below shows three widely recognizedKansas climate zones.
The table below shows typical netannual heat loss, in Btu per lineal foot offoundation, for the three major founda-tion types in the three climate zones.
Kansas Climate Zone
1 2 3
FullBasment
111,000 97,000 76,000
CrawlSpace
47,000 41,000 32,000
Slab-on-Grade
60,000 52,000 40,000
Annual Foundation Heat Loss(Btu per lineal foot per year)
Potential Cost Savings
While foundation insulation has manybenefits, the principal criteria fordetermining how much should beinstalled is the economic value ofenergy savings. Foundation insulationmay actually slightly increase coolingenergy use since the foundation loosesless heat to the ground during thecooling season, but the effect isnegligible in the Midwest. Cost ofspace heating energy (natural gas,electricity, or propane) and theefficiency of the space heating systemare also important.
The prescriptive method of complyingwith the MEC sets out minimuminsulation values for each type offoundation (basement, slab, crawlspace) for individual climate zonesbased on average energy prices. Thetable below shows the MEC requiredminimum foundation insulation for
each of the three foundationtypes for each of the threeclimate zones.
While it is seldom possible tocomply with the MEC withoutfoundation insulation, there isactually a great deal offlexibility. The performancemethod of compliance allowsimproved performance of onebuilding envelope component,
such as windows, walls, or atticinsulation, to offset lower performancein another area, such as foundationinsulation.
MEC Minimum R-Value
Zone 1 Zone 2 Zone 3
FullBasment
10 10 8
CrawlSpace
16 16 10
Slab-on-Grade
5(min. 4 ft)
5(min. 2 ft)
5(min. 2 ft)
Foundation Insulation R-values(MEC prescriptive minimum)
For a more detailed evaluation of such
trade-offs investigate the MECcheck�
software developed by PacificNorthwest National Laboratory for theU. S. Department of Energy. This easyto use software is available from theKansas State University EngineeringExtension Service (785-532-4994) or itcan be downloaded from<http://www.energycodes.org>.
Energy Cost Savings
The foundation insulation levels shownin the preceeding table will yieldestimated annual energy costs savingsshown in the following table. The costlevels used in the table are based in thefollowing delivered heat costs:
Low less than $8.00/million Btu
Medium $8-12.00/million Btu
High more than $12.00/million Btu.
These costs are based on typical energypurchase prices and combustion systemefficiencies. Use the low energy price ifyou have natural gas heating andconventional air-conditioning, anair-source heat pump with costs below$.05/kWh, or a water-source heat pumpwith electric costs below $.08 per kWh.Use the medium energy price if you usepropane in combination with aconventional air conditioner, an airsource heat pump with electric costsbelow $.07 per kWh, or a water-sourceheat pump with electric costs below$.12 per kWh. Use the high energy priceif electric costs exceed those noted
Residential Foundation Insulation
2
Basement Heat Loss
Crawl Space Heat Loss
Slab-on-Grade Heat Loss
12
3
Kansas Climate Zones
above or you use electric-resistanceheat.
Kansas Climate Zone
1 2 3
High Energy Costs
FullBasement
$256 $197 $160
CrawlSpace
$107 $92 $70
Slab-on-
Grade$134 $117 $92
Medium Energy Costs
FullBasement
$182 $140 $107
CrawlSpace
$75 $63 $48
Slab-on-Grade
$95 $83 $65
Low Energy Costs
FullBasement
$126 $92 $68
CrawlSpace
$51 $43 $32
Slab-on-Grade
$66 $58 $46
Foundation Insulation AnnualEnergy Cost Savings(1700 square foot house with 170 lineal ft. perimeter)
Foundation Moisture Control
Most new homes in Kansas havebasements. Home buyers expect themto provide useful space, first for storagebut eventually as finished space.Nothing detracts more from thisexpectation than a damp mustysmelling basement.
Aside from broken pipes and flooding,basements get damp in four ways:
< free flowing surface or ground waterentering through cracks or openings inthe basement wall or floor,
< soil moisture wicking through thebasement wall by capillary action,
< water vapor migration from cool dampsoil to a warmer basement, or
< condensation of water vapor on coldbasement walls.
Causes and solutions for each of thesepotential sources of moisture problemsare reviewed in the following sections.
Surface and Ground Water
Surface water problems are caused byinadequate slope away from thefoundationor poorcontrol ofroofdrainage.Wateradjacent tothe foun-dationseepsthroughperviousbackfilluntil itfinds acrack, coldjoint, orutility penetration through which itenters. Incorporating overhangs in thebuilding design installing gutters and
downspouts, capping backfill withimpervious clay, and providing properdrainage away from the house can pro-vide effective control of surface water.
When ground water rises above thehouse floor it exerts hydrostaticpressure on the floor and wall;penetrating any opening. Drain tiles on
the outside and in some cases both sidesof the footing are required to removehigh ground water. If site conditions donot permit sloping the drain to“daylight” an electrically poweredsump pump is required. Since stormsproducing high water are sometimesaccompanied by power outages, manyelect to install a battery back-up.
On persist-enly wetsites,wheregroundwater isknow torise to orabove floorlevel, orwhere hab-itablespaces arebelowgrade, thebasementwall mustbe waterproofed. Many effective waterproofing products are available, in-cluding liquid and sheet membranes,cementious coatings, built-up tar andfelt, and bentonite clay. Some liquidmembranes and adheshives used withother systems chemically dissolve foaminsulation. In selecting a water proofingsystemmake certain all components arecompatible with any exterior foamfoundation insulation that will beinstalled.
Capillary Moisture Migration
Soil without free flowing water maystill contain considerable moisure. Thewicking of ground moisture throughmaterials with small pore size, oftencalled capillary movement, can be asignificant source of moisturepenetration. To break the capillaryaction between a basement wall and soilthe outside surface of the wall must becompletely covered with damp-proofing. Dampproofing fills the poorsin the concrent to prevent wicking.Waterproofing also provides damp-proofing, but where a basement wall
3
Residential Foundation Insulation
Surface Water Entry
Surface water
moves along
wall to gap.
Hydrostatic
pressure
increases with
depth.
Surface Water Control
Gutter carriesaway rain water.
Overhang divertsrain from side of
building.
Impermeablebackfill capdiverts waterfrom house.
Downspoutcarries water
away from house.
Minimum 5%slope away fromhouse.
Ground Water Entry
Rising groundwater exertshydrostaticpressure onfloors and wallspenetrating anyopening.
does not require waterproofing,dampproofing must be applied. In
addition to waterproofing, approveddampproofing materials include sprayor roller applied bituminous and acrylicmodified cement based coatings.Capillary moisture entry through thefloor is prevented by using a gravelbase. The pore size between stones (3/4inch stones with fines omitted) is toolarge to permit capillary suction.
Vapor Diffusion MoistureMovement
Water vapor will move from high vaporpressure to low vapor pressure. Abovegrade this usually means water vapormoves from the warm (winter) interiorto the cold exterior. Below grade watervapor can, depending on the
circumstances, move in either direction.Diffusion retarders, materials with aperm rating of 1.0 or less, are installedon the exterior of below grade concreteto reduce the inward movement ofwater vapor from the soil into thebuilding. Dampproofing andwaterproofing are effective diffusionretarders on walls. Polyethylene vaporbarriers are placed below floors on topof the gravel bed and can also be usedon exterior walls.
Moisture Condensation onthe Inside of FoundationWalls
Shallow soil temperatures risegradually in the Spring, but at a depth offive feet the temperature typicallyremains around 50-60
oF through
mid-June. An uninsulatedbasement wall will have aninside surface temperatureclose to ground temperatureand will condense moisturefrom 72
oF air with a relative
humidity of 45 - 65%.Insulating the wall shifts thethermal profile, raising theinside surface temperaturemuch closer to the indoor airtemperature, greatly reducingthe risk of condensation.
Improved Indoor AirQuality
Moisture is not a pollutant, but asrelative humidity in a home rises above60% mold, mildew, and dust mites
begin to thrive. Tighter more energyefficient homes often experience higherrelative humidity. There are manysources of moisture in a house, butmoisture problems in upper floors canbe aggrevated by excessive moisture inbasements and crawl spaces. Mositurecan diffuse through the floor system,moist air can flow through cracks andstairs to replace air drawn out of thehouse by wind or stack pressure, orbasement air can be distributed by aforced air heating sytem thatintentionally or accidentally drawsreturn air from the basement.Controlling basement and crawl spacemoisture can reduce the risk of indoorair quality problems.
Improved Comfort
Insulating basement walls raises thesurface temperature of the wall and thefloor above. Insulating crawl spacewalls or the floor above increases thefloor temperature of the space above.Insulating slab-on-grade foundationsincreasing the slab floor temperature.In all three cases foundation insulationimproves the comfort of the habitablespace.
Other Benefits
< Foundation insulation installed duringoriginal construction is usually moreeasily installed properly and lessexpensive than when retrofitted.
< Foundation inulation can often result insmaller and therefore less expensiveheating equipment.
< Foundation insulation makes a basementmore attractive for future ownerconversion to finished space.
< Reduction in fossil fuel use andassociated green house gas emissions haslong term benefits for everyone.
Insulation MaterialProperties
Insulating performance is measured inR-values with units of hr � ft
2�
oF / Btu.
R-values of multiple layers can beadded. The inverse of the R-value (1/R)is the U-value, the coefficient of overallthermal transmission, with units of Btu /hr � ft
2�
oF. U-values can not be added.
An uninsulated concrete foundation
4
Residential Foundation Insulation
Capillary Movement of Ground Moisture
Unprotected concretewalls, footings andfloors act likesponges, allowingcapillary suction todraw moisture fromdamp soil into thebuilding.
Drain Tiles and Water Proofing
Impermeable
backfill
Free-draingbackfill
Waterproofing
Perforated drain tile,
on outside or both
sides of footing, in
bed of gravel free of
fines wrapped in
filter fabric. Slope to
daylight or sump.
Condensation on Cool Basement Walls
Cold
spring
soil
Moist
Spring air
covects
across cool
concrete
wall and
condenses
water.
wall has an overall R-value of about 1.1and a U-value of 0.9. For each degreeof temperature difference between theinside and outside, each square foot ofwall will transmit .9 Btu each hour fromthe warm side to the cold side (U-valuex Area x Temperature difference = Heatflow). If insulation with an R-value oftwo is added to the wall, the totalR-Value becomes 3.1, the U-value .32Btu/hr� ft
2�
oF, and the heat flow .32
Btu per hour, a 65% reduction. If theinsulation is increased to R-6 theU-value and heat flow becomes .14, an84% reduction. The first Rs have themost impact. Sound detailing andproper installation are essential forachieving real performance. Gaps andthermal bridges of conductive materialcan significantly reduce the effectiveR-value.
Strength, beyond the ability to remainintact, matters little for batt insulation.For board insulation below grade on anexterior wall or beneath a slab,compressive strength must beconsidered.
Water Absorption is the amount ofwater absorbed by an insulatingmaterial as a percent of total volumewhen fully immersed for 24 hours.Water absorption reduces effectiveR-value and materials with higherabsorption should not be used inlocations where they will likelyencounter water.
Permeability is the ability of watervapor to pass through a material inresponse to differing vapor pressure onopposite sides. When water vapormoves through a material and reaches atemperature below its dew point,condensation will occur. Water insufficient quantity will cause insulationperformance to deteriorate and materialdamage may occur. Materials with aperm rating of 1.0 or less are consideredeffective vapor barriers, although someprefer the term vapor retarder becausecompletely effective barriers are almostimpossible to achieve. Uninsulatedfoundation walls often have an interiorsurface temperature below dew pointallowing condensation to occur
resulting in a damp and often moldysmelling basement even though nowater leakage has occured. Exteriorfoundation insulation generally raisesthe wall temperature above dew pointpreventing condensation. Interiorfoundation insulation actually causesthe foundation wall surface temperatureto drop, increasing the risk ofcondensation. A vapor barrier isrequired on the inside surface of theinsulation.
Early installation of the vapor barriercan create other moisture problems.The new concrete contains a great dealof water. Because the exterior isdampproofed or waterproofed and incontact with soil most of the excessmoisture must esacpe to the inside asthe concrete cures. Early installation ofa vapor barrier can trap water vaporallowing it to condense inside the wallor within the insulation. Delayinstalling interior foundation insulationuntil late in the construction process toallow the concrete to cure. When theinsulation will be left exposed consideruse of a vapor barrier with smallperferations, such as Certainteed’sbasment wall insulation.
Flame spread and smoke
development ratings of combustiblebuilding materials are based on theASTM E84 test. Values for foaminsulation may not exceed 75 and 450respectively. Unless specificallyapproved otherwise by the buildingcode official, all foams must be coveredwith ½ inch of gypsum wall board orother approved thermal barrier,regardless of location.
Surface protection is required for allexterior insulation above grade. Alltypes must be shielded from structuraldamage and foams must be protectedfrom degradation from the ultraviolet(UV) portion of the solar spectrum.
Environmental Impact Issues
The cost saving benefits of foundationinsulation are accompanied byenvironmental benefits of reducedgreenhouse gas emissions. These
benefits far outweigh the environmentalimpact of manufacturing and installingthe insulation. In selecting whichproduct(s) to use however, you shouldconsider a variety of environmentalimpacts resulting from their production.Check product labels and brochuresregarding the topics listed below.
Embodied energy is the energycontained in the material and consumedin its manufacture, delivery, andinstallation. Materials with lowerembodied energy are preferred.
Ozone depletion, the destruction of theearth’s protective stratospheric ozonelayer, is caused by gases that were untilrecently widey used to blow the bubblesthat make foams effective insulators.Manufacturers have shifted to othergases with lower ozone depletionpotential, includingHCFs andHCFCs.
Global warming potential (GWP)refers to the impact carbon dioxide andother gases have on increasing globaltemperatures. Carbon dioxide has aglobal warming potential of 1. CFC 12,a common foam blowing agent tenyears ago, has a GWP of 7,100. Thegases now used have GWPs rangingfrom 1 - 1,300. Ironically the lowest iscarbon dioxide, but it’s use reducesinsulation performance by about 1/6.
Recycled content is a widelyrecognized environmental feature ofbuilding insulation. Most cellulose andmineral wool insulation aremanufactured from recycled material.Fiberglass and foam insulationmanufacturers are increasing theamount of recycled material they use. Alist of insulation manufacturers usingrecycled materials is available from theU.S. Environmental Protection Agency(EPA) at:
<http://www.epa.gov/epaoswer/non-hw/procure/prod
ucts/building.htm#productinfo>.
Insulation Materials
A wide variety of materials are suitablefor insulating foundation walls. Theycan be divided into three generalcategories; board, batt, and blown.Some products can be used on the inside
5
Reidential Foundation Insulation
or outside of the wall while others areonly suitable for interior use.
Boards
Board insulation materials commonlyused for foundation insulation includeextruded polystyrene (XPS), expandedpolystyrene (EPS), polyisocyanurate,fiberglass, and rockwool.
PolystyrenesExtruded Polystyrene (XPS)
XPS is manufactured from polystyreneresin and a gas blowing agent in acontinuous extrusion process producinga homogeneous cellular structure.
Advantages
< High R-value per inch, high compressivestrengh, low moisture absorption, lowperm rating.
< Widely available in various sizes andthicknesses and easily installed.
Disadvantages
< Requires UV and structural protectionabove grade when applied on the exteriorand thermal protection when installed onthe interior.
< Chemically attacked by some adhesives,dampproofing and waterproofingcompounds.
Expanded Polystyrene
EPS differs from XPS in that it isproduced from styrene beads placed in amold and expanded under heat andpressure with a foaming agent.
Advantages
< The least expensive foam board,available in a wide range of densitites,sizes and thicknesses.
< Available with borate additives to reducetermite risk.
Disadvantages
< Somewhat lower R-value than otherfoams and more easily damaged,particularly if used on the exterior.
< Higher permeability and waterabsportance than other foams.
< Like all foams, requires exteriorprotection above grade and thermalprotection when used on the interior.
Polyisocyanurate
Polyisocyanurates are manufacturedfrom a plastic resin and a foaming agentand can have fiberglass or foil facing.
Advantages
< Highest R-value of any foam. Availablewith foil face which can serve as vaporbarrier and can provide increasedR-value when installed with dead airspace.
< One product, Celotex’s Thermax, can beinstalled without a thermal barrier whenapproved by the local code official.
Disadvantages
< Generally higher in cost than other foamsand initially very high R-values declinesa bit with age.
< Low compressive strength.
Batts
Batt insulation materials includefiberglass and rockwool. Fiberglass inmade from sand and recycled glasscullet. Mineral wool is made from ironore blast furnace slag and natural rocks.Batts can be unfaced, kraft paper faced,foil faced, or poly wrapped. In additionto the many sizes commonly installed inabove grade frame walls, specialty battsare available for interior basement wallsand crawl space walls.
Advantages
< Inexpensive and widely available inmany sizes, thicknesses, and facings.
Disadvantages
< Batt insulation can be saturated anddifficult to dry if moisture penetrationoccurs.
< Furring required for installation andeasily damaged in high traffic areas if notprotected by drywall or paneling.
Blown
Nonload bearing 2 x 4 or 2 x 3 studwalls can be erected directly adjacent toor set back from the basement wallcreating a cavity for foundationinsulation. While batts are typicallyplaced in the stud cavity, blowncellulose, glass fiber, or mineral woolinsulation can be used. Cellulose istypically manufactured from wastepaper with fiber and insect retardentchemicals. A netting may be installedover furring to hold insulation in place.
Advantages
< Inexpensive, compeletely fills cavity.
Disadvantages
< Like batts, sprayed insulations can bequickly saturated and difficult to dry ifsignificant moisture penetration occurs.
< Again, like batts, furring required forinstallation and needs protection in hightraffic areas.
< Special installation equipment required.
Termites
Subterranean termites live in largecolonies 15-20 feet underground. Theylive entirely on plant matter, rangingwidely through a system of tunnels insearch of food. They enter buildingsthrough wood in contact with theground, cracks in foundation walls orslabs, the dry joint between the footingand foundation wall, utilitypenetrations, and through and behindfoundation insulation. Wood structuresattacked by termites can sustainextensive and costly damage. Whilefoundation insulation is not a foodsource and does not increase thelikelyhood that a particular buildingwill be attacked, it may make detectionand treatment more difficult.
Insecticides like chlordane were oncewidely used to control termites. Theywere effective, persisting in the soil formany years, providing long termprotection, but when it was discoveredthey were carcinogenic they werereplaced by other insecticides. Whileeffective in controling termites, todaystermiticides dissipate with timerequiring retreatment. Borates are alsoused to discourage termites.
Termites are small and persistent,capable of squeezing through tinycracks. The best strategy is to avoidinititial infestation entirely using one ormore of the following defenses:
< Avoid attracting them. Duringconstruction keep all wood, includingframing scraps, sawdust, paper, and treeroots and trimming out of the ground foras far back from the house as feasible.
< Keep all wood at least six inches abovegrade and use only termite resistant ortreated wood in contact with thefoundation. Do not use wood mulchnear the house.
6
Residential Foundation Insulation
< Install a continuous metal termite shieldwith soldered or sealed lap joints.Termites can tunnel around it, but theycan then be detected and treated.
< Consider pretreating all wood framingwithin four feet of the ground withborates.
< Consider installing termite bait systemsmarketedby pro-fessionalpest treat-ment com-panies.Theypermitdetectionof termitepresenceand the useof highlyeffective targeted insecticides.
< Consider installing sand barriers. Whilestill experimental and more expensivethan conventional treatment, sandbarriers provide a non-chemical methodof protection. Sand that just passesthrough a 16 grit wire screen takes subtleadvantage of the termites anatomy. Thegaps within the sand are too small forthem to crawl through,but their jaws do notopen wide enough forthem to pick them upand move them. Sandbarriers can be placedaround a foundationwall at grade andaround potential entrypoints in slabs.
< Consider pretreatingthe soil with EPAapproved termiti-cides.
< Have the houseinspectedannually.
< Avoid heatloosinginspectionstrips.
7
Residential Foudation Insulation
Termite Size
3 mm
1 mm
Estimated Foundation Insulation Cost per Lineal Foot
Actual project costs are region and project specific. Variation from the values below should be expected.
Foundation/MaterialHeight
(depth)
Thick-
nessMaterialR-value
Exterior Interior
Basements - Foam Boards
Extruded Polystyrene (XPS) 8 ft. ½ in. 2.5 $7.60 $12.50
(Blue, pink, yellow, green) 8 ft. 1 in. 5 $8.80 $13.60
8 ft. 1-1/2 in. 7.5 $10.70 $15.60
8 ft. 2 in. 10 $12.70 $17.60
Expanded Polystyrene (EPS) 8 ft. 1 in. 3.8 $7.80 $12.70
(White beadboard) 8 ft. 1-1/2 in. 5.6 $9.10 $13.90
8 ft. 2 in. 7.7 $10.30 $15.20
Polyisocyanurate 8 ft. ¾ in. 5.4 $8.50 $13.40
(If foil faced and furring is 8 ft. 1 in. 7.2 $9.00 $13.80
on top to create a dead air space 8 ft. 1- ½ in. 10.8 $9.50 $14.40
increasse the R value by 2.8) 8 ft. 2 in. 14.4 $10.70 $15.60
Exterior cost includes metal flashing protection, reduce $0.40 for cement board, increase $1.70 for stucco.
Interior cost includes furring and ½ in. drywall. Reduce cost $7.00 if omitted (requires code approval)
Glass Fiberboard 8 ft. 1 in. 4.3 $9.00 $13.80
8 ft. 1-1/2 in. 6.5 $12.20 $17.10
Basements - Batts
Std densifty, 48 in. or 72 in. 8 ft. 3- 1/8 in. 11 n.a. $4.20
Std density, 23 in. 8 ft. 3-1/2 in. 11 n.a. $11.60
High density, 23 in. 8 ft. 3-1/2 in. 15 n.a. $12.10
Mineral wool (kraft faced) 8 ft. 3-1/2 in. 12 n.a. $12.00
Cost includes furring and faced batt or vapor barrier. Add $5.30 for drywall.
Crawl Spaces - Foam Boards
Extruded Polystyrene (XPS) 4 ft. 1 in. 5 $10.30 $4.90
(Blue, pink, yellow, green) 4 ft. 2 in. 10 $12.10 $6.80
Expanded Polystyrene (EPS) 4 ft. 1 in. 3.8 $9.80 $4.50
(White beadboard) 4 ft. 2 in. 7.7 $10.90 $5.60
Polyisocyanurate 4 ft. 1 in. 7.2 $10.40 $5.00
(See note above on foil facing) 4 ft. 2 in 14.4 $11.10 $5.70
Exterior includes 2 feet of stucco, interior includes 3 feet of furring and drywall thermal protection.
Crawl Space Batts
Perimeter installation (wrapped batts) 8-3/4 in. 25 n.a. $3.50
Floor installation Sq. ft. 3-1/2 in. 11 n.a. $0.60
(Includes wire retainers, turn Sq. ft. 6 in. 19 n.a. $0.74
facing up) Sq. ft. 8-1/2 in. 30 n.a. $1.08
Slab-on-Grade - Foam Boards (protection same as for basements above)
Extruded Polystyrene (XPS) 2 ft. 1 in. 5 $3.60 $1.20
(Blue, pink, yellow, green) 4 ft. 1 in. 5 $4.60 $2.20
2 ft. 2 in. 10 $4.50 $2.20
4 ft. 2 in. 10 $6.40 $4.10
Expanded Polystyrene (EPS) 2 ft. 1 in. 3.8 $3.30 $1.00
(White beadboard) 4 ft. 1 in. 3.8 $4.10 $1.80
2 ft. 2 in. 7.7 $3.90 $1.60
4 ft. 2 in. 7.7 $5.20 $2.90
Polyisocyanurate 2 ft. 1 in. 7.2 $3.60 $1.30
4 ft. 1 in. 7.2 $4.70 $2.30
2 ft. 2 in. 14.4 $4.00 $1.70
4 ft. 2 in. 14.4 $5.40 $3.00
Exterior cost includes metal flashing protection, reduce cost $0.40 for cement board, increase cost$1.70 for stucco.
Termite Shield
MetalshieldMastic
UV Shield
InsulationWater-proofing
Inspection Gap
Heat Loss at
Inspection Gap
Foundation Insulation Cost
The table above provides estimatedfoundation insulation installed cost perlineal foot of perimeter. Costs showninclude materials, labor, and contractoroverhead and profit. Actual costs areproject specific and significantvariation should be expected.
Foundation Insulation Material Properties
Resistance Size Thickness Density Strength Water Fire
(R per in.) (w x l) (inches) (lb/ft3) Compress
Absorp-
tionVapor
FlameSpread
SmokeDevelopment
Material (Inches) (lb/in2) (%) (Perm) E84 E84
Boards
Plastic Foams
Polystyrenes
Type VIII (EPS) 3.8 24, 48, x 96 1 - 40 1.15 13 3.0 3.5 10 125
Type II (EPS) 4.0 1 - 40 1.35 15 3.0 3.5 10 125
Type X (XPS) 4.216, 24, 48,
x 96
1, 1.5, 2, 2.5,
3, 3.51.30 15 0.3 1.1 5 165
Type IV (XPS) 5.0
16, 24, 48, x96
48 x 108
.75, 1, 1.5, 2,2.5,
3, 3.5, 4
1.60 25 0.3 1.1 5 165
Type IX (EPS) 4.224, 48,
x 961 - 40 1.80 25 2.0 2.0 10 125
Type VI (XPS) 5.0 24 x 961.5, 2, 2.5,
3, 3.5, 41.80 40 0.3 1.1 10 125
Type VII (XPS) 5.0 24, 48,x 96 2.20 60 0.3 1.1 10 125
Type V (XPS) 5.0 24, 48,x 96 3.00 100 0.3 1.1 10 125
Polyisocyanurate
Fiberglass faced 5.848 x 96
48 x 108
.75, 1, 1.5, 2,2.5, 3, 3.5
1.5 - 2.5 20 2.0 4.0 25 45
Foil faced 7.016, 24,48 x 96,108, 120
.75, 1, 1.5, 2,2.5, 3, 3.5, 4
1.5 20 <1.0 <1.0 2065
(1 in)
(Add if foil faces dead air space) 2.8
Glass Fiber 3.9 1.4 - 1.6 0.3 - 2.4 high high
Rockwool 4.236 x 48
48 x 721 11 - 13 25 .25 high
Batts
Glass Fiber (std density) 3.216, 24 x 48, 93
48 x 50 ft
3.5, 5.5, 6.258.5 (+others)
minimal1 Kraft
.5 foil25 50
Glass Fiber (high density) 3.8 16, 24 x 48, 933.5, 5.5,6.25,
8.5minimal
Rock Wool minimal
Blown
Glass Fiber (BIB) 4.0 To fit To fit 1.8-2.3 minimal 5 5
Rock Wool 2.8 To fit To fit minimal
Cellulose 4.0 To fit To fit 1.6 minimal
Foundation InsulationProperties
The table below provides basic physicalproperties of commonly usedresidential foundation insulationmaterials. A very wide range ofinsulation products are available and
the table is not comprehensive. Consulteach individual manufacture’s technicalproduct data sheets, many of which areavailable on the web, for currentinformation.
Residential Foundation Insulation
8
9
Residential Foundation Insulation
Exterior Foam Basement Wall Insulation Interior Foam Basement Wall Insulation
TERMITE SHIELD
UNFACED BATT INSULATION
WOOD JOIST
CONCRETE
FOUNDATION
WALL
SILL SEALER
SEALANT OVER
JOINT FILLER
LOW PERMEABILITY
BACKFILL (CLAY)
FABRIC
FILTER
UNDISTURBED SOIL
PERMEABLE SOIL
(WOOD FREE)
4 IN. PERFORATED
DRAIN PIPE GRAVEL BASE
CONCRETE SLAB
COARSE
CLEAN
GRAVEL
EXTERIOR SIDING
DRAINAGE PLANE
RIGID INSULATING
SHEATHING
PROTECT INSULATION
TO 6" BELOW GRADE W/
METAL, CEMENT BOARD,
OR "STUCCO"
SLOPE GROUND 5%
AWAY FROM WALL
SEALANT
CAVITY INSULATION
GYPSUM WALLBOARD
WITH LOW PERM PAINT
OR POLYETHYLENE
VAPOR BARRIER BEHIND
CANTILEVER FLOOR
PLATFORM TO ALIGN
SHEATHING AND
BASEMENT INSULATION
RIGID FOAM
INSULATION
CONCRETE FOOTING
DAMPPROOFING
(WATERPROOFING IF
HABITABLE SPACE)
TOP SOIL
CAPILLARY BREAK
POLYETHYLENE
VAPOR RETARDER
Exterior basement wall insulation is typically one to two inches offoamboard although fiberglass and rockwool boards are used.Insulation exposed above grade requires protection. A metaltermite shield reduces the risk termites will use the insulation forundetected entry.
DRYWALL
FURRING, IN OR ON
TOP OF INSULATION
POLYETHYLENE
VAPOR BARRIER
CAPILLARY BREAK
TOP SOIL
DAMPPROOFING
(WATERPROOFING IF
HABITABLE SPACE)
CONCRETE FOOTING
RIGID FOAM
INSULATION
GYPSUM WALLBOARD
WITH LOW PERM PAINT
OR POLYETHYLENE
VAPOR BARRIER BEHIND
CAVITY INSULATION
SEALANT
SLOPE GROUND 5%
AWAY FROM WALL
PROTECT INSULATION
TO 6" BELOW GRADE W/
METAL, CEMENT BOARD,
OR "STUCCO"
RIGID INSULATING
SHEATHING
DRAINAGE PLANE
EXTERIOR SIDING
COARSE
CLEAN
GRAVEL
CONCRETE SLAB
GRAVEL BASE4 IN. PERFORATED
DRAIN PIPE
PERMEABLE SOIL
(WOOD FREE)
UNDISTURBED SOIL
FABRIC
FILTER
LOW PERMEABILITY
BACKFILL (CLAY)
SEALANT OVER
JOINT FILLER
SILL SEALER
CONCRETE
FOUNDATION WALL
WOOD JOIST
UNFACED BATT INSULATION
TERMITE SHIELD
SET FLOOR
PLATFORM BACK TO
ALIGN SHEATHING
AND BASEMENT WALL
Interior basement walls can be insulated with the same boardsused on the exterior. Boards can be glued to the wall, butfoamboards required thermal protection. A vapor barrier shouldbe formed on the warm side and a metal termite shield isrecommended.
Total Installed Cost($/lineal foot for R-Value shown)
$7.50 $12.50 $17.50
N.A.
1 = board
3
21
15
114
7
310
3 10
RecommendedMinimum Basement
Wall R-Value
Total Installed Cost($/lineal foot for R-Value shown)
$7.50 $15.00 $22.50
N.A.
1 = board
3
21
15
114
7
310
310
RecommendedMinimum Basement
Wall R-Value
SuitabilityPoor Good Best
N.A.
Energy Cost Savings($/lineal foot/year)
(R-Values Recommended Above)
SuitabilityPoor Good Best
Energy Cost Savings($/lineal foot/year)
(R-Values Recommended Above)
10
Residential Foundation Insulation
Interior Batt or Blown Basement Insulation Interior Crawlspace Insulation
AIR SPACE OR
FOAM INSULATION
DRYWALL OPTIONAL
2 x 4 or 3 STUD
WALL
POLYETHYLENE
VAPOR RETARDER
CAPILLARY BREAK
TOP SOIL
DAMPPROOFING
(WATERPROOFING
IF HABITABLE SPACE)
CONCRETE FOOTING
BATT INSULATION
GYPSUM WALLBOARD
WITH LOW PERM PAINT
OR POLYETHYLENE
VAPOR BARRIER BEHIND
CAVITY INSULATION
SEALANT
SLOPE GROUND 5%
AWAY FROM WALL
RIGID INSULATING
SHEATHING
DRAINAGE PLANE
EXTERIOR SIDING
COARSE
CLEAN
GRAVEL
CONCRETE SLAB
GRAVEL BASE4 IN. PERFORATED
DRAIN PIPE
PERMEABLE SOIL
(WOOD FREE)
UNDISTURBED SOIL
FABRIC
FILTER
LOW PERMEABILITY
BACKFILL (CLAY)
SEALANT OVER
JOINT FILLER
SILL SEALER
CONCRETE
FOUNDATION WALL
WOOD JOIST
UNFACED BATT INSULATION
SET FLOOR
PLATFORM BACK TO
ALIGN SHEATHING
AND BASEMENT WALL
Interior basement walls can also be insulated with batt or blowninsulation placed between furring strips or non-bearing stud walls.The bottom plate should be treated and an effective vapor retarderplaced on the inside surface. Particular care should be taken toavoid surface or ground water penetration.
DAMPPROOFING
POLYETHYLENE
VAPOR RETARDER
CAPILLARY BREAK
TOP SOIL
CONCRETE FOOTING
FACED BATT
INSULATION
SET FLOOR
PLATFORM BACK TO
ALIGH SHEATHING
AND BASEMENT
WALL
GYPSUM WALLBOARD
WITH LOW PERM PAINT
OR POLYETHYLENE
VAPOR BARRIER BEHIND
CAVITY INSULATION
SEALANT
SLOPE GROUND 5%
AWAY FROM WALL
RIGID INSULATING
SHEATHING
DRAINAGE PLANE
EXTERIOR SIDING
COARSE
CLEAN
GRAVEL
4 IN. PERFORATED
DRAIN PIPE
PERMEABLE SOIL
(WOOD FREE)
UNDISTURBED SOIL
FABRIC
FILTER
LOW PERMEABILITY
BACKFILL (CLAY)
SILL SEALER
CONCRETE
STEM WALL
WOOD JOIST
UNFACED BATT INSULATION
Crawl spaces can be insulated with board insulation on theexterior or interior just like a basement wall. Alternatives are toinsulate the floor joist cavities with batts or blown insulation or toinsulate the interior of the foundation wall with poly wrappedbatts. Make sure to install a well sealed vapor barrier on the floor.
Total Installed Cost($/lineal foot for R-Value shown)
$0 $10 $20
N.A.
.1 = R-11 poly faced, R-15 Kraft faced w/ drywall
13
11 15
12
N.A.
N.A.
RecommendedMinimum Basement
Wall R-Value
SuitabilityPoor Good Best
N. A.
N. A.
N. A.
Energy Cost Savings($/lineal foot/year)
(R-Values Recommended Above)
Total Installed Cost($/lineal foot for R-Value shown)
$0.00 $5.00 $10.00
N.A..
1 = batt
5
21
15
114
7
25
11 19
Energy Cost Savings($/lineal foot/year)
(R-Values Recommended Above)
SuitabilityPoor Good Best
N. A.
RecommendedMinimum Crawl Space
Wall R-Value
11
Residential Foundation Insulation
Exterior Slab-on-Grade Insulation Interior Slab-on-Grade Insulation
POLYETHYLENE
VAPOR RETARDER
TOP SOIL
CONCRETE FOOTING
RIGID FOAM
INSULATION
GYPSUM WALLBOARD
WITH LOW PERM PAINT
OR POLYETHYLENE
VAPOR BARRIER BEHIND
CAVITY INSULATION
IN 2 x4 OR 2 x 6 WALL
SLOPE GROUND 5%
AWAY FROM WALL
PROTECT INSULATION
TO 6" BELOW GRADE W/
METAL, CEMENT BOARD,
OR "STUCCO"
RIGID INSULATING
SHEATHING
DRAINAGE PLANE
EXTERIOR SIDING
CONCRETE SLAB
GRAVEL BASE
UNDISTURBED SOIL
LOW PERMEABILITY
BACKFILL (CLAY)
SEALANT OVER
JOINT FILLER
SILL SEALER OVER
TERMITE SHIELD
CONCRETE
FOUNDATION
WALL
CANTILEVER PLATE
TO COVER
INSULATION
Foam boards are the most common form of exterior slab-on-gradeinsulation. The above grade portion must have UV and structuralprotection and a metal termite shield is recommended.Foundations in climate zone 1 in the colder northwest should beinsulated to a depth of four feet.
POLYETHYLENE
VAPOR RETARDER
TOP SOIL
CONCRETE FOOTING
RIGID FOAM
INSULATION
SET BACK PLATE
TO ALIGN INSULATION
WITH FOUNDATION
GYPSUM WALLBOARD
WITH LOW PERM PAINT
OR POLYETHYLENE
VAPOR BARRIER BEHIND
CAVITY INSULATION
IN 2 x4 OR 2 x 6 WALL
SLOPE GROUND 5%
AWAY FROM WALL
RIGID INSULATING
SHEATHING
DRAINAGE PLANE
EXTERIOR SIDING
CONCRETE SLAB
GRAVEL BASE
UNDISTURBED SOIL
LOW PERMEABILITY
BACKFILL (CLAY)
SILL SEALER OVER
TERMITE SHIELD
CONCRETE
FOUNDATION
WALL
Interior slab-on-grade insulation can be horizontal. Interiorplacement avoids the need for protection, but may require cuttingsmall pieces and more difficult details.
Total Installed Cost($/lineal foot for R-Value shown)
$0 $5 $10
N.A.
1 = board 2 ft. depth
5
21
15
114
7
3 10
3 10
RecommendedMinimum Slab
Perimeter R-Value
SuitabilityPoor Good Best
Energy Cost Savings($/lineal foot/year)
(R-Values Recommended Above)
Total Installed Cost($/lineal foot for R-Value shown)
$0 $5 $10
N.A..
1 = board 2 ft. depth
5
21
15
114
7
N.A.
N.A.
RecommendedMinimum Slab
Perimeter R-Value
SuitabilityPoor Good Best
N.A.
Energy Cost Savings($/lineal foot/year)
(R-Values Recommended Above)
12
Residential Foundation Insulation
Exterior Insulation on Trench Footings Interior Slab-on Grade w/ Brick Veneer Wall
RecommendedMinimum Basement
Wall R-Value
SuitabilityPoor Good Best
N.A.
Energy Cost Savings($/lineal foot/year)
(R-Values Recommended Above)
Total Installed Cost($/lineal foot for R-Value shown)
$0 $5 $10
N.A.
1 = board 2 ft. depth
5
21
15
114
7
3 10
3 10
RecommendedMinimum Basement
Wall R-Value
SuitabilityPoor Good Best
N.A.
Energy Cost Savings($/lineal foot/year)
(R-Values Recommended Above)
UNDISTURBED SOIL
LOW PERMEABILITY
BACKFILL (CLAY)
RIGID FOAM
INSULATION
EXTERIOR SIDING
DRAINAGE PLANE
RIGID INSULATING
SHEATHING
PROTECT INSULATION
TO 6" BELOW GRADE
W/ METAL, CEMENT
BOARD, OR "STUCCO"
SLOPE GROUND 5%
AWAY FROM WALL
CANTILEVER PLATE
TO ALIGH SHEATING
AND FOUNDATION
INSULATION
TOP SOIL
CONCRETE
FOUNDATION
GRAVEL BASE
CONCRETE FOOTING
POLYETHYLENE
VAPOR RETARDER
SILL SEALER OVER
TERMITE SHIELD
CONCRETE SLAB
CAVITY INSULATION
IN 2 x 4 OR 2 x 6 WALL
GYPSUM WALLBOARD
WITH LOW PERM PAINT
OR POLYETHYLENE
VAPOR BARRIER BEHIND
Trench footings or monolith pours can be easily insulated byattaching foam board to the perimeter form board. The portionabove grade requires UV and structural protection and a metaltermite shield is recommended.
POLYETHYLENEVAPOR
RETARDER
TOP SOIL
CONCRETE FOOTING
RIGID FOAM
INSULATION
BRICK TIES
ATTACHED TO
FRAMING
GYPSUM WALLBOARD
WITH LOW PERM PAINT
OR POLYETHYLENE
VAPOR BARRIER BEHIND
CAVITY INSULATION
IN 2 x 4 OR 2 x 6 WALL
SLOPE GROUND 5%
AWAY FROM WALL
WEEP HOLES AT
BOTTOM BRICK
COURSE
RIGID INSULATING
SHEATHING
DRAINAGE PLANE
BRICK VENEER
CONCRETE SLAB
GRAVEL BASE
UNDISTURBED SOIL
LOW PERMEABILITY
BACKFILL (CLAY)
SILL SEALER OVER
TERMITE SHIELD
(ALSO SERVES AS
CAPILLARY BREAK)
CONCRETE
FOUNDATION
WALL
Interior slab-on-grade foundation insulation can be installedvertically but to maintain continuity it must be carefully detailedto permit acceptable floor finish. A metal termite shield isrecommended.
Frequently Asked Questions
If a basement is unfinished does itstill need foundation insulation?
Yes, unless the floor above is insulated.Even if used only for storage andheating and cooling equipment thebasement is thermally connected to therest of the house.
Is floor insulation above a basementor a crawl space an alternative tofoundation insulation?
Yes, but keep in mind that pipes, ductsand HVAC equipment located in thebasement would then need to beinsulated to meet the MEC and toprotect pipes from freezing. Sometimesthese can be grouped in a small areawith insulated walls while the floorabove the rest of the basement isinsulated.
Doesn’t placing insulation on theexterior improve energyperformance?
If the basement incorporates passivesolar design with a significant amountof south facing windows, exteriorinsulation will be beneficial, providedthe walls are exposed to solar gain. In atypical basement the energy savings arenegligible.
Should the interior of foundationwalls have vapor barriers?
If interior insulation is used, YES. Theconcrete must be allowed to dry, butmoist basement air typical of Midwestsummers should not be allowed to reachthe cool wall where in can condense.Batt insulation specifically designed forthe interior of foundation walls has aperforated poly facing that prevents airfrom circulating through the batt, butallows water vapor from the wall toescape.
Will foundation insulation increasethe risk of termite entry?
Foundation insulation does not increasethe risk of termine entry. If termites arepresent in the soil and wood is used inthe building, the risk of infestationexists. Exterior insulation may reduce
the probability of early discovery andinhibit treatment when discovered.
Is an inspection band wherefoundation insulation is omitted topermit inspection for termites a goodidea?
In some southern states with a highincidence of termite infestation,including, Florida, South and NorthCarolina, Georgia, Alabama,Mississippi, Louisiana, eastern Texas,southern and central California,Georgia, Tennessee, and Hawaii, rigidfoam insulation is not allowed incontact with the soil. In other areas a sixinch gap between the top of foundationinsulation and any wood framingmember is required to permit visualinspection for termites. Studies done byORNL conclude that “if you include avision strip, you might as well notbother putting any insulation around thefoundation.”
Will exterior foundation insulationmaterials be chemically attacked bydampproofing?
In can happen. Avoid ……and alwaysfollow the insulation and dampproofingmanufacturer’s instructions.
What about water proofing?
Codes often require waterproofinginstead of damproofing if the wall isadjacent to habitable space.Manufactures of some foam productsoffer specific recommendations forwaterproofing of their foam systems.
How long will exterior foundationinsulation last?
Properly installed foundationinsulation, interior or exterior, shouldlast as long as insulation installed anywhere else in the building.
Should foam insulation above gradebe protected?
Foam above grade must be protectedfrom both sun and physical damage.Ultraviolet light degrades or destroysmost foams. In addition, damage fromlawnmowers, balls, and other incidentalcontact can degrade the appearance andperformance of the foam. Common
materials used to protect the foamabove grade include two- or three-layerstucco finishes, brush-on elastomeric orcementitious finishes, vertical vinylsiding, cement board, aluminum coilstock, and fiberglass panels.
Will insulating the foundationincrease the risk of radon problems?
Radon entry into a home is throughcracks and other opening below grade.The use of foundation insulation shouldminimize thermal stresses on thefoundation and help minimize cracking,thus reducing of radon entry.
Should crawl space be ventilated?
The CABO One and Two Family Coderequires one square foot of crawl spaceventilation for each 150 square feet of“floor” area. Operable vents 1/10 aslarge can be used if a vapor barrier isinstalled. Warm damp summer air cancondense on the cool earth, even whencovered with a poly vapor diffusionretarder, increasing the risk of crawlspace moisture problems. Installing avapor barrier and closing the operablevents is preferred. If local codeinterpretation requires crawl spaceventilation, insulating the floor andincorporating a vapor barrier ispreferred.
Do foam insulation boards installedon the interior require fireprotection?
All foams require thermal protectionequal to ½ inch of gypsum wall boardwhen installed on the interior of abuilding, including a crawl space. Theonly exception is Celotex Thermaxpolyisocyanurate which may beinstalled without a thermal barrierwhere approved by the local buildingcode official.
Are insulating concrete form (ICF)systems less expensive than aninsulated poured in place concretewall?
ICFs can be competitive but costs areproject specific. Foam used in thesesystesm should address the sameconcerns outlined above for foamboard.
13
Residential Foundation Insulation
Information Sources
References and On-line Resources
Builders Foundation Design Handbookby J. Carmody, 1991.
Christian, Jeffrey E., Energy EfficientResidential Building Foundations,ASHRAE Journal, November 1991.
Insulation Materials: EnvironmentalComparisons, Environmental BuildingNews, Vol. 4, No 1, January/February1995.
The Model Energy Code andOne and Two Family Dwelling CodeInternational Code Council (formerly CABO)5203 Leesburg Pike, Falls Church, VA 22041Tel: 703-931-4533 Fax: 703-379-1546Email: [email protected] site: http://www.intlcode.org
Kansas Corporation CommissionEnergy Programs1500 SW Arrowhead Road Topeka, Kanss 66604Tel: 785-271-3349Web site: http://www.kcc.state.ks.us/energy
Kansas State UniversityEngineering ExtensionWard HallKansas State UniversityManhattan, KansasTel: 785-532-4994Web site: http://www.OZNET.ksu.edu/dp-nrgy
DOE Energy Standards and GuidelinesPacific Northwest National LaboratoryRichland, WashingtonTel: 509-417-7554 Fax: 509-375-3614Web site: www://energycodes.org/
EPA Energy Star HomesU.S. Environmental Protection AgencyClimate Protection Division401 M Street SW MC:6202JWashington, DC 20460Tel: 888-782-7937Web site: http:/www.energystar.gov
Energy Efficient Building Association490 Concordia Avenue, St. Paul, MN 55103-2441Tel: 651-268-7585 Fax: 651-268-7597E-mail: [email protected] site: http://www.eeba.org
Environmental Building News122 Birge Street Brattleboro, Vermont 05310Tel: 802-257-7300 Fax: 802-257-7304Web site: http://www.ebuild.com
Material Sources (manufacturers)(Consult industry associations for more detailed lists)
Insulation
Boards
Expanded Polytyrene
AFM Corporation24000 W. Hwy 7 Excelsior, MN 55331Phone: 612-474-0809 Fax: 612-474-2074E-mail: [email protected]: www.afmcorp-epsfoam.com
Contour Products4001 Kaw Drive Kansas City, KS 66102Phone: 800-638-3626 Fax: 913-321-8063E-mail: [email protected] site: http://www.contourfoam.com
Polyfoam Packers2320 Foster Avenue Wheeling, IL 60090Phone: 847-669-1176 Fax: 847-398-0653Web site: http://www.polyfoam.com
Extruded Polystyrene
Dow Chemical Co.200 Larkin Center, 1605 Joseph DriveMidland,MI 48674Tel: 800-441-4369 Fax: 517- 832-1465Web site: http://www.dow.com/styrofoam
Tenneco Building Products2907 Log Cabin Drive Smyrna, Georgia 30080Tel: 800-241-4402Web site: http://www.tennecobuildingprod.com
Polyiscyanurate
Celotex Corporation4010 Boy Scout Blvd. Tampa, FL 33607Tel: 813-873-1700 Fax: 813-873-4058Web site: http://www.celotex.com
Johns Manville Corporation717 17th St Denver,CO 80202Tel: 800- 654-3103 Fax: 303-978-2318Web site: http://www.jm.com
Rock Wool
Roxul, Inc.551 Harrop Drive Milton, ON L9T 3H3 CanadaTel: 905-878-8474 Fax: 905-878-8077
Batts
Fiberglass
CertainTeed CorporationP.O. Box 860 Valley Forge, PA 19482Tel: 610-341-7000 Fax: (610) 341-7571Web site: http://www.certainteed.com
Johns Manville Corporation717 17th St Denver,CO 80202Tel: 800- 654-3103 Fax: 303-978-2318Web site: http:// www.jm.com
Owens CorningFiberglas Tower Toledo, OH 43659Tel: 419-248-8000 Fax: 614/321-5606 (fax)Web site: http://www.owenscorning.com
Knauf Fiber Glass GmbHOne Knauf DriveShelbyville,IN 46176Tel: (800) 825-4434 Fax: (317) 398-3675E-mail: [email protected] site: http://www.knauffiberglass.com
Blown
Cellulose
Central Fiber CorporationWellsville, Kansas 66092Tel: 800-654-6117
Blown-in-batt (BIB)
Rockwool
American Rockwool, Inc.P.O. Box 880Spring Hope, NC 27882Tel: 254-478-5111 Fax: 252-478-4172Web site: http://www.amerrock.com
Insulating Concrete Foam Systems
AFM Corporation24000 West Hwy 7 Exelsior, MN 55331Tel: 800-255-0176 fax: 612-474-2074E-mail: [email protected]: www.afmcorp-epsfoam.com
Greenblock WorldWide CorporationP.O.Box 749 Woodland Park, CO 80866Tel: (719) 687-0645 Fax: (719) 687-7820E-mail: [email protected] site: http://www.greenblock.com
ICE BlockPO Box 3089 Odessa, TX 79761Tel: 800-ICE-BLOC Fax: 915-561-5622E-mail: [email protected] site: http://www.concentric.net
Lite-Form, Inc.PO Box 774 Sioux City, IA 51102tel: 800-551-3313, tel: 712-252-3704E-mail: [email protected] site: http://www.liteform.com
Reward Wall Systems4115 S. 87th St. Omaha, NE 68127Tel: 800-468-6344 fax: 402-592-7969E-mail: [email protected] site: http://www.rewardwallsystem.com
Termite Treatment
Sentricon Colony Eliminator SystemDow AgroSciences9330 Zionsville Road Indianapolis, IN 46268-1054fax: 800-905-7326Web site: http://www.sentricon.com
Systematic Termite ControlFMCChicago, IL Tel: 800-321-1FMCWeb site: http://www.fmc-apgspec.com
Industry Associations
North American InsulationManufacturers Association44 Canal Center Plaza Alexandria, VA 22314Tel: 703-684-0084, Fax: 703-684-0427E-mail: [email protected] site: http://www.naima.org
Cellulose Insulation ManufacturersAssociation136 Keowee Street Dayton, OH 45402Tel: 513-222-2462 Fax: 937-222-5794E-mail: [email protected] Site: http://www.cima.org
Polyisocyanurate InsulationManufacturers Association1331 F Street, NW, Suite 975 Washington, DC 20004Tel : 202-628-6558 Fax: 202-628-3856E-mail: [email protected] site: http://www.pima.org
Insulating Concrete Form Association1807 Glenview Road, Suite 203Glenview, Ilinois, USA 60025Phone: 847-657-9730 Fax: 847-657-9728E-mail: [email protected] site: http://www.forms.org