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R-Values of various materials

  • INSULATION R-VALUES & PROPERTIES - CONTENTS: insulation materials R-values, rates of heat loss or gain, flame spread, toxicity, durability. What insulation "R" values should be used in a building insulation? Insulation R-Values of nearly all materials found in or on buildings.
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Insulation R values of various materials:

This article provides a Table of Insulation Values and Properties for Various Insulation Materials useful in procedures to measure or calculate heat loss in a building, defines thermal terms like BTU and calorie, provides measures of heat transmission in materials, building insulation design data, and heat loss in a building.

Page top photo by the author. Formula-R and Owens Corning which may be visible in this photograph of pink Styrofoam insulation boards are registered trademarks of Owens Corning and were photographed at a Home Depot® building supply center.



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Table of Characteristics of Various Insulating Materials: air, fiberglass, masonry mateirals, mineral wool, cellulose, foam insulating board, UFFI, soil or dirt, vermiculite, wood, & most other building materials

Quick Links to Often-Requested Material Insulating Properties

Use these links to skip to the insulation materials listed in the "Popular Insulation Questions" below, or just skip directly to the start of the COMPLETE INSULATION DATA TABLE where you will find that we list additional insulating materials. There nearly all building materials are found as well as the insulating properties of other materials of interest such as air, dirt or soil.

Tip: Also use the page top Search box to look for specific insulating materials and their properties in this article.

AIR SPACES PHENOLIC spray foam
ASBESTOS PLASTER
BALSAM WOOL PLYWOOD
BRICK POLYISOCYANURATE foam
CELLULOSE POLYSTYRENE foam
CONCRETE POLYURETHANE foam
COTTON REFLECTIVE barriers
DRYWALL ROCK WOOL mineral wool
FIBERBOARD ROOFING materials
FIBERGLASS SNOW
FOAM INSULATION Icynene, Phenolic SOIL
GLASS & INSULATED GLASS UFFI Foam
ICYNENE foam VACUUM insulating panels
MASONRY brick, block, concrete

VERMICULITE insulation

MINERAL WOOL WOOD materials
PERLITE  
   

...

Complete Table of Insulation & Other Building Material Properties - Alphabetical Order

Insulation or other Building
Material 9
R-Value1 Density2 Perm3 Absorption4 Flame
Spread
5
Smoke6 Toxicity7 Aging
Effects & Comments
Air gap or air film, 3/4" air space insulating properties 0.87            

The R=0.87 value
Does not consider internal convection effects.
Does not consider presence / absence of reflective barriers.
Does not consider directions of heat flow uip or down nor winter/summer conditions.
Also note that there are differences for inside vs outside air films.

For all of these air space R-values also see Masonry citations below.

For a 3/4" air gap or air space 30

Heat flow direction: up, no reflective surfaces, R=0.75 (Summer) or R=0.87 (Winter)

Heat flow direction: up, one reflective surface, R=2.22 (Summer) or R=2.21 (Winter)

Also see REFLECTIVE barriers

Heat flow direction: down, no reflective surfaces, R=0.85 (Summer) or R=1.02 (Winter)

Heat flow direction: down, one reflective surface, R=3.29 (Summer) or R=3.59 (Winter)

Heat flow direction: horizontal, no reflective surfce, R= 0.84 (Summer) or R=1.01 (Winter)

Heat flow direction: horizontal, one reflective surfce,
R= 3.24 (Summer) or R=3.46 (Winter)

Air film, inside surface, still air, no reflective surface, directions vary: horizontal, vertical, up, or down 0.61 - 0.92
Air film, inside surface, still air, + reflective surface or barrier, directions vary: horizontal, vertical, up, or down 1.32 - 4.55 30
Air film, outside surface, any direction, any position, 15 mph wind in winter 0.17 30

Air film, outside surface, any direction, any position, 7.5 mph wind in summer

0.25 30

Air, exterior film on walls 0.17 30             Presumes no wind or air movement?
Air, interior film on walls 0.68             Presumes no air movement?
Dead air space in wall cavity, 3/4" to 4" (winter) 0.97             Presumes no convection air movement? Convection movements reducing R-values are more likely in wider dead air spaces and are virtually certain if there are leaks or penetrations at wall top and bottom.

Air Krete®26

also see Concrete, Insulating, below

3.9 2.07 lbs/cuFt26 0.1457 in/sec coefficient, or 0.3407 in/sec flow rate at 68 degF H2O27   026 026 no Cementious foam insulation, fireproof, non-toxic, non-shrinking, also used for acoustical sound proofing; MgO cement (Magnesium Oxide); 6 mil poly vapor barrier required
Asbestos, corrugated paper pipe insulation 1.4             Estimated R-value of asbestos insulation per inch for pipe insulation corrugated paper. Asbestos lagging and paste will have a lower value
Asbestos cement board R-value 0.25            

www.msu.edu

 

Asbestos loose packed fibers / powder               Thermal conductivity k = 0.15
Asbestos cement shingle siding 0.03             [30]

Notes on the R-value & K-values of different forms of asbestos:

Rosato (ASBESTOS INSULATION) is the most authoritative source on asbestos properties and gives data for the thermal conductivity of asbestos in different forms and with varying temperatures. For magnesia-asbestos insulation at mean temperatures ranging from 100°F to 400°F the K-value (thermal conductivity, BTU in. per hr per sq.ft. per °F) ranged from 0.35 to 0.46.

Details about the insulating, heat, and other properties of asbestos are at ASBESTOS PROPERTIES

Current sources of asbestos R-values such as engineeringtoolbox provide very inconsistent data: Thermal conductivity k = 0.744 for "cement board", k=0.14 for asbestos millboard, and k= 1.66 for asbestos cement sheets; but the same source puts asbestos cement k = 2.07 and for loosely-packed asbestos k=0.15 - this is very inconsistent data - source: engineeringtoolbox.com retrieved 3/23/2014.

Balsam Wool insulation 2 - 3.5             Spills out of wall or roof insulation if facing is cut
Brick, common 0.218 30             See

BRICK LINED WALLS

BRICK VENEER WALL AIR LEAKS

BRICK WALL INSULATION RETROFIT

Also see Brick Nogging.

[30]

Brick facing, 1" 0.11             [Need citation]
Building Paper, asphalt impregnated felt, 15# permeable 0.06             [30]
Building paper, red rosin paper 0.06             [Need citation]
Cardboard as insulation 3 - 421              
Ceiling Panels, suspended or drop ceilings 0.4 - 6            

varies widely by material

See CEILINGS, DROP or SUSPENDED PANEL

 

Cellulose Insulation R-Values by type

Cellulose insulation loose fill 3.1 - 3.820,24 2.2-3.0 High 5-20% 15-40 0-45 CO

0-20% settlement, corrodes metal, mold resistant

Or R 3.13 - 3.7030

Cellulose insulation, spray-on (wet spray) 2.8 - 3.520, 24              
Cementious Foam 0.35 - 0.6921              
Cement asbestos wall shingles 0.03            

[Need citation]

 

Concrete Insulating R-values by type (Also see "Masonry Materials R-Values" below)

Concrete, air entrained 3.9021              

Air Krete®26

also ThermalKrete and similar air-entraned MgO Products

3.9026 2.07 lbs/cuFt26 0.1457 in/sec coefficient, or 0.3407 in/sec flow rate at 68 degF H2O27   026 026 no Cementious foam insulation, fireproof, non-toxic, non-shrinking, also used for acoustical sound proofing; MgO cement (Magnesium Oxide); 6 mil poly vapor barrier required
See CONCRETE INSULATION, light-weight
                 
Concrete, uninsulated 0.0818 30 - 0.312517             Typical residential weight concrete 8" wall = R 2.5
Concrete, sand & gravel aggregate 0.13 - 0.6430             8" thick concrete slab or foundation wall has an R-value of about 1.04 30 while lightweight aggregate filled 8" thick concrete has an R-value of about 2.18 30
Concrete-insulated 0.85 - 1.2 12-88 Varies Varies 0 0 0 Insulated forms available
                 
Concrete block, 4-inch hollow core 1.11             See citations at "Masonry" below
Concrete block, 8-inch hollow core 1.04 - 2.18, commonly 1.04 30             [30]
Concrete block, 12-inch hollow core 1.90             [need citation]
Concrete block, lightweight 8-inch 2.2              
                 
Carpeting with fiber padding 2.0830              

Carpeting with foam padding

1.2330             Typical low-pile carpeting with foam or rubber carpet padding
 

Cotton Insulation R-Values by type

Insulation or other Building
Material 9
R-Value1 Density2 Perm3 Absorption4 Flame
Spread
5
Smoke6 Toxicity7 Aging
Effects & Comments
Cotton insulation 0.5 .25-10            
Cotton Batts 3.722             "blue jean" insulation batts fireproofed with boric acid
Dirt or Soil 0.25 - 1
0.80 typical at 20% moisture
            Depends on soil properties: density, moisture content, moisture movement
See SOIL R-VALUES
Drywall, 1/2-inch 0.45             [need citation]
Drywall, 3/4-inch 0.56             [need citation]
Fiberboard insulating boards - per inch 2.8 30             Questionable data, Some sources claim 2.64
Fiberboard 1/2" intermediate density, per inch 2.44 30             Questionable; [30] Divide this per inch numberby 2 to obtain the R-value for 1/2" medium density fiberboard = R 1.22
Fiberboard insulating sheathing, regular density, per inch 2.64 30             Questionable; [30] Divide this per inch number by 2 to obtain the R-value for 1/2" regular density fiberboard = R 1.32
Fiberboard insulating sheathing, 25/32" thick, regular density, per inch 2.64 30            

Questionable; [30]
25/32" Board = R 2.06

Fiberboard nail base insulating board, 1/2-inch 1.14 30            

Highly questionable [30]

Also see HARDBOARD R-VALUES

 

Fiberglass Insulation R-Values by type

Insulation or other Building
Material 9
R-Value1 Density2 Perm3 Absorption4 Flame
Spread
5
Smoke6 Toxicity7 Aging
Effects & Comments
Fiberglass chopped, loose fill 2.5 - 3.720              
Fiberglass chopped/blown insulation 3.6 - 4.4   100         6" = about R-22. Installers say expanding fiberglass assists in sealing air leaks
Fiberglass batt insulation 3.1 - 4.320 .6 - 1.2 100 1% 15-20 0-20 Fumes from paper,
binders

May collect debris/allergens/mold
Also see INSULATION CHOICES

3-3 1/2" thick fiberglass insulation = R 11
5 1/4" - 6 1/2" thick fiberglass = R 19
6-7" thick fiberglass = R22
8 1/2 - 9" thick fiberglass = R30
12" thick fiberglass = R38

Fiberglass, batts, high density 3.6 - 521
             
Fiberglass panel, rigid (fiberglass "boards") 2.521             e.g. used in HVAC ductwork or air handlers.
Fiberglass, spray-on 3.7 - 2.920              
                 
Flooring, hardwood, 3/4" thick, per inch: 1.10             3/4" hardwood flooring = R 0.68 30 presuming no air leakage
Flooring, sheet resilient floors, linoleum, or tiles 0.0530             Applies to Asphalt/asbestos floor tiles, linoleum, vinyl, rubber floor tiles, per inch.
 

Glass, insulating properties & R or U Values

Insulation or other Building
Material 9
R-Value1 Density2 Perm3 Absorption4 Flame
Spread
5
Smoke6 Toxicity7 Aging
Effects & Comments

Glass single glazing

Note double glazed glass U-values in Comments at right

0.1418            

U-Values for Glass & Glazing 30

Single pane glass, Winter U = 1.10 30
Single pane glass, Summer U = 1.04

Insulated Glass, double pane U=Values 30

3/16" Air Space, Winter U = 0.62 30
3/16" Air Space, Summer U = 0.65
1/4" Air Space, Winter U = 0.58
1/4" Air Space, Summer U = 0.61
1/2" Air Space, Winter U = 0.49
1/2" Air Space, Summer U = 0.56

Note that the larger air space has a reduced U-value, probably because of convection currents within the sealed thermopane or insulated glass panel.

Glass, triple-glazed 2.27 - 3.22            

U Value, Winter 0.31-0.39 30
U Value, Summer 0.39 - 0.44 30

R = 1 / U

U 1 = R 1
U 0.5 = R 2
U 0.333 = R 3
U 0.20 = R 5
U 0.15667 = R 6

the R-values given at left are questionable.

Glass Storm Windows, 1 - 4" space between storm interior surface & interior window exterior surface 0.50 30             Highly questionable without assessment of the leakiness of the storm window and also of the leakiness of the principal window sash.
                 
Gypsum board 0.6            

Drywall
1/2" Gypsumboard = R 0.45 30
5/8" Gypsum board = R 0.56 30

See DRYWALL R-Values

Home®Foam25

Spray or pour

3.921 0.51 lbs/ft3          

Insulthane 100, See Plastic, foamed insulation below
Home Foam? should not be installed within 2" / 50mm of heat emitting devices producing temperatures in excess of 200deg.

                 
Hardboard, high density, standard tempered 1/4" thick, Per Inch 1 30            

1/4" thick hardboard, high-density = R 0.25 [30]

Note that many builders refer to this wood product hardboard by a specific trade name "Masonite™" or "Masonite hardboard"

Hardboard underlayment, 1/4", per inch: 1.24 30             1/4" thick hardboard underlayment = R 0.31 [30]
 

Insulating Board R-Values

Insulating board, glass fiber organic bonded 4.00 30              
Insulating board, expanded ploystyrene, extruded, cut cell 4.00 30              
Insulating board, expanded polystyrene extruded smooth 5.00 30              
Insulating board, expanded polystyrene molded bead panel 3.57 30            

See POLYSTYRENE foam

Insulating board, expanded polyurethane 6.25 30            

See POLYURETHANE foam

Insulating board, polyisocyanurate foam 7.20 30            

See POLYISOCYANURATE foam

Insulating board, mineral fiber, resin binder 3.45 30            

 

               

 

               

 

 

Icynene Foam Insulation R-Values

Insulation or other Building
Material 9
R-Value1 Density2 Perm3 Absorption4 Flame
Spread
5
Smoke6 Toxicity7 Aging
Effects & Comments

Icynene® Foam-poured insulation

or pour fill insulation

423 .5-2 10 low low low     Fire safety: may not be left exposed in living area; very good air bypass leak sealing properties
Icynene® Foam-sprayed insulation 3.6 - 3.7 23 .5-2 10 low low low     Fire safety: may not be left exposed in living area; very good air bypass leak sealing properties
Mineral Wool insulation
(Rock Wool)
3.2 - 3.720
1.5-2.5 100 2% 0 0 0

May collect debris/allergens/mold, also referred-to as rock wool, slag wool, glass wool (but not fiberglass)

3 3/4" - 5" Mineral Wool = R 11
6 1/2" - 8 3/4" Mineral Wool = R19
7 1/2" - 10" Mineral Wool = R22
10 1/4" - 13 3/4" Mineral Wool = R30
13" - 17 1/4" Mineral Wool = R38

 

Masonry Materials R-Values: concrete block, "cinder block", brick, concrete masonry units, perlite filled concrete block

Insulation or other Building
Material 9
R-Value1 Density2 Perm3 Absorption4 Flame
Spread
5
Smoke6 Toxicity7 Aging
Effects & Comments
Brick, common 0.20 30             [30]
Brick, 4" 0.44             Nil. This is for clay brick.
Brick, 4" + 1" reflective air space                
Brick, facing or veneer 0.11 30              
                 
                 
                 
Concrete Block, two rectangular core, 8" 1.04             Filled with sand and gravel aggregate [30] We consider this questionable and note that moisture content is omitted.
Concrete Block, two rectangular core, 8" 0.44 +
2.89 =
3.33
            Filled with lightweight aggregate [30], same warning as above.
Concrete
Block,
 4"
72% solid
(115#/ft3)
1.19             Nil

(Also see "Concrete" above)
Concrete
Block, 6"
59% solid
1.25             Nil

Concrete
Block, 6"
59% solid
perlite-filled

3.95              
Concrete
Block, 8"
54% solid
1.45             Nil

Concrete
Block, 8"
54% solid
perlite-filled

4.65              
Concrete
Block 10"
52% solid
1.55             Nil
Concrete
Block, 10"
52% solid
perlite filled
5.65              
Concrete
Block 12"
48% solid
1.65             Nil
Concrete
Block, 12"
48% solid
perlite-filled
7.05              
                 

Masonry R-values Source: adapted from "Sample R-Value Calculations" found at www.maconline.org

Notes:

1. Effects of water intrusion on insulating value and R-values are not included in the above nor was there discussion of variation in thermal conductivity at block segments that are solid rather than perlite filled.

2. Additional R-value for a masonry wall constructed using these materials needs to add the insulating value of additional wall components typically included, such as 1" solid foam (polyisocyanurate R 8, extruded polystyrene R 5, expanded polystyrene R 4, or 1" of perlite R 2.7) and for an exterior air film (winter, no wind, R 0.17), an interior air film (again no air movement, R 0.68), 3/4" of reflective air space (no convective air movement, R 2.89), 1/2" drywall (R 0.45), interior wall cavity insulation (see various fiberglass or other insulating values in this table), to achieve a greater overall R-value than that afforded by the masonry block or brick wall alone.

3. Presumably the R-values given are then calcuated for the overall wall structure, averaging the effects of thermal breaks etc. - Ed.

Particleboard 5/8" underlayment, per inch 1.31             5/8" particleboard underlayment has an R-value of 0.82 [30]
                 
Perlite insulation 2.5 - 3.720, 30 2-11 High 0 0 0 0  
                 
Plywood, A/C 1.4             Questionable, [need citation]
Plywood, 1/4"               R 0.31 [30]
Plywood 3/8"               R 0.47 [30]
Plywood 1/2"               R 0.62 [30]
Plywood 5/8"               R 0.77 [30]

Phenolic Foam Insulation R-Values

Phenolic foam spray insulation 4.8 - 721              

Phenolic foam insulation

Phenolic rigid panel

8.3
4.4 - 8.220

4 - 521

 

            Corrosion problems when in contact with steel roofing & moisture; very good air bypass leak sealing properties
 
Plaster, 1/2" lightweight 0.32 30              
                 
Plastic, foamed: Home Foam25 low-density 3.921 0.51 lbs/ft3          

Water-blown

Unidentified ingredients 25

Spray or pour application see HomeFoam® above.

                 
Polyethylene foam 321              
 

Polyisocyanurate Foam Insulation R-Values

Insulation or other Building
Material 9
R-Value1 Density2 Perm3 Absorption4 Flame
Spread
5
Smoke6 Toxicity7 Aging
Effects & Comments
Polyisocyanurate / Polyurethane panel 5.6 - 7.020              
Polyisocyanurate foam panel or board, foil faced 6.821 - initial, pentane expanded
5.521 - aged 5 to 10 years
           

Rigid panel insulation board with foil facing both sides, edges exposed

Aged R-values for foam panels assume aging in-situ for 5-10 years.

                 
Polyisocyanurate spray, poured, or board insulation

4.3 - 8.321

5.5 - 6.2 to 7.04 - 8.0

2 2-3 0 25 55-200 CO Closed cell, HCFC or CFC gases;
0-12% shrinkage, Fire safety: may not be left exposed in living area; thermal drift with aging; foil faced improves performance to R7-8.; very good air bypass leak sealing properties
Also see INSULATION CHOICES 
Polyisocyanurate composite insulation 2.8
(5.8-6.2)
2.0 2-3        

Closed cell

Foil faced21

See POLYISOCYANURATE FOAM and IAQ

 

Polystyrene Foam Insulation R-Values

Polystyrene peanuts for building insulation not recom-
mended
      5-25+ 10-400   Not recommended for building insulation, may be serious fires hazard.
Polystyrene loose fill beads for building or window-wall insulation 2.3       5-25+ 10-400   Static charge makes particles hard to control

Polystyrene board or beadboard 8 MEPS insulation

molded EPS low density

3.6 - 5.0

 

3.8521

0.8-2.0 1.2-3.0 0.7-4% 5-25 10-400 CO Degrades in sunlight (UV); R-value varies by board density
Also see INSULATION CHOICES

Polystyrene Expanded (EPS) insulation

low-density

3.85
3.9 - 4.420

3.6 - 4.721

           

See POLYSTYRENE FOAM INSULATION

Also see INSULATION CHOICES

Polystyrene board, extruded expanded high-density (XPS)

Molded

5 - 5.421

4.221

             
Polystyrene board 5 1.5 1.2-3.0        

Closed cell

See POLYSTYRENE FOAM INSULATION

 

Polyisocyanurate / Polyurethane Foam Insulation R-Values

Insulation or other Building
Material 9
R-Value1 Density2 Perm3 Absorption4 Flame
Spread
5
Smoke6 Toxicity7 Aging
Effects & Comments
Polyurethane spray - closed cell foam insulation.

Thanks to Thanks to Andrew Cole for correcting our data on this product.

5.0 - 6.8

5.5 - 6.521

Initial 7.14
Aged 6.8

2.0 2-3 0 30-50 155-200 CO

Closed cell foam spray insulation;
0-12% shrinkage, Fire safety: may not be left exposed in living area. Initial R of 7.14 declines to 6.8 after several months of curing; very good air bypass leak sealing properties

                 
Polyurethane foam insulation rigid panels 7-821 - Initial
6.25 - aged 5 to 10 years
            CHC/HCFC expanded foam
Polyurethane foam insulation rigid panels 6.821 - Initial
5.5 - aged 5 to 10 years
            Pentane expanded foam
Polyurethane spray foam insulation rigid panels, foil-faced 7.9 - 8.4             Pentane expanded foam, presence of an air-gap may increase panel performance.
RSI = 45-48
Polyurethane spray foam insulation - open cell insulation 3.621 - 7 (est)             Expands & seals more than closed-cell; lower cost; pourable-version available for building retrofit; See URETHANE FOAM Deterioration, Outgassing
 
Insulation or other Building
Material 9
R-Value1 Density2 Perm3 Absorption4 Flame
Spread
5
Smoke6 Toxicity7 Aging
Effects & Comments
Reflective insulation  2 - 1720             Need details of products in this range

Rock Wool Batts

Slag wool Batts

3 - 3.8520             See MINERAL WOOL

Rock Wool, Slag wool Loose Fill insulation R-value

2.5 - 3.720              
Roofing: Asphalt shingles 0.4430              
Roofing: built-up 3/8" thick plies 0.3330              
Roofing: wood shingles 0.9430             Also see below at "wood". The use of this R-valuye is highly questionable since wood shingle roofs do not block air flow whatsoever.
                 
Silica Aerogel 10              
Snow 1              
Soil or "dirt" 0.25 - 1
0.80 typical at 20% moisture
            Depends on soil properties: density, moisture content, moisture movement
See SOIL R-VALUES
Straw Bale 1.45             STRAW BALE CONSTRUCTION
Stucco, conventional plaster/cement 0.20             [30]
                 
Tectum™ insulated roof panels 2.0             Tectum: a patented cementitious wood fiber EPS-core insulating roof deck tile, plank, or panel of several thicknesses.
Thinsulate 5.75             Clothing insulation, not used in buildings
 

Urea Formaldehyde UFFI Foam Insulation R-Values & Properties

Insulation or other Building
Material 9
R-Value1 Density2 Perm3 Absorption4 Flame
Spread
5
Smoke6 Toxicity7 Aging
Effects & Comments
Urea Formaldehyde Foam Panels or in-wall spray 4 - 4.621             Formaldehyde outgassing concerns, especially new, possibly
UFFI insulation
(Urea Formaldehyde Foam)

4.2

5.2521

0.6-0.9 4.5-100 18% 0-25 0-30 0 (may outgas formal-dehyde) 1-4% shrinkage,
Fire safety: may not be left exposed in living area; on aging, leaves significant air bypass leaks at shrinkage points
 
Vacuum Insulated Panels
Vacuum "insulated" panel 30-50   Low         Vacuum insulated panels (VIPs) are rigid, air-tight hollow-core panels from which air has been evacuated. An internal support is needed to keep the panel walls from collapsing when evacuated.

The effectiveness as a vacuum insulating panel will also vary by panel thickness (e.g.l 25mm), as panel walls close together may transer heat by radiation and by the temperatures on the two sides of the panel as radiation transfer of heat increases with the temperture difference.
Vacuum Powder Insulation 25 - 3020              
Vacum powder insulated panels 20 - 10020             U.S. DOE. Others cite R-30 - R-50.
Vermiculite insulation 2.1319 - 3.0
2.10 - 3.720
4-10 High 0 0 0 0 (may contain asbestos) May contain asbestos, virtually always installed as loose-fill.
Some sources cite R = 2.08
Some sources cite R = 2.13 - 2.2730
Vinyl Siding 0.61   Low 0       1/16" (0.175")to 3/32" (0.093") thick vinyl siding, hollow-backed
Vinyl Thin Film Window Covering     Low 0       U-value and emissivity values vary depending on the type of film, with emissivity values from 0.07 to 0.81 - DeBusk [29]
 

Wood, Hardwood, Softwood Insulation R-Values

Insulation or other Building
Material 9
R-Value1 Density2 Perm3 Absorption4 Flame
Spread
5
Smoke6 Toxicity7 Aging
Effects & Comments
Wood R-Values
Log wall R-Values vary16
1.01 - 1.41 (softwoods)
0.71 (hardwoods)
           

The R-value of wood varies by wood density, species, moisture content.

R-value of typical 3/4" thick pine softwood = about R 1.25 [30]

Wood door, solid, per inch 1.56             Varies by species, no authoritative source.
Wood, soft 1.25             Questionable, [need citation]
Wood Flooring, assume 3/4" hardwood 0.68             [need citation]
Wood sheathing panels (Plywood,OSB) 2.521             [need citation]
Wood shingle siding, single course 0.87             [30]
Wood siding, 1/2-inch clapboard or shiplap 0.81             [30]
                 
                 
 

Notes to the Table of Building Insulation Properties

Because no amount of insulation can keep a drafty building warm, also review ENERGY SAVINGS PRIORITIES. See BLOWER DOORS & AIR INFILTRATION for a discussion of measuring air leakage in buildings.

Also see HEAT LOSS INDICATORS (where is the building losing heat during the heating season, or gaining un-wanted heat during the cooling season),

and see HEAT LOSS R U & K VALUE CALCULATION for a guide to calculating heat loss (or gain) rates for buildings and building insulation.

  1. R-Value is expressed as rate of heat loss per hour per square foot per inch of thickness of material per deg. F - see "R" value definition at Definitions of R K U values For some building materials (such as sheet flooring) we give an R-value for a specfic thickness other than the standard 1".

    RSI-Values: convert U.S. R-values to SI units or RSI as follows:  R-Value / 5.685 = RSI-Value

    R-1 = 5.678263337 RSI
    or
    RSI-1 = 0.1761101838 R
  2. Insulation density is expressed in pounds per cubic foot of material
  3. Permeability is expressed as the water vapor permeability of the material per inch of thickness. These numbers are most useful to compare one insulating material to another.
  4. Absorption is the tendency of the insulation to absorb water in percent by weight. This is important for assessing the risk of mold in some materials
  5. Flame Spread is a measure of fire resistance of the material. Use these numbers to compare one insulating material to another.
  6. Smoke is a measure of fire safety - that is, the relative amount of smoke produced if the insulation is exposed to flame or combustion
  7. Toxicity is a measure of fire safety - that is, toxins given off if the insulation is exposed to flame or combustion.
  8. Polystyrene may be in molded or extruded forms and like some other plastic or foam insulations may be in open or closed cell form. (Closed cell foams are more moisture resistant). Polystyrene also is referred to as molded expanded polystyrene (MEPS), expanded polystyrene (EPS), and extruded polystyrene (XPS) - the most common foam board insulation product. MEPS & XPS are used in insulated structural panels and in insulating concrete forms (ICFs).
  9. Links to details: Insulation product names in the first table column include links to articles that help identify and provide the properties of each insulating material listed.
  10. Open vs. closed cell: Foam insulation densities vary among closed-cell vs open cell forms. Open cell foams are typically about 1/2 lb/cubic foot; Closed cell foams are more dense and rigid, typically about 2 lb/cu. ft.
  11. C or Thermal conductance of these materials is the reciprocal of the R-value. C is known only when the k, the thermal conductivity of a material is known. k is the heat transmitted through a 1-inch thickness of homogenous material per square foot per hour when there is 1 degree of temperature change. k= (BTU * inch) / sq.ft. * hour * degF.
  12. Air film: This table of R-values does not consider the insulating characteristic of the air film on each side of a surface nor the effects of wind on the air film or on the material itself. Some of these materials are more resistant to wind-caused heat transmission than others.
  13. Moisture: Closed cell foams resist moisture uptake (good) but if construction is improper they can trap moisture (bad) leading to rot or mold problems in other building materials.
  14. Insects: Exterior foam board on foundations can ease attack by wood destroying insects.
  15. Fire & smoke: Foam insulation products present fire-smoke hazards and usually they must be protected with a fire barrier (usually 1/2" drywall).
  16. R-Values for wooden log walls given by the U.S. DOE are in error except for square log walls. D-logs and round logs that are given a nominal log thickness, say 6" logs are calculated by DOE as having an R-value of just over 8. This is incorrect for non-square logs because the cross section of the log is 6" only at the log's widest point. A correct assessment of the R-value of a wooden log wall needs to be calculated based on the average wall thickness, considering the variation in thicknesses over the curvature of the logs. Therefore the DOE's value is on the "high" end of the R-value of a log wall.
  17. R-Values of uninsulated concrete: Concrete Homes Magazine web search 5/18/2010
  18. R-Value for concrete, glass, other materials, Wikipedia web search 5/18/2010 citing Ristinen, Robert A., and Jack J. Kraushaar. Energy and the Environment. 2nd ed. Hoboken, NJ: John Wiley & Sons, Inc., 2006.
  19. E-Star Colorado. Energy Saving Calculations. Energy Living Alliance, 2008. Web 05/18/2010
  20. U.S. Department of Energy, DOE Handbook, see http://buildingsdatabook.eren.doe.gov/TableView.aspx?table=5.1.3 18 May 2010. The DOE in turn cited these sources
    • ASHRAE, 1997 ASHRAE Handbook: Fundamentals, p. 24-4, 22-5
    • DOE, Insulation Fact Sheet, Jan. 1988, p. 6
    • Journal of Thermal Insulation, 1987, p. 81-95
    • ORNL, ORNL/SUB/88-SA835/1, 1990
    • ORNL, Science and Technology for a Sustainable Energy Future, Mar. 1995, p. 17
    • ORNL for vacuum insulation panel
  21. Wikipedia, web search 5/18/2010 R-Values per Inch
  22. EcoHaus UltraTouch cotton insulation batts batts http://www.ecohaus.com/C-121/ultratouch+batts Web search 5/18/2010
  23. Icynene product information see http://www.icynene.com/icynene-insulation/ - Web search 5/18/2010
  24. ICC Legacy Report ER-2833 - Cocoon Thermal and Sound Insulation Products, ICC Evaluation Services, Inc., Website: icc-es.org - Web search 5/18/2010
  25. HomeFoam®, Home Insulation Corp. - see http://www.homefoam.ca/articles/Why_HF.htm - Web search 5/18/2010
    Home Foam® does not contain formaldehyde, fibrous particulate, HFCs1, CFCs2 or HCFCs3 and is a zero-ODP4 product. The Saskatchewan Research Council (SRC) advises that even sensitive individuals may take occupancy just 24 hours after application is complete.
  26. Air Krete®, Air Krete Inc., P.O. Box 380, Weedsport NY 13166-0380 Keene Christopher, Principal Telephone: (315) 834- 6609, Retrieved 05 Dec 2010, AirKrete® Green Insulation Specifications, original source: http://www.airkrete.com/ Specifications for AirKrete® can be found at http://www.airkrete.com/pdf/072101specification.pdf
  27. AirKrete® Water Permeability Coefficient, 03/02/2005, letter provided by AirKrete, retrieved 05 Dec 2010, original source: http://www.airkrete.com/testResults_files/PermRating.pdf
  28. Nomaco Insulation, "Calculation of K Value and R-Value, Technical Bulletin TS12-0909", Nomaco Insulation, 3006 Anaconda Rd., Tarboro NC 27886, Tel: 866-876-2684, Website: nomacoinsulation.com, offers this helpful explanation of K values: Quoting:

    The actual k-factor is based on the number of BTUs per hour that pass through a one inch (1”) thick by one foot (1’) square section of insulation with a 1°F temperature difference between the two surfaces.

    Insulation materials usually have k-factors less than one and are reported at what is called Mean Temperature. To determine the mean temperature, measure the surface te mperatures on both sides of the insulation, add them together and divide by two.

    When comparing the insulation value of different types of insulation it’s important to look at the k-factor AND the mean temper ature. As mean temperature rises, the k-factor on some insulation materials also increase.
    - retrieved 3/23/14, original source: http://www.nomacoinsulation.com/pdf/polyolefin%20faq/TS12%200909.pdf
  29. Steve DeBusk, writing on low-e glass vs window films at Buildings.com, retrieved 4/16/2014 original source: , quoting; Low-e window film U-value and emissivity values can range, depending on the type of film. Standard window films ... U-value and emissivity values vary for standard window films, depending on the type of film, with emissivity values ranging from 0.70 to 0.81,. ... Conventional low-e window film has an emissivity rating of 0.33 ... there are newer low-e window films available with emissivity ratings as low as 0.07
  30. "Resistance Values of Structural and Finish Materials", Ira A. Fulton College, Engineering Faculty, 368 CB, Provo, UT 84602 USA, retrieved 2016/10/25, original source: http://cmfac.groups.et.byu.net/jsmith/Lessons/TempSoundControl/R-Values.pdf
    Watch out: this PDF of the heat transfer resistance of strucutral and finish materials may in fact have obtained some of its numbers from our own data at this web page: beware of circular reference citations.

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