# Thermal Conductivity

The k-value (thermal conductivity) represents the amount of heat that flows through 1 square foot of a homogeneous material 1 inch thick in 1 hour for each degree of temperature difference between the inside and the outside temperatures.

To illustrate, we shall use an example from the ASHRAE data shown in Tables 3-1 and 3-2. You will note that the k-value for face brick listed in Table 3-1 is 9.0. In other words, 9.0 Btu of heat can pass through 1 ft2 of 1-in-thick face brick each hour. The ther­mal resistance (R-value) of this same 1-in-thick face brick is the reciprocal of its k-value:

11 R =1 = 9 = 011

 Conductivity or Description Conductance Resistance (R) Density Per Inch For (lb per Thickness Thickness Material Ft3) 00 (c) L/k Listed l/C Air Spaces Position Heat Flow Thickness Horizontal Up (winter) 3/t-4 in — — 1.18 — 0.85 Horizontal Up (summer) 3/t-4 in — — 1.28 — 0.78 Horizontal Down (winter) 3/t in — — 0.98 — 1.02 Horizontal Down (winter) IV2 in — — 0.87 — 1.15 Horizontal Down (winter) 4 in — — 0.81 — 1.23 Horizontal Down (winter) 8 in — — 0.80 — 1.25 Horizontal Down (summer) 3/4 in — — 1.18 — 0.85 Horizontal Down (summer) IV2 in — — 1.07 — 0.93 Horizontal Down (summer) 4 in — — 1.01 — 0.99 Sloping, 45° Up (winter) 3/t-4 in — — 1.11 — 0.90 Sloping, 45° Down (summer) 3/t-4 in — — 1.12 — 0.89 Vertical Horizontal (winter) 3/t-4 in — — 1.03 — 0.97 Vertical Horizontal (summer) 3/t-4 in — — 1.16 — 0.86
 Table 3-1 Conductivities (k), Conductances (Q, and Resistances (R) of

 Various Building and Insulating Materials

Air

Surfaces Still air

15 mph

Wind

7V2 mph

Wind

Building

Board

Boards,

Panels,

Sheathing,

Etc.

Position

Horizontal

Up sloping (45°)

Vertical

Sloping (45°)

Horizontal

Any position—any

Direction (for winter)

Any position—any

Direction (for summer)

Gypsum or plaster board

Gypsum or plaster board

Plywood

Plywood

Plywood

Plywood

Plywood or wood panels

TOC o "1-5" h z 1.63 — 0.61

1.60

 Heat Flow Up — Up — Horizontal — Down — Down —

— 0.62

1.46 — 0.68

1.32 — 0.76

1.08 — 0.92

6. — 0.17

4. — 0.25

3.10 — 0.32

2.25 — 0.45

1.25 —

3.20 — 0.31

2.12 — 0.47

1.60 — 0.63

1.7 — 0.94

(continued)

Table 3-1 (continued)

 Description Conductivity or Conductance Resistance (R) Material Density (lb per ft[1]) 00 (C) Per Inch Thickness l/k For Thickness Listed l/C Wood-fiber board, 26 0.42 — 2.38 — Laminated 31 0.50 — 2.00 — Or homogenous Wood fiber—hardboard 65 1.40 — 0.72 — Type Wood fiber—hardboard Vi in 65 — 5.60 — 0.18 Type Wood—fir or pine 25/32 in — — 1.02 — 0.98 Sheathing Wood—fir or pine L5/s in — — 0.49 — 2.03 Building Vapor—permeable — — 16.70 — 0.06 Paper Felt Vapor—seal, 2 — — 8.35 — 0.12 Layers of mopped 15-lb Felt Vapor—seal, — — — — Negl Plastic film Flooring Asphalt tile Vs in 120 — 24.80 — 0.04 Materials

Insulating

Materials

Blankets and batts

Carpet and fibrous pad Carpet and rubber pad Ceramic tile Cork tile Cork tile Felt, flooring Floor tile or linoleum—av.

Value Linoleum Plywood subfloor Rubber or plastic tile Terrazzo Wood subfloor Wood, hardwood finish

Cotton fiber

Mineral wool, fibrous form, processed from rock, slag, or glass Wood fiber

Wood fiber, multilayer, stitched expanding

TOC o "1-5" h z 1 in — —

25 0.45

Vs in ———————-

Vs in — 20.00

Vs in 80 —

5/s in————————

Vs in 110———-

1 in — —

25/32 in———- —————-

3/4 in———— —————-

0.8-2.0 0.26

1.5- 4.0 0.27

TOC o "1-5" h z 0.48 — 2.08

0.81 — 1.23

12.50 — 0.08

2.22 —

3.60 — 0.28

16.70 — 0.06

0.05

12.0 — 0.08

1.28 — 0.78

42.40 — 0.02

12.50 — 0.98

1.02 — 0.98

1.47 — 0.68

3.85 —

3.70 —

 3.2-3.6 0.25 1.5-2.0 0.27

 4.00 — 3.70 —

(continued)

Table 3-1 (continued)

 Description Conductivity or Conductance Resistance (R) Material Density (lb per ft3) 00 (C) Per Inch Thickness l/k For Thickness Listed IIC Board Glass fiber Wood or cane fiber Acoustical tile V2 in Acoustical tile Interior finish (plank, tile, lath) 3/4 in 15.0 9.5 0.84 0.35 0.25 0.56 1.19 2.86 4.00 1.78 Interior finish (plank, tile, lath) Roof deck slab V2 in 15.0 0.70 1.43 Approx IV2 in — 0.24 — 4.17 — Approx. 2 in — — 0.18 — 5.56 Approx. Sheathing (impreg. or coated) 3 in 20.0 0.38 0.12 2.63 8.33 Sheathing (impreg. or coated) V2 in 20.0 — 0.76 — 1.32 Sheathing (impreg. or coated) 25/32 in 20.0 — 0.49 — 2.06

Cellular glass

 Board and slabs

Hog hair (with asphalt binder)

Plastic (foamed)

Wood shredded (cemented in preformed slabs)

 Loose fill

Macerated paper or pulp products Mineral wood (glass, slag, or rock)

 Roof Insulation

Sawdust or shavings Vermiculite (expanded) Wood fiber: redwood, hemlock, or fir All types

 V2 in 1 in IV2 in

Preformed, for use above deck Approx.

Approx.

Approx.

W

On

6.5- 8.0

8.5

1.62

22.0

2.5- 3.5

2.0- 5.0

8.0- 15.0

7.0

2.0- 3.5

TOC o "1-5" h z 0.27 —

0.33 —

0.29 —

0.55 —

0.28 —

0.30 —

0.45 —

0.48 —

0.30 —

3.70 —

3.0 —

3.45 —

1. 82 —

3.57 —

3.33 —

2.22 —

2.8 —

3.33 —

 0.72 0.36 0.24

 1.39 2.78 4.17 (continued)

 Description Conductivity or Conductance Resistance (R) Material Density (lb per ft3) 00 (c) Per Inch Thickness l/k For Thickness Listed IIC Approx. 2 in 0.19 — 5.26 Approx. 2V2 in 0.15 — 6.67 Approx. 3 in 0.12 — 8.33 Masonry Cement mortar 116 5.0 — 0.20 — Materials Concretes Gypsum-fiber concrete 51 1.66 — 0.60 — 87V2% gypsum, 12V2% wood chips Lightweight aggregates, 120 5.2 — 0.19 — Including expanded Shale, clay or slate; 100 3.6 — 0.28 — Expanded slags; Cinders; pumice; perlite; 80 2.5 — 0.4 — Vermiculite; Also cellular concretes 60 1.7 — 0.59 40 1.15 — 0.86 30 0.90 — 1.11
 W O>

Sand and gravel or stone aggregate (oven dried) Sand and gravel or stone aggregate (not dried) Stucco

Masonry Brick, common Units

Brick, face Clay tile, hollow:

 1 cell deep 1 cell deep 2 cells deep 2 cells deep 2 cells deep 3 cells deep

 3 in 4 in 6 in 8 in 10 in 12 in

 4 in 8 in 12 in 3 in 4 in 8 in

Concrete blocks, three oval core: Sand and gravel aggregate

Cinder aggregate

TOC o "1-5" h z 0.70 — 1.43

9.0

 20 140 140 116 120 130

— 0.11

12.0 — 0.08

5.0 — 0.20

5.0 0.20

9.0 0.11

 1.25 0.90 0.66 0.54 0.45 0.40

 0.80 1.11 1.52 1.85 2.22 2.50

 1.40 — 0.90 — 0.78 — 1.16 — 0.90 — 0.58 —

 0.71 1.11 1.28 0.86 1.11 1.72 (continued)

 Description Conductivity or Conductance Resistance (R) Material Density (lb per ft3) 00 (c) Per Inch For Thickness Thickness l/k Listed IIC Gypsum partition tile: 3 X 12 X 30-in solid — — 0.79 — 1.26 3 X 12 X 30-in 4-cell — — 0.74 — 1.35 3 X 12 X 30-in 3-cell — — 0.60 — 1.67 3 in — — 0.79 — 1.27 Lightweight aggregate 4 in — — 0.67 — 1.50 (expanded shale, clay, Slate, or slag; pumice) 8 in — — 0.50 — 2.00 12 in — — 0.44 — 2.27 Stone, lime, or sand __ 12.50 __ 0.08 — Plastering Cement plaster, sand 116 5.0 — 0.20 — Materials Aggregate Sand aggregate V2 in — 10.00 — 0.10

Sand aggregate Gypsum plaster Lightweight aggregate Lightweight aggregate Lightweight aggregate on metal lath Perlite aggregate Sand aggregate Sand aggregate Sand aggregate Sand aggregate on metal lath Sand aggregate on wood lath Vermiculate aggregate Asphalt roll roofing

 3/4 in L/l in Vs in 3/4 in V2 in Vs in 3/4 in

 Roofing

 3/s in Vi in

Asphalt shingles Built-up roofing Slate

Sheet metal Wood shingles

W

«O

45

45

2.13

TOC o "1-5" h z 45 1.5

105 5.6

105

105 —

45 1.7

70

70

70 3.12

2.67

0.47

0.67 0.18

11. 10 —

9.10

7.70

2.50

0.59

6.50

2.27

3.00

20.0 —

— Negl

1.6 —

0.32

0.39

0.09

0.11

0.13

0.40

0.15

0.44

0.33

0.05

0.94

(continued)

 Description Conductivity or Conductance Resistance (R) Density Per Inch For (lb per Thickness Thickness Material Ft3) 00 (c) L/k Listed IIC Siding Shingles Materials (On flat Surface) Wood, 16-in — — 1.15 — 0.87 7 V2-in exposure Wood, double, 16-in, — — 0.84 — 1.19 12-in exposure Wood, plus insulation 5/l6 in — — 0.71 — 1.40 Backer board Siding Asphalt roll siding — — 6.50 — 0.15 Asphalt insulating siding — — 0.69 — 1.45 (Vi-‘m bd.) Wood, drop, 1 X 8 in — — 1.27 — 0.79 Wood, bevel, Vi X 8 in, — — 1.23 — 0.81
 Lapped

Wood, bevel, 3/4 X 10 in, lapped

Wood, plywood,

3/s in, lapped Structural glass Woods Maple, oak, and similar hardwoods Fir, pine, and similar softwoods

Courtesy ASHRAE 1960 Guide

TOC o "1-5" h z 45 1.10

32 0.80

1.59 — 0.59

10.0 — 0.10

— 0.91 —

— 1.25 —

Table 3-2 Coefficients of Heat Transmission for Solid Masonry Walls

Resistances Used

Construction Resistance (R)

 None Plaster s/s-in on Plaster on Furring Metal Lath and 3A-in Plaster on Furring Gypsum Lath (3/a-in) and ‘A-in Plaster on Furring Insulation Board Lath (‘A-in) and ‘A-in Plaster on Furring Wood Lath and ‘A-in Plaster (Sand agg.) 0.40 Resistance (Sand °gg-) 0.11 (Lt. Wt. °gg-) 0.39 (Sand °gg-) 0.13 (Lt. Wt. No agg.) plas. 0.4 7 0.32 (Sand Lt. wt. °gg-) °gg-) 0.41 0.64 No (Sand plaster agg.) 1.43 /.52 Material R U U U U U U U U U U U A B C D E F G H 1 K
 Brick (face and common)

 (6 in) 0.61 0.68 0.64 0.54 0.39 0.34 0.36 0.35 0.33 0.26 0.25 0.35 1 (8 in) 1.24 0.48 0.45 0.41 0.31 0.28 0.3 0.29 0.27 0.22 0.22 0.29 2 (12 in) 2.04 0.35 0.33 0.3 0.25 0.23 0.24 0.23 0.22 0.19 0.19 0.23 3 (16 in) 2.84 0.27 0.26 0.25 0.21 0.19 0.2 0.2 0.19 0.16 0.16 0.2 4
 Brick (common only)

 (8 in) 1.6 0.41 0.39 0.35 0.28 0.26 0.27 0.26 0.25 0.21 0.2 0.26 5 (12 in) 2.4 0.31 0.3 0.27 0.23 0.21 0.22 0.22 0.21 0.18 0.17 0.22 6 (16 in) 3.2 0.25 0.24 0.23 0.19 0.18 0.19 0.18 0.18 0.16 0.15 0.18 7
 (continued)
 Exterior Construction Interior Finish No. None Plaster s/s-in on Plaster on Furring Metal Lath and 3A-in Plaster on Furring Gypsum Lath (3/a-in) and ‘A-in Plaster on Furring Insulation Board Lath (‘A-in) and ‘A-in Plaster on Furring Wood Lath and ‘A-in Plaster (Sand agg.) 0.40 Resistance (Sand °gg-) 0.11 (Lt. Wt. °gg-) 0.39 (Sand °gg-) 0.13 (Lt. Wt. No agg.) plas. 0.4 7 0.32 (Sand Lt. wt. °gg-) °gg-) 0.41 0.64 No (Sand plaster agg.) 1.43 /.52 Material R U U U U U U U U U U U A B C D E F G H 1 K
 Stone (lime and sand)

 (8 in) 0.64 0.67 0.63 0.53 0.39 0.34 0.36 0.35 0.32 0.26 0.25 0.35 8 (12 in) 0.96 0.55 0.52 0.45 0.34 0.31 0.32 0.31 0.29 0.24 0.23 0.31 9 (16 in) 1.28 0.47 0.45 0.4 0.31 0.28 0.29 0.28 0.27 0.22 0.22 0.29 10 (24 in) 1.92 0.36 0.35 0.32 0.26 0.24 0.25 0.24 0.23 0.19 0.19 0.24 11
 Hollow clay tile

 (8 in) 1.85 0.36 0.36 0.32 0.26 0.24 0.25 0.25 0.23 0.2 0.19 0.25 12 (10 in) 2.22 0.33 0.31 0.29 0.24 0.22 0.23 0.22 0.21 0.18 0.18 0.23 13 (12 in) 2.5 0.3 0.29 0.27 0.22 0.21 0.22 0.21 0.2 0.17 0.17 0.21 14
 ■u ■b.

 Poured concrete 30 lb/ft3 (4 in) 4.44 0.19 0.19 0.18 0.16 (6 in) 6.66 0.13 0.13 0.13 0.12 (Sin) 8.88 0.10 0.10 0.10 0.09 (10 in) 11.10 0.08 0.08 0.08 0.08 80 lb/ft3 (6 in) 2.40 0.31 0.30 0.27 0.23 (8 in) 3.20 0.25 0.24 0.23 0.19 (10 in) 4.00 0.21 0.20 0.19 0.17 (12 in) 4.80 0.18 0.17 0.17 0.15 140 lb/ft3 (6 in) 0.48 0.75 0.69 0.58 0.41 (8 in) 0.64 0.67 0.68 0.53 0.39 (10 in) 0.80 0.61 0.57 0.49 0.36 (12 in) 0.96 0.55 0.52 0.45 0.34
 Courtesy ASHRAE 1960 Guide

 Vn

 0.15 0.15 0.15 0.11 0.11 0.11 0.09 0.09 0.09 0.07 0.08 0.08
 0.21 0.22 0.22 0.18 0.19 0.18 0.16 0.16 0.16 0.14 0.14 0.14
 0.36 0.38 0.37 0.34 0.36 0.35 0.32 0.34 0.33 0.31 0.32 0.31
 0.14 0.13 0.13 0.11 0.1 0.1 0.09 0.08 0.08 0.07 0.07 0.07
 0.21 0.18 0.17 0.18 0.16 0.15 0.15 0.14 0.14 0.14 0.12 0.12
 0.34 0.27 0.26 0.32 0.26 0.25 0.31 0.25 0.24 0.29 0.24 0.23

TOC o "1-5" h z 0.15 15

0.11 16

0.09 17

0. 08 18

0. 22 19

0. 18 20

0. 16 21

0. 14 22

0. 37 23

0. 35 24

0. 33 25

0. 31 26

Remember, this is the thermal resistance for a 1-in-thick face brick. Because the masonry wall in Table 3-2 contains a 4-in thickness of face brick, you will have to multiply the R-value (0.11) of the 1-in-thick face brick by 4 (4 in) to obtain the R-value (0.44) for the larger (4-in) section.