Vapour Diffusion Resistance Coefficient
In cold to moderate climates, where the indoor temperature is warmer than the exterior temperature, there is a vapour pressure difference that goes inside to outside through the wall. As the vapour goes through the wall, there is a certain amount of resistance applied to its passage. This is defined as the Vapour Diffusion Resistance Coefficient. This coefficient needs to be considered when determining both wall and plaster materials. Just as the water absorption rate must be considered for obvious reasons, the ease or difficulty of water passage carries equal or more importance. Although the coefficients given in this research are only relative to each other and no "good" or "bad" value is specified, this information is to inform the user, to allow them to see how their choice of material compares to others. Each material has its own individual value, and can be altered by adding other various materials to it.
 

 

Vapour Diffusion Resistance Coefficient
In cold to moderate climates, where theindoor temperature is warmer than the exterior temperature, there is a vapour pressure difference that goes inside to outside through the wall. As the vapour goes through the wall, there is a certain amount of resistance applied to its passage. This is defined as the VapourDiffusion Resistance Coefficient. This coefficient needs to be consideredwhen determining both wall and plaster materials. Just as the water absorption rate must be considered for obvious reasons, the ease or difficulty of water passage carries equal or more importance. Although the coefficients given in this research are only relative to each other and no "good" or "bad" value is specified, this information is to inform the user, to allow them to see how their choice of material compares to others. Each material has its own individual value, and can be altered by adding other various materials to it.
Material m
Clayey Loam 7.1
Sandy Loam 7.5
Silty Loam 6.04
Loam w/expanded clay 8.01
Clayey Loam Plaster 7.95
Silty Loam Plaster 9.83
Cowdung-Loam-Sand-Lime Plaster 9.9
High Hydraulic Lime Plaster 10.6
Lime Plaster 11.1
Lime Casein Plaster 13.1
Lime Linseed Oil 16.25

Water Absorption Coefficient

Materials, such as earth blocks, are porous in nature. This means that they are able toabsorb and transport water throughout the structure. "Capillarity" is the term used forthis ability to absorb water, and "Capillary Action" is used for the ability to transportwater. Humidity is moisture in the air which can beabsorbed into and conducted through thesestructures. As air conditions change, porous materials are able to absorb moisture from theair if the climate is to humid or desorb moistureinto the air if humidity levels are to low. It is this exact characteristic that can also be damaging to a structure. If large quantities of water are absorbed to fast,and are unable to be transported adequately through capillary action, the results could be damaging for the entire structure. In cold to moderate climates, in certain seasons there are drastic changes in temperature from the exterior to the interior. If the conditions are right the dew point temperature will be met.The dew point temperature is the point at whichthe temperature must be cooled to becomesaturated. It is at this point that condensationoccurs. If this moisture is allowed to stay in thewall for to long of time, both the effects oferosion and of the freeze thaw cycle could be extremely damaging to the wall.The water absorption coefficient gives a good indication of the amount of water that can beby a certain material. The speed of the absorption also indicates the capillarity abilitiesof that material.
Material t (h)
1 4 9 16 25
Silty Loam 2.5 3.5 4.165 4.25 4.3
Sandy Loam 3.75 3.25 2.83 3 2.6
Clayey Loam + Sand 2 1.625 1.67 1.75 1.5
Clayey Loam 2 2 2 2 2.2
Clayey Loam + 2% Cement 27 16.25 11 8.25 6.6
Clayey Loam + 4% Cement 15 13.5 10.66 8 6.4
Clayey Loam + 8% Cement 7.5 7.5 6.66 6.8 6.2
Silty Loam
Absorption Coefficient w = W / t^. 5
(kg/m^2*h^. 5)
t (h) W w
1 2.5 2.5
4 7 3.5
9 12.5 4.167
16 17 4.25
25 21.5 4.3
Amount of Water
absorbed over a W = w * t^. 5
certain amount of time (kg/m^2)
t (h) w W
0 0 0
0.5 1.98 1.4
1 2.5 2.5
2 2.92 4.13
3 3.27 5.664
4 3.5 7
5 3.69 8.251
6 3.84 9.406
7 3.96 10.48
8 4.07 11.51
9 4.165 12.5
10 4.195 13.27
11 4.21 13.96
12 4.22 14.62
13 4.23 15.25
14 4.238 15.86
15 4.245 16.44
16 4.25 17
17 4.254 17.54
18 4.258 18.07
19 4.263 18.58
20 4.27 19.1
21 4.275 19.59
22 4.281 20.08
23 4.286 20.55
24 4.292 21.03
25 4.3 21.5
Sandy Loam
Absorption Coefficient w = W / t^. 5
(kg/m^2*h^. 5)
t (h) W w
1 2.5 3.75
4 6.5 3.25
9 8.5 2.833
16 12 3
25 13 2.6
Amount of Water
absorbed over a W = w * t^. 5
certain amount of time (kg/m^2)
t (h) w W
0 0 0
0.5 2.93 2.072
1 3.75 3.75
2 3.59 5.077
3 3.44 5.958
4 3.25 6.5
5 3.11 6.954
6 3.02 7.397
7 2.94 7.779
8 2.88 8.146
9 2.83 8.49
10 2.81 8.886
11 2.84 9.419
12 2.87 9.942
13 2.91 10.49
14 2.95 11.04
15 2.98 11.54
16 3 12
17 3.05 12.58
18 3.01 12.77
19 2.96 12.9
20 2.89 12.92
21 2.82 12.92
22 2.75 12.9
23 2.69 12.9
24 2.64 12.93
25 2.6 13
Clayey Loam + Sand
Absorption Coefficient w = W / t^. 5
(kg/m^2*h^. 5)
t (h) W w
1 2 3.75
4 3.25 1.625
9 5 1.667
16 7 1.75
25 7.5 1.5
Amount of Water
absorbed over a W = w * t^. 5
certain amount of time (kg/m^2)
t (h) w W
0 0 0
0.5 1.67 1.181
1 2 2
2 1.95 2.758
3 1.76 3.048
4 1.625 3.25
5 1.59 3.555
6 1.61 3.944
7 1.63 4.313
8 1.65 4.667
9 1.67 5.01
10 1.685 5.328
11 1.7 5.638
12 1.71 5.924
13 1.72 6.202
14 1.73 6.473
15 1.74 6.739
16 1.75 7
17 1.76 7.257
18 1.74 7.382
19 1.71 7.454
20 1.67 7.468
21 1.63 7.47
22 1.59 7.458
23 1.56 7.481
24 1.53 7.495
25 1.5 7.5
Clayey Loam
Absorption Coefficient w = W / t^. 5
(kg/m^2*h^. 5)
t (h) W w
1 2 2
4 4 2
9 6 2
16 8 2
25 11 2.2
Amount of Water
absorbed over a W = w * t^. 5
certain amount of time (kg/m^2)
t (h) w W
0 0 0
0.5 2 1.414
1 2 2
2 2 2.828
3 2 3.464
4 2 4
5 2 4.472
6 2 4.899
7 2 5.292
8 2 5.657
9 2 6
10 2 6.325
11 2 6.633
12 2 6.928
13 2 7.211
14 2 7.483
15 2 7.746
16 2 8
17 2 8.246
18 2.03 8.613
19 2.05 8.936
20 2.08 9.302
21 2.1 9.623
22 2.12 9.944
23 2.15 10.31
24 2.17 10.63
25 2.2 11
Clayey Loam + 2% Cement
Absorption Coefficient w = W / t^. 5
(kg/m^2*h^. 5)
t (h) W w
1 27 27
4 32.5 16.25
9 33 11
16 33 8.25
25 33 6.6
Amount of Water
absorbed over a W = w * t^. 5
certain amount of time (kg/m^2)
t (h) w W
0 0 0
0.5 19.5 13.79
1 27 27
2 20.92 29.59
3 17.52 30.35
4 16.25 32.5
5 14.58 32.6
6 13.35 32.7
7 12.4 32.81
8 11.66 32.98
9 11 33
10 10.43 32.98
11 9.95 33
12 9.52 32.98
13 9.15 32.99
14 8.82 33
15 8.51 32.96
16 8.25 33
17 8 32.98
18 7.78 33.01
19 7.57 33
20 7.37 32.96
21 7.18 32.9
22 7.03 32.97
23 6.87 32.95
24 6.73 32.97
25 6.66 33.3
Clayey Loam + 4% Cement
Absorption Coefficient w = W / t^. 5
(kg/m^2*h^. 5)
t (h) W w
1 15 15
4 27 13.5
9 32 10.67
16 32 8
25 32 6.4
Amount of Water
absorbed over a W = w * t^. 5
certain amount of time (kg/m^2)
t (h) w W
0 0 0
0.5 10.13 7.163
1 15 15
2 14.54 20.56
3 14.02 24.28
4 13.51 27.02
5 12.71 28.42
6 12.23 29.96
7 11.57 30.61
8 11 31.11
9 10.67 32.01
10 10.11 31.97
11 9.64 31.97
12 9.22 31.94
13 8.86 31.95
14 8.54 31.95
15 8.254 31.97
16 8 32
17 7.76 32
18 7.54 31.99
19 7.34 31.99
20 7.15 31.98
21 6.98 31.99
22 6.82 31.99
23 6.67 31.99
24 6.53 31.99
25 6.4 32
Clayey Loam + 8% Cement
Absorption Coefficient w = W / t^. 5
(kg/m^2*h^. 5)
t (h) W w
1 7.5 7.5
4 15 7.5
9 20 6.667
16 27 6.75
25 31 6.2
Amount of Water
absorbed over a W = w * t^. 5
certain amount of time (kg/m^2)
t (h) w W
0 0 0
0.5 5.78 4.087
1 7.5 7.5
2 7.5 10.61
3 7.5 12.99
4 7.5 15
5 7.26 16.23
6 7.02 17.2
7 6.88 18.2
8 6.73 19.04
9 6.66 19.98
10 6.67 21.09
11 6.69 22.19
12 6.7 23.21
13 6.71 24.19
14 6.73 25.18
15 6.74 26.1
16 6.75 27
17 6.68 27.54
18 6.51 27.62
19 6.44 28.07
20 6.38 28.53
21 6.33 29.01
22 6.29 29.5
23 6.26 30.02
24 6.23 30.52
25 6.2 31