Summary Report from Task 3 of MEWS Project at the Institute for Research in Construction Hygrothermal Properties of Several Building Materials

Transcription

1 Summary Report from Task 3 of MEWS Project at the Institute for Research in Construction Hygrothermal Properties of Several Building Materials Kumaran, K.; Lackey, J.; Normandin, N.; van Reenen, D.; Tariku, F. IRC-RR-110 March

2 SUMMARY REPORT FROM TASK 3 OF MEWS PROJECT AT THE INSTITUTE FOR RESEARCH IN CONSTRUCTION Kumar Kumaran John Lackey Nicole Normandin David van Reenen Fitsum Tariku March 2002 Reference: Kumaran, M.K., Lackey, J., Normandin, N., van Reenen, D., and Tariku, F., (2002) "Summary Report from Task 3 of MEWS Project" Institute for Research in Construction, National Research Council, Ottawa, Canada, (NRCC-45369), pp

3 MEWS PROJECT REPORT T3-23: March 2002 SUMMARY REPORT FROM TASK 3 OF MEWS PROJECT AT THE INSTITUTE FOR RESEARCH IN CONSTRUCTION IRC Research Team Peter Beaulieu Mark Bomberg Steve Cornick Alan Dalgliesh Guylaine Desmarais Reda Djebbar Kumar Kumaran Michael Lacasse John Lackey Wahid Maref Phalguni Mukhopadhyaya Mostafa Nofal Nicole Normandin Mike Nicholls Tim O Connor David Quirt Madeleine Rousseau Nady Said Mike Swinton Fitsum Tariku David van Reenen MEWS Steering Committee David Ritter, Louisiana Pacific Corporation Fred Baker, Fortifiber Corporation Michael Bryner, EI DuPont de Nemours & Co Gilles Landry, Fiberboard Manufacturers Association of Canada Stephane Baffier, CPIA Paul Morris, Forintek Canada Corporation Greg McManus, Marriott International Inc. Stephan Klamke, EIMA Eric Jones, Canadian Wood Council Gary Sturgeon, Masonry Canada Sylvio Plescia, CMHC Fadi Nabhan, IRC, NRC Canada David Quirt, IRC, NRC Canada Kumar Kumaran, IRC NRC Canada Michael Lacasse, IRC NRC Canada

4 Executive Summary This report summarizes the findings of MEWS Task Group 3 on the Properties of the following building materials. 1. Oriented Strand Board 2. Plywood 3. Brick 4. Mortar 5. Stucco 6. Wood fibreboard 7. Composite wood siding 8. Water resistive barrier 9. Exterior grade gypsum board 10. EIFS base and finish coats and 11. Spray polyurethane foam The properties that have been experimentally determined include: 1. Thermal conductivity of the dry material as a function of temperature 2. Water vapour permeability/permeance as a function of relative humidity 3. Equilibrium moisture content as a function of relative humidity/suction 4. Moisture diffusivity as function of moisture content 5. Water absorption coefficient 6. Air permeability/permeance For the first eight materials, several products were tested to establish the range of properties shown by each material available in North American market. The main purpose of this investigation was to provide representative material properties as inputs for IRC s hygrothermal model hygirc.

5 Summary Report from Task 3 of MEWS i Table of Contents 1 Introduction Experimental Procedures References Example Applications of Various Methods to determine the Hygrothermal Properties of Aerated Concrete Representative Hygrothermal Properties of Plywood and OSB Products in North America Air Permeances and Water Vapour Permeances of Nine Types of Water Resistive Barriers Hygrothermal Properties of Six Bricks Hygrothermal Properties of Mortar Mixes Used in North America Hygrothermal Properties of Three Types of Stuccos Used in North America Hygrothermal Properties of Eight Fiberboard Sheathing Products Hygrothermal Properties of Five Siding Products Hygrothermal Properties of EIFS Base Coat + Finish Coat Hygrothermal Properties of Exterior Grade Gypsum Board Water Vapour Permeability of a Spray Polyurethane Foam Insulation Product...68

6 Summary Report from Task 3 of MEWS 1 1 Introduction The Task Group 3 in MEWS project at the Institute for Research in Construction was struck to systematically determine the hygrothermal properties of building products that are currently used in North America. The main objective was to determine the range of each property for each set of products and provide that information as input to the computer model hygirc, for parametric analyses. At the first meeting on May , the task group decided to concentrate on materials out board of the studs starting with sheathing. As a result the following products were included in the investigation. Product Name Number of Products Comments OSB 6 The bulk densities were in the range 575 to 725 kg m -3 and varied from 10 to 11.5 mm. The strands included aspen, poplar, birch as well as southern yellow pine. Plywood 6 The bulk densities were in the range 400 to 600 kg m -3 and the thickness from 9.5 to 13 mm. The products were certified as conforming to Canadian plywood manufacturing standards CSA O151 Canadian Softwood Plywood (CSP), or CSA O121 Douglas Fir Plywood (DFP). These standards permit a variety of wood species to be used in veneer plies, except that Douglas Fir is required for the outer plies of CSA O121 DFP. Fibreboard 8 Two of the products investigated were natural fiberboard (no coating or facer) and four were coated with a thin layer of black material on both major surfaces. One product had a paper facer on one major surface while another one had an aluminum foil facer. The nominal thickness of the products varied between 11 mm and 13 mm. The densities varied between 235 kg m -3 and 330 kg m -3. Composite Wood Siding Water Resistive Barrier 5 The substrates of three of the products were compressed fiberboard, the fourth one OSB and the fifth one plywood. All had vinyl coatings on one major surface. The thickness of the products varied between 10.5 mm and 15.1 mm. The densities varied between 580 kg m -3 and 930 kg m The products included paper based (rated 10 min or 30 min or 60 and # 15) and polymer based (spun-bonded polyolifine, poly-acetate and polyethylene.

7 Summary Report from Task 3 of MEWS 2 Brick 6 Clay brick, cement brick and calcium silicate brick are included. Mortar 4 Portland Cement-Lime Mortar and Masonry Cement Mortar types N and S are included. Stucco 3 Regular Lime Stucco, Regular Portland Stucco and Acrylic Stucco. EIFS 1 Polymer cement as the base coat and Latex Acrylic with Integral Colour and Texture as the finish coat. Sprayed Polyurethane Foam Exterior Grade Gypsum 1 As applied on a 4' x 4' plywood substrate at a nominal thickness of 2.25", in three passes of the spray. 1 Fibrous facers on either major surface. Vinyl Siding 1 Strips are impenetrable to air and moisture. For the parametric analyses hygirc needs information on the following properties. 1. Thermal conductivity of the dry material as a function of temperature 2. Thermal conductivity as a function of moisture content 3. Water vapour permeability/permeance as a function of relative humidity 4. Equilibrium moisture content as a function of relative humidity 5. Moisture diffusivity as function of moisture content 6. Water absorption coefficient 7. Heat capacity of dry material (constant) 8. Heat capacity as a function of moisture content 9. Air permeability/permeance 1.1 Experimental Procedures Well-developed experimental procedures or international standard test procedures exist to determine the properties listed above, except for the thermal conductivity and the heat capacity of moist materials. In the latter cases combining rules [1] are used to estimate the properties from that for the dry material and water. The principles of the experimental procedures that are used to determine the hygrothermal properties of building materials in the present investigation are given below. Thermal Conductivity of Dry Materials The heat conduction equation is directly used to determine the thermal conductivity of dry materials. Equipment that can maintain a known unidirectional steady state heat flux (under known constant boundary temperatures)

8 Summary Report from Task 3 of MEWS 3 across a flat slab of known thickness is used for the measurements. The most commonly used equipment is the guarded hot plate apparatus or the heat flow meter apparatus. ASTM Standards C 177, Standard Test Method for Steady-State Heat flux Measurements and Thermal Transmission Properties by Means of the Guarded-Hot-Plate Apparatus and C518, Standard Test Method for Steady-State Heat flux Measurements and Thermal Transmission Properties by Means of the Heat Flow Meter Apparatus are widely used for this purpose. The latter is used in the present investigation. Similar standards are available from the International Standards Organization and the European Union. In the ASTM Standards, the heat conduction equation is written for practical applications as: λ = Q l/(a T) (1) Where, Q = Heat flow rate across an area A l = Thickness of test specimen T = Hot surface temperature Cold surface temperature The thermal conductivity calculated according to (1) is called apparent thermal conductivity. It is a function of the average temperature of the test specimen. Water Vapour Permeability/Permeance The vapour diffusion equation is directly used to determine the water vapour permeability of building materials [2]. The measurements are usually done under isothermal conditions. A test specimen of known area and thickness separates two environments that differ in relative humidity (rh). Then the rate of vapour flow across the specimen, under steady-state conditions (known rh s as constant boundary conditions), is gravimetrically determined. From these data the water vapour permeability of the material is calculated as: δ p = J v l/(a p) (2) Where, J v = Water vapour flow rate across an area A l = Thickness of the specimen p = Difference in water vapour pressure across the specimen surfaces Often, especially for membranes and composite materials, one calculates the water vapour permeance, δ l, of a product at a given thickness from the above measurements as: δ l = J v /(A p) (3) ASTM Standard E96, Test Methods for Water Vapour Transmission of Materials, prescribes two specific cases of this procedure- a dry cup method that gives the permeance or permeability at a mean rh of 25 % and a wet cup

9 Summary Report from Task 3 of MEWS 4 method that gives the permeance or permeability at a mean rh of 75 %. A new CEN Standard 89 N 336 E is being developed in the European Union based on ISO standard. More recently a number of technical papers that deal with various technical aspects, limitations and analyses of the experimental data of these procedures have appeared in the literature [3-5]. For many hygroscopic materials, such as wood and wood products, the water vapour permeability/permeance is a strong function of the local relative humidity and increases with rh. The ASTM Standard E 96 is being revised to address this behaviour of building materials more quantitatively. For practical building applications, in addition to the traditional dry and wet cup conditions, it is desirable to determine the permeance or permeability of hygroscopic materials at a mean rh of 85 %. This can be done using the wet cup method of E96, but the rh in the humidity chamber shall be maintained at 70 %. Sorption/Desorption Isotherm For sorption measurements, the test specimen is dried at an appropriate drying temperature to constant mass. While maintaining a constant temperature, the dried specimen is placed consecutively in a series of test environments, with relative humidity increasing in stages, until equilibrium is reached in each environment. Equilibrium in each environment is confirmed by periodically weighing the specimen until constant mass is reached. From the measured mass changes, the equilibrium moisture content at each test condition can be calculated and the adsorption isotherm drawn. The starting point for the desorption measurements is from an equilibrium condition very near 100% RH. While maintaining a constant temperature, the specimen is placed consecutively in a series of test environments, with relative humidity decreasing in stages, until equilibrium is reached in each environment. Equilibrium in each environment is confirmed by periodically weighing the specimen until constant mass is reached. Finally, the specimen is dried at the appropriate temperature to constant mass. From the measured mass changes, the equilibrium moisture content at each test condition can be calculated and the desorption isotherm drawn. A new CEN standard 89 N 337 E is under development for the determination of Hygroscopic Sorption Curve. ASTM C16 Committee also is developing a standard. Suction Isotherm: The test specimens are saturated with water under vacuum. Those are then introduced in a pressure plate apparatus that can maintain pressures up to 100 bar for several days. The plates in perfect hygric contact with the specimens extract water out of the pore structure until an equilibrium state is established. The equilibrium values for moisture contents in the specimens and the corresponding pressures (measured as the excess over atmospheric pressure; the negative of this value is referred to as the pore pressure while the absolute value is the suction) are recorded. The equilibrium pressure, p h, can be converted to a relative humidity, ϕ, using the following equation:

10 Summary Report from Task 3 of MEWS 5 M lnϕ = p h (4) ρrt Where, M = the molar mass of water R = the ideal gas constant T = the thermodynamic temperature and ρ = the density of water A Nordtest Technical Report [6] briefly describes a procedure for pressure plate measurements and reports the results from an interlaboratory comparison. No standard procedure is yet developed for the determination of suction isotherm. Also, the suitability of the pressure plate method and equation (4) for determining the equilibrium moisture content of wood above 95% relative humidity has not been independently verified. Moisture Diffusivity: Moisture diffusivity, D w, defines the rate of movement of water, J l, within a material, induced by a water concentration gradient according to the following equation: J l = - ρ 0 D w grad u (5) Where, ρ 0 = density of the dry material u = moisture content expressed as mass of water / dry mass of material In the experimental procedure, liquid water in contact with one surface of a test specimen is allowed to diffuse into the specimen. The distribution of moisture within the specimen is determined as a function of time at various intervals until the moving moisture front advances to half of the specimen. Gamma spectroscopy is used as the experimental technique. The data are analyzed using the Boltzmann transformation [7,8 ] to derive the moisture diffusivity as a function of moisture content. There is no standard test procedure for the determination of moisture diffusivity. There are many publications in the literature that describe the technical and experimental details [9-12].

11 Summary Report from Task 3 of MEWS 6 Water Absorption Coefficient: One major surface of each test specimen is placed in contact with liquid water. The increase in mass as a result of moisture absorption is recorded as a function of time. Usually, during the initial part of the absorption process a plot of the mass increase against the square root of time is linear. The slope of the line divided by the area of the surface in contact with water is the water absorption coefficient 1. A new CEN Standard 89 N 370 E on the determination of water absorption coefficient is under development. Air Permeability/ Permeance: Test specimens with known areas and thickness are positioned to separate two regions that differ in air pressure and the airflow rate at a steady state and the pressure differential across the specimen are recorded. From these data the air permeability, k a is calculated as: k a = J a l/(a p) (6) Where, J a = Air flow rate across an area A l = Thickness of the specimen p = Difference in air pressure across the specimen surfaces Often, especially for membranes and composite materials, one calculates the air permeance, K a, of a product at a given thickness from the above measurements as: K a = J a /(A p) (7) ASTM Standard C 522, Standard Test Method for Airflow Resistance of Acoustical Materials prescribes a method based on this principle. Bomberg and Kumaran[13] have extended the method for general application to building materials. 1 When this method was applied to membranes, the membranes were put is perfect hygric contact with a substrate such as OSB.

12 Summary Report from Task 3 of MEWS References 1. Li, C. C., "Thermal Conductivity of Liquid Mixtures," AIChE Journal, Vol. 22, No. 5, pp , Joy, F. A. and Wilson, A. G., Standardization of the Dish Method for Measuring Water Vapour Transmission, Proceedings of the International Symposium on Humidity and Moisture, Washington, D. C., Vol. 4, Chapter 31, 1963, pp Hedenblad, G., Moisture Permeability of Some Porous Building Materials, Proceedings of the 4th Symposium, Building Physics in the Nordic Countries, Espoo,Volume 2, 1996, Hansen, K. K. and Lund, H. B., Cup Method for Determination of Water Vapour Transmission Properties of Building Materials. Sources of Uncertainty in the Method, Proceedings of the 2nd Symposium, Building Physics in the Nordic Countries, Trondheim, 1990, pp Lackey, J. C., Marchand, R. G., and Kumaran, M. K., A Logical Extension of the ASTM Standard E96 to Determine the Dependence of Water Vapour Transmission on Relative Humidity, Insulation Materials: Testing And Applications: Third Volume, ASTM STP 1320, R. S. Graves and R. R. Zarr, Eds, American Society for Testing and Materials, West Conshohocken, PA, 1997, pp Also Kumaran, M. K., An Alternative Procedure for the Analysis of Data from the Cup Method Measurements for Determination of Water Vapour Transmission Properties, Journal of Testing and Evaluation, JTVEA, Vol. 26, pp , Hansen, M. H., "Retention Curves Measured Using Pressure Plate and Pressure Membrane," Nordtest Technical Report 367, Danish Building Research Institute, 1998, p Bruce, R. R. and Klute, A, "The Measurement of Soil Diffusivity," Soil Science Society of America Proceedings. Vol. 20, pp , Kumaran, M.K., Mitalas, G.P., Kohonen, R., Ojanen, T, "Moisture transport coefficient of pine from gamma ray absorption measurements," Collected Papers in Heat Transfer, 1989 : Winter Annual Meeting of the ASME (San Francisco, CA, USA, 1989) pp , 1989(ASME Heat Transfer Division vol. 123). 9. Marchand, R.G. and Kumaran, M. K., "Moisture diffusivity of cellulose insulation," Journal of Thermal Insulation and Building Envelopes, Vol. 17, pp , Kumaran, M.K. and Bomberg, M.T., "A Gamma-spectrometer for determination of density distribution and moisture distribution in building materials," Moisture and Humidity: Measurement and Control in Science and Industry : Proceedings of International Symposium (Washington, D.C., USA, 1985), pp , 1985.

13 Summary Report from Task 3 of MEWS Filip Descamps., "Continuum and Discrete Modelling of Isothermal Water and Air Transfer in Porous Media," Ph. D. Thesis, Katholieke Uniersity, Belgium, pp , Pel, L., "Moisture Transport in Porous Building Materials," Ph. D. Thesis, Eindhoven University of Technology, the Netherlands, pp , Bomberg, M. T.and Kumaran, M.K., " A Test method to determine air flow resistance of exterior membranes and sheathings," Journal of Thermal Insulation, Vol.9, pp ,1986.

14 Summary Report from Task 3 of MEWS 9 2 Examples of Applications of Various Methods to determine the Hygrothermal Properties of Aerated Concrete The test conditions reported in this section for different test methods are generally followed throughout the project. Also, the procedures used in this section for data reduction and analyses are followed for all materials in this report. The test specimens used for various measurements reported here are taken from one block of aerated concrete, approximately 1 X 1 x 1.5 in size. Density: (460 ± 15) kg m -3 Heat Capacity (According to International Energy Agency Annex 24 Report 2 ): 840 J K -1 kg -1 Thermal Conductivity: Measurements are according to ASTM Standard C518; 30 cm X 30 cm specimens are used in these measurements. The temperatures of the plates are maintained within 0.02 C for these measurements, during a steady state for 12 h. Table 2.1: Thermal Conductivity of Aerated Concrete. Specimen Thickness mm Hot Plate Temperature C Cold Plate Temperature C Conductivity W m -1 K Note: The heat flow meter apparatus is built to measure the heat transmission characteristics of insulating materials and for those materials the measurement uncertainties are within 2 %; aerated concrete is more conductive than traditional insulation and the large heat fluxes measured may give measurement uncertainties as high as 5 %. 2 M K Kumaran, Final Report, Volume 3, Material Properties, International Energy Agency Annex 24 Report, Published by K. U. Leuven Belgium, 1996

15 Summary Report from Task 3 of MEWS 10 Sorption Desorption Measurements 3 : Up to eight specimens, 41 mm X 41 mm X 6 mm each are used in these measurements; the numbers in parentheses indicate the experimental uncertainties. Sorption: Table 2.2: Sorption data for Aerated Concrete. RH, % Temperature, C Moisture Content, kg kg , total saturation Lab at 22 (1) 1.72 (0.01), eight specimens 100, capillary saturation Lab at 22 (1) 0.83 (0.02), six specimens 88.1 (1) 23.0 (0.1) (0.002), three specimens 71.5 (1) 23.0 (0.1) (0.001), three specimens 50.6 (1) 23.0 (0.1) (0.001), three specimens Desorption: Table 2.3. Desorption data for Aerated Concrete. RH, % Temperature, C Moisture Content, kg kg (0.01) Lab at 22 (1) 0.92 (0.12), eight specimens (0.01) Lab at 22 (1) 0.81 (0.08), eight specimens (0.01) Lab at 22 (1) 0.77 (0.07), eight specimens (0.01) Lab at 22 (1) 0.75 (0.06), eight specimens (0.01) Lab at 22 (1) 0.72 (0.05), eight specimens (0.01) Lab at 22 (1) 0.70 (0.05), eight specimens 99.71(0.01) Lab at 22 (1) 0.68 (0.04), eight specimens (0.01) Lab at 22 (1) 0.66 (0.04), eight specimens 99.47(0.01) Lab at 22 (1) 0.64 (0.04), eight specimens (0.01) Lab at 22 (1) 0.55 (0.02), six specimens (0.01) Lab at 22 (1) 0.34 (0.05), six specimens 88.1 (1) 23.0 (0.1) (0.001), three specimens 71.5 (1) 23.0 (0.1) (0.001), three specimens 50.6 (1) 23.0 (0.1) (0.001), three specimens 3 In the hygroscopic range, the measurements are done using the proposed procedure for ASTM Standard C1498, which in turn is based on CEN 89 N 337 E, Hygroscopic Sorption Curve ; at the higher range the pressure plate method is used. Details of the pressure plate method are given by: Hansen, M. H., "Retention Curves Measured Using Pressure Plate and Pressure Membrane," Nordtest Technical Report 367, Danish Building Research Institute, 1998, p 63.

16 Summary Report from Task 3 of MEWS 11 Water Vapour Transmission (WVT) Rate measurements 4 : For each test condition, 3 circular specimens, each 15 cm in diameter, are used. Table 2.4. Dry Cup Measurements on Aerated Concrete Specimens: The numbers in parentheses indicate the experimental uncertainties Specimen Thickness Chamber RH Chamber Temperature WVT Rate mm % C kg m -2 s (1) 23.0 (0.1) 1.09E-06 (5.5E-09) (1) 23.0 (0.1) 1.14E-06 (5.6E-09) (1) 23.0 (0.1) 1.03E-06 (4.0E-09) (1) 23.0 (0.3) 1.69E-06 (6.0E-09) (1) 23.0 (0.3) 1.79E-06 (3.3E-09) (1) 23.0 (0.3) 1.63E-06 (5.3E-09) (1) 23.0 (0.3) 2.18E-06 (6.5E-09) (1) 23.0 (0.3) 2.30E-06 (4.4E-09) (1) 23.0 (0.3) 2.23E-06 (5.6E-09) Table 2.5. Wet Cup Measurements on Aerated Concrete Specimens: The numbers in parentheses indicate the experimental uncertainties Specimen Thickness Chamber RH Chamber Temperature WVT Rate mm % C kg m -2 s (1) 23.0 (0.3) 1.30E-06 (1.7E-08) (1) 23.0 (0.3) 1.40E-06 (1.4E-08) (1) 23.0 (0.3) 1.49E-06 (1.5E-08) (1) 23.0 (0.2) 1.13E-06 (1.5E-08) (1) 23.0 (0.2) 9.60E-07 (1.0E.08) (1) 23.0 (0.2) 9.69E-07 (1.0E.08) The average thickness of still air in the cups is 11 mm 4 Measurements are done as described by: Lackey, J. C., Marchand, R. G., and Kumaran, M. K., A Logical Extension of the ASTM Standard E96 to Determine the Dependence of Water Vapour Transmission on Relative Humidity, Insulation Materials: Testing And Applications: Third Volume, ASTM STP 1320, R. S. Graves and R. R. Zarr, Eds, American Society for Testing and Materials, West Conshohocken, PA, 1997, pp

17 Summary Report from Task 3 of MEWS 12 Derived Water Vapour Permeability 5 Table 2.6. The dependence of water vapour permeability of Aerated Concrete on relative humidity. RH, % Permeability kg m -1 s -1 Pa -1 RH, % Permeability kg m -1 s -1 Pa E E E E E E E E E E-11 The relation between WVT and Chamber RH is shown in Figure 2.1. Rank 1 Eqn 8002 [Exponential] y=a+bexp(-x/c) r 2 =0.993 DF Adj r 2 =0.992 FitStdErr=1.17e-07 Fstat= e-06 a=-7.41e-07 b=7.54e-07 c= e-06 W V T Rate, kg m -2 s e-06 2e e-06 1e-06 5e CHAMBER RH, % Figure 2.1. All data are interpreted as dry cup measurements; RH inside the cup is zero and chamber RH is the RH outside the cup. The numeric summary of the analyses is listed below. The commercial software package called TableCurve2 is used for the curve fit. The terminology below is from the package. 5 The analysis is done as described in : Kumaran, M. K., An Alternative Procedure for the Analysis of Data from the Cup Method Measurements for Determination of Water Vapour Transmission Properties, Journal of Testing and Evaluation, JTVEA, Vol. 26, pp , 1998.

18 Summary Report from Task 3 of MEWS 13 The equation that represents the relation between x = chamber RH and y = WVT rate is [Exponential] y= a + b exp(-x/c) r 2, Coefficient of Determination = Fit Std Error = 1.7E-07 F-value = 965 Parameter. Value Std Error t-value 90% Confidence Limits a -7.41e e e e-07 b 7.54e e e e-06 c From the above statistics, the estimated uncertainty in the derived value of the permeability may be up to 28 %. This type of uncertainty is quite common for building products that are not homogeneous.

19 Summary Report from Task 3 of MEWS 14 Water Absorption Coefficient 6 : Five test specimens, 5 cm X 5 cm X 5 cm each, were used in these measurements. Water is maintained at (22 ± 1) C. The numbers in parentheses give the standard deviations. Table 2.7. Water absorption data for Aerated Concrete. Square Root of time, s ½ Water Absorption kg m (0.13) (0.17) (0.21) (0.25) (0.29) (0.34) (0.37) (0.44) (0.47) (0.53) (0.56) (0.62) (0.69) Linear regression using all the data from the first linear part of the absorption process for the five specimens gives: Water Absorption Coefficient for the major surfaces = ± kg m -2 s -½. 6 The procedure used is based on: CEN/TC 89/WG 10 N95 Determination of water absorption coefficient,

20 Summary Report from Task 3 of MEWS 15 Moisture Diffusivity: Gamma ray method 7 is used to measure the distribution of moisture in three test specimens, 5 cm X 30 cm X 2.4 cm each, during the moisture uptake through the edge. The principle of the methodology is described by Kumaran et. al 8. Marchand and Kumaran 9 have reported the procedure used for the data reduction. The running average method that is described by Marchand and Kumaran gives the characteristic curve shown in Figure 2.2, for this aerated concrete. Several hundreds of data pairs obtained on the three test specimens, in 36 sets of measurements over a period of seven days are included in the analysis. 300 Running Avg. Moisture Content, kg m Running Avg. Boltzmann Variable, m s -½ Figure 2.2. The characteristic curve for aerated concrete resulted from moisture uptake and distribution measurements. 7 Kumaran, M.K. and Bomberg, M.T., "A Gamma-spectrometer for determination of density distribution and moisture distribution in building materials," Moisture and Humidity: Measurement and Control in Science and Industry : Proceedings of International Symposium (Washington, D.C., USA, 1985), pp , Kumaran, M.K., Mitalas, G.P., Kohonen, R., Ojanen, T, "Moisture transport coefficient of pine from gamma ray absorption measurements," Collected Papers in Heat Transfer, 1989 : Winter Annual Meeting of the ASME (San Francisco, CA, USA, 1989) pp , 1989(ASME Heat Transfer Division vol. 123). 9 Marchand, R.G. and Kumaran, M. K., "Moisture diffusivity of cellulose insulation," Journal of Thermal Insulation and Building Envelopes, Vol. 17, pp , 1994.

21 Summary Report from Task 3 of MEWS 16 The moisture diffusivity derived from the above characteristic curve is given in Table 2.8. Table 2.8. The dependence of moisture diffusivity of Aerated Concrete on moisture content. Moisture Content kg kg -1 Diffusivity m 2 s -1 Moisture Content kg kg -1 Diffusivity m 2 s E E E E E E E E E E E E E E E E E E E E E E-08 Note: The area enclosed by the characteristic curve in Figure 2.2 is ~ kg m -2 s -½ and this value is very close to the water absorption coefficient = kg m -2 s -½ that was directly determined. This should be the case and the correspondence between the two shows the internal consistency of the two methods. However, the uncertainty in the derived moisture diffusivity is estimated to be as high as 30 to 50 %.

22 Summary Report from Task 3 of MEWS 17 Air Permeability: Bomberg and Kumaran 10 have reported the principle of the method used in these measurements. Appendix XIII of the Client Report to ASHRAE, B A Thermal and Moisture Transport Property Database for Common Building and Insulating Materials 1018-RP dated 1 April 1999 reports the details. Three circular test specimens, each approximately 15 cm in diameter, are used in these measurements. The measurements are conducted at a temperature = (22 ± 1) C. The summary of the statistical analyses of all data obtained from two series of measurements on each specimen is shown in Figure 2.3 as three separate sets Flow, l m -2 s Pressure Difference (Pa) Data Points Upper Confidence Interval Mean Permeance Lower Confidence Interval Figure 2.3. The dependence of airflow rate on pressure difference for aerated concrete. For the range of pressure differences between 25 Pa and 700 Pa, the flow rate linearly varies with the pressure difference. The air permeability is (4.9 ± 2.6) E-09 kg m -1 Pa -1 s Bomberg, M. T. and Kumaran, M.K., " A Test method to determine air flow resistance of exterior membranes and sheathings," Journal of Thermal Insulation, Vol.9, pp ,1986.

23 Summary Report from Task 3 of MEWS 18 3 Representative Hygrothermal Properties of Plywood and OSB Products in North America Background: Ten plywood and seven OSB products were acquired for the investigation. These were either supplied by the partners or purchased in consultation with experts. As reported at the Task Group 3 meeting in September 1998, two series of screening tests were conducted on all: Water absorption rate through the major surfaces Water vapour permeability between 70 % and 100 % RH Based on the screening tests, and as agreed upon by the MEWS members, four plywood and four OSB products were chosen as follows: two to represent the extremes and two from the middle range. General Physical Properties: The bulk densities, ρ, of the plywood products were in the range 400 to 600 kg m -3 and that for OSB 575 to 725 kg m -3. The thickness for the former varied from 9.5 to 13 mm and for the latter from 10 to 11.5 mm. The heat capacity of both products, according to the IEA Annex 24 report is approximately 1880 J K -1 kg -1. Thermal conductivity of dry materials: The report T3-08 listed the results on the thermal conductivites of 12 test specimens each of plywood and OSB at two mean temperatures (nominal 0 and 24 C). The average temperature coefficient of thermal conductivity is 2.1 x 10-4 W m -1 K -2 for plywood and 2.0 x 10-4 for OSB. Figure 3.1 and Figure 3.2 show the dependence of thermal conductivity (W m -1 K -1 ), λ (nominal temperature 24 C), on bulk density, ρ, for plywood and OSB respectively. Linear relations may approximate the dependence: λ = a + b ρ For plywood, a = W m -1 K -1 and b = 1.67x10-4 (W m -1 K -1 )/ (kg m -3 ) and For OSB, a = W m -1 K -1 and b = 2.05x10-4 (W m -1 K -1 )/ (kg m -3 )

24 Summary Report from Task 3 of MEWS CONDUCTIVITY, W m -1 K DENSITY, kg m -3 Figure 3.1. Dependence of the thermal conductivity of plywood on density (at 24 C) 0.13 CONDUCIVITY, W m -1 K DENSITY, kg m -3 Figure 3.2. Dependence of the thermal conductivity of OSB on density (at 24 C)

25 Summary Report from Task 3 of MEWS 20 Water Vapour Permeability: follows: As presented in the report T3-05, the range of the water vapour permeabilities for the two products is as Table 3.1. Water Vapour Permeability of Plywood RH, % Permeability kg m -1 s -1 Pa -1 Lower Limit Upper Limit E E E E E E E E E E E E E E E E E E-11 Table 3.2. Water Vapour Permeability of OSB RH, % Permeability kg m -1 s -1 Pa -1 Lower Limit Upper Limit E E E E E E E E E E E E E E E E E E-12

26 Summary Report from Task 3 of MEWS 21 Moisture Diffusivity: From detailed measurements on spatial and temporal distribution of moisture in test specimens during a moisture uptake process across the edges, the following ranges are derived for the moisture diffusivity. Table 3.3. Moisture Diffusivity of Plywood Moisture Content Diffusivity (Lower) Diffusivity (Upper) Moisture Content Diffusivity (Lower) Diffusivity (Upper) kg m -3 m 2 s -1 m 2 s -1 kg m -3 m 2 s -1 m 2 s E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E-09

27 Summary Report from Task 3 of MEWS 22 Table 3.4. Moisture Diffusivity of OSB Moisture Content Diffusivity (Lower) Diffusivity (Upper) Moisture Content Diffusivity (Lower) Diffusivity (Upper) kg m -3 m 2 s -1 m 2 s -1 kg m -3 m 2 s -1 m 2 s E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E-10

28 Summary Report from Task 3 of MEWS 23 Water Absorption Coefficient: Table 3.5. Water Absorption Coeficient of Plywood and OSB Absorption Coefficient (Across the major surfaces) plywood kg m -2 s -½ OSB Average Standard deviation Air Permeance: Both products are very airtight materials. Measurements on three test specimens of each of the six products for either material gave the following results. Plywood: Air permeance varies between 1.3 x 10-4 and 1.0 x 10-2 litre (75 Pa) -1 m -2 s -1. OSB: Air permeance varies between 6.6 x 10-4 and 1.4 x 10-2 litre (75 Pa) -1 m -2 s -1. Results on individual products are listed below. Table 3.6. Air Permeance of Plywood and OSB Plywood OSB Product No. litre (75 Pa) -1 m -2 s -1 litre (75 Pa) -1 m -2 s -1 1 (2.1 ± 2.0) 10-3 (7.7 ± 3.9) (3.0 ± 3.6) 10-3 (6.6 ± 4.3) (1.6 ± 1.7) 10-3 (1.9 ± 1.8) (2.4 ± 0.2) 10-3 (1.4 ± 0.1) (1.0 ± 1.2) 10-2 (3.2 ± 2.4) (1.3 ± 0.8) 10-4 (1.2 ± 0.7) 10-2

29 Summary Report from Task 3 of MEWS 24 Sorption/ Desorption/ Suction Isotherms: Table 3.7 (a) Results from Sorption/Desorption Measurements on six OSB products RH, % Average Moisture Content, kg kg-1 Standard Deviation kg kg-1 48 (desorption) (sorption) (desorption) (sorption) (desorption) (sorption) (desorption) Table 3.8 (b) Results from Pressure Plate Measurements on six OSB products Suction Pa Average Moisture Content, kg kg-1 Standard Deviation kg kg-1 1 x x x x x x Table 3.9. (a) Results from Sorption/Desorption Measurements on six Plywood products RH, % Average Moisture Content, kg kg-1 Standard Deviation kg kg (sorption) (desorption) (sorption) (desorption) (sorption) (desorption)

30 Summary Report from Task 3 of MEWS 25 Table 3.8 (b) Results from Pressure Plate Measurements on six Plywood products Suction Pa Average Moisture Content, kg kg-1 Standard Deviation kg kg-1 1 x x x x Note that zero suction corresponds to vacuum saturation. Some of the specimens swelled by as much as 30 % by volume up on saturation.

31 Summary Report from Task 3 of MEWS 26 4 Air Permeances and Water Vapour Permeances of Nine Types of Water Resistive Barriers Background: The products investigated include paper based materials such as 10 minute, 30 minute, 60 minute and # 15 felt and several polymer based products such as spun bonded polyolifines, polyacetates and perforated polyethylene. For these products only the air permeances, water vapour transmission characteristics and water absorption coefficients are measured. Air Permeance: Table 4.1. Air permeances of various Water Resistive Barriers Material Thickness, mm Mass/area, g/m -2 Air permeance litre (75 Pa) -1 m -2 s -1 IA* ± 1 II ± 0.1 III ± 0.15 IVA* ± 0.09 VA* ± 0.02 VC* ± VI impermeable VII ± VIII ± 1.4 IX ± 0.31 *IB, IVB and VB shown in Table 4.2, Table 4.3 and Table 4.4 are from IRC data bank; the measurements were done in other projects. Water Absorption Coefficient: The water absorption coefficients of paper based products (10 min, 30 min and 60 min) are all between and kg m -2 s -½. Those of all polymeric products are below kg m -2 s -½.

32 Summary Report from Task 3 of MEWS 27 Water Vapour Permeance: Table 4.2. Water Vapour Permeances of Various Water Resistive Barriers (kg m -2 s -1 Pa -1 ) RH, % I I II III IV IV V V V VI VII VIII IX A B A B A B C E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E-09

33 Summary Report from Task 3 of MEWS Table 4.3. Water Vapour Permeances of Various Water Resistive Barriers (ng m s Pa ) RH, % I I II III IV IV V V V VI VII VIII IX A B A B A B C

34 Summary Report from Task 3 of MEWS 29 Table 4.4. Water Vapour Permeances of Various Water Resistive Barriers (perm) RH, % I I II III IV IV V V V VI VII VIII IX A B A B A B C

35 Summary Report from Task 3 of MEWS 30 5 Hygrothermal Properties of Six Bricks Background: As per the recommendation of Masonry Canada, three clay bricks, two concrete bricks and one calcium silicate brick were included in Task 3, for material characterization. Masonry Canada supplied all test samples. General Physical Properties: The bulk densities of the bricks ranged between 1750 and 2300 kg m -3. The heat capacity of brick, according to the IEA Annex 24 report is approximately 800 J K -1 kg -1. Thermal conductivity of dry materials: Thermal conductivities, as measured on one specimen of each brick at two mean temperatures are listed in Table 5.1. On the average, the temperature coefficient of thermal conductivity for the bricks is W m -1 K -2. Table 5.1. Thermal conductivities of the bricks at two mean temperatures Thickness Density T(mean) Thermal Conductivity Brick No. and Type mm kg m -3 C W m -1 K White Concrete Brick Red Matt Clay Brick Buff Matt Clay Brick Textured Coated Clay Brick Concrete Brick Calcium Silicate Brick

36 Summary Report from Task 3 of MEWS 31 Water Vapour Permeability: The water vapour permeabilities (kg m -1 s -1 Pa -1 ) of the six bricks are listed in Table 5.2 and plotted in Figure 5.1. Table 5.2. Water Vapour Permeabities of Brick RH, % 1. Concrete 2. Clay 3. Clay 4. Clay 5. Concrete 6. Cal Sil E E E E E E E E E E E E E E E E E E E E E E-12 2E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E-11 Vapour Permeability, kg m -1 s -1 Pa E E E E E E-11 Concrete Clay Clay Clay Concrete CalSil 1.0E E RH, % Figure 5.1. Water vapour permeabilities of six bricks.

37 Summary Report from Task 3 of MEWS 32 Water Absorption Coefficient: The water absorption coefficients of the six bricks are given in Table 5.3. Table 5.3: Water absorption coefficients for the six bricks. No Type Concrete Clay Clay Clay Concrete Cal.Sil. Absorption Coefficient kg m -2 s -½ Air Permeability: The measured air permeances for the bricks are found in Table 5.4. Table 5.4. Air Permeance of Brick Brick Type Specimen Thickness mm Air Permeance l m -2 s -1 (75 Pa) -1 Concrete X 10-3 Clay X 10-4 Clay X 10-3 Clay X 10-3 Concrete X 10-4 Calcium Silicate X 10-3 Sorption/ Desorption/ Suction Isotherms: The results from sorption/desorption/suction measurements on the six bricks are shown in Table 5.5. The equilibrium moisture content at each relative humidity is given as mass of moisture per unit mass of the dry material. The results are plotted in Figure 5.2.

38 Summary Report from Task 3 of MEWS 33 Table 5.5 Sorption/desorption/suction isotherms for the six bricks. Moisture content, kg kg -1 RH, % Suction Concrete Clay Clay Clay Concrete Cal Sil Pa x x (sorption) (desorption) (sorption) (desorption) (sorption) (desorption) MOISTURE CONTENT, kg kg Concrete Clay Clay Clay Concrete Cal Sil RH, % Figure 5.2. Sorption/desorption/suction isotherms for the six bricks; the suction data from the pressure plate measurements are converted to relative humidity according to equation (4) on page 5.

39 Summary Report from Task 3 of MEWS 34 Moisture Diffusivity: The moisture diffusivities of the six bricks are given in Table 5.6 and plotted in Figure 5.3. These values are those calculated using the water absorption coefficient and saturation moisture content for each product 11. Table 5.6. Moisture diffusivities (m 2 s -1 ) of the six bricks. Moisture Content Concrete Clay Clay Clay Concrete Cal Sil kg m E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E M. K. Kumaran. Moisture Diffusivity of Building Materials from Water Absorption Measurements. Journal of Thermal Envelope and Building Science, 22, p 349, 1999.

40 Summary Report from Task 3 of MEWS 35 MOISTURE CONTENT, kg m E E E-08 DIFFUSIVITY, m 2 s E E E E E E E E-16 Concrete Clay Clay Clay Concrete Cal Sil Figure 5.3. Moisture diffusivities of the six bricks.

41 Summary Report from Task 3 of MEWS 36 6 Hygrothermal Properties of Mortar Mixes Used in North America Background: Two types of mortar, Type N and Type S, are commonly used across North America for masonry veneer on wood frame construction. Each of these two mortar types has two "mix formulations": one includes Portland cement and lime and the other Masonry cement. So four mortar mixes are included in the testing programme for MEWS. These are listed in Table 6.1. Table 6.1: Mortar mixes used for the determination of hygrothermal properties. Mix Formulation Mortar Type Parts by Volume Portland Cement Hydrated Lime Aggregate Portland Cement- S (Coded 1-S) 1 ½ 3½ to 4½ Lime Mortar N (Coded 1-N) 1 1 4½ to 6 Masonry Cement Masonry Aggregate Type S Cement Type N Masonry Cement S (Coded 2-S) 1 0 2¼ to 3 Mortar N (Coded 2-N) 0 1 2¼ to 3 General Physical Properties: The bulk densities, ρ, of the mortar mixes were in the range 1500 to 1800 kg m -3. The heat capacity of mortar, according to the IEA Annex 24 report is approximately 900 J K -1 kg -1. Thermal conductivity of dry materials: Thermal conductivities, measured on two specimens of each mix at two mean temperatures are listed in Table 6.2.