7:23 X Science Connec... ting gh Example: low The walls in your home have 25 mm of expanded ter polystyrene and 25 mm of rigid urethane foam. What is the R-value of your insulation? . Check the R-value of 25 mm of expanded tal polystyrene. . Check the R-value of 25 mm of rigid urethane foam. The total R-value of these two materials would be: 3.96 + 7.50 = R 11.46. Table 6.2 R-values of Common Building Materials Thickness of Insulating Material Approximate R-value 25 mm of air space in a wall cavity 2.04 25 mm of air space with reflective surface 5.54 on inside of wall cavity 25 mm of expanded polystyrene 3.96 25 mm of rigid urethane foam 7.50 25 mm of fibreglass 4.25 25 mm of solid wood 1.25 25 mm of wood shavings 2.42 25 mm of clay brick 0.11 25 mm of concrete 0.19 one thickness of glass 1.00 thermal glass (2 thicknesses with air space) 1.80 Controlling Heat Transfer . MHR 111 SKILLCHECK Initiating and Planning * Performing and Recording Analyzing and Interpreting * Communication and Teamworke 14: Module 2 5 Assignment Booklet 2B 16. Calculate the R-val -values for the following combinations of insulati . Shy the table of R-values on page 111 of the textbook.) e a. 25 mm of rigid urethane foam plus 12.5 mm of solid wood plus 100 mm of fibreglass b. 50 mm of rigid urethane foam plus 200 mm of concrete