Masonry Magazine July 1975 Page. 15
NCMA-TEK
An Information series from National Concrete Masonry Association
Tables of U-values
For Concrete Masonry Walls
Introduction
This TEK presents a tabulation of calculated U-values for concrete masonry walls as affected by various details of construction. It is intended as a guide for estimating U-values where more specific information is not available.
Resistance values used in determining the U-values are shown in Tables 1 and 2. Review of recent thermal transmittance test results for concrete masonry walls suggests that the R-values in Table 1 are ultra conservative in many respects. It is anticipated that these values will be modified upon completion of the necessary research and testing.
Table 2. R VALUES USED FOR COMPILING TABLES:*
| Insulation: | MATERIAL | R-VALUE |
| ----------- | ----------- | ----------- |
| 1" | Rigid Glass Fiber | 4.00 |
| 1" | Polystyrene | 5.00 |
| 1" | Polyurethane | 6.25 |
| 2" | Rigid Glass Fiber | 8.00 |
| 2" | Polystyrene | 10.00 |
| 2" | Polyurethane | 12.50 |
| 2"-24" | Blanket | 7,00 |
| 3"-3%" | Blanket | 11.00 |
| Loose Fill in Cavity Walls: | | |
| 2" | Cavity | 4.00 |
| 4" | Cavity | 8.00 |
| | Gypsum Wallboard, " | 0.45 |
| | 4" Masonry Units for exterior wythe of Composite & Cavity Walls | 0.44 |
| Surface Conductance: | | |
| | Outside (15 mph wind) | 0.17 |
| | Inside | 0.68 |
| Air Space Conductance: | | |
| | "-4" | 0.97 |
| | Same with bright foil lining, one side | 3.08 |
*Based on values published in the 1972 edition of the ASHRAE Guide. Some agencies accept different R-values which result in lower U-values.
Table 1. Resistance Values for Concrete Block and Loose Fill
R VALUES FOR HOLLOW CONCRETE BLOCK WITH HOLLOW CELLS EMPTY AND FILLED WITH LOOSE FILL INSULATION*
| Unit Thickness | Insulation In Cells | Density of Concrete in Block, Ib./cu. ft. | | | | |
| ----------- | ----------- | ----------- | ----------- | ----------- | ----------- | ----------- |
| | | 60 | 80 | 100 | 120 | 140 |
| 4" | Empty | 2.07 | 1.68 | 1.40 | 1.17 | 0.77 |
| | Filled | 5.59 | 4.59 | 3.72 | 2.95 | 1.59 |
| 6" | Empty | 2.25 | 1.83 | 1.53 | 1.29 | 0.86 |
| | Filled | 7,46 | 6.06 | 4.85 | 3,79 | 1.98 |
| 8" | Empty | 2.30 | 2.12 | 1.75 | 1.46 | 0.98 |
| | Filled | 9.35 | 7.46 | 5.92 | 4.59 | 2.35 |
| 10" | Empty | 3.00 | 2.40 | 1.97 | 1.63 | 1.08 |
| | Filled | 10.98 | 8.70 | 6.80 | 5.18 | 2.59 |
| 12" | Empty | 3.29 | 2.62 | 2.14 | 1.81 | 1.16 |
*From NCMA TEK 38, Thermal Insulation of Concrete Masonry Walls, 1972,