Wallmate CW Boards contain a flame retardant additive to inhibit accidental ignition from a small fire source. The boards are, however, combustible and, if exposed to an intense fire, may burn rapidly. All fire classifications given in Dow literature on Wallmate CW insulation boards are based on small scale tests and may not reflect the reaction of the material under actual fire conditions.
Additional useful information on aspects of fire performance of extruded polystyrene in building applications is listed in BS 6203: 1989; Fire Characteristics and Fire Performance of Expanded Polystyrene Materials used in Building Applications.
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Four standard thicknesses of Wallmate CW insulation boards are available. Used in a typical cavity wall with outer leaf of brickwork and inner leaf of medium density blockwork ( 1500 kg/m3) the U-values in Table 1 below can be achieved.
Physical Characteristics of Wallmate CW
The properties and characteristics of Wallmate CW boards meet all the requirements of BS 3837 Part 2: 1990 Grade E 1.
Table 2 below gives typical values: more detailed test results are available from Dow on request.
Wallmate CW boards melt at 120°C: the maximum recommended continuous operating temperature is 75°C.
|Board thickness (mm)||U-Value (W/m2 K)|
|Board size||-||mm||1200 x 450|
|Thicknesses||-||mm||25, 30, 40, 50|
|Tolerances Length |
|+ 6 |
|Thermal conductivity* |
(at 10°C. 90 days)
|BS 3837 Part 2: 1990 |
|Compressive strength^||BS 4370 Method 3||kN/m²||200|
|Water absorption||BS 3837 Part 2: 1990 |
|Water vapour permeability||BS 3837 Part 2: 1990 |
|Water vapour resistivity||BS 3837 Appendix C||MNs/gm||625|
*Measured at 10°C. 90 days, maximum value.
^At yield or 10% deflection (whichever comes first) minimum value.