RussFast HR Underlay is a heavy-duty underlay which is suitable for both warm and cold roof constructions and is used in conjunction with high and low level ventilation. Manufactured using high-quality material, the underlay offers high performance in all UK locations, providing resistance against wind uplift on the roof and acting as a reliable secondary barrier against wind-driven rain and snow.
Roll Size: 45m x 1m
Certification
Resistance to wind pressure – 1732Pa, tested to BS5534.
Fully independently certified by BM Trada.
UKCA marked.
Key features
• Can be used in all UK locations (zones 1-5)
• Excellent nail tear strength
• Fully watertight and airtight
• Absorbent undersurface prevents condensation drop off
• Easy to cut and lightweight for handling
• No tapes required
| Technical Information | ||
|---|---|---|
| Weight | 145 (-5) gsm | |
| Resistance to water penetration Before artificial ageing: After artificial ageing: | Class W1 Class W1 | |
| Maximum tensile strength | MD 265 (-15)N/50mm 260 (-15)N/50mm | CD 250 (-25)N/50mm 215 (-25)N/50mm |
| Elongation: Before artificial ageing: After artificial ageing: | 80 (+5)% 60 (-0)% | 100 (+0)% 70 (-0)% |
| Tear Resistance (nail shank) | 180 (-30)N | 200 (-25)N |
| Flexibility at Low Temperature | -40°C | |
| Reaction to Fire | (NPD) | |
