WinterGuard™ waterproofing shingle underlayment is the solution for winning the battle against water penetration in your roof's most vulnerable places. WinterGuard™ is a composite material of asphalt polymers, formed into a rolled sheet. The asphalt makes it vapor-tight, and the polymers make the asphalt elastic and sticky. This protective barrier is able to stretch and seal around nails driven through it. Placing WinterGuard™ a minimum of 24" past the interior wall line at the eave provides your first line of defense. WinterGuard™ Sand Finish.