Liquid Housewrap. StoGuard is a liquid coating that's applied with a sprayer directly onto wood or gypsum-based sheathing. The maker claims that the coating is compatible with all common types of siding and exterior finishes; that it qualifies as both an air and a moisture barrier; and that it won't rip or blow off. Installation costs range from $1 to $1.20 per square foot. Sto Corp., 800/221- 2397, stocorp.com
