Research has shown that the majority of frame damage occurs through wicking of moisture through the exposed bottom of mulls and frames.  The innovative Mull Boot from Endura prevents moisture damage from wicking in a simple, cost-effective manner.  With Mull Boots in place, mulls are sealed off and raised out of the danger zone, preventing water from traveling up the end of the wood.

An unprotected mullion when exposed to water will cause mold to form and rot to appear. 
Water wicks up the end grain causing moisture damage and a leaking door unit.