Ever wondered this about weather barriers?

The Technical Services team at Carlisle Coatings & Waterproofing answers hundreds of questions each month from architects, contractors and other design professionals. Most of the questions are project specific and the team prides itself on providing custom support solutions. At the end of the day, however, common questions about weather barriers are certain to pop up.

Over the next several posts, we’ll cover those weather barrier questions that come up most, like this one:

Q: When using a rubberized asphalt based air barrier (fluid applied or peel and stick) on a window frame, can I use a silicone sealant?

A:  Silicone sealant may be used to seal the window frame perimeter and can be applied over the facer of the rubberized asphalt membranes in most cases.  It’s best to confirm sealant compatibility with both the air barrier and sealant manufacturer prior to installation to ensure proper adhesion and compatibility.  Most manufactures publish approved sealant lists that have been tested to ensure long-term performance.  

However, it is important to understand that the plasticizer in silicone sealants have a tendency to break down the rubberized asphalt in the self-adhering membranes.  This can cause the rubberized asphalt to soften and the oils to leech out.  The result is an ugly stain on your newly installed sealant and potential adhesion issues.