Masonry Magazine June 2010 Page. 22
FLASHING & DRAINAGE
brane is synthetic. Some newer flashings, both copper and synthetics, allow for the use of urethane or silicone sealants, making installation much faster and cleaner.
The corners of a wall or end dams at windows often are problem spots where moisture gets behind the flashing, either for lack of a good lap seam, or lack of one at all. The process of cutting, folding and seaming rolled flashings to form corners again correlates directly to the workmanship of the person installing it. Most flashing manufacturers offer premade corners or end dams in compatible materials to help alleviate this problem.
Flashing installations differ from type of material and backup wall condition. A copper flashing laid into the bed joint of a CMU backup wall is ideal, as its termination in the wall holds it in place and makes moisture finding its way behind the flashing from the top impossible. This type of installation never should be performed with a synthetic flashing without checking with the manufacturer, however, since the acids in mortar mixes actually may start to break the membrane down in the joint. Synthetic membranes should always be vertically terminated with a stainless-steel or plastic bar, and then the added steps of cutting the flashing flush with the top edge of the bar and sealing it with a compatible sealant or mastic. It's a good idea to seal off the fasteners used with the bar as well, as they have a direct route to the backside of the flashing. The flashing height should be consistent with the anticipated height of excess mortar collecting on top of it. Rule of thumb
BUILDING A CENTURY OF TRUST.
Indiana Limestone Company continues to earn the trust of a generation of Masons and Mason Contractors by delivering the highest quality building stone at the industry's most competitive prices.
Indiana University Bloomington
Multidisciplinary Science Building-2
INDIANA LIMESTONE COMPANY
We're ready to bid your next project. Call (800) 457-4026 or visit Indiana LimestoneCompany.com