Thru-wall Flashing

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Author Message Brett M. Wilbur Senior Member Username: brett Post Number: 16 Registered: 12-2004 Posted on Wednesday, January 26, 2005 - 12:52 pm:    Can someone help me with the proper definition of "through-wall flashing"? (or sp. thru-wall). Our office standard details use the term thru-wall flashing with no description or clarification of the type. We specify copper laminated or bonded type, i.e. asphalt, fabric, or Kraft paper as our typical thru-wall flashing material, but we also have a flashing which is a PVC membrane. Then we have self-adhering membrane flashing as an alternative to copper. We are not supposed to tell the contractor about means and methods, but with all these options, how do we know for what we are paying? How do we know what is actually being installed? Is the right product being used in the right application? I guess the real question here is whether the specs need to be more specific about indicating locations and applications for each of the membrane types, or should we be more specific on the drawings, or should we leave it the installer to know the difference? Ralph Liebing Senior Member Username: rliebing Post Number: 135 Registered: 02-2003 Posted on Wednesday, January 26, 2005 - 01:08 pm:    My take: Through-wall flashing "goes through the whole of the width of the wall"; example, flashing under the cut stone coping which goes across the entire wall width and is turned down to drip on both faces of the wall. This is opposed to "in-wall" flashing which is that flashing like the sill flashing under a brick veneer which is then turned up into the cavity space and nailed off onto the sheathing/building paper. Locations should be specifically called out on the drawing, not in the specs, and least of all should not be left open-ended for the Contractor to make assumptions [one way or another, incluing leaving it out altogehter]. George A. Everding, AIA, CCS, CSI Senior Member Username: geverding Post Number: 18 Registered: 11-2004 Posted on Wednesday, January 26, 2005 - 03:12 pm:    Other terms to consider using: “embedded flashing” or “concealed flashing”; both used in MasterSpec, along with "through-wall". If you own MasterSpec, the evaluations contain a good overview of various types and installation methods. Also, BIA Tech Notes contain explanations, definitions, and details. www.bia.org Start with #7 and #7A. Doug Frank FCSI CCS Senior Member Username: doug_frank_ccs Post Number: 94 Registered: 06-2002 Posted on Wednesday, January 26, 2005 - 03:46 pm:    According to MasterFormat 04, the work result of this type is to be spec’d in Section 04 05 19.16 “Masonry Embedded Flashing”. I usually include it in the masonry spec section itself rather than create a separate section.. As to material, I’ve struggled long and hard with that issue and attempting to justify my decisions with accepted knowledge of other industry organizations. Most significantly, BIA strongly recommends that flashings extended beyond the face of the wall and are bent down to form a drip. You can’t do that with flexible membranes. To solve that problem we’ve gone to a prefab 2” wide stainless steel strip by DurOWall and others at the face of the wall and then a peel and stick membrane up the inside face of the cavity. Laminated copper would seem a good choice of flashing membrane but you can’t get sealant to stick to the asphalt/kraft surface. Peel and stick membranes offer a good solution in some instances but they must be somehow supported across an open cavity. I happen to have been visited by the “York” folks yesterday and they have an interesting new product called “Flash Vent”. It’s copper with a drainage material laminated to the top side only. The copper can be extended beyond the face of wall and bent down, sealant will stick to the bare copper, it can span open cavities, and copper has a proven record of performance in place. I may consider this material as my new standard. Steven Hauk Advanced Member Username: sh1net Post Number: 5 Registered: 12-2004 Posted on Wednesday, January 26, 2005 - 07:39 pm:    It won't matter what the "proper" definition of thru-wall flashing is if you do two things correctly...(1) draw clearly what you want and clearly label it "thru-wall flashing" and (2) define the term "thru-wall flashing" in your spec as one particular material. The specified material can be sheet metal, laminated copper, a product with a metal drip, whatever. But there should be one and only one clear definition of each term used on the drawings. If you have three different kinds of thru-wall flashing, you need a thru-wall flashing schedule or you need to call them out as Type 1, Type 2, etc. or you need a more specific term. By closely coordinating the term you use on the drawings with the term you use in the spec's you could call the thru-wall flashing literally anything you want. It's defined accurately in the spec's and its extent is show in the drawings. David R. Combs, CSI, CCS, CCCA Senior Member Username: davidcombs Post Number: 19 Registered: 08-2004 Posted on Thursday, January 27, 2005 - 09:18 am:    Brett, You forgot "how do we check the Submittals?" and "how do we enforce the provisions of the Contract Documents during CA?" and "how do we certify the Pay App if we are unsure of what the Contractor installed is correct?" (if the Pay App is certified, there's an implication that what the Contractor installed was correct. If it's not correct, is the Architect prepared to withhold payment on such vague and flimsy grounds? Holy Rock-and-a-Hard-Place, Batman!!) And RE: "Is the right product being used in the right application?" To which I would respectfuly submit - What product is being used for which application is the Architect's decisions and responsibility, not the Contractor's. I concur with the posting above. Use the same terminology on the Drawings as is being used in the specifications. The Specifications should not list applications / locations, but only define the quality of the material and installation. If there are three products listed in the specification under the heading "Through-Wall Flashing," then the implication is that the Contractor has the choice of using whichever product he wants (regardless of the quality, appropriateness for a particular application, or design intent). I would suggest altering the terminology of the heading, or at least adding or providing a distinctly different heading (coordinated with the terminology used on the Drawings) for each flashing material, i.e. Through-Wall Flashing, Embedded Flashing, Membrane Flashing, or other disriminating terminology. Then under each of those headings, list the appropriate product that is desired (laminated copper, PVC, self-adhering, etc.) for that application. I would also like to stress that this is NOT a "Means and Methods" issue. This is a design issue, and needs to be given the full repsect and due diligence of the design team, and be completely and correctly addressed in the Documents. The potential liabilities of a moisture-related wall failure are too great for a design team to shirk its responsibilities and pass it off as a "Contractor's problem." Robert W. Johnson Senior Member Username: bob_johnson Post Number: 6 Registered: 08-2004 Posted on Thursday, January 27, 2005 - 12:15 pm:    This thread is a great illustration of why we as an industry need to work on coming to a much better concensus on the use of terminology. I also did some research on trying to use good terminology in this subject area quite a few years ago. Unfortunately, there is not much concensus among related industry associations for terminology for flashing - flashing is used in many situations such as masonry, exterior wall, waterproofing, roofing, etc. - there has not been any concensus terminology to help differentiate the different types by the use of consistent terminology - very frustrating! You will note in MasterFormat 2004 a movement in that area by a more concerted effort towards recommended terminology; at least at the specification section title level. In the case of this subject, MasterFormat subjects do not go very deep, but you will find Masonry Embedded Flashing at 04 05 19.16 for masonry flashing and Flexible Flashing at 07 65 00 for flexible flashings for roof and wall construction. So MF 2004 is recommending Embedded Flashing as the general term for masonry flashing. MF 2004 does not deal with the further classification of the types of Masonry Embedded Flashing. I have found it helpful to use the term Through-Wall Flashing to differentiate the flashing that goes through the masonry from face to face such as under copings because I usually have different specification requirements for this type of embedded flashing versus embedded flashing at other locations. CSI has made a decision to try to do something about achieving more terminology consistency by authorizing a task force which to my knowledge has not been appointed yet. I invite you to contact CSI Board Members and the CSI Technical Committee to encourage them to proceed in that effort! Anonymous   Posted on Wednesday, February 16, 2005 - 04:43 pm:    We used the York type laminated copper flashing in a brick-and-block project recently. The CMU went up first, to receive the bar joists and roof deck. When the brick veneer work finally started, the copper flashing had been flapping in the wind for so long that it was almost all torn off the wall. Needless to say, that's not an easy problem to fix.