I'm going to be installing nailing fin vinyl windows using a new construction application in a stucco wall. I'd like to install them properly with gasketed and caulked casing bead around the edges to account for the different coefficients of expansion for the stucco and vinyl windows and prevent cracking.

I can get plastic casing bead, but noticed that for a negligibly greater amount of money, I could get painted galvalume metal J-channel and drip caps intended for roofing. Examples:

http://www.homedepot.com/p/Metal-Sales-Drip-Cap-in-White-4204430/204256751 http://www.homedepot.com/p/Metal-Sales-J-Channel-Flashing-in-White-4227430/204256712

I quite like this option since the metal is bound to hold up better than plastic. I can also get them in non-white colors which could create a nice contrast between the white window and the white stucco.

Is there any reason why this wouldn't work?

2 Answers 2


Galvalume is a trade name and is not the same material as galvanized steel. Englert, a major roofing manufacturer has a good technical description that specifically cautions against placing Galvalume in contact with mortar.

Believe it or not, the entire construction is not comprised of imbeciles, and building codes actually provide sound guidance in regard to what works.

  • Thanks, that is super helpful! Guess I won't be using that material for my casing beads. Not sure where I implied here that contractors were imbeciles or that building codes were worthless. Though I can't seem to find anything at all about casing beads--let alone appropriate materials for them--in publicecodes.cyberregs.com/icod/irc/2012
    – iLikeDirt
    Sep 4, 2014 at 3:16
  • @iLikeDirt In the IRC 2006, Section R703.6 Exterior Plaster covers the requirements. ASTM C 926 and ASTM C 1063 are incorporated by reference and cover all the material requirements. Should you purchase and read them? Probably not. It is usually more productive to purchase products intended for exterior plaster installation. On the other hand, it makes a great deal of sense to own a hardcopy of the applicable building code, and to proceed as if the problem when you can't find something is you don't know where to look, not that anything goes.
    – user23752
    Sep 4, 2014 at 4:13
  • You're right. I'll gladly eat a little crow...
    – iLikeDirt
    Sep 4, 2014 at 14:56

Stucco is common where I live now (southern california) and typically new build windows have a integrated J channel built into the frame. I have never see any casings used between the window and stucco.

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