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General => General Forum => Topic started by: dug on September 13, 2010, 10:23:58 AM

Title: Exterior window trim
Post by: dug on September 13, 2010, 10:23:58 AM
I would like to add some trim on the exterior side of my windows and need some advice on how to properly do it.

My windows are vinyl  and protrude about 1 and 1/8 inch from the outside sheathing, taped and flashed as normal. Should I just install the trim over the tape and call it good? I would think water could and would get behind the trim, especially on the top piece, and thought about putting some metal flashing over it but worry about making an incision in the paper and introducing an opportunity for water to find its way under the window flange. Also, I assume that I would caulk the edges?

The exterior siding will be stucco if that makes a difference.
Title: Re: Exterior window trim
Post by: astidham on September 13, 2010, 02:08:49 PM
I have the same question as dug, less the stucco.
Title: Re: Exterior window trim
Post by: PEG688 on September 14, 2010, 08:06:59 AM


I'll put something up tonight if no one chimes in.

Basically follow the Grace / Vycor booklet for wrapping a window, Mtn. Don has  a link to it some where here on the site. Maybe he'll bump that up for you.

  Wrap and tuck , lead the water to day light or at least on top of , not under your building wrap , what ever wrap you use ,  15 lbs Felt, Typar , Tyvek , etc.

  Same basic rules , stucco and drive-it can add a wrinkle or two to the process.

G/L PEG 
Title: Re: Exterior window trim
Post by: MountainDon on September 14, 2010, 10:30:55 AM
I have too many links, sometimes I can't find them myself.  ???   Here are some from Grace.....   lifted from another topic here..


This page... http://www.na.graceconstruction.com/template.cfm?page=/Window_and_Door_Flashings/dd_vycor.html&did=26 (http://www.na.graceconstruction.com/template.cfm?page=/Window_and_Door_Flashings/dd_vycor.html&did=26)   has links to documents on an assortment of methods for the window flashing; windows in before wrap, after wrap, severe weather conditions.....

This page...  http://www.na.graceconstruction.com/custom/flashings/downloads/26324_Guide-B.pdf (http://www.na.graceconstruction.com/custom/flashings/downloads/26324_Guide-B.pdf)  is a PDF with installation photos in color....

This page...  http://www.na.graceconstruction.com/product.cfm?mode=c&did=26&id=41#4361 (http://www.na.graceconstruction.com/product.cfm?mode=c&did=26&id=41#4361)   has some video links. Scroll down on the left sidebar. The last two items are videos, one is flashing before weather resistant barrier and the other flashing after.


I think the thing to remember with flashing is that it doesn't really matter much what the finish layer is. Stucco, whatever is mainly cosmetic, or should be looked at that way. What's underneath is where the real weather barrier is. Of course one does not want to apply the cosmetics in a manner than will lead to problems. A metal flashing over the top of any window or door can be a good idea, sometimes one that the inspector will insist upon. Caulk should also be looked upon as a cosmetic thing first and a barrier against water last, IMO, or caulk is insurance if you like to look at it that way.

Water always wins if given a path. Anyone who lives on sloped land can attest to that.
Title: Re: Exterior window trim
Post by: PEG688 on September 14, 2010, 08:53:59 PM


Those will work , nice job Mtn. D :)
Title: Re: Exterior window trim
Post by: dug on September 15, 2010, 01:26:43 PM
Thanks for posting the links Don, very helpful.   :)
Title: Re: Exterior window trim
Post by: Jeff922 on September 15, 2010, 01:33:40 PM
I wondered about this too Dug.  Here's what I came up with:  Although my vinyl windows have a "built in trim/J-channel", I really wanted some color and an architectual detail.  I made a rain cap at the top which protrudes beyond the vinyl window.  It slopes away from the wall and has a saw kerf drip edge on the bottom front edge.  I will probably also use some aluminum flashing on top of that tucked under the tyvek.  The bottom corners of the window have aluminum flashing tucked under the window's nail flange.  this flashing will go on top of a coarse of cedar shingles.  The tarpaper splines behind the trim will also serve to drain any water on top of a coarse of shingles.  There is peel & stick behind the splines also.  It's probably overkill, but I like at least two lines of defense.  I really hate the idea of relying solely on caulk.

(https://i833.photobucket.com/albums/zz254/Jeffie922/windowtrim001.jpg)


(https://i833.photobucket.com/albums/zz254/Jeffie922/windowtrim003.jpg)