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Fluid Applied Tyvek Saves A Botched Recessed Window Install

  I’m building a new house with Dick Clark Architects and it generally has pretty standard Tyvek weatherization details.  We’re using DuPont Tyvek Drainwrap along with DuPont FlexWrap for sills, and Straightflash for jambs/heads of windows, then blanketing the whole house with 3/4″ rigid foam.  The cladding is a mixture of Wood Siding, Hardie Siding, and Stucco.  (Side note, I’m a big fan of the Tyvek products, but you must use ALL their products together in a weatherization system.)
  The windows are a mix of Ram (Thermally Broken Commercial Aluminum), and Andersen 100 (high performance composite windows).  All the windows are installed in the standard nailing flange method, but I’ve got one window that has a funky recessed detail.  I didn’t talk to the framer about the install details for how to install that recessed window and here’s what the guys did…
That is what we call in our industry…”Ugly”.  The window itself was installed perfectly, but they didn’t layer the Tyvek correctly.  Recessed windows are difficult on the best day to flash correctly, so it’s my fault for not telling the guys to hold off on installing that window till I met them on the jobsite.


See how the outer opening was “X” cut and you can see OSB?  This install is further complicated by the fact that the outer portion of the recess isn’t parallel to the inner portion.  There’s about 2″ of recessed depth on the right side and 8″ of depth on the left side.


So, here’s what I did.  First, I called my DuPont rep Corey Ball and asked him to show me how the new “Liquid” Tyvek works.  Dupont calls it “Fluid Applied Tyvek“, but Liquid Tyvek sounds cooler to me.  He met me at the job site yesterday and we peeled back the outer layer.  As I mentioned the inner window was set correctly.  The guys used Flexwrap for the window sill, and the jamb/head was flashed over the nailing flange with DuPont Straightflash (both of these are approved substrates for Fluid Applied Tyvek to run on top)  We then used Flexwrap over the lower “sill” portion of the recessed window, followed by the jambs of the outer recess, then the head portion.

Here is the prepped opening prior to pulling out the cool new Fluid Applied Tyvek.  The DuPont products are meant to work with each other, but the FA is not intended to be brushed on top of Tyvek house wrap.  This FA Tyvek comes in three formulations with different viscosities.  The two we used on this recessed window were Flashing & Joint Compound (the really thick stuff), and Brush Formulation.

Here we started by caulking the seams with the thick version “Flashing and Joint Compound”.
Next we gunned on a zig zag bead of “Brush Formulation”.  This is less thick and looks kinda like a thin version of painters latex caulk.


The brush is a cheap disposable one that brushed it onto the OSB and about 1″ on top of the Flexwrap on the top & bottom.


Corey is adding a bit more of the Brush Formulation.

Doing the upside down head was the hardest part of the install.  You don’t want to goop this Liquid Applied Tyvek all over the window so we took our time and used the thicker Flashing & Joint compound on the head portion.
Here’s a close up of the finished head.

 And here’s the final window.  It’s now bulk water tight, air tight, and vapor permeable!  WOW, I really like this new Fluid Applied Tyvek.  That’s a tricky window detail and it took us less than 30 minutes to fully flash this window with a couple of “suits” doing the work.  This is a very cool new product.

Corey brought his sample wall with a full Fluid Applied Tyvek install.  I only did my recessed window with the Fluid Applied, but I’d really like to do a whole house with their system.  I also believe it will help me get an even better air tightness rating. BUILD TIGHT, VENTILATE RIGHT. (sorry couldn’t help myself)

I didn’t use this, but here’s a photo of the 5 gallon bucket of Tyvek Fluid Applied.  This is the thinnest viscosity version and you would power-roll this onto the sheathing to form a 25 mil thick elastic raincoat over the whole house.  Amazing product!  It has a similar perm rating to regular rolled Tyvek too at 21 perms.  I also like that it stretches and snaps back to it’s original cured shape, this is perticularly good for wood framed houses that will experience some movement due to wood shrinkage.  Tyvek took their time in develping this product and it really shows.  Hopefully I’ll have a full house to blog about the total system of Fluid Applied Tyvek.  Thanks to Corey Ball for his help in my tricky window flashing install too.  Matt Risinger – Risinger Homes in Austin TX