If we want the 3D look of window drywall returns, let's get a fix for the mull-jamb-chop

[GeneDavis]

Here is a trendy look we see in windows today.  The frames and sash are relatively slim in profile, the color, in and out, is black or dark bronze, and inside, drywall returns execute the minimalist look.  Here is a view of a mulled pair of Andersen Series 100 casements.  The mull join piece is 1/2" thick, per Andersen specs.

 

 

Ignore that the pic shows brick finish on exterior.  We're going to go with clapboard siding and casings outside.

 

So I examine Andersen's dimensioned section detail for this 100 Series casement, and model the mulled pair.  Here is a section view of the window head, and in this view, you can see adjacent the Chief-modeled section, one in which is inserted the Andersen section from their CAD downloads.

 

Ignore that I have drawn this with a jamb extension and an interior casing.  What's important is that the window has its elements sized to match the manufacturer's specs, and it is positioned correctly in the in-out position, with its exterior plane projecting 1-5/16" out from its mounting surface, the face of sheathing.

 

Here is the view from outside.  You can see that 1/2" mull join space.  We are not gonna discuss the color problem here.  That's another topic.  Mull materials match casing materials, in and out.

 

 

 

Here is one view inside, with casing shown.  We want the no-casing look, but I wanted to show this with the casing material, which is the same material as the inside face of the 1/2" mull.

 

 

And then when we remove the casing inside, to try for our drywall-return look, we get this.

 

 

It's not quite OK in 3D, in that real drywall returns would be inside the opening.  Chief makes you put them there manually, using a 3D molding.  But let's look at that little chop-out.  That's what I want fixed.  See it close here.

 

 

It's annoying enough that the mull color thing presents a hassle, but add this, and it's another burr under the saddle.

 

You can "fix" it by not spacing the windows 1/2" apart.  You won't have to fiddle with the absolutely unworkable mull insets, and if you upsize each window by 1/4" in width, your R.O. will be right.  Your size callouts in your schedule won't be right, though, if you care about those details.