Can Roof Butt to Wall Main Layer instead of Exterior Layer?

[JuanR2]

I have a 6" CMU Parapet Wall with 2" Continuous Insullation, the Roof is butting against the Exterior Layer (rigid insullation) instead of the Main Layer which is my CMU bearing wall.

 

Pic 01 - On Wall Type Definitions you can decide which Layer to use for the Foundation and Dimension placement, but not for the Roof ;

Pic 02 - On Plan View the Roof is short of butting against the Interior Wall;

Pic 03 - I changed the lower portion of the parapet wall but the Roof butts against the upper portion -against the Exterior Layer- instead of the Main Layer which is my bearing wall.

Pic 04 - To force the Roof butt against the Main Layer I manually extend the Roof by removing "special snapping" but with this fix I loose the "pony wall" and can't change the lower portion of the parapet wall. I neither want the continuous insullation on the interior of the room nor is the Roof actually butting against the Main Layer, rather it penetrates the wall.

Pic 05 - The only solution I could find is changing the Wall Definition - removing the Exterior Layer - and manually draw the continuous insullation directly on the Facade?

 

 

[DzinEye]

I think the problem is that your roof has square-cut eaves, not plumb-cut at the top where it hits the wall, which is preventing the roof surface from hitting the wall.
Try in your roof options setting a 'plumb-cut', rebuild your roof and see what happens

[JuanR2]

Tks but Plumb cut did not "elongate" the structure to butt against the Main Layer, the problem is still there. I keep thinking it is a Wall Setting for the "wish list".

[DzinEye]

Post your plan. 

With 'no special snapping' you should still be able to have a pony wall.

If you want the foam to continue both above and below the roof to where you're showing it ending... then that's not going to happen

[JuanR2]

My plan is 80+ MB I can't upload it. I could save a portion and upload that

 

On my Pic 03 I have a pony wall with foam above and not below the roof: that is exactly how I need it. But the problem is the Foam (Exterior Layer) does not let the Structure of the Roof butt against the CMU (Main Layer): the structure needs to butt against the bearing wall and not the foam. Another way to put this is that the upper portion of the pony wall goes too far down and into the roof structure, instead of my foam butting against the structure or plywood of the roof. The plan view of the Roof does not butt against the surface of the interior wall which is aligned to the parapet wall, as seen in Pic 02. 

If from here I manually extend the Roof with the "no special snapping" I  loose the the pony wall: I does not let me keep the pony wall.

 

[JuanR2]

Thanks DzinEye, finally solved!

I had a Parapet Wall with lower portion of wall - below the roof - without the foam: which behaves like but was not a pony wall.

What I did was change the Parapet Wall into a Pony wall to decide up to what elevation I needed the foam; matching the roof finish. With this I did not need to change the bottom portion of the pony wall below the Roof. I manually extended the Roof to butt against the Pony Wall .

 

The only small thing I could not fix is that my design look better with the square than with the plumb cut. The square cut on the overhang is more noticeable than the butting of the roof that "invades" the wall. 

[DzinEye]

Glad you got it to work. Normally you can choose square cut and only the eave will be square, but I could see yours was square at the top for some reason.  If it's still doing that you can always assign a custom rafter tail even if you choose plumb cut

[robdyck]

"No Special Snapping" is the key for having manual or dimensional control of where the roof butts up against a wall. This will not address the display of the wall's layers above or below the roof plane.

 

[JuanR2]

20 hours ago, DzinEye said:

Normally you can choose square cut and only the eave will be square, but I could see yours was square at the top for some reason.

Seems the unwanted "square cut" at the Top happens when the Parapet Wall Exterior Side is facing the Roof. In such case you need the "no special snapping" on and manually extend the Roof to the Pony wall - as in PIC 08. (After this point I did not like my construction solution with the useless foam above the Roof!);

 

On Pic 09 I reversed the Layers, now the foam is on the "exterior" of the Room -where I really need it- and now the cut is perfect! It does no need the "no special snapping" since it snaps perfectly to the wall.

 

As a conclusion, the Roof needs to butt against the interior side of the parapet wall -which is logical- in order for the Roof to cut as expected on the top. In my case I still did a pony wall to partially add foam to the portion of the wall that needs it.

 

THANKS for providing insight into solving this issue, your time is greatly appreciated!

 

 

[DzinEye]

2 hours ago, JuanR2 said:

After this point I did not like my construction solution with the useless foam above the Roof!

I was kind of wondering why you wanted to insulate just one side of your parapet wall...though it appears you have it on the parapet on other side of the flat area too?
I should point out to you that you're going to get no insulation help from that bit of foam you're showing on the other side of the masonry wall behind where the roof hits.  The exposed masonry everywhere else on the wall is going to conduct it's heat and cold into the area that you're covering with foam.   Also note that starting/ending that foam low on the wall there is going to be an awkward flashing detail.  Much easier to bring it all the way up to the top and use the parapet cap to flash it.... however I think you should just skip it altogether unless you work out a very different insulation solution.

[JuanR2]

1 hour ago, DzinEye said:

I was kind of wondering why you wanted to insulate just one side of your parapet wall...though it appears you have it on the parapet on other side of the flat area too?

Installation-Guide-Hebel.pdf

 

First I got tied up wrestling with the software in regards to the model, until I got to the opportunity of focusing on the construction solution. Thanks for your concern besides the software!

• I'm using 6" thick Solid Hebel (autoclaved aereated concrete) for Exterior Walls with R=6.01. Being a Mass Wall it needs R=7 in Zone 2, so I'm going above that by adding 2" Foam with R=4.
• I'll be using a pre fab Hebel Floor so I can have a big Terrace above the house, and will also add the Foam on its perimeter to match the finish plane of the walls underneath it.
• For Parapet walls I'm using 6" CMU which in general does not "need" to be insullated, but in some cases will like the following: 

Right side Parapet Wall - I'm using foam to have the finish on the same plane as the floor and walls: with a high R value on the wall and Floor portion, and low R value (low density) on the Parapet. The "inside" of the Parapet not insullated since it is just sitting above the Hebel Floor and I'm using it to hide Air Conditioning Units;

Left side Parapet Wall - since we don't use wood rafters -in Mexico- and instead metal purlins, I will either add a concrete beam or U-Block CMU's to receive the purlins (will discuss this with the PE). Above either of the solutions I will have a Hebel parapet instead of the CMU. That is why I have a small piece of foam just to cover the possible concrete beam, which will be cut in a 45 degree angle so I can extend the fiberglass mesh and attach it to the Hebel, will not be using a flashing. 

 

Thanks again for your time and concern!