Wall framing issues with raised heel roof trusses

[tundra_dweller]

Here's a problem I run into often as at least 80% of the projects around here utilize roof trusses for a majority of the roof framing, mostly with energy heels, many with scissor trusses.

 

Using Chief's roof truss and ceiling plane tools to create scissor trusses with energy heels generally works well, but when the wall framing is built, it will build the top plate at the roof baseline height instead of the room ceiling height. Checking the "Flat Ceiling over this Room" in the room dbx will fix the top plate issue but of course you then lose the sloped ceilings. Deleting the ceiling finish material in the room dbx will get rid of the flat ceiling, but the custom sloped ceiling planes will not show unless flat ceilings are unchecked. 

 

So now the wall framing shows incorrectly in section view and material lists, and the auto story pole dimensions will pick up the top of plate at the roof baseline height. You can usually manually drag the dimension to the correct top plate height and then manually enter "Top of Plate" or whatever in the corresponding story pole marker segment. Not ideal.

 

I have a workaround for this (that is also a PITA) that entails framing the walls with a flat ceiling first, then checking the  "Retain Wall Framing" option in the wall dbx's, then unchecking flat ceiling and building the roof trusses. This is fine until something changes in the walls that would need to be re-framed, you then have to change the ceiling back to flat in order to auto frame the walls or else they will re-frame to the roof baseline, so on and so forth.

 

It sounds like there are changes coming in X15 for framing with roof trusses, hopefully this behavior is also addressed. I'm just wondering if I am missing something, or if anyone out there has a better way of dealing with this in the meantime? Sample plan is attached, Thanks.

 

 

 

TEST PLAN 2.zip

[GeneDavis]

What's the problem?  I want to frame efficiently with regards to available materials, so I am going with precut stud wall heights that are right for the sheetrock modules.  That's 8, 9, and 10 feet plus the 1.25".  So there is my room height.  And that is where walls will frame to, every time.  Reframe, and they frame up to those 97.125, 109.125, or 121.125 tops.

 

So, room heights.  Set them and forget them.

 

The heel height for the trusses is either determined by energy, meaning something like a 12" rise, or by structural engineering, meaning what minimum it's gotta be to handle load with span.  I'm always working where the ground snow load is about 100 psf so I have a truss engineer on speed dial for scissors in that second category.

 

So there you go.  Your room height for your ceiling plane base, and your heel height for the baseline height of the roof above.

[tundra_dweller]

8 minutes ago, GeneDavis said:

What's the problem?  I want to frame efficiently with regards to available materials, so I am going with precut stud wall heights that are right for the sheetrock modules.  That's 8, 9, and 10 feet plus the 1.25".  So there is my room height.  And that is where walls will frame to, every time.  Reframe, and they frame up to those 97.125, 109.125, or 121.125 tops.

 

So, room heights.  Set them and forget them.

 

The heel height for the trusses is either determined by energy, meaning something like a 12" rise, or by structural engineering, meaning what minimum it's gotta be to handle load with span.  I'm always working where the ground snow load is about 100 psf so I have a truss engineer on speed dial for scissors in that second category.

 

So there you go.  Your room height for your ceiling plane base, and your heel height for the baseline height of the roof above.

Sure, that's how it should work and does work in real life. The problem is Chief's framing the walls so that the top plate of the wall ends up at the roof baseline rather than at the room ceiling height, as shown in the pictures. The actual room ceiling heights and truss heel heights are inconsequential, Chief's wall framing is the issue.

 

Not a real big deal, I was just hoping that someone knew of a way to force Chief to put the top wall plate where it should be in these cases, at the room ceiling height with the bottom truss chord bearing on the top plate, without a convoluted workaround.

[para-CAD]

I think there is a detailed thread on energy heel trusses somewhere.  That might explain it better for you.

 

Not sure if this is relevant, but it does expand ones understanding in this area.

[tundra_dweller]

Thanks para-CAD, I've definitely mined that thread for info in the past.

 

I have no problem getting what I'm after in energy heel trusses with flat ceilings (bottom chords), I only run into this problem with raised heel roof trusses that have sloped bottom chords to form vaulted ceilings (typically called scissor trusses around here), and I believe parallel chord roof trusses cause the same behavior with the wall framing.

 

This is mainly only bugs me in that I'm trying to create an accurate model with minimum extra CAD work to be done in section view. 

[GeneDavis]

Room heights rule.

[GeneDavis]

Do a simple 4 wall plan.  Do a roof so its baseline is 12 inches above room height, make the roof a 10 pitch.  Do 5-pitch ceiling planes under, lower end at your ceiling height.

 

Autoframe the walls.  Since you have not generated trusses yet, those wall heights ("plate heights") are not what you want for the roof structure with trusses.

 

Draw the trusses.  If you have wall autoframing on, those side walls under the trusses will properly frame.

 

Add windows to the walls, and they will autoframe, again with top of wall right for truss bearing.  

 

What is the issue?

[tundra_dweller]

Well I guess I'm missing something then, because as soon as I uncheck "flat ceiling over this room", whether I have any roof trusses drawn or not, my wall top plates jump up from the correct height (room ceiling height 9'), up to the roof baseline height (10'), unless I lock the wall framing before unchecking flat ceiling over this room.

[GeneDavis]

Read my earlier.  You gotta build the trusses to get the walls to frame true.

[joey_martin]

The problem, if I'm reading this right, is most likely that when you create your ceiling plane, you need to ensure that the settings for the CEILING plane are set at the room height. Once you turn off the flat ceiling, the ceiling plane you draw in now takes precedent. Check your ceiling base height.

[tundra_dweller]

My ceiling planes are set to room ceiling height, so that isn't the problem either. Everything works as expected until I frame the walls with "flat ceiling over this room" unchecked.

Thanks guys for taking a look.

 

Everything set up the way I want, room height 9', roof baseline 12" above top of room height, sloped ceiling planes, looks good.

 

 

Roof trusses built, they are sitting right where they should at room ceiling height with a 12" energy heel, still looking good.

 

Then when I have Chief frame the walls, the top of the wall frames to the roof baseline (the top of the top chord of the truss) instead of keeping the top plate at room ceiling height. The trusses don't change, they are fine. It's just those sidewalls that want to build to the roof plane as if no room ceiling height or manual ceiling planes exist. 

 

Like I said I must be missing something, but even if so, it seems like this aspect of the wall/roof framing in Chief could be improved. I'll just keep using my workaround and move on.

[GeneDavis]

Sequence:

 

Draw walls to make "room".  A four wall house.  Leave room height at whatever default you have established up front, but know it.  Mine is 109.125.

 

Build the roof above the house, elevated up to have a 1' heel height for the trusses, and a pitch twice what you want for your vaulted ceiling below.  I did a 10 pitch for a 5 pitch ceiling.  Edit the "room" AKA house to NOT have a flat ceiling above.  Draw the ceiling planes, setting their bottom elevation ('fascia') at room height, in my case 109.125.  One of my pics shows my ceiling plane limits at the drywall layer of walls.

 

Now draw trusses.

 

Then, after trusses are edited however necessary to look right to you (Chief needs work for energy heels), frame the walls.  Michael's trick of doing 1" widths for all elements (chords, webs, etc.) to get the truss to look right at the heel, then reset all back to 3.5 seems to work nicely.  But the energy heel is not the issue here.

 

What are you doing differently?

 

 

[GeneDavis]

Here's my plan.  Where's yours?

Test truss.plan

[tundra_dweller]

6 minutes ago, GeneDavis said:

Here's my plan.  Where's yours?

Test truss.plan 3.93 MB · 0 downloads

I'll take a look at yours, I attached a plan to my OP but here is another one.

 

As far as I can tell I'm not doing anything differently. I agree that neither the trusses or energy heels are the issue. I think it has something to do with the sloped ceiling and the fact that the roof baseline (energy heel) is higher than what Chief thinks it should be for the roof structure size, but that should not matter for trusses in real life.

If I turn off auto wall framing before I uncheck "flat ceiling over this room" then all is well with the wall framing, the top plate stays at room ceiling height.

 

I'm using the OOB plan template in this case. I have my roof build preferences set to "Trusses", auto birdsmouth unchecked with a positive value entered for "Raise Off Plate" to reach my desired heel height in combination with the vertical structure depth. I leave the 3 1/2" roof structure because that shouldn't matter for roof trusses. Maybe I have to set the structure depth so that the vertical structure depth matches what I want my heel height to be and leave the "Raise Off Plate" value to zero.

test plan 2.plan

[tundra_dweller]

Yeah that's the difference between how we're doing it. You don't have the "Trusses (no Birdsmouth)" option checked in the roof preferences and you are leaving the "Automatic Birdsmouth" option checked, with your roof structure set so the vertical structure depth matches your desired heel height.

 

I guess this is the solution, but to me it's not the logical way it should work if you're using trusses.

[GeneDavis]

I see what happens now.  I never use that TrussesNoBirdsmouth option, but it is clear that when it is checked, it prevents the walls from framing properly.

 

Gonna turn in a ticket to Chief.  

[tundra_dweller]

Thanks Gene, I feel better now that I know I haven't been missing something totally obvious all these years.

[HumbleChief]

I wonder how X15's (purported) auto truss framing will behave in this case?

[GeneDavis]

OK, after a nice conversation with a Chief tech, and writing and then deleting a suggestion for change, I have arrived at the correct way to do scissors trusses and wall framing, when you want to control your wall heights.

 

Build with room heights as you want, delete all your flat ceilings as you regularly do when doing scissor trusses for vaulted ceilings, and draw the ceiling planes with their bottom edges to OUTSIDE of framing.

 

Build roof planes and edit as needed to get the roof height where you want for the desired truss envelopes.

 

Here is a key step.  Open all the walls upon which trusses bear, and in the structure page, check the radio button for Platform Intersections>Ceiling Platform to be Stop at Ceiling Above.  In the section view attached, the wall on the right has its ceiling plane drawn over, and is specified this way.  The wall on left has its ceiling plane drawn to inside of framing, and the platform intersection is specified as Automatic.

 

You created the ceiling above at your desired elevation when you placed its outboard (bottom) edge at outside of framing.  This stops the wall at that height and the wall will frame with desired plate height.

 

The walls can then be framed before truss generation, or after.

[tundra_dweller]

I'll dive into this again later when I have a little more time, but after following the steps you laid out I still can't get the wall tops to stay put even with the bottom of the ceiling planes extended to the exterior face of the wall framing, and with the truss bearing walls' radio button selected for "Stop at Ceiling Above" at the structure page. I am still using the "Trusses (no Birdsmouth)" setting in the roof dbx, maybe that's part of the problem.

 

Thanks again for taking the time to follow up on this, I'll mark your post as the solution as soon as I get it figured out. I may have to call in and talk to Chief support to iron it out, which I suppose I should have done in the first place.

 

 

[GeneDavis]

Here is the image I forgot to attach to the post above.  Right side follows procedure, left side not.

 

This, before I have built trusses.

[HumbleChief]

Thanks Gene, very helpful for future work.

[Alaskan_Son]

Despite some of the posts above that purport there are wall, ceiling plane, or roof plane settings that will stop the walls from ballooning up through, I have yet to see any solid evidence of this and believe it to be a simple bug/program limitation.  I'd be very interested to see if anyone can take the plans posted by @tundra_dweller and keep the wall from framing up through without changing anything about the roof structure and without turning off auto framing.  I can get the walls to stop generating through, but not without changing the Baseline Height, Roof Pitch or some other crucial setting. 

[Alaskan_Son]

 

On 2/13/2023 at 8:09 AM, GeneDavis said:

Here's my plan.  Where's yours?

Test truss.plan 3.93 MB · 6 downloads

 

Change the Baseline Height and Roof Pitch to match the design criteria presented in the plans posted by @tundra_dwellerand see if your approach still works. 

[robdyck]

11 hours ago, Alaskan_Son said:

I have yet to see any solid evidence of this and believe it to be a simple bug/program limitation.

I agree. The only settings that I can find that will consistently control the framed wall height automatically are in the roof dialog. And yes, it would stump anyone because it's logically incorrect. The summary:

ROOF TAB:

1. Trusses (no Bridsmouth): Unchecked
2. Raise/Lower from Ceiling Height: 0"
3. Automatic Birdsmouth Cut: unchecked
4. Raise Off Plate: 0"
5. Birdsmouth Seat: 0"

STRUCTURE TAB:

1. Roof Layers / Structure: Enter a value equal to your desired heel height. This would also set the baseline elevation at the exterior of the top plate. Ignore the fact that this will cause odd sized rafters where rafters would be built automatically or manually.

This leaves us with 2 choices because we will have to fix / lock either the wall framing or roof rafters. If you are using a complete truss roof, then you probably have very few rafters (if any) to fix. Alternatively, we can keep the Flat Ceilings, then open the affected wall dialogs and check Retain Framing. Then remove the flat ceilings.

And in X14, all the roof trusses will still be modeled incorrectly at the exterior of the top plate, as Chief will build a bottom chord that extends out to the truss tail.