Vaulted ceilings changes top plate height - why?


robdyck
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When using vaulted ceilings, Chief will (almost always) change the top plate height of the exterior wall. Then, when opening the roof tab, Chief reports a different top plate height than what it should (this also conflicts with what is stated in the manual). The top plate height should remain as defined by the room / floor, shouldn't it? With scissors trusses creating vaulted ceilings, the vault typically starts inside the top plate, which is similar to a birdsmouth on a rafter.

I've never been able to figure out why Chief lifts the top plates. I use a lot of vaulted ceilings and I'd like to avoid manually editing wall details.

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If I draw a new, matching roof plane in the same location (while keeping the existing roof plane, then Chief drops the plates back to the correct height. But, if I replace the initial roof plane with that new roof plane, the plates bump back up.

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3 hours ago, robdyck said:

When using vaulted ceilings, Chief will (almost always) change the top plate height of the exterior wall. Then, when opening the roof tab, Chief reports a different top plate height than what it should (this also conflicts with what is stated in the manual). The top plate height should remain as defined by the room / floor, shouldn't it? With scissors trusses creating vaulted ceilings, the vault typically starts inside the top plate, which is similar to a birdsmouth on a rafter.

I've never been able to figure out why Chief lifts the top plates. I use a lot of vaulted ceilings and I'd like to avoid manually editing wall details.

image.thumb.png.935ea6d47fa7b1de5845a7ba29f0c127.png

 

Think about it like this:

Chief normally build walls till they hit a ceiling or roof plane above right?  So what happens when you uncheck Flat Ceiling Over This Room?  Chief will build the wall up till it finds either a ceiling or roof plane.  This is the reason that I believe Chief states that "The Baseline of a ceiling plane should be drawn along the outer surface of the bearing wall’s Main Layer."

 

Admittedly, I draw ceiling planes inside the wall all the time, but if you want the behavior you desire, just model as Chief suggests and I think you'll be happier with the results.

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Robert,  this has never been a problem .....  until recently.

 

I too have noticed that the ceiling plane draws about 2.5 inches lower than it should.  I should report this bad behavior....   to sure if it started with X13

 

I agree with you Michael,  I too draw the ceiling planes on interior face and not the exterior face.

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On 2/12/2022 at 11:31 AM, Alaskan_Son said:

just model as Chief suggests and I think you'll be happier with the results

FWIW, this appears to make no difference to the wall framing. Rather, it is the roof settings that control the plate height, not the ceiling plane.

I figured out what I need to do differently. I need the roof structure depth to be equal to the vertical depth of the truss top chord, plus the depth of the truss bottom chord (for a flat  ceiling).

This setting then generates the plates at the correct height.

This would be a hassle when using multiple roof pitches on different levels because that depth then needs to be customized for each roof plane. Because a typical residential roof truss has the top chord pivoting on the bottom chord (regional practice), one can use a Raise Off Plate value of 3 1/2" and then every roof plane will be set at the correct height, regardless of pitch.

In this case, I have a 6:12 pitch so by adjusting the structure depth to 7 7/16", the plates generate correctly. Where it gets odd is that in my original examples, the plates are about 1" below the roof framing, even though the roof structure was set to 3.5".

Now that I've figured this out, I will leave my default roof structure at 3.5" and adjust individual roof planes when needed as it will be quicker than manually editing wall details.

 

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On 2/12/2022 at 11:33 AM, dshall said:

Robert,  this has never been a problem .....  until recently.

 

I too have noticed that the ceiling plane draws about 2.5 inches lower than it should.  I should report this bad behavior....   to sure if it started with X13

 

I agree with you Michael,  I too draw the ceiling planes on interior face and not the exterior face.

 

 

hmmmm....

 

I just tried this with OOB.....  OOB drew correctly whether I drew ceiling  plane on inside of wall or on outside....  this is new to me...  it appears to behave correctly with an OOB plan.

 

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1 hour ago, dshall said:

it appears to behave correctly with an OOB plan

Yes, it's because the roof structure depth is equal to or greater than the heel height (the difference between top of plate and baseline). In my original example, my roof structure thickness was 3.5".

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4 hours ago, robdyck said:

FWIW, this appears to make no difference to the wall framing. Rather, it is the roof settings that control the plate height, not the ceiling plane.

 

I haven't actually seen your plan file and it may or may not make any difference in there depending on your various settings, but ceilings planes can and often do cause walls to frame entirely differently.

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6 hours ago, robdyck said:

Yes, it's because the roof structure depth is equal to or greater than the heel height (the difference between top of plate and baseline). In my original example, my roof structure thickness was 3.5".

 

 

aha.....  thanks for the insight.....  not good behavior ..... 

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5 hours ago, Alaskan_Son said:

but ceilings planes can and often do cause walls to frame entirely differently.

Yup and while I didn't clarify it specifically, I was referring to that one file. Interestingly enough, I have cases where the wall on one side of symmetrical vaulted ceilings frames to my expectation while the wall on the other side extends upwards. So it's a bit weird to understand, but at least now I know that adjusting the roof structure thickness can make a difference.

 

 

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