Framing Truss Help

[heidistokoe]

Hello,

 

I am working on truss building currently and have already manually built my roof planes. However, upon messing around with the program I have figured out that my trusses only build correctly if I auto build the roof and check the box "Trusses (no birdsmouth) under the pitch. I need my trusses to look like picture #1 but when I build my trusses for my manually built roof they look like picture #2. 

 

Does anyone know how to build the trusses to look like #1 with manual roof planes? 

[heidistokoe]

Hi @solver, Thanks for your response . I will paste the link to my file here - it is the whole plan so its on google drive. I have 10' ceilings and a 4/12 pitch for the roof. I can't see what the difference would be with my manual roof planes vs. auto generated ones. I am only focusing on the roof above the 1 car garage side of the house for now while i am trying to figure out how to get it to work. Yes the trusses look perfect when I auto build the roof. If I lower my roof planes to match the specs from the auto roof the drywall on the ceiling inside will start to slant downward on the edges of the rooms. I use manual roof planes because with the "tower" over the entrance the program doesn't auto build roofs that will work for me at all it seems to glitch somehow.

 

Any help would be so appreciated. 

 

Here is the link https://drive.google.com/file/d/1TjMq1pPrCoZGsMujlibU-XLNE_FOek1k/view?usp=sharing

 

Thank you,

Heidi

[Chrisb222]

18 hours ago, heidistokoe said:

If I lower my roof planes to match the specs from the auto roof the drywall on the ceiling inside will start to slant downward on the edges of the rooms.

 

Caused by the thickness of the roof deck. Open the roof plane, go to Structure tab, Roof Layers section.

[heidistokoe]

Hi @Chrisb222, thank you, I couldn't find anywhere where anyone had this same issue. This is a picture of my roof structure, I don't see somewhere to change the thickness of the roof deck. What should the thickness of the roof deck be?

[GeneDavis]

Surface includes roofing and deck.  Yours reads 5/8.  Open it to edit.  But that is not the problem here.

 

I did not open your plan and so cannot comment on your particulars, but Chief considers the 3D space between the ceiling (defined by room spec if flat) and bottom side roof sheathing (i.e. that line drawn between the ridge elevation and the baseline elevation) the envelope for generating truss 3D.  So whether your deck thickness is 1/16" or 16", the trusses that get generated in the space are identical.  Roof sheathing and roofing thickness (added together are "surface") have no effect on truss generation.  They built atop the Chief roof plane.

[heidistokoe]

Thanks @GeneDavis - I don’t know why when I lower my manual roof plane to match where chief would place the auto roof plane it slants the sides of the drywall in the rooms. Any ideas why that may be happening?

[GeneDavis]

I have your plan open now.  Your building is a very long way from the 0,0 origin in Chief space, and that can cause other problems, mostly in 3D viewing.  But that is not relating to your truss thing.

 

I don't see any roof trusses in the plan.  I did all layers off and only turned on the framing, roof trusses layer (which was already showing me no content) and saw nothing.

 

Here is a tip.  Never begin to furnish spaces with cabinets, fixtures, lighting, furniture, plants, trees, anything other than building elements (walls roofs windows doors) until the building is done to the specs you need.  And done means the building renders correctly, the way you expect, in plan views, elevations, sections, and 3D overviews.  

 

Something is off in the way you specified foundation, and I'll not look at this any longer until you fix it up and repost.  I did an edit area thing to copy the plan without all the fixtures, furniture, etc., and pasted it centered on 0,0 in a new plan.  Look at what a floor overview looks like for floor 0 and floor 1, attached.

[heidistokoe]

Thanks @GeneDavis I am new to this program so any help is greatly appreciated. I will do what you suggested and repost. I am wondering with the second photo you uploaded it shows a basement somehow? My construction will be a cement slab with 2x4 framing. I added the second story to create a flat roof over the 1 car garage so there should be no basement. Not sure if that matters?

[Chrisb222]

4 hours ago, heidistokoe said:

I don't see somewhere to change the thickness of the roof deck. What should the thickness of the roof deck be?

 

The structure setting. Yours is 9-1/4" which is the default setting for a rafter roof. When you check trusses on auto build, the structure is thinner which lowers your roof plane. Change the structure setting to 3-1/2" should get you what you want.

 

The slope you saw in your ceiling was the bottom of your thick roof deck being pushed down into the room when you lowered the roof plane. Not the right way to do it.

[Alaskan_Son]

On 10/13/2022 at 12:16 PM, heidistokoe said:

Hello,

 

I am working on truss building currently and have already manually built my roof planes. However, upon messing around with the program I have figured out that my trusses only build correctly if I auto build the roof and check the box "Trusses (no birdsmouth) under the pitch. I need my trusses to look like picture #1 but when I build my trusses for my manually built roof they look like picture #2. 

 

Does anyone know how to build the trusses to look like #1 with manual roof planes? 

 

@Chrisb222 already pointed out the main issues, but to clarify a bit:

 

First thing to understand as that when you check Trusses (no Birdsmouth), 2 important things happen:

1).  Chief changes the Structure Thickness to match your Default Truss Top Chord Depth.

2).  Chief automatically places the Baseline height of the roof so that the bottom of the Truss Top Cord sits right on top of your wall at the Baseline. 

 

The above is true for BOTH automatically generated roofs and for manually drawn roofs (assuming you change the setting before manually drawing your roof).

 

You can find all this information and more if you get into the habit of clicking the Help button.  In this case, open the Build Roof dialog, click the little Help button down in the corner, and read up on the Trusses (no Birdsmouth) setting.  Follow any related links if you don't find what you need in that particular article. 

 

 

[Alaskan_Son]

1 hour ago, Chrisb222 said:

 

The structure setting. Yours is 9-1/4" which is the default setting for a rafter roof. When you check trusses on auto build, the structure is thinner which lowers your roof plane. Change the structure setting to 3-1/2" should get you what you want.

This isn't quite right (or its at least an incomplete picture).  Changing the structure setting in Roof Defaults will only cause the roof to be lowered for newly drawn roof planes.  It will not however affect any existing roof planes and even newly drawn roof planes will get set at the wrong height since rafter framed roofs get the baseline height set differently than it would if Trusses (no Birdsmouth) were checked. 

[Chrisb222]

1 hour ago, Alaskan_Son said:

This isn't quite right (or its at least an incomplete picture).  Changing the structure setting in Roof Defaults will only cause the roof to be lowered for newly drawn roof planes.  It will not however affect any existing roof planes

 

That's why I suggested opening the Roof Planes and changing the structure setting there.

 

1 hour ago, Alaskan_Son said:

and even newly drawn roof planes will get set at the wrong height since rafter framed roofs get the baseline height set differently than it would if Trusses (no Birdsmouth were checked). 

 

Yes after more experimentation I see that simply making the structure thickness of a previously-drawn manual plane 3-1/2" doesn't work.

 

After changing the structure thickness, moving all the planes up 4" seems about right but will depend on the roof pitch.

 

The OP mentioned they had already built the manual roof planes. My suggestion was a way for them to obtain the desired result without having to rebuild the roof. I'm not aware of another method to do so, if you do please add. Thanks for your clarification and correction.

[Alaskan_Son]

On 10/15/2022 at 11:58 AM, Chrisb222 said:

The OP mentioned they had already built the manual roof planes. My suggestion was a way for them to obtain the desired result without having to rebuild the roof. I'm not aware of another method to do so, if you do please add. Thanks for your clarification and correction.

 

If a person is going to use trusses, then the Structure thickness won't even matter.  It's all about setting the Baseline Height correctly.  For existing roof planes that were initially drawn using the incorrect settings, I can think of at least a few options, but in all cases you are correct that the Structure Height should be changed to match the correct Truss Top Cord Depth.

1. Check Trusses (no Birdsmouth) in your Roof Defaults, draw a new roof plane, open it, copy the baseline height, delete the roof plane, open your other existing roof plane(s), Lock Pitch, and paste that baseline height into the baseline field. 
2. Open another existing (but correct) roof plane, copy the baseline height, open your incorrect roof plane(s), Lock Pitch, and paste that baseline height into the baseline field. 
3. You can draw a truss, take a section view and simply measure how far your roof plane needs to move.
4. After changing the Structure Depth as @Chrisb222 suggested, inspect the Vertical Structure Depth on the General tab.  Lock pitch, and set the Baseline Height to Top of Plate+Vertical Structure Depth.

[Chrisb222]

On 10/15/2022 at 4:27 PM, Alaskan_Son said:

If a person is going to use trusses, then the Structure thickness won't even matter.

 

I've been playing around with your suggestions and can't get the right results without first changing the structure thickness that is generated when using the OOB settings (9-1/4"). The baseline height comes out right and the truss is drawn correctly, but the ceiling and wall height issues are still there. The clip below is what I keep getting:

 

 

I keep going over your instructions but it always comes out like the above.

 

Tried resetting wall top heights, didn't change it...

[GeneDavis]

Nice video for explaining, Eric.

 

What Eric did is to build the roof auto and with that absolutely key step of specifying trusses right in the same box as where pitch is specified.  That radio button for trusses, when checked, sets the baseline height (and structure depth) in accordance with the default top chord for trusses, which is set in the framing defaults.  The out of box number is 3-1/2 inches for the top chord.  It overrides that 9-1/2" depth you have for structure that keeps giving you that ceiling drop.

 

See how in the section cut that the top chord sits precisely on the outer tip of the top plate of the framed wall below.  That baseline point is up the vertical distance of the pitched 2x4 top chord.

 

So if Eric had done an music audio track for his video, the big chorus with the drums and backup singers would have been rolling right when he checked that TRUSSES button. 

[Chrisb222]

1 hour ago, solver said:

@Chrisb222

 

 

 

 

 

 

 

Right. But the OP already had manually-built roof planes they wanted to preserve, and had not checked Trusses, No Birdsmouth before doing so. That's when the program uses the rafter thickness (9-1/4" in OP's case) to build the roof deck.

 

The test I did was using the OOB template also, but first building the roof without checking the Trusses option. That's what the OP did. Then I tried just lowering the roof and building trusses, to see if it mattered whether or not I changed the Structure thickness, as I suggested the OP do. So far I haven't been able to get the desired result without doing that.

 

 

[Chrisb222]

1 hour ago, GeneDavis said:

What Eric did is to build the roof auto and with that absolutely key step of specifying trusses right in the same box as where pitch is specified.  That radio button for trusses, when checked, sets the baseline height (and structure depth) in accordance with the default top chord for trusses, which is set in the framing defaults.  The out of box number is 3-1/2 inches for the top chord.  It overrides that 9-1/2" depth you have for structure that keeps giving you that ceiling drop.

 

Yeah, that has already been covered. The OP had manually-built roof planes they wanted to preserve. Checking Trusses wouldn't solve the problem with the existing roof planes.

[Joe_Carrick]

Would "Edit All Roof Planes" help by allowing the structure to be changed ?

[Chrisb222]

24 minutes ago, Joe_Carrick said:

Would "Edit All Roof Planes" help by allowing the structure to be changed ?

 

Yes that makes it easy to reset the structure thickness on all the planes at once. Still need to lower the roof, and that's where Michael's suggestions are helpful for getting an accurate baseline height. Edit All Roof Planes works there as well.

[Chrisb222]

Auto-built rafter roof with OOB 9-1/4" Structure thickness changed to 3-1/2":

 

After using Michael's method of switching Roof Defaults to Trusses, no Birdsmouth, drawing a manual roof plane, noting the baseline height, then applying that value to all roof planes using Edit All Roof Planes:

 

Only now the gutter board is out of place...

 

[GeneDavis]

My comment had nothing to do with how to fix what got done.  I was pointing out the key thing to do up front to avoid the issue.  That little radio button for truss building.

 

Fixing it after is simply a matter of setting the structure depth at 3.5 inches and setting existing roof planes at the right elevation for the truss build.  But I think we all know that, and how to determine the elevation.

 

The OP would be better off just deleting the roofs, carefully running all around the plan to edit room heights and walls in prep for an auto roof build, then autoroofing, and trussing.

[Joe_Carrick]

3 minutes ago, GeneDavis said:

The OP would be better off just deleting the roofs, carefully running all around the plan to edit room heights and walls in prep for an auto roof build, then autoroofing, and trussing.

 

Until Chief provides "Auto Truss Framing" that will still be a PITA.

[Alaskan_Son]

17 hours ago, Chrisb222 said:

 

I've been playing around with your suggestions and can't get the right results without first changing the structure thickness that is generated when using the OOB settings (9-1/4"). The baseline height comes out right and the truss is drawn correctly, but the ceiling and wall height issues are still there. The clip below is what I keep getting:

 

 

I keep going over your instructions but it always comes out like the above.

 

Tried resetting wall top heights, didn't change it...

 

You are completely correct.  The Structure setting does (or at least can) indeed affect other things in the model--particularly if you are lowering the roof so that the bottom of the defined structure starts to encroach into the ceiling and wall framing below.  I corrected my post to reflect that.  I guess I've very rarely had to lower any of my roof planes.  I'm almost always making them higher so the Structure settings don't affect much of anything. I should have known better. 

 

Anyway, thanks for bringing this up.  I stand corrected.  The Structure depth should be changed if you're trying to lower a roof after it was initially built using the wrong settings.  I'm not sure it matters if you're going to raise the roof, but as a matter of good habit, it should probably be changed in either case.  Thanks again.  Good catch.

[heidistokoe]

Thank you so much everyone for all of the knowledge and help. I think I will end up rebuilding each one at a time once I check the proper settings in "Build Roof". Thank you, I could've not figured this out alone. I appreciate all of your input!