Inconsistent Fascia Heights on Hip Walls Within Same Room

[DefinedDesign]

Dilemma: Attaching a Garage to an Existing Home
Both the existing house and the connecting room to the garage have identical ceiling heights of 97 1/8”. However, the hip walls on the connecting room are resulting in two different fascia top heights. I need both fascia tops to align with the existing house’s fascia height of 94 5/8”.

 

Grateful for any insight. I’ve triple-checked everything, but I still can’t pinpoint why this is happening.

 

 

 

 

[SHCanada2]

when you build the roofs are you setting the same height eaves checkbox?

 

You could also just raise the roof planes using the transform replicate button, in the Z direction

 

As a note, the fascia heights will be different elevations if the roof pitches are different and eave width are the same, and you do not set same height eaves.

 

Alternatively to raising the roof, you could also change the width of the eave unitl you got the facia elevations to match...but that might not be desirable

[DefinedDesign]

3 minutes ago, SHCanada2 said:

You could also just raise the roof planes using the transform replicate button, in the Z direction

Thank you so much for taking the time to respond! I really appreciate the suggestion—using the transform replicate tool in the Z direction is a great idea. I hadn’t thought of that, and I’m excited to give it a try. Grateful for your help!

[SHCanada2]

i use it all the time because the CA truss heel height can only be set per plan, and not per roof plane

[DefinedDesign]

@SHCanada2 I thought this was going to be the solution, but unfortunately, it raises the top plate. Since the two walls have different fascia heights, this results in mismatched top plate heights. I need both the top plates and fascia to align with the existing house.

 

I’ve confirmed that “Same Height Eaves” is checked when building roofs, and I’ve double-checked all the wall settings and measurements to see if something is off. It’s concerning because I need everything to be accurate for construction drawings.

 

Certainly grateful for any further insight you may have!

[DefinedDesign]

3 hours ago, basketballman said:

As a last, dreaded resort could you not turn view into a cad detail and address it like before we had 3D 

Or just draw a quick cad detail from scratch notating the areas/issues of concern ?

Thank you so much for the suggestion—I really appreciate you taking the time to help. At this point, I’m not looking for a manual workaround. I’m trying to figure out why the software isn’t doing what it should. I must have something set incorrectly, but I can’t find what it is. 

[Mark3D]

Upload your plan it will get you a quicker solution and it will be better for people helping you.

If it is to big compress, it or share with dropbox or others

[SHCanada2]

10 hours ago, DefinedDesign said:

Since the two walls have different fascia heights, this results in mismatched top plate heights. I need both the top plates and fascia to align with the existing house.

see attached with 2 sections, both with same elevations for top plates, then I raise the roofs on the right structure and rebuild the framing. You can see the top plate stays the same

 

I must be missing something, you probably want to post the plan

[DefinedDesign]

On 5/4/2025 at 11:14 PM, SHCanada2 said:

then I raise the roofs on the right structure and rebuild the framing

 

Thanks for making the video! Because both hip walls have different fascia top heights, I’ve had to adjust each roof plane separately to align with the existing house’s fascia height of 94 5/8”. Unfortunately, when I do that, it also changes the top plate height, per the roof plane specification box.

[DefinedDesign]

On 5/4/2025 at 6:12 PM, Mark3D said:

Upload your plan

 

[SHCanada2]

1 hour ago, DefinedDesign said:

Here you go

Is this more what you are looking ofr

 

[DefinedDesign]

35 minutes ago, SHCanada2 said:

Is this more what you are looking ofr

Thank you!  I followed your video and it seems what you did differently to connect the fascia heights is in the Roof Specification Box you unchecked 'Same Roof Height at Exterior Walls'.  I also did not check 'Retain Manually Drawn Roof Planes' and 'Retain Edited Automatic Roof Planes.'  I get the same results as you.

 

What I am trying to get to is: Only 2 roof planes over the connecting room and they need to have top of plate heights of 97 1/8” with a fascia height of 94 5/8” (this matches the existing house). (see image)

 

Following your steps I get multiple roof plans over the connecting room and when I select the hip roof of the existing house it shows the Top of Plate is raised to 105 5/16" and the Fascia Height is 103 7/16"

The front hip roof plane on the connecting room is showing Top of Plate at 107 7/16" and Fascia Height at 103 1/2"

The back hip roof plane on the connecting room is showing Top of Plate N/A and Fascia Height at 103 7/16"

and I need the other mystery roof planes over the connecting room to go away, not sure why the software is doing this and what I need to change so it doesn't create these extraneous roof planes.

 

Grateful for your efforts in helping me to resolve this.

[SHCanada2]

1 hour ago, DefinedDesign said:

Following your steps I get multiple roof plans over the connecting room and when I select the hip roof of the existing house it shows the Top of Plate is raised to 105 5/16" and the Fascia Height is 103 7/16"

where do you see that? I do not

 

 

[SHCanada2]

It still shows correct top plate. after the rebuild of the roofs, the proper way to eliminate roofs is to use the roof intersect tool.

 

the one I modified is too big to attach, but deletde all roofs but the main tw0 over the breezeway and then, modify those 2 to meet the garage

 

 

[DefinedDesign]

8 minutes ago, SHCanada2 said:

It still shows correct top plate.

This is what the roof plan specification box says for the front hip roof plan on the connecting room - I'm having difficulty understanding why your elevation is showing the Top of plate correct when the roof specification box states something entirely different.  
 

[BenPalmer]

If I'm following this correctly, you want to have 2 roof sections perfectly align by having:

1. same plate height
2. same fascia height
3. same overhang distance
4. but different pitches? (your posted plan has 12/12 pitch at existing and 4/12 pitch at new connection)

If that is correct, that isn't possible.  All of those would have to be equal for them to be equal.

 

You can however make adjustments to get the fascia heights to match. Such as:

1. different overhang distances than each other (extend the 4/12 overhang to get it to the desired height, but will result in a larger overhang...can increase pitch to minimize the overhang distance)
2. different plate heights (lower new room height in this case due to the lower pitch...you could raise that pitch to minimize how much to lower plate height)
3. or just accept that the fascia heights will not align if you have to have the plate heights the same and the overhangs the same
4. etc. 

[Mark3D]

28 minutes ago, BenPalmer said:

If I'm following this correctly, you want to have 2 roof sections perfectly align by having:

1. same plate height
2. same fascia height
3. same overhang distance
4. but different pitches? (your posted plan has 12/12 pitch at existing and 4/12 pitch at new connection)

If that is correct, that isn't possible.  All of those would have to be equal for them to be equal.

 

You can however make adjustments to get the fascia heights to match. Such as:

1. different overhang distances than each other (extend the 4/12 overhang to get it to the desired height, but will result in a larger overhang...can increase pitch to minimize the overhang distance)
2. different plate heights (lower new room height in this case due to the lower pitch...you could raise that pitch to minimize how much to lower plate height)
3. or just accept that the fascia heights will not align if you have to have the plate heights the same and the overhangs the same
4. etc. 

I agree unless there is missing information

[DefinedDesign]

30 minutes ago, BenPalmer said:

but different pitches?

The roof pitch on the main house is 12:12 the pitch on both roof planes on the connecting room needs to be the same, preferably around a 3 or 4:12. 

[BenPalmer]

9 minutes ago, DefinedDesign said:

The roof pitch on the main house is 12:12 the pitch on both roof planes on the connecting room needs to be the same, preferably around a 3 or 4:12. 

 

Right, so the connecting room with it's 3/12 or 4/12 pitch (whichever you choose as the designer) will not have the same fascia height as the existing house with it's 12/12 pitch because they have different pitches (12/12 vs 4/12).  Per your original post, you want the plate height and fascia heights to be the same as the existing house. That isn't possible with different pitches without making adjustments, such as those I listed in my previous post.

 

Side note:

I'm a little confused by your comment quoted above "both roof planes on the connecting room needs to be the same" ...because the plan you posted they are the same...?  Is your issue with those planes or with the fascia heights being the same as the existing like your original post declares?

[Alaskan_Son]

Ben is correct.  It seems that you are trying to accomplish something that is a mathematical impossibility.  The only way to have the same fascia height, the same overhang, and the same plate height (ALL 3) while at the same time have different pitches would be to use trusses and make the heel height taller on one section or the other.  With rafters its simply impossible.  

[DefinedDesign]

@SHCanada2, @Mark3D, @BenPalmer, @Alaskan_Son 

Thank you all so much—truly. I’m really grateful for the time and insight each of you has shared. I can tell you are operating on a much higher level of understanding than I am, and I fully admit that I’m outside of my area of expertise here. My construction knowledge is limited, especially when it comes to framing and roof geometry.
 

I now understand that the fascia height won’t match the original 12:12 roof on the house, and I really appreciate the explanation that this is a mathematical limitation when working with rafters. That was very helpful to hear clearly.  That said, the part I’m still struggling to understand is why the two hip roof planes on the connecting room don’t have the same fascia height—shouldn’t they be equal if the room has the same ceiling height? Could it be because one wall is 4 inches thick and the other is 6 inches?  Ideally the client wants a 3:12 pitch to keep costs down, but when I change the pitch on those two roof planes the top of plate height changes.
 

Also, I’m seeing gaps or holes in the walls where the roof connects to the garage. I’m not sure if that’s related or a separate issue, but it has me stumped.
 

Any additional insight would mean a lot. Thank you again for your patience and willingness to help someone still learning.

[Mark3D]

The rooms on the right hand side of your plan have a lowered floor height -56 1/4" witch lowers your top plate height and roof plane pitching height as for the gaps they can be fixed by drawing attic walsl latter

 

If you want i could do a screen share and help you if that interest you send me a private message

[SHCanada2]

3 hours ago, DefinedDesign said:

The roof pitch on the main house is 12:12 the pitch on both roof planes on the connecting room needs to be the same, preferably around a 3 or 4:12. 

your roof pitches are 8:12 and 3:12 when auto built:

 

the bottom wall has it as 8:12

 

 

[SHCanada2]

one side of your gable has 12" overhang while the other has 18"...not sure if that is intentional

 

[SHCanada2]

On 5/3/2025 at 7:33 PM, DefinedDesign said:

Existing Home

as well, if this is existing house, to be accurate you would need to know the heel height or  difference in top plate to bottom of fascia  If rafters, the birdsmouth depth is not certain l

 

Below you have

 

On 5/3/2025 at 7:33 PM, DefinedDesign said:

I need both fascia tops to align with the existing house’s fascia height of 94 5/8”.

is that as measured from the top of subfloor on site?

 

Typically to know for sure, one would have to go into the attic, or open up the soffit or do some math on relative heights (such as measure from top of window to eave, then measure from ceiling to top of window inside)