Build the attic floor

[Evolution]

I seem to be progressing fairly well, however now that I have the roof built, I do not have an attic floor showing. I have been retired from using CA for quite some time and the proper steps to build the attic aren't coming back to mind. Build framing is another topic for later as I am now preparing to develop the construction plans for submission to the Building Department for permitting after I get the structural back from the engineer. Thanks in advance!

   

COASTAL RESIDENCE FOR CECIL and HELEN WILLIAMS for CHIEF TALK FORUM.zip

[para-CAD]

I don’t think the attic ever has a floor. I’m pretty sure you could just add another floor to your model and make it very shallow like 3/4 of an inch or something so that you could actually have a floor system in your attic. I’m not in front of a computer so I can’t verify that this might work

[JiAngelo]

Add another floor then tell roof dialog to ignore 3rd floor.  Any walls and rooms you draw up there will automatically fit under the roof extending from the second floor.

[PitMan71]

You could add the floor above the joist in the Structure panel>>Ceiling Structure setting of your second floor. Click "Insert Above", change to plywood, set your thickness, uncheck framing for that item. Anyway, worth trying.

[Doug_N]

Just a quick note regarding the floor in the attic.  It seems that the ceiling joists are 2 x 6 with a span of 35' or so.  Putting a floor on such members raises some serious questions about the structural design.  That being said, adding a 3rd foor, and setting the roof dbx to ignfor the 3rd floor solves the floor surface in the attic,

 

Here is what the framing view looks like with a floor structure for the 3rd floor, telling the roof build to ignore the 3rd floor and raising the roof a bit to account for the floor thickness.

 

[Evolution]

On 11/25/2025 at 12:09 PM, JiAngelo said:

Add another floor then tell roof dialog to ignore 3rd floor.  Any walls and rooms you draw up there will automatically fit under the roof extending from the second floor.

JiAngelo- I added the floor, after watching and re-watching the training video for the One-and-a-half-story roof. the first take the roof was wonky, so I selected the roof planes and transform/replicate and raised it in the "Z" direction until the roof line straightened out. Now the issue is: The person this is for decided they didn't like the "HIP" roof so I changed the roof to full gable, (all around) but in order to keep the over-all height at the max allowed on the coast, I had to drop the pitch to 6/12 which they didn't like so I changed the roof back to hip but now the roof on one end of the home remains full gable (even though) I have the hip roof selected, while the opposite end changed back to hip with no problem.

 

Any idea's of what is going on? 

 

  

 

 

 

  

COASTAL RESIDENCE FOR CECIL and HELEN WILLIAMS for CHIEF TALK FORUM.zip

[JiAngelo]

Just to clarify,

Is your maximum building height 35'?  And are you trying to use all of the 3rd floor?

I ask because you've built your 3rd floor directly over your second floor perimeter walls.  The room defaults to 12" tall.  It should default to 109 3/8" or similar if you are ignoring top floor.

Typically you check ignore 3rd floor because you want the roof built on top of the 2nd floor walls and somewhere inside this rooftop you plan to place an attic area inside of trusses. 

 

Here's a plan I'm working on now.  The red lines are my truss control lines.  The blue lines define a 5' kneewall that slopes to 8' ceilings on the left side of the house and 9' ceilings on the right side of the house.  The blue lines are my attic room limits.  If my roof was hipped, I'd have a red outer box and a blue inner box over this same area.

 

 

Here's my room trusses Red is 9' ceiling area, White is 8' ceiling area, Blue is the 8' ceiling area for the shorter trusses on the left.  I did this to stay under 35' from the front door sill which is our area's requirement. 

 

 

Applying this logic to your current model results in the following.  I used an 8/12 pitch to determine where my 5' kneewalls and 8' ceiling heights would be within this hipped area.  This assumes you are permitted 32' 9" to the ridge.

And a 9/12 pitch would widen the room areas, but the highest ridge is then 34' 6".  Is that allowed?

 

Also, notice you have a couple of greater problems.  

1. Your stairwell & door are in the wrong place.  That's not where stairs up from below lands.  I've drawn the correct location above with a note.
2. The correct location also requires 81" ceiling minimum at the top of the steps and all hips won't achieve that at 8/12 or 9/12.   

Here's a 3D cross section at 5' high.  Again the 2nd door needs to fall under the roof line.

 

 

Here's a dormer drawn to capture the 2nd door (I've deleted the first.)  The interior shot shows 5' kneewalls rising to 8' ceiling plane.

Notice the door still cuts the exterior roof plane.  You can widen the dormer and extend the roofline down (cathedral into the stairwell), but its hard to mirror that look on the other side because the two gables bumps aren't equilateral.

 

If you could give me a bit more direction, like max height and what usable room space you are trying to achieve, I can work through it with you.  I would also assume you want a rear dormer overlooking the view from the deck.

 

Let me know your thoughts.

[Evolution]

11 hours ago, JiAngelo said:

Just to clarify,

Is your maximum building height 35'?  And are you trying to use all of the 3rd floor?

I ask because you've built your 3rd floor directly over your second floor perimeter walls.  The room defaults to 12" tall.  It should default to 109 3/8" or similar if you are ignoring top floor.

Typically you check ignore 3rd floor because you want the roof built on top of the 2nd floor walls and somewhere inside this rooftop you plan to place an attic area inside of trusses. 

 

Here's a plan I'm working on now.  The red lines are my truss control lines.  The blue lines define a 5' kneewall that slopes to 8' ceilings on the left side of the house and 9' ceilings on the right side of the house.  The blue lines are my attic room limits.  If my roof was hipped, I'd have a red outer box and a blue inner box over this same area.

 

 

Here's my room trusses Red is 9' ceiling area, White is 8' ceiling area, Blue is the 8' ceiling area for the shorter trusses on the left.  I did this to stay under 35' from the front door sill which is our area's requirement. 

 

 

Applying this logic to your current model results in the following.  I used an 8/12 pitch to determine where my 5' kneewalls and 8' ceiling heights would be within this hipped area.  This assumes you are permitted 32' 9" to the ridge.

And a 9/12 pitch would widen the room areas, but the highest ridge is then 34' 6".  Is that allowed?

 

Also, notice you have a couple of greater problems.  

1. Your stairwell & door are in the wrong place.  That's not where stairs up from below lands.  I've drawn the correct location above with a note.
2. The correct location also requires 81" ceiling minimum at the top of the steps and all hips won't achieve that at 8/12 or 9/12.   

Here's a 3D cross section at 5' high.  Again the 2nd door needs to fall under the roof line.

 

 

Here's a dormer drawn to capture the 2nd door (I've deleted the first.)  The interior shot shows 5' kneewalls rising to 8' ceiling plane.

Notice the door still cuts the exterior roof plane.  You can widen the dormer and extend the roofline down (cathedral into the stairwell), but its hard to mirror that look on the other side because the two gables bumps aren't equilateral.

 

If you could give me a bit more direction, like max height and what usable room space you are trying to achieve, I can work through it with you.  I would also assume you want a rear dormer overlooking the view from the deck.

 

Let me know your thoughts.

John, thanks for the detailed response. Note: this is the only tutorial I could find that addressed my issue of building a room in the attic without adding a full third floor, which is my goal-Designing a One-and-a-Half Story Roof - Video | Chief Architect and according to that Tut I needed to set the height low, thus 12" knee wall.

 

(YOU SAID: I would also assume you want a rear dormer overlooking the view from the deck.) Yes, I now have a space (room) I can use (if needed) but the intent is the boss wants to use it to add a balcony over-look where you have drawn the dormer (facing the water). He already has so much deck but insist on having that one extra spot to go out onto to look at the "sunsets". He will probably add the walls to enclose the space about +/-17' wide and the length is whatever he can get and may-may not finish it.

 

 That said, I basically have the area / attic space to work in. The main issue now is I couldn't get the walls on the end of the house away from the water to be "hip" style (although I have "HIP" selected for those walls) even after checking them to be hip. I am surprised that you were able to. Also, I may be able to go with a 12/12 pitch if the jurisdiction will allow. I'm waiting to hear from the building inspector to confirm the max-height.   Can you send the file back to me or did you overwrite it in X17? 

Thanks again, regards!

[JiAngelo]

Bob,

I am still on X16.  I've dabbled with X17, but it doesn't excite me.  I've attached the updated file.  Version 3 is using your perimeter walls, Version 4 is using a 16" truss heel height.  I abbreviated your file name.

 

I forgot to answer your original question.  You didn't have auto-roofs turned on.  That's why the roofs weren't changing to hip.  When I turned it on it said you had some edited roofs which it deleted and redrew as all hips.

 

Also, ignore top floor won't work with dormers (because it is ignoring top floor.)  And I just realized you have floor to ceiling windows, which means you need a floor above to place headers over the exterior openings on the second floor.  (or you need a raised heel height for trusses to hang on those headers.)

 

I went back to the second file you'd sent me.  I unchecked ignore top floor, changed 12" ceiling height to 1-1/2" (basically a 2x6 sill atop the floor structure.) And then turned on autoroofs. (for version 3)

In version 4 I changed your heel height to 16", deleted the perimeter walls and only used the dormer walls, adjusted to fit under the side roof planes.  This version has the roof building off the outer walls +16".  In both I extended the roof down over the stairwell to encapsulated it within the roof planes.  (I trimmed those walls to 6" overhang so that it didn't project past the Hip ridge.  The dormer is drawn at 97 3/8" ceiling height.  I didn't want to mess with the 60" kneewalls until you had stairwell figured out.  In V4 I went ahead and built some room trusses along the main area, using a quadruple truss where the dormer starts to thrust out.  I also created a cross section to make sure the stair height was equal or greater to 81" nosing to ceiling.  It looks like you may need to raise that heel height to 18" or 20".  V3 will build the roof trusses on top of the 3rd floor. (another downfall of that method.)

 

In both I tried extending the dormer to the rear of the home, but it is not centered on the door below, and can't cantilever past since there is no header below to carry the load.

 

Take a look, I hope this helps guide you.

 

CR WILLIAMS for CTF3.zip CR WILLIAMS for CTF4.zip

Edited Wednesday at 10:08 PM by JiAngelo
spelling

[Evolution]

13 hours ago, JiAngelo said:

Bob,

I am still on X16.  I've dabbled with X17, but it doesn't excite me.  I've attached the updated file.  Version 3 is using your perimeter walls, Version 4 is using a 16" truss heel height.  I abbreviated your file name.

 

I forgot to answer your original question.  You didn't have auto-roofs turned on.  That's why the roofs weren't changing to hip.  When I turned it on it said you had some edited roofs which it deleted and redrew as all hips.

 

Also, ignore top floor won't work with dormers (because it is ignoring top floor.)  And I just realized you have floor to ceiling windows, which means you need a floor above to place headers over the exterior openings on the second floor.  (or you need a raised heel height for trusses to hang on those headers.)

 

I went back to the second file you'd sent me.  I unchecked ignore top floor, changed 12" ceiling height to 1-1/2" (basically a 2x6 sill atop the floor structure.) And then turned on auto roofs. (for version 3)

In version 4 I changed your heel height to 16", deleted the perimeter walls and only used the dormer walls, adjusted to fit under the side roof planes.  This version has the roof building off the outer walls +16".  In both I extended the roof down over the stairwell to encapsulated it within the roof planes.  (I trimmed those walls to 6" overhang so that it didn't project past the Hip ridge.  The dormer is drawn at 97 3/8" ceiling height.  I didn't want to mess with the 60" knee walls until you had stairwell figured out.  In V4 I went ahead and built some room trusses along the main area, using a quadruple truss where the dormer starts to thrust out.  I also created a cross section to make sure the stair height was equal or greater to 81" nosing to ceiling.  It looks like you may need to raise that heel height to 18" or 20".  V3 will build the roof trusses on top of the 3rd floor. (another downfall of that method.)

 

In both I tried extending the dormer to the rear of the home, but it is not centered on the door below, and can't cantilever past since there is no header below to carry the load.

 

Take a look, I hope this helps guide you.

 

CR WILLIAMS for CTF3.zip 3.19 MB · 0 downloads CR WILLIAMS for CTF4.zip 3.17 MB · 0 downloads

Thanks for your intense help however, I am unable to open the files as I'm running X12 and I can't without upgrading to the newer version of Chief and it's not worth the expense. 

Also, you said (And I just realized you have floor to ceiling windows, which means you need a floor above to place headers over the exterior openings on the second floor.  (or you need a raised heel height for trusses to hang on those headers.) I’d planned to use I-joist or floor trusses to add support over the windows. When our Engineer provides his comments/structuraldesign, I will most likely need to drop the window heights to adjust for heavier headers.

 I went back to the second file you'd sent me.  I unchecked ignore top floor, changed 12" ceiling height to 1-1/2" (basically a 2x6 sill atop the floor structure.) And then turned on autoroofs. (for version 3) I used an auto-floating dormer on my latest rendition and was going to add framing later to frame the opening but for now I’ve got to figure out how to create an access to a small observation platform via doors in the dormer in lieu of windows. That will require some playing with the software if I can figure it out at all! I advised them we are already at max allowable height and the inspector may not like that idea plus it adds another opportunity for roof leaks.

In version 4 I changed your heel height to 16", deleted the perimeter walls and only used the dormer walls, adjusted to fit under the side roof planes.  This version has the roof building off the outer walls +16".  In both, I extended the roof down over the stairwell to encapsulated it within the roof planes. Obviously, you are more “experienced” with the software and since I’ve never been as deeply involved with using the various tools, I’m not quite sure how to do the things you mention here?

again, thanks for your time and help!

[JiAngelo]

Bob,

I fired up X12, worked exclusively on the CTF4 version.  I raised the roof 12" to allow headers over those windows and used an 8.5" pitch, adjusting the dormer room to fit.  I then switched to the second floor and drew a truss, changed it to Attic, then opened the detail and increased the middle bottom chord to 9-1/4" (the floor).  I copied the trusses, using a 4-ply at each end to support the joists under the dormers.

On the deck side, I held the dormer back a few feet to keep the hip look with larger windows.  

The attic space is a little over 600sf and you can reach it using your original stairwell, but the head height doesn't work on the landing. 

 

I've attached the X12 file.

 

CR WILLIAMS for CTF4-X12.zip

[Evolution]

Ji- I certainly didn't expect you to do all this!!!! Looks like if I raise the roof pitch to 12/12 would fix the header over the landing.  I'm calling this one solved with your gracious help and expertese with the Soft-ware.