Parapet Roof Framing: different ceiling and roof heights room to room

[triscot]

I am making the third addition to a slab foundation parapet roof single story house.  The original house was built 1946 and I am trying to use Home Designer Pro 10 to create a framing plan:

• ceiling joists are 96 ½” above finished floor and are 2x6’ 16 o.c. and run South to North.

• The floor to bottom of parapet roof joists is 108”.  The joists are 2x4 16” o.c. These also run North to South with a slope of ¼” per foot.

• The exterior walls are slump block 12’ height

First room addition 15’x26’ 1992:

• Walls are 2x6 16” o.c. 12’ tall to match existing roof line

• Roof/ceiling 2x12 16” o.c. running East to West with a slope of ¼ per foot

• Ceiling height 123.75” (east side) 120” (west side)

Second room addition 15’x15’ 2013:

• Walls are 2x6 16” o.c. 12’ tall to match existing roof line

• Roof/ceiling 2x12 16” o.c. running South to North with a slope of ½ per foot

• Ceiling height 122 1/2” (South side) 115” (North side)

Third, in planning stage multi room addition:

This final addition is a multi room addition which removes part of the original roof, raises it to match the 1992 addition, and removes a 1946 garage roof and incorporates this freestanding structure to be part of the main house.  It’s roof/wall system to match the 1992 specs.

 

The problems I am having are trying to create roof framing plans where:

• All roof planes are flat (¼ pitch minimum)

• All exterior walls are 12’

• different rooms have different ceiling/roof heights, different ceiling roof compositions, or use the roof as the ceiling (1992, 2013)

• different rooms have different roof heights

• different rooms have different joist directions

I have read tutorials on the methods to make a parapet roof structure, built a second story with short walls, no roof or ceiling, and use the 2nd story’s  floor as the 1st stories roof.  This technique works great if the roof is the same height for the whole building, but I cannot make it work with a varied roof height. So three big problems:

1. The wall framing is wrong; instead of one wall made up of 2x6x144” lumber I get 1st floor wall with a “pony wall on top.

2. The bigger problem is I cannot figure out how to “change the absolute 2nd story floor height (1st floor to bottom of 2nd story floor) room to room.

3. The last problem is I cannot seem to get the joist direction tool or bearing line tool to work.  I can apply them but the 2nd story floor joists do not change direction.

Any help welcome!

 

[solver]

Without a better understanding of what you are trying to model, making specific suggestions is difficult.

 

Do you have pictures you could post. An aerial view showing the roof would help.

 

 

[triscot]

Thanks Eric your rending technique is just what I need if it can be done or a room by room basis. Could you explain the steps used to create? Can the next room have the roof at a different height? and in the next roof can you change the roof joists to run 90 degrees to the first room?

 

I cannot figure out how to add images to this thread so I created a gallery https://chieftalk.chiefarchitect.com/index.php?/gallery/album/152-parapet-roof-problelms/​

 

I hope you can see this gallery.​

[solver]

To add images, More Reply Options (right by Post), then Choose the image, and Attach This File.

 

I see the gallery, but somehow it's on the Chief Architect site and not the Home Designer site.

 

I was thinking images of the actual house. Often it's the small details that make a difference in what is recommended.

 

For example, is there a parapet around each room/section, or only around the perimeter, or some combination?

 

The image I posted is a room with a 10' ceiling, No Roof and No Ceiling. I manually drew a roof plane within the walls, and lowered it to 8' with a 1/4" pitch.

 

The rafter/joist direction runs the direction of the pitch, and I'm not sure how to change it.

 

[triscot]

Thanks for the tips, and sorry for slow reply.  Using your methods I rebuild plans and was able to control joist direction, and roof/ceiling height!  Two issues left I cannot figure out.

1. How to get the joists to "scabb" over the top of load bearing walls, or butt to the side of load bearing walls
2. How to draw a ceiling below this parapet roof technique.

I have uploaded several pictures to attempt to show the issues 

[solver]

I believe only floor or ceiling joist may be set to lap over a wall, not rafters.

 

You can draw in a ceiling plane just like drawing in a roof plane.