Attic Trusses

**TeaMan** · 08-02-2009, 06:47 PM

I found a good article in the help database for Cheif Architect, Article 933. It explains it perfectly. I wasn't able to find an article in the HDP database. I found an article in the HDP database for a bonus room over a garage, article 904 that explains how to add a bonus room. It says to add a second floor to the structure, then go through the steps to add the bonus room. If I don't want a secon floor over the whole house, should I check room open below from the 2nd floor and create the ceiling planes manually? Am I on the right track, or is there a better way?
Thanks
TeaMan

**Curtis Johnson** · 08-02-2009, 09:09 PM

If your attic truss area is a bonus room, whether living space or just storage, the actual framing for the attic trusses will depend on the planned floor loading, if different than code requirements, and the spans of the framing members. The depths of the individual bottom chord members will be dependent on those specifications. I have seen some truss manufacturers build the floor components of the attic trusses like "floor trusses" and with single 2x members (e.g., 2 x 10's or 2 x 12's). So, depending on the detail you plan to show in your construction drawings, you may want to get your truss manufacturer to provide that information to eliminate any guess work on your part.

**tlsapp** · 08-03-2009, 03:01 AM

Teaman, is there a checkbox in the "create roof" section of HDP for " ignore second floor"?

Also, read this thread, there are some detailed instructions in it. http://www.chieftalk.com/showthread....344#post106344
Let me know if you have problems.
I don't use HDP, but the program may be similar enough to X2 that I can help you.

**TeaMan** · 08-03-2009, 03:18 PM

Leslie, yes I can tell HDP to ignore the 2nd floor. My plan since the garage isn't that wide was to put 4' stub walls above the 2nd floor and build somewhat of a sissors truss to make the ceiling. My pitch is 8 in 12 and width of the garage is 26' so I'll have to get the roof up a bit on stub walls to make a reasonable room. I guess I wasn't planning on attic trusses for this room, they worked well on teh 40' wide workshop, but here the room will be too small.

If I create a roof and ignore the 2nd floor, will it give me trouble in the garage where I want to put the stub walls and build the roof over them?

Am I on the right track?

TeaMan

**lbuttery** · 08-03-2009, 03:48 PM

remember floor A can't have rooms defined

Lew

**TeaMan** · 08-03-2009, 04:19 PM

What do you mean Lew? If I don't create a second floor for the whole house, I can't create a second floor above the garage?

TeaMan

**lbuttery** · 08-03-2009, 04:35 PM

Yes, you can have floor 2 in one area and not another

I was just reminding that floor A can't have rooms defined

Lew

**TeaMan** · 08-03-2009, 05:12 PM

Gottcha, but now I'm confused. How do I create a second floor over just part of the house, the garage? Reading article 904 to create a bonus room doesn't deal with this, but it seems to me to be the way this should be done. I tried building the roof ignoring the second floor, and drew the stub walls on the second floor above the garage and it did just as I told it, and ignored the second floor.

Somethings not working. I'll start from scratch.

TeaMan

**tlsapp** · 08-03-2009, 06:11 PM

Try creating a second floor for the garage, with your ceiling height on that floor set to the height of your stub walls. Don't check "ignore second floor". It sounds like what you are trying to do is not an attic truss, but a scissor truss sitting on a short wall.

**lbuttery** · 08-03-2009, 06:42 PM

use the create floor tool and instead of "create floor same as floor1" select "create blank floor" and then draw the walls over the garage as needed

or "create floor same as floor 1" and then delete unneeded walls

Lew

**Allen42acj** · 08-04-2009, 02:13 AM

You need to use Ceiling planes at a lower pitch under the main roof.

**TeaMan** · 08-05-2009, 04:33 PM

Allen, would that be for the area where the ceiling plane is the same angle as the roof plane, ie between the stub wall and the flat ceiling? I would guess for more insulation value?

TeaMan

**Curtis Johnson** · 08-05-2009, 04:51 PM

I think if you consult with your truss manufacturer, he could design and build your attic trusses such that the sloped part of the attic truss could have extra depth or thickness for insulation where the knee walls (actually your attic truss verticals would be the knee walls) connect with the trusses. If you don't want a portion of the ceiling to be flat (i.e., scissor or parallel chord), then you'll need to define those elements for the truss guy and I am sure he'll squawk if what you want to do would be difficult to build trusses for. So, set your ceiling planes up how you think you will want them and then rebuild an attic truss and see what it looks like ... then shoot it to your truss guy and see what he says.

**Curtis Johnson** · 08-05-2009, 06:07 PM

Here's a quicky I did to show how an attic truss would look with a scissor ceiling. The roof is 10:12; the ceiling 7:12. The roof planes were generated from the first floor but probably should have been built from the 2nd floor. Chief will build the truss but, without a flat ceiling and floor system (see warning), it will not generate an "attic truss" per se. When I built the 2nd floor I gave it a 2' ceiling height. Also, I deliberately made the bottom chord of the truss to be a 2 x 12 in the truss tab of the framing dbx. As I said before, I think a truss builder could build a truss like this. I could have made the sloped ceiling planes parallel with the roof planes ... and probably use a flat ceiling with this option ... depending on the truss guy, maybe just parallel the roof planes to a peak similar to the vaulted ceiling I am showing. I think there is a minimum amount of depth that they can make parallel chord trusses with, depending on spans and snow loads. You'd have to check on that.