rfcomm2k

Manual truss top chord extends beyond bottom chord

Recommended Posts

I manually built the trusses and have a problem with the top chords. The bottom of the bottom chord members rest on top of the double top plate for the walls. The top chord should end at the same place, but instead it is extending past the bottom chord. The bottom tip of the top chord member is exactly 14 1/2" below the top of the wall plates, but it should be flush with it. Also, the bottom chords do not extend beyond the walls, which is probably where the problem is but I cannot see how to adjust them. I tried unchecking "Trim To Soffis" but that did not help.

 

To describe it in another way, picture the ceiling rafters extending past the walls by the distance specified for the eave overhang (in this case 24"). Then the roof rafters END at the end of these ceiling joists in a plumb cut to which the fascia is attached.

 

I cannot upload a plan right now because this PC is NOT the same PC I am using for the software at this time.

 

Share this post


Link to post
Share on other sites

Maybe you could comment on these 2?

Snap97.jpg

Share this post


Link to post
Share on other sites

Thanks Eric. The one in the background is what I am striving for, but the one in the foreground is what I have

 

Share this post


Link to post
Share on other sites

Eric, I do not have Rafter Tails option in HDP 2014

 

Share this post


Link to post
Share on other sites

This has nothing to do with rafter tails. Look at the first panel in the Build Roof dialog.

Share this post


Link to post
Share on other sites

OK, I am looking at the first panel in the build roof dialog, and there is no place to specify roof height. And there is no tab called rafter tails either.

Share this post


Link to post
Share on other sites

OK, I see the box you are circling here. I set mine to 12", made sure the check boxes are as you have them, and clicked OK. I then clicked Build Framing Roof Truss, and added my first truss. It still turned out just like the one in the foreground of your pict.

 

Share this post


Link to post
Share on other sites

I just started my 2015 version of Pro and it has the option.

 

Your 2014 version may have it in a different place. Have you searched Help for Roof Height?

Share this post


Link to post
Share on other sites

I was not building or showing roof framing because I was using trusses instead. I purposely skipped the roof framing because I did not want to add additional material to the material list that was not required. But then, I never got around to checking how much material was being added. For all I know, maybe the TRUSS material is not even calculated. Will check that later.

 

Apparently I HAVE to build roof framing in order to build trusses properly.

 

I am almost there with the design, but the top chord of the truss still extends past the bottom of the bottom chord, but now only about 2.5"

 

Share this post


Link to post
Share on other sites
2 minutes ago, rfcomm2k said:

Apparently I HAVE to build roof framing in order to build trusses properly.

 

No. You do need to build/rebuild the roof before drawing the truss.

 

3 minutes ago, rfcomm2k said:

I am almost there with the design, but the top chord of the truss still extends past the bottom of the bottom chord, but now only about 2.5"

 

The 12" raise may need to be adjusted, depending on your overhang. You can do the math, or just raise / lower a bit and then rebuild.

Share this post


Link to post
Share on other sites

Well, I just cannot get my trusses to look like yours do Eric. I have attached the plan now, and if you look at an elevation of the north wall you will see I placed 1 truss. You may need to turn off roof planes in order to see it properly.

 

barn 1 framed walls.plan

Share this post


Link to post
Share on other sites

I drew a second structure in your plan and had the same problem as you.

 

I copied your walls into a new plan, and the trusses built correctly.

 

Guessing there is an incorrect setting somewhere. Try a new plan.

 

Don't build any framing, just the roof planes. Place a truss.

 

 

Snap103.jpg

Share this post


Link to post
Share on other sites

Tried restarting everything, including the PC. New plan, first thing done was to edit the defaults to set the rafter size to 5 1/2 instead of 9 1/4 and ridge to 9 1/2 instead of 11 1/4. Then clicked OK

 

Next was I built 4 exterior walls.

 

Then I clicked Build/Roof, checked auto rebuild roofs, changed raise/lower from ceiling to 12", left the eave overhang at 18" for now.. checked the box for build roof planes and clicked OK

 

Then I clicked Build/Framing/Roof Truss and drew in the first truss. I then did a wall elevation. The truss top chord extends below the bottom chord by 2". So I changed the Raise/lower from ceiling height to 14" and rebuilt the roof. I deleted the old truss and added a new one. IT WORKED!

 

So to test a theory, I changed the eave to 24" but left the raise/lower setting at 14". This time the top chord extends below bottom chord by 4". So I changed the raise/lower setting from 14" to 18" and it worked again.

 

So now I have an understanding about the relationship between the raise/lower setting and the eaves.

 

Thanks Eric for making me think about this and for your advice!

 

Share this post


Link to post
Share on other sites

Please sign in to comment

You will be able to leave a comment after signing in



Sign In Now