×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Monitor Roof Truss

Monitor Roof Truss

Monitor Roof Truss

(OP)
Has anyone ever done a monitor roof truss?

I am designing an outbuilding that is 30' wide and I want to place a truss with a 12' attic space and a monitor configuration. I just wondered if anyone has experience with these.

Thanks

RE: Monitor Roof Truss

Have done many room-in-attic trusses.  Not sure what a monitor configuration is??  Pic or drwg??

RE: Monitor Roof Truss

I think this is a hammerhead configured truss.

Mike McCann
MMC Engineering
Motto:  KISS
Motivation:  Don't ask

RE: Monitor Roof Truss

(OP)
Here is a rough sketch. I am looking at building a bank barn with the attic level for an office/storage space. I want a classic barn look, but do not want to try to roof a gambrel way up in the air.

I am a bit concerned about the uprights on either side of the attic room. They would seem to have a lot of force pushing in on them.

I am coming up with a total height if 11'1 3/16". Is this transportable?

Any suggestions for modifications and cost savings would be appreciated.

Thanks again.

Cliff

RE: Monitor Roof Truss

I see said the blind man as he picked up his hammer and saw.

This is going to be a tough one.  This config gives little truss action - acts more like a beam.  The bottom chord will probably be a 2x10 or 2x12 all the way across.  

The height should be OK..

I would get with your local truss supplier sooner than later.  They have access to software that can analyze these types of trusses very quickly and give you a price.  They can also verify their shipping capabilites.

RE: Monitor Roof Truss

All of these I have dealt with or seen in barns had a row of posts and beams supporting the center area walls.  None of them were free spanning trusses supported only on the side walls.

RE: Monitor Roof Truss

That's post and beam construction, not a truss.

RE: Monitor Roof Truss

A VERY high grade of 2x12 - maybe 8'' or 12'' oc might work??  Deflection might(will) be a problem!!

IF you can put a wall or beam down the middle - should not be problem!!

Go see a truss guy

RE: Monitor Roof Truss

It appears to me that you will have problems with the 2nd story walls as they will have to transfer the lower top chord compressive forces to the side of the walls which will have to be stiff enough to tranfer (through bending) to the little truss at the middle of the building.  A simple truss program can analyze this, but it's going to be expensive to build.  Do you have any snow loads or high wind loads?

RE: Monitor Roof Truss

This shape is most likely not possible due to lack of triangulation. There will be excessive shear and bending stresses in the vertical elements due to the lower sloped chords pushing up against the walls.

In addition, there is shape-induced drift loading on this truss. The shape of the frame itself will cause snow accumulation on the lower roof areas, something which you need to take into account.

Your main option is to provide additional supports, preferably under the vertical wall elements of the frame.

Alternatively, it is possible to run a compression element from the ceiling chord down to where the lower sloped chords intersect the vertical members. These elements will resist the "push" of the lower chord, and will significantly stiffen this frame. The only drawback is that you're going to lose ceiling height because the members will cut into your room area. Maybe not a problem if its storage only, but if you want an office it may not be practical.

Approach a truss design company and they should be able to conceptualize this design for you and tell you if it works or not.

RE: Monitor Roof Truss

(OP)
Thanks for all the suggestions. You are being very helpful. I am just trying to find something practical BEFORE wasting someone's commercial time.

My house has a similar situation with a 34' gable span and a 15' attic room. Worked great, but I do not like walking on the 8:12 pitch roof.

Would trussing under the floor help my problem? I would not mind raising the roof a little if I can still make this work. I am also not completely against going to a gambrel roof. The gambrel just makes it hard to roof and I loose my side windows.

Thanks again,

Cliff

RE: Monitor Roof Truss

Yes, trusses spanning the 37' would work fine.  Then you can build the attic floor and roof off the trusses.  That takes care of vertical support...now remember the lateral forces.

RE: Monitor Roof Truss

I have done this in the past with TrusWal and TeeLok software. I assume you can't add any internal bearings....it's pretty difficult if you can't. You can make a mansard truss, add live floor load to the top of the bottom chord in the dropped section along with point loads for the walls and other vertical loads from the rest of the roof and room....some lateral loads for wind, etc..... You may have to decrease the oc spacing quite a bit. You can also get a PE to design or if the program will let you sister a floor joist beside it to carry the room and point loads. Like I said, not easy, but I it may be doable. I wish I still had the software.

RE: Monitor Roof Truss

you might consider using 8' trusses running perpendicular to the plane of this section with small monoslope trusses for the lower roof.

RE: Monitor Roof Truss

depending on the garage dimension in the other direction, you could use 3' deep or so girder trusses to support the monotrusses and then build a 5' tall wall on top to give you your 8'. Girder truses can span then out of plane direction

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources