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No idea how the trusses are going to look like

No idea how the trusses are going to look like

No idea how the trusses are going to look like

(OP)
Ok, so I have this big residential duplex project.  The shape of the roof is so complicated with bunch of dormers facing on all sides.  The owner/contractor said that the roof is going to be trusses.  I have no idea how the trusses are going to be laid.  How will I be able to design this?  Kinda hard to design the house if you dont know where the girder trusses are going to be.  In so areas, I dont even know which direction the truss is going to run.  Shall I insist the owner to give the drawings to the truss manufacturer first?  Then they can give me the shop drawings then I can design the rest of the house.  The owner wants to get his permit asap and then contact the truss manuf.  I think it should be the other way around.  I am so confused because top of the windows at the dormers are higher than the top plates of the upperfloor walls.  Any input?

RE: No idea how the trusses are going to look like

Get the preliminary truss drawings first.

Only way you can design the building...

Windows thru the top plate... That might be a problem using them as chords for the roof diaphragm..

Good luck

RE: No idea how the trusses are going to look like

You can specify where to put girders.  The truss manufacturer will design it per your design, unless it doesn't make any sense where you locate them.  
Are the dormers "active" or are they "false".  If they are active, you will need girder trusses on either side of the dormer.  If not, they can build the dormer walls directly on top of the roof.  

RE: No idea how the trusses are going to look like

Trusses generally run either perpindicular to the ridge or perpindicular to the walls.  Do niehter of those work?  

I would make telling the owner you have no idea my absolute last resort.  That just makes you look bad.  Now I'm not saying to do something you are not qualified to do, but you should have put on your thinking cap and exhausted your intellect before telling the client you don't have a clue.

If you have problems with framing the trusses because of high windows, dormers or other fun things, remember that you can add a bearing wall(s) if necessary and turn the framing another direction, add girders, beams, whatever you need to make it work.  All that requires coordination with the architect or owner but that's what we do.  If necessary you may also have to stick-frame a portion, but I would avoid that also if possible.  Since you've budgetted for trusses, you may not have time left in the budget for additional work due to designing roof framing.

RE: No idea how the trusses are going to look like

I would suggest you get the owner to get a preliminary layout from the truss manufacturer first. You could use the excuse that the truss manufacturer best knows the most economical layout and you want to avoid any redesign if they choose to do it differently than what you think.

I would then talk to the architect about the local dormer details e.t.c. and explain the consequences and try to get them to agree to a simpler detail.

It is always best to try and talk the architect out of difficult details in the beginning of a project (politically: "suggestions for economy") than to try and talk them out of it whan they have already fully detailed it.

RE: No idea how the trusses are going to look like

If the top plate is interrupted by the windows, what happens to the ceiling?

RE: No idea how the trusses are going to look like

(OP)
Ill post some pictures in a few hours.  I have a feeling the trusses will go the other direction @ the dormers.  I think there will be a lot of overframing.  I'll show you guys 1st thing in the morning at work.

RE: No idea how the trusses are going to look like

(OP)
Ok, here is the roof plan. Notice, there are a lot of dead spaces because the spring height is not high enough.  So probably the trusses will sit on the inner walls. Please go to this link.

http://www.usagani.com/other/ROOF.jpg

RE: No idea how the trusses are going to look like

I haven't had so much fun since the orphanage burned down...

Can you give a hint about the scale? and can you indicate which windows go above the top plate?

The TPIC recommends engineered involvement in the installation for trusses in excess of 60' and some local codes use 40'. TPIC also recommends engineering involvement for trusses that are piggybacked due to the height.  Lateral bracing for this would also be an issue.

RE: No idea how the trusses are going to look like

(OP)
The east wall is 31' wide, the length is 141'.  

RE: No idea how the trusses are going to look like

and the windows?

Dik

RE: No idea how the trusses are going to look like

Are you planning on building the trusses yourself?  If so, do your own design.

If you are planning on buying the truss from a wood or light gauge manufacturer, LET THEM DO THE DESIGN.

Most truss manufacturers would be happy to help you with your prelim dwgs - I know my company would.  They know the limitations of their product and they know how things are typically done.

Why bang your head against a wall, and end up with something the truss manuf. will likely change anyway?  If there are bearing issues, like at your dormers, let them tip you off right away!

You won't look "stupid" asking for help, but you will when trusses arrive onsite that don't work if you do the design yourself.  

Engineering is knowing how to find answers to your problems - not necessarily coming up with all the answers yourself.

RE: No idea how the trusses are going to look like

Looking at the roof plan and there are some major issues regarding lining up the window openings on each side.  You require intermediate supports because a girder truss framing on each side of a dormer, lands in the middle of the gable on the opposite side.  It's possible to put girder trusses on the far sides of the dormers on either side and use longer grider trusses framing between these... but it's really messy...

Dik

RE: No idea how the trusses are going to look like

(OP)
Yes, it sounds like asking for a preliminary truss design is the best way to do this project.  Ill tell the owner/contractor to do that first.  

RE: No idea how the trusses are going to look like

I would not even think about finishing without having the truss layout from the truss guys.  Just a matter of educating your owner (easier said than done sometimes).

RE: No idea how the trusses are going to look like

I just had to applaud this statement.

"Engineering is knowing how to find answers to your problems - not necessarily coming up with all the answers yourself."

I know this is an old thread. I hope you got it all figured out.


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