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Internet engineers, Can I raise this truss?

TrikeKid

TrikeKid

Junk Hoarder
Joined
May 19, 2020
Member Number
246
Messages
1,785
Loc
Spana-graham, WA
My home shop is a little 20x30 pole building, it ain't much but it beats the fuck out of what I had before. Biggest hang up I have with it is the walls and ceiling are lower than I would've built them, kinda lacking on head room.

It's not so bad except this stupid fucking truss right smack in the middle. The previous owner of the place sheet-rocked this thing and that made it even worse for feeling like two separate rooms. I pulled the sheet-rock off tonight and it's better with the lights being able to shine through it, but it's still just there taking up space. Is my shit gonna collapse if I double up the top chords and put a collar tie in where the existing 2x4 web/gussets meet them now, then hack all the existing lower bits out?

PXL_20231225_020102606.jpg
 
TrikeKid said:
My home shop is a little 20x30 pole building, it ain't much but it beats the fuck out of what I had before. Biggest hang up I have with it is the walls and ceiling are lower than I would've built them, kinda lacking on head room.

It's not so bad except this stupid fucking truss right smack in the middle. The previous owner of the place sheet-rocked this thing and that made it even worse for feeling like two separate rooms. I pulled the sheet-rock off tonight and it's better with the lights being able to shine through it, but it's still just there taking up space. Is my shit gonna collapse if I double up the top chords and put a collar tie in where the existing 2x4 web/gussets meet them now, then hack all the existing lower bits out?

PXL_20231225_020102606.jpg
Click to expand...
How is the rest of the roof supported? Scissor trusses up higher?
 
Benny said:
How is the rest of the roof supported? Scissor trusses up higher?
Click to expand...
2x6's across the top chords of the trusses. They're doubled up kinda oddly (to my non carpenter brain), one lays flat (wide face) down on the top chord then another up on edge along them
 
What is the span from that truss to either end wall? It looked way longer than the standard 10-12'
 
Interesting . 10ft is the farthest span I’ve seen with 2x6’s as purlins . The Amish like to build them that way and they seem to hold up fine .
 
Is there building codes where you are? Do you know if this building was inspected? Just curious

If I had to get rid of that truss, I would build a replacement from I-beams. Someone smarter than me can recommend sizes. Just follow the shape of the top chord.
 
Codes yes, probably inspected at some point I don't really know. This county it's easier to just build something and ask forgiveness later vs going through the permitting/inspection process so that's what a lot of folks do. This has been up since 2000-ish when the house was remodeled.

My old man built a 40x60 shop and several additions on the house over the years with zero permitting/inspection. County just notices it on their aerial photos and stops by to add it to your tax bill as long as it's not an obvious hazard.
 
Yes, that's a bad idea. The lower member of the truss is critical to the strength, and it needs to join the top member at the ends where it's supported. Trusses work because they are engineered as a complete structure, and they don't react well to people trying to modify them. No way to get around that, especially with the truss carrying that much length of roof.

Only thing I could see would be a steel beam structure, and even that isn't exactly trivial because of the angled joint at the top. Then you also run into the problem of needing to properly secure it to the supports, and roof structure to the beam, especially with it having to go in the same spot as the existing truss. Probably just as easy at that point to jack the whole building up and replace the posts under it.
 
sdmuleman said:
Trusses work because they are engineered as a complete structure, and they don't react well to people trying to modify them. No way to get around that, especially with the truss carrying that much length of roof.
Click to expand...

Pretty easy to modify shit and come out ahead if you aren't as hellbent on reducing material cost as whoever did the initial build was.
 
For what it's worth, I got the idea here. Presumably glthfj60's house hasn't fallen down yet but he's got more trusses than me

irate4x4.com

GLTHFJ60's Garage Chronicles

Had a "build" thread to document this stuff on GJ, but GJ seems to be full of geriatric people who pay people to do work these days, not so much people building things themselves. I've got another phase of structure changes coming up soon hopefully so I figured I'd move some junk here. GJ...
irate4x4.com irate4x4.com
 
With that kind of span, I wouldn’t mess with it without talking to a structural enginerd.
The likely result probably won’t give you what you’re after anyway.

What’s the end game? Hoist/lift?
 
NORDFORD said:
With that kind of span, I wouldn’t mess with it without talking to a structural enginerd.
The likely result probably won’t give you what you’re after anyway.

What’s the end game? Hoist/lift?
Click to expand...
Just more headroom/open space to move tall shit around in the shop, more room to jack up a pickup without having to make sure the cab isn't under this thing.
 
Weasel said:
Ryan283 he designs trusses daily

If I'd had to guess I'd say no.
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No to the specific question being asked.
that truss is part of an engineered structure. Removing the bottom chord of the truss will create ridiculous horizon deflection.
(structure blowing outwards).
adding a collar tie mid truss depth is a novel remedy, but not adequate or appropriate.

you may contact the truss supplier and request a field-repair, siting VERY specific conditions for modificatio.

put down the sawzall until given a green light.
 
Theres only one way to find out. Have a couple drinks, hang some lumber, and bust out the chainsaw.

You will know soon if it was a good idea...
 
Ryan283 said:
No to the specific question being asked.
that truss is part of an engineered structure. Removing the bottom chord of the truss will create ridiculous horizon deflection.
(structure blowing outwards).
adding a collar tie mid truss depth is a novel remedy, but not adequate or appropriate.

you may contact the truss supplier and request a field-repair, siting VERY specific conditions for modificatio.

put down the sawzall until given a green light.
Click to expand...
That's what I needed to hear from someone in the biz, thanks. I think I'll let it be.
 
Can you pour footings and brace the building from outside the way that a lot of barns that are built for storage of bulk material are?
 
Ryan283 said:
No to the specific question being asked.
that truss is part of an engineered structure. Removing the bottom chord of the truss will create ridiculous horizon deflection.
(structure blowing outwards).
adding a collar tie mid truss depth is a novel remedy, but not adequate or appropriate.

you may contact the truss supplier and request a field-repair, siting VERY specific conditions for modificatio.

put down the sawzall until given a green light.
Click to expand...
That looks like a stack of multiple trusses, what about having a set of scissor trusses built to fit under the top chord, then taking the bottom chord/braces out one truss at a time and setting the new truss under it?
Something following the red line:
1000086947.png

I would say replace the whole truss system one at a time, but the roof 2x6s are probably nailed in solidly enough to make that difficult.

Aaron Z
 
If your truss is the same height as the door, can’t really see changing it. It would be nice if you put a trolly/hoist on it. That would make it look like it’s supposed to be there.

I would also put a curtain on it so you could heat one half or paint booth.
 
Is there a ridge beam up in the roof structure supporting the rest of the rafters? Had to tell how this was built, it's a weird mix of styles.

My garage has not fallen down. A structural engineer friend of mine gave me the green light before I started.
 
GLTHFJ60 said:
Is there a ridge beam up in the roof structure supporting the rest of the rafters? Had to tell how this was built, it's a weird mix of styles.

My garage has not fallen down. A structural engineer friend of mine gave me the green light before I started.
Click to expand...
It sounds like it's setup something like this: Pole barn roof question
1000087002.png




Aaron Z
 
Potential clients are always coming to me with questions along these lines. My response is typically "Anything is possible, how much time and money do you want to throw at it?"

What you want to do is basically removing the structure of the truss, so you have to replace that with something else. As aczlan shows, it looks like your situation is similar and that the truss is the main support without a ridge beam. As Ryan283 says, there are a lot of forces going on in a truss. The top chord is supporting the load, but the bottom chord is resisting the outward push against the walls and pulling it back together while the web is keeping the top chord and bottom chord from deflecting. Moving or eliminating any of them redistributes and potentially magnifies all those loads. And even if you don't get snow, there is always the possibility of wind. I see too many things that were "fine" right up until the moment they weren't...

My inclination would be to replace it with a rigid steel frame if you're serious about changing it. Build a temporary wall on either side of the trust to support the purlins, cut out the truss and remove the columns, and put the steel structure in its place. Welded or bolted connections are going to handle the rotational forces at the connections easier than trying to do it with wood.
 
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