Truss Modification for Car Lift

[Falcon67]

Had forgotten about this thread - well done. Give me a good idea how to fix up my lift area. Easier here because my framing members are already way bigger than what was used in your original trusses.

 

[Jim greengo]

Maybe I'm the only one... but all this was quite confusing since there was no link to the modifications that astroracer did to his trusses?

I did some searching and found that astroracer's truss modifications are discussed on post #13 here: http://www.garagejournal.com/forum/showthread.php?t=330774&highlight=truss

Here's his quote:



Looks like a lot of structure has been added and the installation looks great. All that additional sheathing really helps to strengthen the framing.

Neither I nor anybody else here can say if this will or won't work without knowing more.

Looks pretty well thought out to me.

 

[Jim greengo]

Thank You!
The modifications WERE well engineered and well executed. I am VERY confident they will continue to do the job they were designed to do.
I posted them up as an example of what can be done. I did not expect the unabashed deriding I received. NO ONE has asked how the mods were engineered or even asked for more info. They just start swinging away with their holier then thou bats.
The lack of respect on this site is really getting old...
Mark

 

[tulowd]

In the midst of laying out an oversized triple car garage (41x25) workshop....with only 8 ft height from the bottom of trusses to the floor. Am going to include at least one 2 post asymetrical hoist/lift in the plans, since there is a 67 Camaro the owner wants me to finish restoring for him once this is operational. The 2 pc internal truss sistering solution is likely more practical / possibly less expensive to receive a stamped drawing for insurance purposes. Going to hopefully get into the ceiling and measure/make a sketch of the existing trusses (2 ft OC, 25 ft clear span), methinks its a 5 on 12 roof pitch but need to confirm obviously.

There are two truss manufacturers within 15 min, so at least there will be some options. Thinking 4 or 5 trusses are in the way, clearance 'box' needs to be 11 H x 8-10ft W x 10 L. Of course, if we want to put his Ram 2500 Cummins in the air the H number will need to go up a couple of feet.

Appreciate everyone's comments thus far; I have discussed the beginnings of this with my brother who runs a construction company and my best pal from high school who is a mechanical engineer. Their advice was to flesh out the 2 pc custom truss additions, since it will be one stop shopping for the drawing and the trusses. The supplier of choice should also be able to supply or recommend a contractor to install them. Will add info as it becomes available. Here is the initial rough sketch of the floor plan and some pics as an FYI.

And yes, of course the hoist bay garage door will need a different solution as well, which could impact the whole solution method as well.

 

[Mainiac Mat]

"buy 3 new scissors trusses that match the pitch and heel height of the existing trusses, then install them next to the existing trusses, then cut away the bottom chord of the existing truss."

I think this is the best advise posted so far. But I personally, would never modify a truss framed roof.

 

[tulowd]

"buy 3 new scissors trusses that match the pitch and heel height of the existing trusses, then install them next to the existing trusses, then cut away the bottom chord of the existing truss."

I think this is the best advise posted so far. But I personally, would never modify a truss framed roof.

Thank You; so I understand fully - you wouldn't mod the trusses or add scissor trusses sistered in at all?
In other words, live with the roof as is?

 

[Oatmealman]

I modified the trusses in my shop to make height for a lift, I did it one at a time and added knee braces that tied the walls to the truss and moved the rafter ties up to my desired height and laminated every joint with 1/2 inch ply and liquid nails and 8 or so nails from each side. I started at the front and moved my way to the back and used a floor jack and a 4x4 to hold the ridge beam in place while modifying each one and the ridge beam stayed exactly the same measurement as before. I also had a portly neighbor go up the roof and stand on the ridge and measured for deflection and saw none.

 

[Meames01]

I modified the trusses in my shop to make height for a lift, I did it one at a time and added knee braces that tied the walls to the truss and moved the rafter ties up to my desired height and laminated every joint with 1/2 inch ply and liquid nails and 8 or so nails from each side. I started at the front and moved my way to the back and used a floor jack and a 4x4 to hold the ridge beam in place while modifying each one and the ridge beam stayed exactly the same measurement as before. I also had a portly neighbor go up the roof and stand on the ridge and measured for deflection and saw none.

LOL, Field Tested.

 

[Oatmealman]

LOL, Field Tested.

I mean I wanted to know if it was gonna deflect and I figured I should know that before it snowed so I could make corrections before hand. To call him portly isn't fair, he's a solid 350-400lbs.

 

[Mainiac Mat]

Thank You; so I understand fully - you wouldn't mod the trusses or add scissor trusses sistered in at all?
In other words, live with the roof as is?

I personally wouldn't modify a truss framed roof. But I may be more conservative than others.

If you're going to do so, I think the scissor truss option recommended by others is the best plan.

However, installing this may be a ******. And if your roof pitch is shallow, then you might not gain that much headroom for all your efforts.

 

[firebirdparts]

You know, we used to have raise=the=ceiling threads one a week, but we haven't had any at all for months, maybe a year. Wonder why.

Anyway, for a modest size building and just one lift for tulowd bumping the thread, it's not hard. Having a purlin style roof over the lift will work. Wall stiffening will work (look carefully at rafter attachment). Scissor trusses too low in this low building.

 

[adsinnott1]

I don’t post this much due to the “OMG, you will die”. I have had half my shops trusses modified for 2 years now with plenty of ice/ snow. No deflection.

Mostly followed this guys video:

 

[Oatmealman]

I don’t post this much due to the “OMG, you will die”. I have had half my shops trusses modified for 2 years now with plenty of ice/ snow. No deflection.

Mostly followed this guys video:

OMG YOUR GONNA DIE!

but on a more serious note, what lift is that?

 

[adsinnott1]

OMG YOUR GONNA DIE!

but on a more serious note, what lift is that?

Its an older lift. Brand is Gemini Lifts out of Texas. No longer in business. Parts are still somewhat available and interchangeable with some older rotary lifts. Was a FB marketplace find less than a mile from my house. The guy never got it fully up and functional. Had brand new lift cylinders, slider blocks, cables, and frame pads for it. I would have preferred a clear floor with 3 stage arms, but for $700 and all new parts I couldn't beat it. Its perfect for what I do. I have even lifted my CC, long bed F350, but can't lift it all the way because the truck is too long for my shop..

 

[C-S-H]

A homebrewed scissor truss design:

Load on it = (2' truss spa)(30' span)(15psf DL + 25 psf Snow) = 2400 Lbs
Bending Moment = (2400 Lbs)(30' span)(12"/')/8 = 108,000 Lb-in at midspan
Force in bottom chords = (108,000 Lb-in)/(24" structural depth at midspan) = 4500 Lb. (horizontal component)

How are you going to properly connect the two bottom chords of a scissor truss with bolts, nails or screws? It takes truss plates.

 

[firebirdparts]

Due to the size of the building, I think that is the worst option, but it might be acceptable.

 

[carcruse]

Anyone needing more ceiling height should consider a tray ceiling truss, if the additional height is only needed in one area. Picture shows a standard truss, scissors truss and a tray ceiling truss.

 

[C-S-H]

The bottom two trusses drawn above require 4 supports, and the middle truss is not a scissor truss.

My point in my post above is that it is almost impossible to build a truss without the truss plates. The connection forces at the heel and at chord splices are just too high. Buy properly designed and fabricated trusses.

 

[carcruse]

The bottom two trusses drawn above require 4 supports, and the middle truss is not a scissor truss.

My point in my post above is that it is almost impossible to build a truss without the truss plates. The connection forces at the heel and at chord splices are just too high. Buy properly designed and fabricated trusses.

You are correct. They were labeled that way in the graphic and I didn't look at it closely enough before posting. There are tray or coffer trusses available that require only two points of support.