Truss modification tie plate prong vs. nail/screw

[fairlaniac]

I hired an engineer to engineer a truss solution in my garage. I need one truss modified so that I can raise my 4 post lift. The filed engineering drawings call for Mitek tie plates. The prong type. The engineer indicated to me that he has the proper press to press the plates for $250/day rent. I have 10 connection points, 20 total plates. For numerous reasons I don't want to rent the press. Is there any reason why I could not get some plates with just holes and use screws? I see Simpson has some SD screws. The engineer wants me to use the Mitek and press.

Next, who has 8x10 plates without prongs? Then if I find plates, how many holes/screws do you use?



thanks,

 

[strutaeng]

Talk to your engineer and communicate your situation. Ask him is there's an alternative. He may have something he's used in the part.

If necessary, ask for an email confirmation of the substitute for everyone's records.

 

[Zeke]

2 pieces of 8 x 10 1/4" steel plate and 4 C clamps.

 

[TRWham]

You are hostage to whatever the engineer calls out. There may be valid alternatives, but if what you install does not match what is in the letter, and the AHJ sees it, then you should fail. We ask the engineer we work with to revise details all the time, but he works for us frequently.

I will add that connections are not trivial. I recall doing a problem in school where simply adding bolts to one side of a bracket caused the other side to fail because the difference in deflection caused enough difference in stress to overload one side.

 

[Half-fast eddie]

I agree you’re stuck with using standard pronged plates, because they have been tested and the performance is known. So the question is … can you install them without his device? Zeke might be on the right track … cobble together a hydraulic jig. Or ask the engineer if you can substitute heavy gauge drilled steel plates with structural screws or bolts.

 

[Trapps]

I wonder if your engineer has some incentive to use Mitek.

Alternatives in addition to Simpson:

Eagle
Alpine

Another alternative is plywood gusset plates. However, an engineer would need to prescribe the thickness and grade of ply as well as the fasteners (screws or nails) and their schedule.

 

[Walkers]

For $250 just rent the machine and be done with it.

if you don’t want to rent the machine then cobble an alternative with a hydraulic jack.

 

[jack stand]

I also find it "funny" that your engineer happens to rent the plate press. Surely 3/4" plywood on both sides of the whole friggin truss would be stronger just glued and nailed let alone screwed.

 

[nmk_61802]

Surely 3/4" plywood on both sides of the whole friggin truss would be stronger just glued and nailed let alone screwed.

And cost more than the $250 press rental

 

[nmk_61802]

Unless the Engineer will revise his drawing and resubmit, you are kind of stuck....

However Mitek does allow for a standard plywood gusset as a repair to missing plates:

https://www.mitek-us.com/wp-content/uploads/uploadedFiles/_RedesignSite/Content/documents/engineering/details/roof-truss-repair-details/ENG-ROOF-Missing%20Plate.pdf

 

[Zeke]

For $250 just rent the machine and be done with it.

if you don’t want to rent the machine then cobble an alternative with a hydraulic jack.

I want to see that!

 

[fairlaniac]

Here is the type of press he rents. I just see it as a pain in the *** holding it up in the air when it comes to attaching to the existing truss.
Mitek Truss Plate Press video

 

[bluedog225]

A little weird for the engineer to have the equipment he is specifying. Bit of a conflict. But at $250, no big deal.

 

[fairlaniac]

$250/day and he's a 90 minute drive. I figure I might need it over two days just because of travel and doing the labor. I'm a mechanical engineer by trade, not a truss builder so I'd be taking my time not to screw things up. So it's a minimum of 6 hours travel in a day to try it all in a day. So I'm looking at $500. Decisions.....................

 

[Walkers]

I want to see that!

Why? It would probably look like the small hydraulic presses that are so ubiquitous. Nothing real exciting about it, but a lot of effort for 250 bucks.

 

[Walkers]

$250/day and he's a 90 minute drive. I figure I might need it over two days just because of travel and doing the labor. I'm a mechanical engineer by trade, not a truss builder so I'd be taking my time not to screw things up. So it's a minimum of 6 hours travel in a day to try it all in a day. So I'm looking at $500. Decisions.....................

Have you checked to see if you could rent it locally? Ask him if you can return it the next day. It is only one truss, so I just don’t see how that is going to take you all day.

 

[theoldwizard1]

Next, who has 8x10 plates without prongs? Then if I find plates, how many holes/screws do you use?

Through holes actually weaken the the wooden member under stress. I'm with Zeke !

 

[Half-fast eddie]

Here is the type of press he rents. I just see it as a pain in the *** holding it up in the air when it comes to attaching to the existing truss.
Mitek Truss Plate Press video

Looks like a 3-person job, setting the plates up in the air.

$250/day sound a bit steep for this size job, offer $250 total.