Gang nail plate assessment

[Adrenalinej]

I have been asked to complete an assessment of an existing prefabricated truss but have been unable to find any information on the capacities of the gang nail plates. I spoke with Wolf nail plates and they just said it was proprietary software that is only available to truss manufacturers and they have no available information. Has anyone got indicative load capacity information?

 

[KootK]

The plates are cumbersome to evaluate without the proprietary software. In North America, at least, it works like this:

1) The plate manufacturers test their plates and come up with base capacities of the lb/in^2 variety.

2) Standards are published that describe the method of plate design which utilize the base plate capacities: TPI

3) The proprietary software provided by any particular plate supplier incorporates [1] & [2].

 

[Harbringer80]

What is the purpose of the assessment? Condition assessment for damaged trusses or added loading?

 

[bones206]

Look for ESR reports. Mitek and Simpson have them. (ESR-1311, -1988, -1352, -2762,)

 

[jayrod12]

I know PhamENG has been through this a few times if my memory serves, hopefully he can chime in.

 

[phamENG]

thanks @jayrod12 ....trying to lie low here.

Don't have much to add beyond what KootK said. I've used TPI to determine capacities at joints, but it's not easy. That standard is also no longer free. I usually try to come up with a repair or reinforcement that can bypass any questionable connections. You may want to reach out to a local truss engineer and see if you can hire them as an expert consultant to run the numbers for you in their software. It will probably be cheaper than trying to do it by hand.

 

[XR250]

Isn't like 80 PSI capacity?

 

[ChorasDen]

I too am curious what issue you are trying to solve. What is the chord/web material and grade, is it MSR? They may have different plate capacities for MSR or select struct when compared to visual graded lumber. I know that engineered wood chords have different nail plate capacities based on grade.

 

[RontheRedneck]

A few notes and observations -

Plate values vary with lumber species. And grades, to some degree. Lumber that's more dense will obviously have better holding values.

There are different types of plates even within a brand. Like a standard 20 gauge plate is different than one made from high strength steel.

Without knowing the brand and type of the plate it's difficult to come up with anything specific.

Alpine has some info here that might be helpful:

Understanding Plate Tooth Count and Placement - Alpine - An ITW Company

Imagine a third-party truss inspector is in the yard checking truss plates as part of quality control. The plate placement diagram indicates the web needs twenty-five teeth; however, the inspector counts twenty. Even though the shop positioned the plates as designed, is the plate placement...

alpineitw.com

If you can find the plate brand, you might be able to get a truss designer to run a tooth count report for you. Then you could count the teeth in each piece to determine if the plates are acceptable.

 

[bones206]

The plate design values are all freely available in the ESR’s I mentioned above. Knowing how to plug those values into the TPI equations is a separate issue.

 

[XR250]

A few notes and observations -

Plate values vary with lumber species. And grades, to some degree. Lumber that's more dense will obviously have better holding values.

There are different types of plates even within a brand. Like a standard 20 gauge plate is different than one made from high strength steel.

Without knowing the brand and type of the plate it's difficult to come up with anything specific.

Alpine has some info here that might be helpful:

Understanding Plate Tooth Count and Placement - Alpine - An ITW Company

Imagine a third-party truss inspector is in the yard checking truss plates as part of quality control. The plate placement diagram indicates the web needs twenty-five teeth; however, the inspector counts twenty. Even though the shop positioned the plates as designed, is the plate placement...

alpineitw.com

If you can find the plate brand, you might be able to get a truss designer to run a tooth count report for you. Then you could count the teeth in each piece to determine if the plates are acceptable.

I'm surprised they have a 40ksi and a 60 ksi 20ga plate. Seems like a recipe for mixing them up. How much are they actually saving by going to a 40 over a 60?

 

[RontheRedneck]

I'm surprised they have a 40ksi and a 60 ksi 20ga plate. Seems like a recipe for mixing them up. How much are they actually saving by going to a 40 over a 60?

I don't know plate prices offhand. But the packages are labeled pretty clearly. I don't recall having the plant guys ever get them mixed up.