Screw Pull Out Force

[td9]

Need pull out force for a #6 x 2" coarse thread drywall screw embedded 1-5/8" into yellow pine.

Thanks,

TD

 

[Ron]

Test it.

Check with manufacturer....they MIGHT have data that specific, but usually more general.

 

[td9]

Thanks Ron,

Have emailed Hilti and Grip Rite.

Hope to have reply next week.

I remember reading a text that had general info on screw pull out strength, but can not remember the text.

May have to just test several screws with a pull out gage if I can not get any answers.

Thanks,

TD

 

[RHTPE]

Your best information will come from a series of tests.

You could reference the 2005 NDS, Section 11 for more information - you will need to know the specific gravity of the wood. For a #6 wood screw, the values vary from 38 to 209 pounds per inch of penetration into the side grain, multiplied by the appropriate adjustment factors in Table 10.3.1. Your final calculated values from the NDS will likely be substantially less than your test results. But then, your test results will also vary dramatically depending upon the nature of the grain that the screws are driven into.

None of the above considers the tensile strength of the screw itself.

Ralph
Structures Consulting
Northeast USA

 

[RHTPE]

Hilti and Grip Rite will likely tell you the strengths of their fasteners alone - the final value will depend on the wood.


Ralph
Structures Consulting
Northeast USA

 

[rscassar]

I can't comment on NDS but the wood standard I use gives a withdrawal capacity of 170 lbs per inch of penetration for a No. 6 screw. It will vary depending on the quality of the wood. The thread doesn't come into the calculations for withdrawal from wood.

 

[woodman88]

Drywall screws are not wood screws so the withdrawal values will probably not be the same. Without a ICC report on the withdrawal values of the drywall screws, I would use the nail values, knowing that the actual value would be higher.

As for testing, you will need to verify that the wood you are testing in meets the actual sg for that species as 95% of that species should be higher than the species sg. This is because of the 5% rule for determining the lumber values under the grading rules.

Garth Dreger PE
AZ Phoenix area

 

[slomobile]

Agree with Woodman, Drywall Screws are NOT wood screws. They are also very brittle, if you have any type of cyclic loading, the use of drywall screws is not realistic and should not be considered as a structural connector as they are not intended or tested to be such.

 

[msquared48]

OP:

I thought this was only applicable to dogs.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[RHTPE]

Mike,

You are BAD!

(Had to think about for a bit)

Ralph
Structures Consulting
Northeast USA

 

[msquared48]

Thank you.. Thank you.. Thank you very much.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[dhengr]

Mike:
Is that called a stuck stiffie? What a bitch.