Only 6" of 24" lag screw is threaded

[LittleJack]

I've joined the converted and am moving from rebar to lag screws this year. I ordered a bunch of 24" lag screws, and they came today. Unfortunately, only the first 6" of them is threaded, the rest is just plain shank. Will these hold okay?

I'm planning to drive them 12" - 18" into the playa to be the posts for my monkey hut. For the past 9 years I've used 24" rebar pounded 12" in, and it's always worked fine. I'm worried that 6" of thread won't be enough to hold the lag screws in place.

Thoughts?

[MrFortuna]

only the first 6" of them is threaded, the rest is just plain shank.

This is normal from my experience. I didn't get purchase with the threads until about 12 inches down in some spots last year. While it may technically reduce the amount they can hold, for something like monkey hut posts it should be fine.

[motskyroonmatick]

Lag screws (bolts) are based on wood fastening engineering. At a certain point it is unnecessary for wood fastening capability to add more threads as more threads will not improve the holding power or strength of the connection. More threads might work better on playa but we are repurposing a wood fastener specifically engineered for wood as a tent stake.

[Elliot]

What Motsky said.
And if I may add; You don't mention diameter, but I expect your 24" lags will hold just fine for your purpose.
If they had more threads... it might even be too difficult to screw them in and out. I have twisted the head off a few 3/8 x 14.

[LittleJack]

Ah, they're 1/2" x 24". So it sounds like these will work just fine.

Thanks!

[Elliot]

At 24" long, they better be at least 1/2" diameter -- to my way of thinking (though... I am not an engineer).
Regardless... it appears you are all set. See you in the Dust!

[Kenshiro]

You get most of your anchoring from the more solidly packed, deeper part of the playa anyway.