What is the type of purpose of these particular screws?

I think they are for screwing landscape timbers together.

they look like grk screws and are high strength.and cost a lot of money and are worth every penny.if you got em for free,save em.i used to sell that brand.high quality.

-- working with my hands is a joy,it gives me a sense of fulfillment,somthing so many seek and so few find.-SAM MALOOF.

its a truss head screw, used in cabinet building and other builds, large washer type head gives great grab and pressure, one sometims has to be careful if using power torque driver to not strip unit, quite a few come with the ddrill head to ease install

-- Living the dream

they look like grk screws and are high strength.and cost a lot of money and are worth every penny.if you got em for free,save em.i used to sell that brand.high quality.

- pottz

I concur and used similar to these recently. Torx heads don’t cam out when using an impact driver.

Look like GRK Brand. Structural rated.

Hmm, just a tad long for pocketholes on 19mm stock.

... and cost a lot of money and are worth every penny.if you got em for free,save em.i used to sell that brand.high quality.

- pottz

Used to sell them pottzy... what s the story, abandoned quality Yankee stuff and now selling Chinese crap?

- LittleBlackDuck

switched to a similar brand thats just as good but about 30% cheaper. most of our customers it’s all about pruce sadly.

-- working with my hands is a joy,it gives me a sense of fulfillment,somthing so many seek and so few find.-SAM MALOOF.

+1 GRK RSS Rugged Structural Screws.
The secondary spiral just above the threads make id easy.
Typically used with pressure treated lumber on outdoor projects due the corrosion resistant coating.

-- If it wasn't for bad luck, I wouldn't have no luck at all, Doom, despair, agony on me… - Albert King - Born Under a Bad Sign released 1967

The Contractor would have likely remembered to pack those screws back on the truck as he paid for them. Employees can get in a hurry and fail to walk the jobsite one final time to check for items missed. Ask me how I know. I go to jobsites and find boxes of wire, step ladders and other items left behind. Probably buy 10 Kline 10 in one screwdrivers a year for employees’ that already have them. Got to the office at 8:00 AM and the van was idling in the lot I turned it off. Employee didn’t leave until 8:40, oh I might add that I am wearing short sleeves today.

Assuming the deck is connected to the house, these were most likely used to attach the deck ledger board to the house rim joist.

Yes, structural screws and expensive. A quick browse through your local big box “borg” center would show you all kinds of fancy screws. Worth the time as you can find out all things that are not obvious.

my selection of grk screws.

-- working with my hands is a joy,it gives me a sense of fulfillment,somthing so many seek and so few find.-SAM MALOOF.

Assuming the deck is connected to the house, these were most likely used to attach the deck ledger board to the house rim joist.

- JohnDon

I don’t do decks anymore but they used to be bolt thru into rim joist. Current code here is for deck to be free standing and not attached to house

-- WAR IS PEACE. FREEDOM IS SLAVERY. IGNORANCE IS STRENGTH --

my selection of grk screws.

- pottz

Enough there to justify hiring a security guard.

my selection of grk screws.

- pottz

Enough there to justify hiring a security guard.

- Richard Lee

luckily i got them at cost !

-- working with my hands is a joy,it gives me a sense of fulfillment,somthing so many seek and so few find.-SAM MALOOF.

my selection of grk screws.

- pottz

Enough there to justify hiring a security guard.

- Richard Lee

luckily i got them at cost !

- pottz

And yazall have a go at my expensive Fe$tool, yet ya don’t hold back on the cost of a screw.

-- If your first cut is too short... Take the second cut from the longer end... LBD