Construction Lag Screw 5/16in x 14in Type 17 - Heavy Duty

Our review of these construction lag screws finds they are aimed squarely at builders and DIYers who need strong, reliable fasteners for structural outdoor work; the single biggest reason to buy is their combination of heat treated steel and a triple coating that passed a 1200 hour salt spray test, which gives real confidence in corrosive or ACQ-treated lumber applications. The Type 17 notched point starts quickly without wandering and often reduces the need for pre-drilling, so the kit saves time on deck and framing tasks where depth and clamping force matter.

Key Features

• 5/16in Thread Diameter: provides a robust shank that handles high shear and compression forces for structural connections.
• 14in Length: reaches deep into 4x stock and large timbers, allowing tight pull-down of beams and posts.
• Heat Treated Steel: increases tensile strength and durability for heavy duty use on decks and outdoor framing.
• Triple Coated Finish: resists corrosion and is compatible with ACQ-treated lumber for long outdoor life.
• Type 17 Notched Point: cuts quickly into wood to reduce walking and often lessens the need for pre-drilling.
• Passed 1200 Hour Salt Spray Test: gives proven protection against coating failures in harsh environments.

Who It's For

This is best for professional carpenters, deck builders and serious homeowners who need structural fasteners that hold up outdoors and in pressure-treated lumber. The long 14in length and heavy duty construction suit projects like deck ledger-to-post connections, timber framing and any application that requires deep penetration and high clamping force.

Those doing delicate trim work or installing into thin or soft materials should look for smaller diameter or shorter screws; these are built for strength and depth rather than finishing surfaces or fast, frequently removed connections.

Pros & Cons

Pros

• High strength from heat treated steel gives confidence in structural applications.
• Triple coating and a 1200 hour salt spray pass mean strong corrosion resistance for outdoor use.
• Type 17 notched point starts quickly and reduces the need for pre-drilling on many timbers.

Cons

• At 14in length and 5/16in diameter these are overkill for light carpentry or finish work where smaller screws are more appropriate.

Specifications

Thread Diameter	~5/16in
Head Diameter	11/16in
Length	14in
Material	Heat treated steel
Drive Type	Torx/Star
Point Type	Type 17 notched extra sharp
Coating	Triple coated, passed 1200 hour salt spray

Our Verdict

These lag screws are a solid value for anyone needing heavy duty, corrosion resistant fasteners for outdoor structural work; their heat treated core and proven coating make them a dependable choice for decks, timbers and ACQ-treated lumber where deep penetration and long-term durability matter.

Frequently Asked Questions

Are these suitable for pressure treated lumber?
Yes, the triple coating and stated compatibility make them appropriate for ACQ-treated lumber.

Will I need to pre-drill for 4x6s?
The Type 17 notched point often reduces the need for pre-drilling, but material density and equipment may still make pilot holes advisable for exact alignment.

Can these be used for decking ledger connections?
Yes, the 14in length and strong shank make them suitable for deep ledger and beam connections in deck construction.