SPAX 1/4 in x 5 in Interior Washer Head Structural Wood Lag Screws

In this review the SPAX 1/4 in x 5 in Interior Washer Head Structural Wood Lag Screws are judged on durability, ease of installation and value for contractors and serious DIYers. The review finds these screws best for structural wood to wood connections where strength and reduced splitting matter most, thanks to patented serrated threads and a heat treated Grade 5 core. The included T-Star compatibility and bulk 500 pail make this a jobsite-focused option, though buyers should verify they have the correct driver bit despite mixed reports about the bit included.

Key Features

• Patented thread serration: The serrated threads reduce splitting and let the screw be driven faster and with less effort in most wood species.
• Heat treated Grade 5 durability: Heat treatment increases core strength and lowers the risk of breakage during heavy structural work.
• Washer head design: The washer head gives a larger bearing surface for secure connections in wood to wood assemblies.
• T-Star drive compatibility: The 6-lobe T-Star drive provides superior bit engagement for quicker installation and less cam-out.
• Code recognized: ICC-ES report ESR-1782 means these screws are suitable for recognized structural wood to wood applications.
• Bulk 500 pail: Supplied in a 500 count pail for efficient jobsite use and fewer trips to restock.

Who It's For

This product is aimed at professionals and experienced DIYers who need reliable, code-recognized lag screws for structural wood to wood connections, such as deck ledger attachments, heavy timber framing, and significant retrofit work. The bulk pail and high strength finish make it practical for contractors working across multiple jobs.

Those working on small, occasional home projects or who prefer single-use retail packaging may find the 500 count pail excessive. Also confirm the driver bit compatibility before purchase if you do not already have a T-Star bit collection, since customers reported mixed experiences about the included bit.

Pros & Cons

Pros

• Superior drive performance from the T-Star 6-lobe design reduces slippage and speeds installation.
• Patented serrated threads lower splitting and ease driving, especially in dense wood.
• Heat treated Grade 5 construction increases strength and reduces breakage under load.
• Bulk 500 pail is economical for frequent users and jobsite stocking.

Cons

• Reports are mixed about the included bit; some users may need to supply a separate T-Star bit.
• Bulk packaging is not ideal for infrequent DIY users who need only a few screws.

Specifications

Brand	Altenloh, Brink & Co
Size	1/4 in x 5 in
Head type	Washer head
Drive	T-Star 6-lobe (bit compatible)
Finish	Corrosion-resistant
Count	500 per pail
Certification	ICC-ES Report ESR-1782

Our Verdict

The SPAX 1/4 in x 5 in washer head PowerLag screws are a strong, jobsite-ready choice for structural wood connections where reduced splitting and superior drive engagement matter. For contractors and heavy DIY projects the heat treated strength, serrated threads and code recognition deliver clear value, but occasional users should consider smaller packaging and confirm bit needs before purchase.

Frequently Asked Questions

Does this product include a driver bit?
Some packages include a bit but customer reports are mixed, so plan to have a T-Star bit on hand to ensure compatibility.

Are these screws suitable for structural wood to wood connections?
Yes, they are ICC-ES recognized for structural wood to wood applications under report ESR-1782.

Will these screws reduce splitting in hardwoods?
The patented thread serration is designed to reduce splitting and make driving easier in most wood species.