Engineered for durability in outdoor environments, the Simpson Strong-Tie No. 10 x 3-1/2 in. Lobe Flat Head Deck Screws pair premium 316-grade stainless steel with a protective coating to resist moisture, humidity, and the wear of seasonal weather. Designed specifically for exterior deck applications, these screws deliver lasting hold and a clean, professional finish as they stand up to sun, rain, and salt exposure.
Key features at a glance
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Material and finish: 316 stainless steel with a coating for superior corrosion resistance in outdoor settings.
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Head and drive: Flat head sits flush with the deck surface for a smooth, finished look; Lobe drive minimizes cam-out for steady, consistent driving.
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Size and quantity: No. 10 diameter, 3-1/2 in length, with a 4.5 lb box containing 250 screws.
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Packaging: Boxed, not collated, for straightforward handling and controlled installation.
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Outdoor suitability: Specifically designed for exterior decking projects and common lumber species used in outdoor builds.
Why these screws stand out
Unlike general-purpose deck fasteners, these screws combine the rugged corrosion resistance of 316 stainless steel with a precision Lobe drive that helps you maintain consistent seating and reduces the likelihood of stripping during install. The flush, flat-head profile creates a seamless surface across boards, giving your deck a polished, professional appearance. With a robust 3-1/2" length, they provide solid anchorage for standard deck boards while the No. 10 size is versatile enough for a wide range of board and framing combinations.
Ideal use cases
Perfect for outdoor deck construction where reliability matters: attaching deck boards to a wood substructure, working with pressure-treated lumber, cedar, pine, or hardwood boards, and projects near coastal or damp environments where corrosion resistance is essential. The 250-count, boxed format keeps you stocked for larger builds or multiple projects without frequent ordering, while the non-collated design provides flexible, on-demand use board by board.
Practical tips for best results
- Pre-drilling may be advisable for hardwoods to prevent splitting and to achieve a clean, flush finish with the flat head.
- Drive at a steady rate with a compatible driver to maximize the effectiveness of the Lobe drive and achieve consistent seating.
- Pair with appropriate substructure screws and a high-quality deck sealant to extend the life of outdoor installations.
