The Simpson Strong-Tie SDWS22400DBMB Strong-Drive SDWS Timber Screws (Exterior Grade) is a 4 inch structural wood screw for exterior wood-to-wood fastening. This is a structural wood screw designed for fastening wood members in outdoor and treated-lumber applications. Model Number: SDWS22400DBMB. With its 0.220 inch shank, washer head, and aggressive thread, this screw is built for contractors and serious DIY users who want a faster alternative to traditional lag screws or through-bolting in many structural wood connections.

What makes this screw matter on the job is how it cuts down installation time without giving up holding power. Simpson Strong-Tie uses a bold thread design for strong grip in wood, and the SawTooth point is there for one simple reason: faster starts with less effort. In most applications, that means no predrilling, which saves time on repetitive fastening and helps when you are working overhead, on ladders, or moving through a ledger or railing job where every extra step slows you down.

The head and drive design are just as important as the thread. This screw uses a T40 6-lobe drive for more positive bit engagement, so the bit stays seated better under load and is less likely to cam out when you are driving into dense framing or engineered wood. The washer head spreads clamping force over a larger area than a standard screw head, which helps pull members tight and hold them there. Underhead nibs help the head sit flush with less splintering at the surface, so the finished connection looks cleaner and seats more consistently.

For this specific version, Simpson Strong-Tie pairs the 4 inch length with a 2-3/8 inch thread length and a 0.760 inch head diameter. That combination gives you a screw that is long enough for many common structural wood connections while still being manageable to drive with a standard drill or impact driver using the correct T40 bit. The head is also marked for size identification, which is a small detail but a useful one when you have different lengths open on the same jobsite.

This screw is also meant for exterior conditions where corrosion resistance matters. The double-barrier coating is rated by Simpson Strong-Tie as providing corrosion resistance equivalent to hot-dip galvanization, making it suitable for certain exterior and preservative-treated wood applications as described in the evaluation report. If you are building outdoors, tying ledgers, assembling fencing, or working on pergolas, planter boxes, and similar exposed structures, that coating is not a throwaway spec. It is a big part of why this fastener belongs in those jobs.

Application-wise, Simpson Strong-Tie positions the SDWS timber screw for structural wood-to-wood and engineered wood fastening, including ledgers and mass timber connections such as cross-laminated timber wall-to-wall, floor-to-floor, surface splines, and lap joints. That gives this fastener a broader use range than a basic exterior wood screw. It is not just for decking or trim. It is intended for structural fastening where holding strength and repeatable installation matter.

If you are the buyer comparing this to a lag screw, here is the practical difference: this style of structural screw is usually quicker to install, easier to drive, and simpler to use in repetitive work. You still need to follow approved application guidance, but for the right wood-to-wood connection, it is a cleaner and faster way to get the job done. For fence rails, ledger details, heavy outdoor assemblies, and general exterior structural wood fastening, this 250-count pack makes sense for crews who want jobsite-ready quantity without stepping up to a bulk contractor bucket.

One of the easier ways to get structural wood connections done without messing with lag screws

The Simpson Strong-Tie SDWS22400DBMB Strong-Drive SDWS Timber Screws (Exterior Grade) gives you the kind of speed, bite, and exterior-ready protection that makes sense for real wood framing and outdoor build work.

• Who it's for: Contractors, remodelers, deck and fence builders, and serious DIY users working on structural wood-to-wood fastening outdoors.
• Why it stands out: The fast-start SawTooth point, strong thread design, washer head, and T40 drive make it quicker and cleaner to run than a lot of old-school alternatives.
• Worth knowing: This is a 250-count tan pack, so it is a good fit when you need jobsite quantity. Just make sure you are matching it to approved structural applications and using the right T40 bit.

• What kind of fastening is this screw designed for? It is designed for structural wood-to-wood fastening, including ledgers and certain engineered wood and mass timber connections.
• Does this screw usually require predrilling? Simpson Strong-Tie states the SawTooth point eliminates the need for predrilling in most applications.
• What driver size does it use? This screw uses a T40 6-lobe drive.
• Is this version intended for exterior use? Yes. It has a double-barrier coating that Simpson Strong-Tie says provides corrosion resistance equivalent to hot-dip galvanization for certain exterior and preservative-treated wood applications.