When a standard screw won't cut it, lag screws, also called lag bolts, are built for the job. These large, heavy-duty fasteners feature coarse threads and a hex head, making them the go-to choice for demanding wood-to-wood connections and structural builds. Whether you're tackling a deck, a fence or a timber frame, the right lag screws for wood give you the holding power and durability your project demands.
What Are Lag Screws Used For?
Lag bolts for wood are designed for applications where strength and reliability matter most. Here are the most common uses:
- Deck framing and ledger boards: Lag screws for deck projects keep structural connections secure, even under heavy load and constant weather exposure.
- Fences and gates: Heavy duty lag screws hold posts and panels firmly in place for long-lasting results.
- Pergolas and timber frames:Large lag screws provide the clamping force needed for thick, load-bearing lumber connections.
- Mounting hardware to studs: Ideal for attaching barn door tracks, shelving systems and structural brackets.
- Masonry and concrete applications: When paired with the right anchors, lag screws can fasten wood components securely to concrete or block walls.
Types of Lag Screws
Choosing the right finish for your lag screws is just as important as choosing the right size. Here's what to know about each option.
Stainless Steel Lag Screws
Stainless steel lag screws are the premium choice for harsh environments. Their built-in corrosion resistance makes them ideal for:
- Coastal and marine settings where salt air accelerates rust
- High-moisture outdoor applications
- Projects where long-term durability and minimal maintenance are priorities
Galvanized Lag Screws
Galvanized lag screws are hot-dip coated in zinc, making them a reliable and cost-effective option for most outdoor projects. They work especially well with:
- Pressure-treated lumber on decks and fences
- Exterior structures exposed to rain and humidity
- General outdoor construction where stainless steel isn't required
Zinc-Plated Lag Screws
Zinc-plated lag screws are well suited for interior and dry-environment applications. Choose these for:
- Indoor framing and structural connections
- Dry storage or workshop builds
- Projects where corrosion exposure is not a concern
Lag Screw Sizes
Lag screws come in a wide range of sizes to match the demands of your specific project. Diameter typically runs from ¼" to ¾" or larger, while lengths range from 1" for lighter connections up to 6" or more for structural and heavy-duty applications.
Here's a quick guide to help you find the right lag screws sizes:
- ¼" diameter, 1"–3" length: Light-duty brackets, trim and hardware installation.
- ⅜" diameter, 2"–5" length: General construction and lighter deck connections.
- ½" diameter, 3"–6" length: Deck framing, ledger board attachment and gate hardware.
- ⅝"–¾" diameter, 4"–12"+ length: Heavy duty lag screws for structural timber, load-bearing builds and large lag screw applications.
Pro tip: Always pre-drill a pilot hole before driving a lag screw. This prevents the wood from splitting and ensures a clean, secure connection.
Explore Related Fasteners
Lag screws are just one part of a well-stocked hardware collection. Depending on your project, you may also need:
Browse the full screws and anchors collection for everything your project needs\.
Shop Lag Screws Near You at Ace Hardware
Shop the full selection of lag screws near you at Ace Hardware. Prefer to shop online? You'll find a broad selection of lag bolts in a full range of sizes and finishes, shipped fast and backed by our helpful staff if you have questions.
