The Best Way to Reinforce a Wooden Structure with Structural Fasteners

Wood is easy to cut and work with, meaning any average Joe with a handsaw and power drill can fairly easily build something.

But here's the thing: just because wood is tough and incredibly strong (it's actually comparable to concrete, able to hold up about 5000 pounds per square inch without breaking!) doesn't mean every wooden structure is strong enough to hold the people, furniture, and the rest of the structure.

There are so many times when average Joes or even contractors built wooden structures that looked great initially, but then they started to wobble, feel unsafe, or even become a real hazard because of poor reinforcement or low-quality structural fasteners.

That's just why we created this guide. We've built a lot of outdoor structures for clients with properties in different locations, with different climates. So, we understand what it takes to keep your deck, your pergola, and whatever outdoor structure you’re building safe, strong, and reliable.

How to Make a Structure More Sturdy Using Structural Screws

When people ask us how to make a structure more sturdy using structural screws, the first reaction is often, “What structure exactly? A ceiling joist? A dock frame? A deck post?”. And that’s a fair point. Reinforcing wood isn't a one-size-fits-all answer because not every wooden structure has the same function, stress, or exposure to the elements.

That said, making a wooden structure sturdier usually comes down to two things:
(1) choosing the right structural fasteners, and
(2) applying the right bracing techniques.

We’ve built and reinforced thousands of wood structures using structural screws over the years, and no matter the project, these two principles always apply.

Now, here’s one rule that covers all bases: use whatever your local building code requires. Period. Whether you’re reinforcing a deck, roof, or structural wall connection, the best screws are the ones that are code-compliant, tested, and rated for critical load-bearing connections.

From our decades of experience, here's how you approach reinforcement using structural screws:

Understand What “Structural” Really Means

Structural screws are not your everyday wood screws. When we talk about structural fasteners, we mean the screws used in critical connections. We’re talking about the parts of a structure that keep your deck from pulling away from the house, your roof from separating during high winds, or your posts from shifting over time.

Use ICC-Certified Screws

In 2025, code is more specific than ever. The International Code Council (ICC) outlines exact requirements for different fastening methods, like hanging a ledger board or connecting a top plate to a rafter.

The code may reference lag screws or bolts, but it also allows for substitution, as long as the product has an approved code report.

That means if you’re using structural screws instead of lag bolts, the product must prove it’s equal to or better in:

1. Load strength and pull-out resistance: The Simpson Strong-Tie SDWH Timber-Hex Stainless Steel Screw and SDWS Timber Structural screw are ICC-certified and specifically designed to replace lag screws. They meet the IRC, IBC, and FBC–Residential code requirements for common wood framing applications.

2. Corrosion resistance: If you’re building structures that are 3 miles or 5 kilometers away from the coast or lakes, you should only use 316-grade stainless steel screws.

Verify Product Testing and Reports

Look for code report documentation (like ESR numbers or ICC-ES listings).

Simpson Strong-Tie provides third-party test data and technical reports that confirm compliance with ICC/IBC code standards. Simpson’s ICC‑ES evaluation reports (like ESR‑2236) include published load tables and installation guidelines.

Match the Fastener to the Location

• Interior connections can use coated or plain structural screws.
• Exterior or coastal applications require stainless steel or specially coated screws to prevent rust and meet long-term durability standards.

Make A Wooden Frame More Sturdy With Bracing

While structural screws do much of the work in holding joints together, bracing is just as important in making the frame of your wooden structure sturdy. Adding diagonal bracing or cross-bracing, or V- or X-bracing, stabilizes your wooden structure. Structural bracing prevents sway, racking, or outward bowing.

Whether you're reinforcing tall pergola frames or decks with long spans, using a cross brace strengthens your wooden structure. Cross braces stiffen a wooden frame by locking key connections in place, distributing lateral loads, and helping prevent the structure from shifting over time due to wind, shifting soil, or heavy use.

Next, we’ll break down how to use structural screws and bracing techniques to reinforce common wooden structures.

Decks

Diagonal Bracing

From our decades in the field, we’ve seen how diagonal bracing (V-bracing) paired with the best deck screws gives a deck that's high off the ground a rock-solid feel. We always install diagonal bracing for decks that are over 5 feet tall, especially when the span from the house to the outer beam is long (10–20 feet).

If your existing deck sways side to side, diagonal bracing is the best way to reinforce your swaying deck. Here's how to build a strong deck using structural screws to install a cross brace to support joists:

1. Use 2x6 pressure-treated lumber, ideally in 20-foot lengths for longer spans.
2. Plan your V from the centerline of the deck out toward both beams, creating stable, diagonal support.
3. Clamp your brace in place, trace it, and cut both pieces (44 to 45 degrees is ideal).
4. Use G-Tape or flashing tape on the top edge to protect against moisture.
5. Use 4-inch structural screws. We recommend using the SDWS Timber Stainless Steel screws for this. Secure with two screws per joist intersection along the brace. Maintain spacing of 18–24 inches.

Installing Mid-Span Blocking

We’ve seen even the thickest joists wobble under load without proper reinforcement. Blocking not only stiffens the structure but also makes deck board installation easier and cleaner. Here's how to sturdy up a deck using structural screws to install blocking:

1. Use 2x6 pressure-treated lumber for blocking.
2. Mark a centerline down your joists and lay out staggered blocking left and right of this line.
3. Temporary top alignment boards across the joists help hold everything square while you install.
4. Clamp each block in place between joists.
5. Use two 4-inch structural screws per side per block. We recommend using the SDWS Structural Stainless Steel screws for this.
6. Be sure blocks sit slightly high, not low, to avoid interfering with soffit or fascia installation.
7. Stagger blocks side-to-side to allow room for driving screws and reduce any future twisting.
8. For outer rim joists, consider pre-drilling and countersinking screws to accommodate fascia clearance.

Adding Support Beams

In decks with wide spans or undersized joists, we’ve reinforced many frames by adding support beams beneath the joists.

If your joists are spaced too far apart, or your deck carries heavy furniture or sees a lot of foot traffic, adding support beams is one of the most reliable ways to stiffen it. Here’s how we reinforce a deck by installing support beams using structural screws:

1. Measure the distance between the house and the outer edge of your deck. For spans over 10 feet, consider adding a beam at the midpoint.
2. Cut a beam (e.g., doubled 2x10s) to run perpendicular to the joists. Use pressure-treated lumber.
3. Install vertical posts beneath the beam, anchored to proper concrete footings. Make sure everything is level and code-compliant.
4. Secure the beam directly to the underside of the joists using joist hangers or heavy-duty structural screws. We recommend using the SDWH Timber-Hex Stainless Steel screws for this.
5. Use SDWS screws for framing, spaced per manufacturer recommendations.

Pergolas

Diagonal Bracing

We’ve reinforced dozens of freestanding pergolas or pergolas in windy areas by adding structural bracing. Diagonal braces lock the pergola frame together, preventing racking or wobble.

Here’s how we install diagonal bracing on pergolas using structural screws:

1. Cut 6x6 pressure-treated lumber at a 45-degree angle. Use a circular saw with at least a 10 1/4" blade for clean, deep cuts. If you don’t own one, borrow or rent one.
2. Use your first brace as a template for the rest. Consistent lengths and cuts make for a clean finish and predictable installation.
3. Temporarily fasten cleat blocks on the posts so the braces can rest in place while you install.
4. Position the brace between the post and beam, clamp it in place, and confirm fit before drilling.
5. Use 6-inch structural wood screws and drive two screws at each end of the brace. Predrill recesses for flush or hidden fastener heads. We recommend using SDWH Timber-Hex Stainless Steel screws for this.
6. Mark symmetrical locations on the posts and beams using a speed square for a clean, professional appearance.
7. Apply wax or sealant to any exposed end grain to protect from moisture.
8. Once fasteners are fully set, remove cleats and temporary braces

Docks

We recommend using 316-grade stainless steel screws for structurally sound decks. Never use 304-grade stainless steel structural screws when reinforcing your docks, as 304-grade SS structural screws are only ideal for mild environments.

Here's how we strengthen docks using structural screws:

Add Cross Beams for Support

Crossbeams add stability and give you solid points to mount floats.

1. Install additional crossbeams within each box section.
2. Fasten beams to the frame using SDWS Structural Stainless Steel screws, especially where they connect with joists or rim boards.
3. These beams stiffen the dock and reduce flex under load.

Mount the Floats Securely

Your dock’s buoyancy depends on floats being evenly spaced and firmly attached.

1. Calculate load needs (wood, people, gear) and match with float capacity.
2. Align floats according to your plan, and attach them using lag screws with washers or the SDWS Structural Stainless Steel screws.
3. In some areas, you may need to add extra framing to line up with mounting holes.

Reinforce with Diagonal Bracing

To maintain squareness and reduce lateral movement, install temporary or permanent diagonal braces.

1. Use 2x4s or 2x6s fastened with the SDWS Structural Stainless Steel screws.
2. This prevents racking when you move the dock or when it’s under pressure from wind or current.

Fences

Fences may not carry loads like decks or docks, but they take plenty of abuse from wind, weather, and shifting soil. Here’s how we reinforce fences using structural screws:

Stabilize Leaning Fence Posts

If a post is leaning, we often install a second post nearby and add a diagonal brace between the two.

1. Place the new post in line with the lean direction.
2. Cut a diagonal brace that reaches from the base of the new post to near the top of the leaning one.
3. Attach using the SDS Heavy-Duty Hex Connector screws, tightening the leaning post into a plumb position.

Add Sister Rails

When horizontal rails are sagging or weakened, we reinforce them with a sister rail.

1. Cut a matching rail from pressure-treated wood.
2. Clamp it beneath the original rail and attach it using structural screws or carriage bolts.
3. For added stability, use metal connectors at joints.

Install Metal Brackets

Metal brackets, like T-brackets or corner brackets, add serious support at rail-to-post connections.

1. Align brackets at the needed joint.
2. Pre-drill holes to avoid splitting.
3. Secure with corrosion-resistant structural screws.

Reinforce Rails and Midspan Blocking

For tall fences or high-wind areas:

1. Add horizontal or diagonal wind bracing between posts.
2. Install midspan blocks under long rails, securing them with #8 deck screws or structural screws.

Raised Garden Beds

Raised garden beds see constant exposure to moisture and shifting soil. Over time, that pressure can cause bowing sides, separating joints, and corner failure. We’ve helped many gardeners reinforce their large garden beds using the right structural screws.

Strengthen with Corner and Midpoint Posts

Using 4x4 pressure-treated posts in each corner and along longer spans keeps your raised beds from bowing outward.

1. Dig in 4x4 posts slightly into the ground at all corners.
2. For long sides (6 feet or more), add one or two 4x4s evenly spaced between corners.
3. Attach the bed walls to each post using 4-inch structural wood screws, predrilled if needed. We recommend using the SDWS Structural Stainless Steel for this.

Use Structural Screws for Strong Joints

We prefer structural screws over lag bolts or standard deck screws.

1. In areas with thick wood-to-wood connections (like 2x lumber to 4x4s), predrill and drive 3"–4" structural screws.
2. Fasten from inside corners first, then into outer walls.
3. Use a clamp or even a shovel as a wedge to keep tight contact while screwing.

Add Interior Bracing

For added strength, especially in beds over 4 feet wide:

1. Install 2x4 or 2x6 horizontal braces across the middle, connecting opposing side walls.
2. Fasten braces to the interior face of midpoint posts or directly into the walls using structural screws.
3. This reinforcement keeps the walls from bowing under pressure after heavy rain or seasonal movement.

Why We Only Trust Simpson Strong-Tie to Build a Strong Wooden Structure

Never trust general-purpose wood screws from big box stores. Most of the time, these screws are incredibly weak and break very easily under load.

At ATC Construction Fasteners, we’ve spent decades building and reinforcing wood structures across every climate and condition you can imagine. We've tested just about every brand of structural screw on the market, and we only put our name behind Simpson Strong-Tie.

Simpson doesn’t just manufacture fasteners. They invest in R&D, they listen to builders, and they engineer products that solve real-world problems faster, cleaner, and stronger than anything else we’ve used.

And if you’ve got questions? Just like Simpson, our expert support team is ready to help. We’re here to help you build stronger, faster, and smarter.

FAQs

What are the best structural screws to use to reinforce a wooden structure?

The best structural screws for reinforcing a wooden structure depend on your application, location, and whether the structure is indoors or outdoors. However, for most structural framing, deck building, pergolas, fences, docks, or garden beds, the top-performing structural screws trusted by professionals and DIYers are Simpson Strong-Tie’s SDWS and SDWH screws.

The SDWS Framing screws are ideal for multi-ply beams, ledger boards, and general wood framing. These screws are available coated for mild environments. The SDWS is also available in stainless steel for wood structures in coastal and lakefront areas.

The SDWH Timber-Hex screws are designed to replace lag screws with no pre-drilling required. ICC-certified for high load-bearing performance.

What Are Three Reliable Ways to Increase Structural Stability?

The three most reliable ways to increase structural stability are bracing, reinforcement, and even load distribution.

Bracing (Triangulation): Adding diagonal bracing helps keep your structure from swaying or twisting. This is critical for tall or stand-alone builds like decks or pergolas.

Reinforcement: Use strong structural screws, sistering, or metal brackets (like Simpson Strong-Tie) to make weak areas stronger and handle more weight.

Even Load Distribution: Space your joists and beams evenly. Make sure your fasteners have consistent spacing. If these elements are evenly spaced, it spreads out the weight so your structure stays strong and lasts longer even under stress.