Deck Framing: Screws or Nails? Fastener Rules by Connection

Neither wins everywhere. On a deck frame the connection decides: joist hangers take the fasteners printed on the hanger (nails, or the maker’s own structural screw where it is listed), ledgers take 1/2-inch lag screws or bolts, and framing nails should be threaded. This guide gives the rule for each connection from the American Wood Council deck guide and Simpson Strong-Tie, plus the coating rules for treated lumber.

Short Answer: Use the Fastener the Connector Lists

The most common mistake is treating this as a nails-versus-screws contest. Every structural connection on a deck already names its fastener. A joist hanger comes with a table that lists the nail size and count, and the American Wood Council notes that connector manufacturers regard a connector with missing fasteners as an improper installation and support it only with the type and number of fasteners in the product literature. So the real question is not which one is stronger in general, but which one this connector is tested with.

A myth worth correcting: you will often read that building code “requires nails in joist hangers and bans screws.” The deck guide does not say that. It says hangers are selected from an approved manufacturer’s product data, and its commentary adds that, when the hanger manufacturer permits it, using screws instead of nails to attach hangers to the ledger can reduce the chance of the joist pulling away. What is not allowed is swapping in whatever screw is in the truck. Simpson Strong-Tie’s rule, as summarized from its connector guidance, is that when screws replace nails you use only its SD screws, you never mix screws and nails in the same connector, and every hole gets filled.

This is general information, not an engineering design. Your local building department and the hanger data sheet have the final word, and any structural doubt belongs with a licensed engineer or your inspector.

Which Fastener Goes Where on a Deck Frame

The table below pulls each connection from the American Wood Council’s Prescriptive Residential Wood Deck Construction Guide (DCA 6), 2015 edition. Check which edition your jurisdiction has adopted, because local code may differ from it.

Connection	Fastener named by the guide	Detail that gets missed
Joist to ledger or beam with a hanger	The fasteners on the hanger schedule: every hole filled	Hanger chosen from an approved maker’s data; depth at least 60 percent of the ledger or beam depth
Ledger to house band joist	1/2-inch lag screws or bolts with washers, spaced per the guide’s Table 5	Pilot holes of 1/2 inch in the ledger and 5/16 inch in the band joist; never drive lag screws with a hammer
Blocking to rim joist (non-ledger decks)	5 threaded 10d nails per the guide, or a framing angle rated 600 lb lateral	Flashing over the rim joist is required
Beam to post	Notch the post and through-bolt, or use an approved post cap	Three-ply beams must use a post cap; side attachment without notching is prohibited
Diagonal bracing	1/2-inch diameter lag screws	Fixed to the post at one end and the beam at the other
Decking to each joist	2 threaded 8d nails or 2 #8 screws	Space boards about 1/8 inch apart
Lateral tie-down to house	Hold-down devices rated at least 1,500 lb, in two locations within 2 feet of the deck edge	The guide says use lag screws or through-bolts when fastening to a band joist
Guard post to rim or outside joist	Hold-down anchor rated at least 1,800 lb tension for a 36-inch guard	Install exactly per the anchor maker; guard posts are not a place for improvised screws

Two things stand out. First, the only places the guide names a plain screw count are decking (2 #8 screws or 2 threaded 8d nails) and one stair detail: for a stair-stringer footing carrying about 500 lb, its commentary calls for seven #8 wood screws in Southern Pine or eleven in Northern species, and says 16d box or common threaded nails would be comparable. Second, everything that holds the deck to the house or keeps a guard standing is a bolt, lag screw or tested hold-down, never a generic screw or nail. The full ledger rules are in our guide on whether deck screws are structural.

What Nails Do Well and What Screws Do Well

For plain nailed joints such as blocking and rim joist connections, the guide specifies threaded nails. Its commentary explains why: smooth-shank nails are prone to backing out of wood as moisture cycles through it, while spiral and ring-shank nails resist that. Ask for “spiral” or “ring-shank” by name at the lumber yard, as the guide itself suggests. Smooth-shank connector nails are the exception, and only because the connector schedule is written around them; they are driven through a steel hanger that holds the joist in place.

Screws earn their place where a connection can be pulled apart instead of pushed. The guide notes that hanger-to-ledger connections resist lateral loads, which is why a manufacturer-permitted screw there can lower the chance of a joist pulling away. A screw also lets you back a fastener out and adjust, which a hammer does not. Simpson states that its #9 SD screw delivers single-fastener load values above a 10d common nail and its #10 SD screw above a 16d common nail, which is why those two screws are listed as alternatives in hangers that permit them.

• Use nails when: the hanger schedule calls for them, you are blocking or nailing a rim joist with threaded nails, or you are fastening decking with threaded 8d nails.
• Use the maker’s structural screw when: the hanger lists it as an alternative, or a listed structural screw’s ledger table covers your joist span.
• Use lag screws or bolts when: the connection is a ledger, a brace or a guard post and the guide names them.
• Do not substitute: a deck screw, drywall screw or any structural-looking screw that has no listing for that connector.

The fastener-replacement rules matter more than any strength comparison. A hanger loaded with the wrong screw has no published rating at all, which is the situation an inspector looks for first.

Coating Rules That Apply to Both Nails and Screws

Treated lumber corrodes bare steel quickly, and the guide spells out what to use. All screws, bolts, washers, nuts and nails in preservative-treated wood must be hot-dipped zinc-coated galvanized steel, stainless steel, silicon bronze or copper. Hot-dip galvanized fasteners must meet ASTM A153, Class D for diameters 3/8 inch and smaller, or Class C above 3/8 inch. Our fence screw guide explains the same treated-lumber chemistry with outdoor examples.

Here is the detail most guides skip. The guide allows mechanically deposited zinc coatings (ASTM B695, Class 55 minimum) only for fasteners other than nails and timber rivets. So a mechanically galvanized screw can pass where a mechanically galvanized nail cannot: a nail in treated lumber has to be hot-dip or stainless. For nail grades and sizes see our pressure-treated wood nail guide.

• Connectors: galvanized (G-185 coating if hot-dipped before fabrication, or ASTM A123 if hot-dipped afterward) or stainless steel.
• Within 300 feet of salt water: stainless steel grade 304 or 316 for fasteners and connectors.
• Matching: fasteners and connectors must be the same corrosion-resistant material, so no stainless nails in a galvanized hanger.

Installation Details That Decide Whether a Connection Passes

Simpson Strong-Tie’s deck guidance adds installation points the guide does not repeat. Joists must seat tight against the ledger or rim board, with gaps under 1/8 inch, because larger gaps reduce capacity; Simpson cites losses of up to 30 percent in download and 40 percent in uplift depending on the gap. Joists also need 1.5 inches of bearing on wood ledgers when hangers are used.

• Fill every fastener hole in the connector, and use the same fastener type throughout it.
• Drive screws normal to the wood surface and fully seat the head against the connector; do not overdrive or underdrive nails.
• Use the length the schedule gives. A shorter fastener is a different connection, not a close substitute.
• Keep the ledger flashed. The guide requires flashing or caulking so water does not reach the house band joist, and a wet ledger is a weak ledger whatever fastener holds it.

Concentrated loads such as hot tubs, stairs and planters are beyond what the deck guide covers, and its ledger rules assume a sheathed wood-framed wall: the guide says do not attach a ledger to brick veneer. If your house or load falls outside that, an engineer’s design replaces the table. For the broader build see how to build a deck yourself and, for footing contact with slabs, pressure-treated wood on concrete.

Common Mistakes With Deck Framing Fasteners

• Leaving hanger holes empty because the screws seemed like enough.
• Mixing screws and nails in one hanger.
• Using bright or zinc-plated fasteners in treated lumber.
• Using mechanically galvanized nails where the guide requires hot-dip.
• Hammering lag screws instead of turning them into proper pilot holes.
• Attaching a ledger to brick veneer.

Frequently Asked Questions

Are screws or nails better for deck framing?

Neither is better on its own. Each connection has a named fastener: threaded nails for blocking and decking, lag screws or bolts for ledgers and bracing, and the hanger’s listed nails or the maker’s structural screw in joist hangers. Follow the connector schedule and your local code.

Can I use screws in joist hangers?

Only if the hanger manufacturer permits it. Simpson Strong-Tie lists its SD structural screws as an alternative in hangers that allow them, and says to use only SD screws, fill every hole and never mix screws with nails. Generic wood or deck screws have no rating in a hanger.

What nails should I use for deck framing?

Use threaded (spiral or ring-shank) nails where the guide calls for nails, because smooth-shank nails tend to back out as the wood swells and shrinks. In treated lumber the nails must be hot-dip galvanized to ASTM A153 or stainless steel. Connector nails for hangers follow the hanger schedule.

Do deck framing screws and nails need to be galvanized?

Yes, in preservative-treated lumber. The deck guide requires hot-dipped galvanized, stainless steel, silicon bronze or copper fasteners, and stainless grade 304 or 316 within 300 feet of salt water. Fasteners and connectors must be the same corrosion-resistant material.

Sources Read for This Article

American Wood Council, Prescriptive Residential Wood Deck Construction Guide (DCA 6), 2015 edition, for the connection fasteners, spacing rules, coating rules and commentary quoted above. Simpson Strong-Tie, Decks Done Right series, for gap, bearing and hold-down guidance. Simpson’s SD screw substitution rules were taken from its connector guidance as summarized by a search, not from a full page I could open, so confirm them on your hanger’s own data sheet before you buy fasteners. Codes vary by jurisdiction and edition; follow your local building department.