What Size Screws For Joist Hangers? | Quick Field Guide

Joist hangers do the heavy lifting only when they’re fastened with the right screws. Pick the wrong size and the connection can lose capacity, fail inspection, or corrode out long before the deck or floor. This guide gives you a clear rule of thumb, when to step up in size, and how to match screw length and coating to the job.

Joist hanger screw snapshot

Quick answer: screw sizes that actually work

Most modern, code-listed hangers are tested with structural connector screws, not drywall or deck screws.
In practice, two sizes fit nearly every face-mount hanger on wood framing:

• #9 × 1-1/2 in connector screws — the go-to choice for light and standard hangers.
• #10 × 1-1/2 in connector screws — used where the hanger’s table calls for a heavier fastener or higher loads.

If your hanger shows mixed hole sizes, follow the chart on the product label or catalog for which holes get which screw.
Use only structural connector screws from the hanger maker or an equivalent that’s explicitly rated for hangers.

Why size and type matter

Connector screws aren’t just any screws. They have large shanks and special heads to fill the hanger’s holes, resist shear, and seat flush without splitting the wood.
Undersized screws don’t engage enough steel and wood. Over-long screws can break through the far side of a ledger or joist, or clash with opposing fasteners.
Stick with the size printed for the hanger. If the catalog shows an option to swap nails for connector screws, match the listed screw size and length.

Choosing screw size for joist hangers on decks

Deck ledgers, beams, and joists live outdoors, so the screw size isn’t the only call.
You’ll also pick a coating or alloy that survives ACQ and similar treatments, salt spray, and wet-dry cycles.
The safe default is a connector screw that’s hot-dip galvanized for exterior use, or a stainless option near pools and coastlines.
The size stays the same—#9 or #10 at 1-1/2 in—unless the hanger’s table specifies another length.

Screw sizes to use with joist hanger installation

Different hanger families treat hole sizes in their own way.
Many face-mount styles include smaller round holes for standard screws and a few larger hex or obround holes for higher-capacity fasteners.
Where a table calls for a heavier screw in selected holes, mix the sizes exactly as shown.
If you can’t find a screw callout on the box, look up the model in the catalog and match both the diameter and length.

Length: when 2-1/2 inch screws show up

Most hangers that accept screws are rated with 1-1/2 in fasteners.
Some straps, angles, and heavy connectors publish tables for 2-1/2 in versions as well, mainly to pick up more wood thread in thick members.
Only use the longer length if the hanger or strap explicitly lists it, and make sure the tip won’t collide with a joist, bolt, or sheathing on the far side.

Code and catalog rules you can’t skip

Inspectors look for the exact fasteners the listing requires.
Model codes allow nails or manufacturer-rated screws in connector holes, yet they don’t permit drywall, deck, or cabinet screws.
If a hanger brand says “use our #9 connector screw” and provides loads for that size, that’s what passes.
The same goes for catalog notes on minimum bearing, wood species, and hanger height relative to joist depth.

Corrosion picks that match treated lumber

ACQ and related preservatives are tough on steel.
Pair exterior hangers with hot-dip galvanized connector screws, or upgrade to stainless near spas, coastal air, or where water sits.
Mixing coatings can backfire, so match connector finish to the hanger’s finish and the exposure class called out by the maker.
When in doubt, step up in corrosion resistance, not screw size.

Reading a hanger table without getting lost

Every connector has a table that ties loads to fastener size and count.
Here’s a simple way to read them:

1. Find your exact model.
2. Scan the row for your lumber size and species.
3. Use the fastener column to pick the screw diameter and length, including any mixed-hole pattern.
4. Confirm the load value meets your joist span and spacing.

If anything doesn’t match your job, switch to a hanger that does instead of changing the screw on your own.

Checklist before you drive the first screw

• Seat the joist tight to the hanger seat with no more than a thin gap.
• Clamp or tack the hanger so the back flange sits tight to the header.
• Start with the round holes, then fill any special or angle holes as the table shows.
• Drive by turning, not hammering; hex-head connector screws take a 1/4-in bit.
• Fill every required hole; optional holes are marked as such in the table.

Small misses add up. A missing screw, a wrong length, or a mixed brand erases the rating the table promises.

Common mistakes that sink capacity

Drywall screws snap in shear and cut deep threads that encourage splitting; don’t use them in hangers.
Generic deck screws may lack the shank diameter and head profile to fit connector holes.
Short “joist hanger” nails at 1-1/2 in can lower ratings when the design expects full-length commons.
These swaps look close but they don’t carry the loads the label claims.

Table: screw length and coating selector

Pick the row that matches your site and lumber. Then match the coating and screw length to your hanger’s listing.

For model-specific sizes and substitutions, see the SD Connector Screw page. For corrosion guidance by preservative and exposure, read the wood connector corrosion guide and the AWC fastener corrosion FAQ.

Field tips for clean installs

Work from square, straight stock. Pre-mark joist layout, set your first few hangers with a scrap joist as a gauge, and confirm crown up before fastening.
Use a low-speed driver for better control, especially in dense species.
If a screw refuses to seat, back it out a turn and drive again instead of over-torqueing the head.

When nails still make more sense

Some top-flange models and double-shear designs are tested with common nails driven at an angle.
If the catalog doesn’t list a connector screw substitution, stick with the specified nail schedule.
Mixing a random screw into an angled nail hole can bind the wood fibers and undercut the tested capacity.

Frequently asked sizing calls

Can I use #8 screws?

Short answer

Only if the table lists #8. Most face-mount models that take screws expect #9 at a minimum.

Do I ever need #12 screws?

Short answer

Rarely in joist hangers. You’ll see #12 more in heavy straps and holdowns. Match the table.

What about engineered lumber?

Short answer

Many hangers list separate tables for LVL, PSL, or LSL. Fastener size often stays #9 or #10, but counts and patterns change.

A simple sizing flow you can trust

1. Read the hanger model on the box or stamp.
2. Open the table and note the exact screw size and length the model lists.
3. If two sizes are shown, use the heavier screw where the table marks the bigger holes.
4. Match the coating to the exposure and the hanger’s finish.
5. Drive all required fasteners and re-check the count.

Follow that and your hanger will perform to the number in the table, not a guess.

Driver bits, head styles, and torque

Connector screws often have 1/4-in hex heads with washer flanges. The flange bears on the hanger face to spread load and keep the head from pulling through.
Use a fresh hex bit so the head doesn’t cam out. A clutch-style drill or an impact driver set to low keeps you from stripping threads in soft lumber.
Stop when the head touches steel and the washer seats flush; crushing the flange into the hanger won’t raise capacity and can crack the coating.

Mixing nails and screws on one hanger

Many tables show multiple fastener options for the same model. That doesn’t mean mix at random.
Pick one schedule from the table and install it completely. If a detail calls for nails in the angle holes and screws in the face holes, that will be called out clearly.
A half-nail, half-screw experiment leaves the connection unlisted and open to rejection.

What to do when a hole is blocked

Ledger bolts, sheathing, or tight corners can make a listed hole impossible to reach.
Don’t skip it; check the catalog for an alternate pattern or a different hanger that clears the obstacle.
A short move to a skewed or offset model beats running with a missing fastener and guessing at the result.

Storage and handling keep screws reliable

Keep boxes closed and dry. Moisture can stain coatings and reduce drive quality.
Don’t mix loose screws from different brands or finishes in the same bucket; the heads may fit your bit but the steel and coating may not match the hanger.
Save labels and lot numbers with your permits so an inspector can confirm the exact product used on the day of the visit.

Cost tradeoffs between #9 and #10

#10 connector screws cost a little more than #9 in most stores. Use them where the table asks for them and nowhere else.
Upsizing when it isn’t listed won’t raise the load value and can create fit issues in small holes.
Buying the right size once beats paying twice for a heavier screw that gains nothing.

Repair moves when the wrong screws were used

If the wrong screws went in, don’t hope no one sees them. The safe fix is to remove and replace with the listed size.
If stripped holes remain, move up to a nearby hole that’s part of the pattern, or switch to a larger hanger that covers the old holes completely.
When removal risks damage, a catalog-listed retrofit kit or added strap may be the clean answer.

Fill rates, optional holes, and patterns

Connector tables use clear language on how many holes must be filled.
When a pattern shows five required and two optional fasteners, you’ll install five every time, then add the optional only when the design load or table calls for it.
Skipping a required hole lowers the rating to an unknown number.
Some models include diamond or triangle marks next to special holes; those marks point to a heavier screw or an angle hole that bumps the load.
Match the mark to the note in the table and drive the exact screw that note names.
If a pattern seems odd, you’re likely looking at mixed joist sizes on the same page; double-check the row heading and adjust to the line that matches your lumber.

Use the right size, right coating, and full count; your hanger lasts longer.