410 Stainless Steel Flat Head Concrete Screws

Countersunk 410 stainless steel concrete screws for flush fastening into concrete, brick, grout-filled CMU and hollow block. Available in 3/16" and 1/4" diameters and lengths from 1 1/4" to 6", in Simpson Strong-Tie Titen® and DeWalt Crete-Flex®. Choose a diameter below to see available lengths. If a raised head is acceptable and you want more driving torque, see the hex head screws in the same lines, or return to all 410 stainless concrete screws.

When to Use a Flat Head Concrete Screw

Reach for the flat head anywhere a raised head would be a problem: sleepers and furring strips that receive finish flooring or panelling, door and window frames, threshold plates, stair stringers against a foundation wall, and any fixture that gets covered or walked on. In wood, the tapered head pulls itself flush as it drives. In steel or other rigid fixtures, countersink the clearance hole first — driving a flat head against a flat surface loads the head edge instead of seating it, and the fixture will stand proud.

Key Features

• Countersunk flat head — sits flush or below the fixture surface
• 410 stainless steel — good corrosion resistance for exterior and high-moisture use
• One-piece concrete screw — no shield, plug, or expansion sleeve required
• Anchors into concrete, brick, grout-filled CMU, and hollow block
• Available in 3/16" and 1/4" diameters, in lengths from 1 1/4" through 6"

Diameters, Drives and Drill Sizes

How to Install a Flat Head Concrete Screw

1. Drill the clearance hole through the fixture and countersink it if the material will not let the head pull itself flush.
2. Drill into the base material with the bit size for your screw — see the table above — going at least 1/2" deeper than the intended embedment.
3. Blow the hole clean with compressed air. Dust left behind is the most common reason a screw will not seat.
4. Drive with a fresh bit under firm, steady axial pressure until the head is flush — a #2 Phillips for Simpson Titen®, a T25 star for DeWalt Crete-Flex®. Ease off as the head closes in — overdriving strips the threads cut into the masonry.

Frequently Asked Questions

Do I have to countersink the hole?

In wood and other soft fixtures, no — the tapered head cuts its own seat as it draws down. In steel, aluminum, or dense composite, yes. Without a countersink the head cannot seat and the fixture will not pull tight against the base material.

What size drill bit do I need?

It depends on the diameter and the line, not the nominal size alone. Simpson Titen® 1/4" screws take a 3/16" carbide bit; DeWalt Crete-Flex® 3/16" screws take a 5/32" bit; the extra-long #14 Crete-Flex® takes a 1/4" bit — that one measures .268" at the thread crest, so a 1/4" bit still falls under the crest and the screw taps its own threads. Check the individual product page before you drill.

Can I use these below grade or in salt air?

410 stainless holds up well in exterior and high-moisture conditions and far outlasts plated carbon steel, but it is not a marine-grade alloy. For direct salt spray, splash zones, or submerged work, use a 316 stainless concrete screw instead.