Applications & FAQ

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SPAX® Multi-purpose Construction Screws

For flush or countersunk installation, use SPAX® Unidrive or T-STAR plus flat head construction screws. Where flush or countersunk installations are neither possible nor desired, SPAX® pan head construction screws provide superior draw down and holding performance.

• Fabricating wood shelving

• Replacing loose or stripped screws

• Installing cabinetry

• Sawhorses

• Installing window framing

• Outdoor furniture

• Installing plumbing supports

• Installing plywood or OSB

• Countertops

• Fixture to concrete

• Furring strips to concrete

• Thresholds to concrete

• Medium-duty hanger supports to concrete

• Brick molding 

• Drywall

• Composite trims

• Hinges

• Indoor furniture

• Outdoor lighting

• Pegboard

• Modular storage units

• Wooden bridges & wooden walkways

• Heavy wood timbers

• Shelf brackets

• Signs, clocks, pictures

• Subfloor sheathing

• Stair treads

• Recreational wood crafts

• Siding

• Wood fencing


SPAX® PowerLags®

• Deck ledger board attachment (DrJ TER No. 1711-01)

• Deck rim joist and girders

• Deck railing and balusters

• Multi-ply - LVL beams and girder truss assemblies (DrJ TER No. 1802-03)

• Retaining walls

• Exterior privacy fences

• Clothesline poles

• Sign posts

• Outdoor furniture

• Pergolas

• Gazebos

• Shelving

• Sheds

• Mailbox posts

• Mailboxes

• Landscaping timbers

• Spas


SPAX® T-STAR plus Wafer Head Screws

• Installation of fine cabinetry


SPAX® Rear Panel Screws

• Attachment of back panels to bookcases, storage units and cabinetry


SPAX® MDF/Hardwood Screws

• Assembly of medium density fiberboard (MDF) cabinetry and storage units

• Oak and other hardwoods to help guard against splitting

• Connecting cabinetry through the front style frames

• Attachment of lightweight, high-density polyurethane trim and moldings




Why do you call your fasteners “multi-purpose?”

The SPAX® fastener has patented features that allow it to perform in a wide variety of applications and materials other than wood, including concrete, masonry, light gauge sheet metal (24ga.) and plastics.


What does Unidrive mean?

Unidrive is a Phillips/Square Drive combo system for the SPAX® fastener. The user has the option of using either a Phillips drive bit or a Square drive bit to install the SPAX® fastener.


Where are SPAX® fasteners available?

SPAX® fasteners are available at most local home improvement retailers, industrial supply houses and online specialty woodworking outlets in the U.S. We are currently working to build a nationwide network of lumberyard and building materials suppliers.


Your packaging says “no pre-drilling.” Does that include concrete?

No pre-drilling is referencing application with hardwoods — not concrete. Concrete applications for our multi-material fasteners require pre-drilling with a carbide bit before installing the SPAX® fastener. Required hole size is published on the back of our product packaging.


Are there any tips to using SPAX® multi-material fasteners in concrete?

Yes. Keep in mind these are primarily medium-duty fasteners, and each application is different. Always use the correct diameter fastener for the applications and carbide bit required. Embedment into the masonry should be ¾” min. to 1-1/4” max. Also, pre-drill the hole ¼” deeper than thread engagement for maximum performance of the fastener. Here is a pilot hole drill chart for these applications:


For multi-material fasteners used in masonry/concrete, pre-drill a hole at least 1/4" to 1/2" longer than the length of the screw (refer to chart). No anchor required. In sheet metal, no pre-drilling is required up to 24 gauge.

Screw DiameterDrill BitWeight
#6Not recommendedNot recommended



Can I use SPAX® fasteners in treated lumber?

Yes! Our 304 series stainless steel deck and construction screws, as well as our multi-purpose construction screws with HCR-X™ and powerLags® with high corrosion resistant (HCR®) coatings are compatible with ACQ lumber.


What exactly is HCR®?

HCR® (High Corrosion Resistant) is a dual barrier coating system designed to extend the longevity of the SPAX® fastener when installed in treated lumber applications. The first barrier is an electrically applied substrate with a proprietary organic topcoat offering 1000 hr. salt spray performance. NOTE: HCR® from SPAX® is typically green in color.


What is HCR-X™?

HCR-X™ (Extra High Corrosion Resistance) is the latest proprietary dual barrier coating system developed by SPAX® U.S. It offers similar corrosion protection to that of SPAX® HCR® coating in that it has been approved for use in freshwater environments and for use in treated lumber. Note: HCR-X™ from SPAX® is typically grey/silver in color.


What are SPAX® screws made of?

Excluding our 304 series stainless steel line, all of the SPAX® fasteners are heat treated to Grade 5 durability carbon steel, from the small #6 diameter fasteners up to the ½” diameter PowerLags®.


What is the difference between blue zinc (silver) and yellow zinc?

The first difference is the color itself, which gives the user an option for aesthetics. The yellow zinc is a slightly higher grade of plating for corrosion protection vs. the blue zinc.


How many fasteners do I need?

We would like you to decide that by the practical life expectation you have for your specific wood project or concrete application.


Why can’t I use the PowerLags® in concrete?

The PowerLags® thread pitch and threads-per-inch design is different than our multi-purpose fasteners. PowerLags® are designed to be high-performance fasteners for wood-to-wood applications only.