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Pressure-treated lumber is wet, dense, and often tougher on bits than ordinary framing lumber. The right choice depends on the hole: a few clearance holes call for a different bit than repeated deep holes for wiring or plumbing. For most jobs, a sharp auger bit or ship auger is the best balance of speed and control. For small, shallow holes, an ordinary brad-point or twist bit is usually enough.
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Choose the bit by the hole
For holes around 1/4 to 1/2 inch in diameter and no more than a couple of inches deep, a sharp high-speed-steel twist bit is an inexpensive, sensible option. A brad-point bit can start more cleanly and wander less, especially when the entry point matters. Neither is ideal for repeated deep holes: packed chips raise friction, slow the drill, and can overheat or dull the cutting edges.
For deeper holes through joists, posts, or beams, use an auger bit with a screw point and wide flutes. The point pulls the bit into the wood, while the flutes carry chips out of the hole. A ship auger is a good choice for longer reaches and larger framing holes; its long shank can get through thick material, but it needs a steady drill and more room to maneuver. Browse wood auger bits with hex shanks if you need a general-purpose set for framing work.
For large, shallow holes such as a recess for a pipe or fastener, a spade bit costs less and cuts quickly. It leaves a rougher hole, tends to wander more, and is a poor choice for deep boring. A self-feed bit can make large holes faster and cleaner, but it demands substantial torque and can grab hard when it breaks through. For occasional holes in softwood, the cheaper spade bit is often fine.
Bit comparison
| Bit type | Best use | Typical trade-off | Best fit |
|---|---|---|---|
| Twist or brad-point | Small, shallow holes | Can clog or wander in deep holes | Occasional holes up to about 1/2 inch |
| Auger | Deep holes in framing lumber | Needs chip clearing and controlled torque | Repeated holes through joists or posts |
| Ship auger | Deep, larger holes with long reach | Long bit can flex; needs a capable drill | Thick framing and access through assemblies |
| Spade | Large, shallow holes | Rough finish and more wandering | Low-cost, occasional clearance holes |
| Self-feed | Fast, large holes in framing | High torque; can grab at breakthrough | Many large holes with a strong drill |
What pressure treatment changes
Pressure-treated lumber is not one uniform material. It may be wet from treatment, relatively dry, or dense from its species and grade. Wet wood can swell around a bit and produce stringy chips; resin and preservative residue can also build up on the cutting edges. These conditions make sharpness and chip removal more important than buying a premium coating.
For wood, a standard sharp steel bit is usually appropriate. Carbide masonry bits are not for this job, and a coating marketed for metal drilling does not make a bit a better wood cutter. If you expect many holes, choose a sturdy auger bit with a replaceable or resharpenable cutting edge where available. If you only need a handful of holes, a basic quality bit is a reasonable buy. Avoid continuing with a bit that smokes, squeals, or leaves a dark, scorched rim; back out, clear chips, and let the bit cool.
Match the bit to the drill
Check the shank before buying. Many small twist bits use round shanks, while common wood augers are available with hex shanks that seat securely in a drill chuck. A hex shank can still slip if the chuck is loose or worn, so tighten it firmly. Do not use a bit whose shank is too large for the chuck, and do not assume an impact-rated hex shank means the bit should be run in impact mode.
A standard cordless drill can handle small and medium auger bits if its battery is charged and the bit is sharp. Large self-feed bits and long augers can stall a compact drill. Use low gear for larger diameters, hold the drill with both hands, and keep the work secured. A side handle is useful when the drill supports one, because a snagged bit can twist the tool suddenly. If you are buying specifically for larger framing holes, compare right-angle drill options and attachments for tight spaces, but confirm the attachment is rated for the torque and bit size involved.
Bore cleanly and avoid binding
Mark the hole and clamp the work where possible. Start straight, using moderate pressure rather than leaning hard on the drill. With an auger, let the screw point feed the bit; excessive pushing can overload the drill and make it harder to control. For a deep hole, bore partway, withdraw the bit to clear chips, then continue. The need to clear chips becomes more important as the hole gets deeper and the bit diameter increases.
Near the exit face, slow down and ease the pressure. Breakout is common when a bit punches through unsupported wood. If both sides are accessible, drill from one side until the point just emerges, then finish from the other. For a clean visible exit, clamp a scrap backing board behind the work. Check the lumber for nails or screws before drilling; striking metal can damage the cutting edges or make the bit kick.
What to buy for your job
For a deck repair or a few small pilot and clearance holes, buy a basic sharp twist-bit set and use the right diameter rather than forcing an undersized bit. For repeated holes through framing, choose an auger set that includes the sizes you actually need—commonly 1/2, 3/4, and 1 inch—rather than paying for a large assortment that will sit unused. A long ship auger makes sense when the lumber thickness demands reach, not simply because it looks more substantial.
Before drilling structural lumber, verify that the planned hole is permitted for the member and its location. A good bit can make a clean hole, but it cannot make an oversized or badly placed hole safe.