Small parts, large effect
Fasteners cost very little compared with lumber, posts and labor, which makes them easy to treat as an afterthought. Yet they are the points where a fence is held together, where moisture gets in, and where rust stains often start. A fence built with good lumber and poor fasteners can loosen, streak or fall apart far sooner than expected.
The two decisions are the type of fastener (nail, screw, bolt, bracket) and its finish (the coating or metal that resists corrosion).
Nails versus screws
Nails are fast, especially with a pneumatic nailer, and they flex slightly under load rather than snapping. That shear flexibility is a real advantage when wood moves with the weather. Their weakness is holding power: a nail relies on friction along the shank, and wood that swells and shrinks can work it loose over time. Ring-shank or spiral-shank nails grip better than smooth ones.
Screws thread into the wood and typically resist pulling out much better than smooth nails. That matters for pickets and boards that cup or warp, since screws help hold them flat. They are also easier to remove for repairs. The tradeoffs are cost, slower installation, and the fact that some screws can be brittle and snap under shear load if the wrong type is used. Deck-style or exterior screws with coatings made for outdoor use are generally better suited than general interior screws, which can corrode or snap.
Many builders combine them: screws for pickets and rails where holding power matters, and structural connectors or bolts where heavy loads are involved. Neither is better in every case, and local practice or manufacturer instructions may recommend one. Fence systems in vinyl, aluminum or composite often specify their own fasteners and should be built that way.
Sizing and placement
A fastener has to be long enough to reach well into the framing behind the board, but not so long that it pokes through. A rough rule is that most of the fastener’s length should sit in the receiving piece, though specifics depend on the materials. Keep fasteners away from board edges and ends, where wood splits more easily, and pre-drill near ends if the species is prone to splitting.
Fastener count matters too. Two per board per rail is a common pattern for pickets, but follow your fence design.
Finishes: where corrosion and staining come from
The finish determines how long the fastener lasts and whether it marks the fence. Common choices include:
- Bright or plain steel: no real protection. Not suitable for outdoor use.
- Electroplated (zinc-coated): a thin coating that may be adequate in dry, mild conditions but wears through faster than heavier coatings.
- Hot-dip galvanized: a thicker zinc coating, widely used outdoors and generally recommended for treated lumber. Exposure can still eventually wear through the coating.
- Coated or ceramic-coated exterior screws: designed for outdoor wood and common for decks and fences.
- Stainless steel: generally the most corrosion-resistant option, often chosen for coastal air, cedar and other woods that stain easily. It costs more, and grade matters.
- Aluminum: corrosion-resistant but soft, and often used for specific applications such as aluminum fence systems.
Pressure-treated lumber is a special case. Many modern preservatives contain copper compounds that can corrode some metals faster than older formulations did. For that reason, treated wood manufacturers commonly recommend hot-dip galvanized or stainless fasteners. Check the label or the manufacturer’s guidance for the product you are using.
Why stains happen
Black or brown streaks running down from nail heads are a common sign of the wrong fastener. They typically come from two causes:
- Iron corrosion in a fastener that is not rated for outdoor use or whose coating has worn through.
- A reaction between certain woods and metals. Cedar and redwood contain natural compounds that react with iron in the presence of moisture, producing dark staining.
Using stainless steel or high-quality coated fasteners with these woods reduces the chance of streaking. Mixing metals is also worth avoiding where you can: using fasteners of different metals near each other can speed up corrosion in the presence of water.
Once stains appear, they can sometimes be lightened with cleaning products made for wood, but the underlying fastener will keep corroding. Rust stains on metal parts need different treatment; see the guidance on fence rust removal.
Hardware beyond nails and screws
A fence also uses structural hardware:
- Post brackets, rail hangers and joist-style hangers support rails at posts.
- Post anchors and bases hold posts above ground or on pads.
- Carriage bolts and lag screws are used on heavier connections such as gate posts.
- Straps and ties for added strength at corners or ends.
- Hinges and latches for gates. Gate hardware should be chosen for the gate’s weight, and hardware in wet places benefits from corrosion-resistant hardware that suits wet climates.
Hardware should be made for outdoor use and rated for the load it carries. If it is part of a gate or anything safety-related, follow the manufacturer’s instructions.
Practical tips
- Match fastener finish to the lumber and the climate. Coastal air and heavy rain raise corrosion risk.
- Buy all fasteners for a project at the same time and from the same line if you can, to avoid mixing metals.
- Avoid driving nails or screws too hard; overdriven fasteners can split wood and hold less well.
- Do not mix interior drywall or general-purpose screws into exterior work.
- Check fasteners during seasonal fence maintenance, and re-secure boards where nails have backed out.
Weighing cost
Better fasteners cost more per box, but across a whole fence the difference is usually small compared with the cost of lumber. Replacing corroded fasteners later takes more time than buying the right ones at the start.