Metal Fence vs Wood Fence: An Honest Comparison
Wood is cheaper up front, easy to modify and looks right on some houses. It also moves, rots at the soil line and needs refinishing. Here is the comparison without the sales pitch.
Most fence comparisons are written by someone who sells one of the two options. This one is written by a metal contractor, so read it with that in mind — and note that it includes the things wood does better, because pretending otherwise would not help anyone choose.
The Fundamental Difference: Wood Moves
Wood is hygroscopic. It takes on moisture from humid air and gives it up in dry air, and it changes dimension as it does — considerably across the grain, hardly at all along it. That differential is the source of nearly every problem a wood fence develops.
As a board dries, the outer fibres shrink before the core does, and the resulting stress opens checks along the grain. Because a board shrinks more in the direction of the growth rings than across them, it cups — the face away from the pith becomes concave. Boards with grain that runs at an angle to their length twist as they dry. Southern Ontario's seasonal swing from humid summers to dry, heated-air winters cycles this every year.
This is why the even gaps you install in a wood slat fence do not stay even, why boards cup away from the frame, and why fasteners work loose. Nothing failed. The wood is doing exactly what wood does.
Rot at the Soil Line
A wood post does not rot uniformly. It rots in a band at and just below the ground surface, and the reason is that decay fungi need both moisture and oxygen. Deep in saturated soil there is not enough oxygen. Well above grade there is not enough sustained moisture. At the interface there is plenty of both, plus the temperature swings that keep fungi active.
Pressure-treated wood resists this and it does not stop it forever. Field cuts expose untreated interior wood and need to be treated with an end-cut preservative — a step that is skipped constantly. And treated wood is only as good as the depth of preservative penetration, which varies by species and by treatment.
The Fastener Problem
Modern pressure-treatment chemistry — the copper-based ACQ and CA formulations that replaced older treatments — is more corrosive to steel than what came before. Plain or lightly plated steel fasteners in treated lumber corrode, and a fastener that loses section in a fence rail is the fence's weak point.
The correct answer is hot-dip galvanized or stainless fasteners and connectors, rated for use with treated lumber. It is not expensive and it is skipped often enough that corroded fasteners are a routine finding on wood fences a decade old.
The Maintenance Cycle
A wood fence has a real, recurring maintenance requirement, and its appearance depends on keeping it.
- ✓Left bare, wood greys as UV breaks down surface lignin. Many people like the weathered look; it is a legitimate choice and it does not by itself shorten the fence's life.
- ✓Stained or sealed, the finish has to be renewed on a cycle — more often on south- and west-facing runs, less often on sheltered ones. Skipping it does not destroy the fence but it does change how it looks.
- ✓Cleaning and re-coating means preparing the surface, which means washing, sometimes sanding, and always waiting for dry weather. It is a weekend, repeatedly, for as long as you own the fence.
- ✓Individual boards will need replacing as they cup, split or rot, and the replacement will not match the weathered colour of its neighbours for a season or two.
What Metal Does Differently
Aluminum and steel are dimensionally stable in the face of moisture. They do not absorb water, so they do not cup, check, twist or shrink. The gaps you install are the gaps you have in ten years. There is no fungal decay, so there is no rot band at the soil line, and insects have no interest in it.
Metal is also stronger per unit of section, so the members can be slimmer for the same job. A metal fence reads lighter and more precise than a wood fence of the same height, which suits some houses and not others.
Metal's Real Maintenance Requirement
A powder-coated metal fence does not need refinishing on a cycle the way a stained wood fence does. It does need washing. Road salt, road film and organic debris sitting against a coating are what eventually cause problems, particularly at the bottom of the fence where slush accumulates.
Anyone describing a powder-coated fence as maintenance-free is overselling it. The honest description is that the maintenance is washing rather than refinishing, and that it is annual rather than every few years — a different kind of commitment, not the absence of one.
Where Wood Is Genuinely Better
There are real advantages on the wood side and they should not be glossed over.
- ✓Lower upfront cost. Wood fencing is typically less expensive to build than metal fencing of equivalent height and privacy. That is a real consideration and it is often the deciding one.
- ✓Field modification. A wood fence can be cut, notched, extended and altered on site with basic tools. A metal fence is largely made to order, and cutting it on site exposes bare metal that has to be sealed.
- ✓Immediate availability. Lumber is on the shelf. Custom metal panels are manufactured to order with a lead time.
- ✓Repair of localized damage. One damaged board comes off and a new one goes on. A damaged metal component has to be sourced in the right profile and colour.
- ✓Appearance in the right setting. A cedar board fence on a century home in an established neighbourhood looks correct in a way that a contemporary metal screen may not. Materials should suit the house.
- ✓Warmth and texture. Real wood has a depth of grain and a tactile quality that a printed finish approximates but does not equal at close range.
Where Metal Is Genuinely Better
The metal advantages are mostly about time.
- ✓It holds its geometry. The line stays straight, the gaps stay even, the gate stays square.
- ✓No rot at grade, which removes the single most common cause of wood fence failure.
- ✓No refinishing cycle, only washing.
- ✓Consistent appearance across a long run, because the components are manufactured rather than sorted from a lumber pile.
- ✓Better options for tall, slim, contemporary designs, because the material is strong enough to do them in slender sections.
- ✓It is not fuel, which matters in some settings.
One Thing That Is Identical
The structural conversation does not change with the material. A 6-foot solid privacy fence collects the same wind load whether it is cedar boards or aluminum slats, and it hands that load to the posts either way. A wood fence needs the same post spacing discipline, the same footing depth below the local frost line, and the same crowned footing tops as a metal one. Choosing wood does not make the groundwork easier — and a wood post has the additional problem that the very zone the footing protects is also the zone where it will eventually rot.
Frequently Asked Questions
Does a metal fence last longer than a wood fence?
In Ontario's climate a properly built and maintained metal fence generally outlasts a wood one, mostly because it does not rot at the soil line and does not move with humidity. How much longer depends heavily on the quality of both — a well-built cedar fence that is kept finished can last a long time, and a poorly detailed metal fence in road salt will not.
Is metal fencing more expensive than wood?
Metal typically costs more up front than wood of equivalent height and privacy. The counterweight is that metal does not have a recurring refinishing cycle and does not have the board replacement that comes with wood movement. Whether that trade works out for you depends on how long you plan to keep the fence.
Can I mix wood and metal in one fence?
Yes, and it is a common approach — metal posts and frames with wood infill, which removes the rot-at-grade problem while keeping the appearance of wood. The main things to get right are isolating the wood from the metal where water can be trapped between them, and using fasteners rated for treated lumber.
Why do wood fence boards cup and twist?
Because wood shrinks more in the direction of the growth rings than across them, so a board dries into a cupped shape, and grain that runs at an angle to the board's length causes twist. Ontario's humid summers and dry heated winters cycle this every year.
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