# Is a wood fence with metal posts better than one with wood posts? > Wood fence with metal posts or treated wood posts? How each fails, how footings are sized in Ontario's sandy soil, and when galvanized steel is worth the cost. URL: https://groveontariofencebuilders.com/guide/steel-vs-wood-fence-posts/ Decision Guide Galvanized steel and ground-contact treated wood both hold up a good fence. The difference shows at the grade line, in the wind and in sandy ground. Last Updated: October 31, 2026 The post is the only part of a fence that lives in the ground. That is where most wood fences here give out. For most 6-foot wood privacy fences in Ontario’s sandy soil, galvanized steel posts are the more durable choice. They cannot rot or feed termites, and they flex less in a Santa Ana gust. Ground-contact treated wood posts cost less and are simpler to build on, and stay a sound choice when the footing is sized and drained well. [Grove Ontario Fence Builders](https://groveontariofencebuilders.com/) builds [wood fences](https://groveontariofencebuilders.com/wood-fence-installation/) on both kinds of post across Ontario and the west Inland Empire, with the work carried out by licensed and insured fence contractors. This guide explains how each post fails, why the soil decides the footing, and how to choose for your line. Key takeaways - Wood posts usually fail at the grade line, where moisture, oxygen and termites meet; steel posts fail mainly where the coating wears through. - Central Ontario is mapped as Tujunga loamy sand and Ontario Ranch as Delhi fine sand, so footings get their grip from depth and width. - No single post depth fits every fence: height, panel type, wind, soil and gate loads set it. - Frost is not a design factor on the valley floor; wind and soil are. - Rancho Cucamonga requires solid wood screening fences to be built on steel frames. ## How each kind of post fails A wood post rots from the outside in, at the grade line. The few inches just above and below the soil surface stay damp after every sprinkler cycle while also getting air, which is the combination decay fungi need. A concrete collar that was finished flat or dished can hold water against the wood and speed it up. Homeowners report posts that looked fine above ground snapping 2 inches below grade inside their footings. Long, hot summers add a second stress: NOAA’s 1991-2020 normals for Ontario International Airport average 93 days a year at or above 90°F, and a post drying that hard checks, twists and loosens its fasteners. Termites are the third. UC IPM’s [subterranean termite pest note](https://ipm.ucanr.edu/home-and-landscape/subterranean-and-other-termites/) says wood in contact with soil should be chemically treated or naturally resistant, and lists untreated fence posts near a structure among the things that can contribute to an infestation. The [termites and fence posts guide](https://groveontariofencebuilders.com/guide/termites-fence-posts/) covers the signs. A galvanized steel post has none of those problems, but it is not indestructible. The zinc coating protects the steel until it wears through, which happens fastest where water sits: a dished footing, a sprinkler aimed at the base or soil heaped against the post. A steel post can also bend under a vehicle impact, and its weak point is often the bracket hardware that joins it to the wood rails. ## Steel and wood posts side by side | | Ground-contact treated wood | Galvanized steel | | --- | --- | --- | | Rot | Resists it while the treatment holds; cut ends and the grade line are weak spots | Does not rot | | Termites | Treatment deters them; untreated wood near a house is a risk | Nothing to eat | | Stiffness in wind | Stiff when new; can loosen as it dries and checks | Stiffer for its size and stays straighter | | Building on it | Rails nail or screw straight to the post | Rails bolt on through steel brackets planned before the boards are cut | | Looks | Matches the fence | Hidden from the street side; visible on the owner’s side unless wrapped in wood | | Replacing one | Dig out the old footing, set a new post | Rarely needed; a bent post is cut out and replaced | | Place in the price | The base of the $30 to $70 per foot range for 6-foot redwood or cedar | Moves a job toward the top of the same range | Both sit inside the typical Southern California installed range for a 6-foot redwood or cedar privacy fence, about $30 to $70 per linear foot. The [fence cost guide](https://groveontariofencebuilders.com/guide/fence-cost-ontario-ca/) explains what else moves a price within it. ## Why the soil decides the footing USDA soil survey data maps central Ontario on Tujunga loamy sand, about 80 percent sand to 5 feet deep, and much of Ontario Ranch on Delhi fine sand at roughly 96 to 97 percent sand. Both drain quickly and barely shrink or swell, which is good news: there is little seasonal heave to jack posts out of the ground. The trade-off is grip. Loose sand sloughs into a freshly dug hole, so the hole has to be kept open, sometimes with a form tube, and the finished footing resists wind mostly through its own depth and diameter rather than through soil cohesion. Ontario’s structural design criteria, [Information Bulletin 103](https://content.ontarioca.gov/sites/default/files/2026-02/IB%20103%20%28Structures%20Design%20Criteria%20-%202025%20Codes%29%20eff%201-1-2026.pdf), use a default lateral soil bearing value of 100 psf per foot of depth unless a soil report says otherwise. Because the soil’s resistance in that method grows with depth, a deeper footing usually adds more holding power than a wider one. The soil changes a few miles away. Rancho Cucamonga and Upland sit largely on Hanford coarse sandy loam, which tends to hold a hole better. Chino Hills slopes are mapped as Fontana clay loam with soft bedrock at a typical depth of about 28 inches and moderate shrink-swell, so a footing there may hit rock before it reaches its planned depth, and clay that swells and shrinks can work a shallow post loose. The [Chino Hills area page](https://groveontariofencebuilders.com/service-areas/chino-hills/) covers fence work on those slopes. ## Depth, spacing and the wind: no universal number A fence post is a lever. Wind pressure on the panel pushes the top, and the footing resists at the bottom. Double the height of a solid panel and the turning force at the base roughly quadruples, because twice the area catches wind on a lever twice as long. That is why one depth printed for every fence is wrong, and why a post plan starts from these inputs: - **Height.** A 6-foot privacy fence loads its posts far more than a 3-foot front-yard picket. - **How solid the panel is.** Solid board-on-board catches the full wind; open iron or spaced pickets let most of it through. - **Wind exposure.** IB 103 sets wind Exposure C, the open-terrain category, with a 110 mph design wind speed under the residential code. The National Weather Service office in San Diego issued 44 High Wind Warnings for the Inland Empire valley zone between January 2016 and October 2026, most from October through February. - **Soil.** Sand needs more depth and diameter than firm loam to resist the same load. - **Gates.** A gate hangs its weight off one side of a post, so hinge posts need heavier sections and bigger footings than line posts. Footings for 6-foot privacy fences in sand commonly run deeper than footings for open fences, and gate posts deeper still. Wood fence posts are commonly spaced up to about 8 feet apart, and closer spacing is a standard answer to a windy, solid run. Frost does not enter the calculation here: the same NOAA normals show about 1.7 nights a year at or below freezing at Ontario’s airport, so there is no frost line to get below. The [Santa Ana winds guide](https://groveontariofencebuilders.com/guide/santa-ana-winds-fence/) goes deeper on wind loads. ## Setting a post in concrete Whatever the post, the footing details decide how long it lasts. The post goes in plumb on a string line, the concrete is placed around it, and the top of the concrete is crowned so water sheds away from the post instead of collecting at its base. Under a wood post, a few inches of gravel at the bottom of the hole lets water drain out of the end grain instead of soaking in. The concrete is left to cure before rails and boards load the post; the [fence installation process guide](https://groveontariofencebuilders.com/guide/fence-installation-process/) explains why that wait matters and what sets its length. ## Leaning posts: what they tell you A post that leans after a few years is telling you something about the footing. Sprinkler water washing sand from around a shallow footing, a tree root pushing from one side, a footing too small for a solid 6-foot panel in the wind, and a post rotted at grade all produce the same lean. One or two leaning posts in an otherwise sound line can often be reset or replaced as a [fence repair](https://groveontariofencebuilders.com/fence-repair/); many leaning posts along a run usually mean the original footings were undersized, which points toward [fence replacement](https://groveontariofencebuilders.com/fence-replacement/). The [repair or replace assessment](https://groveontariofencebuilders.com/tools/fence-repair-or-replace-assessment/) helps sort which you have. Gate posts are the classic case, and the [sagging gate guide](https://groveontariofencebuilders.com/guide/fix-sagging-gate/) starts with them. ## Rancho Cucamonga’s steel-frame rule In Rancho Cucamonga the choice is partly made for you. The city’s residential fence handout requires screening and privacy fences and gates in residential districts to be solid wood with steel frames, solid vinyl, or tubular steel or wrought iron backed with metal sheeting painted to match. A wood privacy fence there is built on a steel frame by rule, and chain link with slats is not accepted as screening. The [Rancho Cucamonga area page](https://groveontariofencebuilders.com/service-areas/rancho-cucamonga/) covers the rest of the city’s fence rules. Ontario’s own code allows wood, PVC and ornamental steel or iron fences without specifying the post material. ## Which post fits your fence Steel posts make the most sense on long runs, windy or exposed lines, solid board-on-board styles, any fence close to the house where termites are a concern, and every fence in Rancho Cucamonga. Treated wood posts fit shorter runs, low picket fences, tighter budgets and repairs where the new post has to match old wood posts on either side. For gates, a steel hinge post or a heavier 6-by-6 wood post in a larger footing is the usual answer either way. Species and grade of the boards are a separate decision, and the [cedar vs redwood guide](https://groveontariofencebuilders.com/guide/cedar-vs-redwood-fence/) covers it. To plan the posts for your line, call Grove Ontario Fence Builders at [(909) 324-5352](tel:+19093245352) or [request an estimate](https://groveontariofencebuilders.com/contact/). The post type, spacing and footing are the first items on the plan, before any boards are ordered. ## Questions about this guide ### Why is there no standard depth for fence posts? Because the load on a post changes with the fence. Depth is set by the fence height, how solid the panels are, the wind exposure, the soil and any gate load. Loose sand gives a footing less grip than firmer ground, so footings for a 6-foot privacy fence or a gate post in sand usually run deeper and wider than for a low, open fence on the same lot. ### Can a broken wood post be replaced with a steel one? Usually, yes. A failed wood post can come out with its old footing and a galvanized steel post go in its place, with the existing rails fastened to it through brackets. It works best when the rails and boards are still sound. When most posts along the line are failing, a rebuild on new posts is often the better scope. ### Do galvanized fence posts rust in the ground? The zinc coating protects the steel for a long time, but it can wear through where water sits against the post. A concrete footing crowned so water runs away, sprinklers aimed off the fence and no soil piled against the post all help. Ontario is far enough inland that salt air, which shortens hardware life on the coast, is not a factor. ## Related service ### Wood fences → Redwood, cedar and fir privacy fences, dog-ear and board-on-board, on wood or steel posts. ## More guides Learn Are termites eating your fence posts? How to tell and what to do Two kinds of termite damage wood fences in Southern California, and they leave different evidence. Here is how to read it, and what it means for the posts. Learn How much wind can a fence withstand in a Santa Ana? There is no single wind rating for a fence. What it survives depends on how solid it is, how far apart the posts are and how deep they sit in sandy ground. Learn How do you fix a sagging fence gate? A gate that drags or misses its latch is telling you what moved. Find that first, then choose between an adjustment, a reset post and a rebuilt gate. Decision Guide Cedar or redwood fence: which wood is better? The species name gets the attention, but the grade stamped on the board tells you more about how a fence will hold up. Here is how to compare the two woods honestly. Learn How long does it take to install a fence in Ontario, CA? The calendar time for a fence is mostly approvals and curing concrete, not nailing boards. Here is each step, in order, and what sets its length.