Should You Use Steel Posts for a Wood Fence?
Steel fence posts for a wood fence are worth considering if you want the look of wood without a wood post in the ground. The post is the part of a wood fence that fails first, and galvanized steel does not rot. Master Halco's PostMaster, one of the best-known products of this type, is made from 11-gauge galvanized steel that is 0.120 inch thick, according to the manufacturer's specification sheet.
The manufacturer also publishes numbers that wood posts do not come with. The same sheet states that the product meets a minimum 73 mph ultimate wind load when a 6-foot solid privacy fence is built with posts set to full fixity every 8 feet on center, and it carries a residential warranty that lasts as long as the original purchaser owns the home. This post covers how steel posts work with wood fences, what they cost you in looks and money, and when they make sense in Western Pennsylvania.
What Are Steel Posts for a Wood Fence?
A steel post for a wood fence is a galvanized steel post made to carry wood rails and pickets in place of a 4x4. There are two common kinds.
The first is a formed steel post designed for wood fencing. PostMaster measures 3 1/2 inches by 1 3/4 inches and has pre-punched holes spaced 1 inch apart so the rails can be screwed directly to the steel. Its G90 zinc coating is 0.90 ounces per square foot.
The second is round galvanized pipe, the same type of post used for chain link, with brackets that hold the wood rails.
Either way, everything above the post is still a wood fence. The rails, pickets, caps, and trim are built the usual way.
Why Do Wood Posts Fail First?
Because of where they stand. A fence picket hangs in open air and dries after rain. A post sits in soil that holds moisture against it year-round.
A Michigan State extension bulletin on fence posts notes that high moisture content often occurs where wood touches the ground or is used within 18 inches of the ground surface. That band at the ground line is where posts rot through.
USDA Forest Service researchers recommend posts with an in-depth preservative treatment, preferably pressure treatment, for below-ground use. The American Wood Protection Association's residential guide calls for lumber rated Use Category 4A or higher for structural posts. A properly rated wood post is a sound choice. The trouble is that the rating has to be right, the treatment has to reach deep enough, and you cannot see either one after the post is set.
When a wood post does go, the fence leans, and the fix is digging out concrete. Our post on what causes fences to warp or lean in PA covers the warning signs.
How Strong Are Steel Fence Posts for a Wood Fence?
The published figures for PostMaster give a useful benchmark:
Steel: 11 gauge, 0.120 inch thick, galvanized
Coating: G90 zinc, 0.90 ounce per square foot
Spacing: posts spaced uniformly at 8 feet on center maximum unless otherwise indicated
Wind: minimum 73 mph ultimate wind load for a 6-foot solid privacy fence with posts set to full fixity every 8 feet on center
Warranty: lifetime for residential use, defined as for as long as the original purchaser owns the home, and 20 years from purchase for commercial use
Two phrases in that wind rating deserve attention. "Solid privacy fence" means the rating already accounts for a fence that catches wind like a wall. "Full fixity" means the post is anchored so it cannot rotate in its footing. The steel is only as good as the hole and the concrete around it.
Other steel post products have their own specifications. Ask for the manufacturer's sheet for whatever is being quoted and compare gauge, coating and spacing line by line.
Do Steel Posts Change How the Fence Looks?
They can be nearly invisible, or they can be the first thing you notice. It depends on the style.
A formed post only 1 3/4 inches deep takes up little more room than the rails. On the finished side of the fence, the pickets run past it and you see unbroken wood. On the back side, you see a strip of galvanized steel at each post. It can be covered with a wood board so both sides read as wood.
Round pipe posts are harder to hide and usually stay visible on the rail side.
Think about which side you will look at. Some municipalities require the finished side of a fence to face the neighbors, which puts the post side toward your own yard. If that view matters to you, plan for post covers or a board-on-board layout that wraps the posts. See how a board on board fence provides privacy for that style.
Do Steel Posts Still Need Concrete and Frost Depth?
Yes. Steel does not rot, but it can still be lifted or tilted by the ground.
In this part of Pennsylvania, local building codes put the frost line at 36 inches. The building code chapters for Hempfield Township, North Huntingdon Township and Murrysville each state a frost line depth of 36 inches. A post footing that stops above that depth can be pushed up when the soil freezes.
A steel post for a 6-foot fence has to be long enough to reach that depth and still stand full height above grade. Confirm the post length in the quote.
Concrete matters for the wind rating too. The 73 mph figure assumes full fixity, and a post in loose backfill does not have it. For more on footing depth, see how deep fence posts should be in PA soil.
What Fasteners and Hardware Go With Steel Posts?
The rails attach to the steel with screws through the pre-punched holes, and the pickets attach to the rails as usual.
If the rails are pressure treated, fastener choice matters. Simpson Strong-Tie recommends stainless steel or copper and silicon bronze fasteners with treated wood that has higher copper retention levels, and cautions that electroplated coatings should not be treated as hot-dip galvanized. Use the fasteners the post manufacturer specifies for the post connection and corrosion-resistant fasteners everywhere else.
Gate posts need more thought than line posts. A gate hangs its full weight off one post and slams against another. Ask how the gate posts are being reinforced or upsized. A sagging gate often points back to the hinge post.
When Are Steel Posts Worth the Extra Cost?
Steel posts cost more than wood 4x4s, and the fence around them costs the same. Whether that premium pays off depends on your situation.
They make the most sense when:
You plan to stay in the home long enough to replace the pickets at least once on the same posts
The yard is wet, shaded or poorly drained
The fence is 6 feet, solid and exposed to wind
You have already replaced rotted wood posts once and do not want to do it again
They matter less when:
You are fencing a short run on a tight budget
You expect to sell within a few years
The style shows the posts on both sides and you want an all-wood look
If rot is your main worry, also compare materials that take wood out of the picture entirely. Our post on the most durable fence materials covers vinyl, aluminum and steel.
FAQ
Do steel posts last longer than wood posts?
Galvanized steel does not rot, which removes the usual cause of wood post failure at the ground line. Master Halco warrants its PostMaster product for as long as the original residential purchaser owns the home.
Can you see steel posts on a wood fence?
Not from the finished side on most styles. On the rail side, a formed steel post shows as a narrow strip unless it is covered with a board.
How far apart are steel posts set?
Master Halco specifies 8 feet on center maximum for PostMaster unless otherwise indicated.
Do steel fence posts rust?
The galvanized coating protects the steel. Ask for the coating specification in the quote. PostMaster uses a G90 zinc coating.
Can steel posts be added to an existing wood fence?
Sometimes. If the rails and pickets are still sound, failed wood posts can be replaced with steel. It is labor-heavy, so compare the cost with replacing the fence. Our guide to knowing when it is time to replace your fence can help.
Are steel posts allowed by local fence codes?
Zoning ordinances regulate height, location and sometimes which side faces out. Post material is rarely the issue. Check your HOA covenants, which can be stricter on appearance.
Wood Fences With Posts That Last
Just Fences is a locally owned fence company in Harrison City that has installed wood, vinyl, aluminum, chain link and custom fences in Westmoreland County and Greater Pittsburgh since 2007. Free quotes are available, and installations carry a 2-year workmanship warranty. Ask about post options when you request a quote through the custom fences page.
Visit Just Fences or call (724) 392-4416 today. Contact us for more information.
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