Most home fences are either wood or metal. Wood fences, often called “privacy fences” are usually made of cedar pickets, attached to 2”x 4” rails, which in turn are attached to 4”x 4” wood fence posts. Metal fences are usually chain-link, do not offer any privacy, and are attached to metal rails and fence posts. But can the two be combined?
The big problem with wood fences is that the wood eventually rots, causing the fence to fail. This problem can be mitigated somewhat by using pressure-treated fence posts, but few people are willing to send the extra to buy those. Besides, the life expectancy of pressure treated fence posts really isn’t all that much more than normal wood fence posts. So, that leaves the new owner of a house faced with having to deal with a fence that is in bad shape or even falling.
By comparison, fence posts should last:
- 15 to 20 years if wood fence posts are used
- 20 years if pressure treated fence posts are used
- 70 years if galvanized metal fence posts are used
This clearly means that it’s better to go with galvanized metal fence posts, whenever possible. But what does one do when the privacy of a wood fence is wanted, but the long life of a metal one is needed?
The solution is to build a wood fence, with metal fence posts.
Building a Wood & Metal Fence
Building a wood fence, with galvanized steel fence posts is actually no harder than building a wood fence, although it is a bit more expensive. The fence posts themselves are a little more than double the cost, plus there is the cost of the metal brackets needed to attach the wood fence rails to the steel fence posts. But that’s the only additional cost over installing an all wood fence.
To start, the fence posts need to be set. This involves digging a two foot deep hole for the posts to set into and then filling that hole with concrete, once the post is in place. Care must be taken during this part, to both ensure that all the posts are in a straight line and that they are all exactly plumb.
In order to ensure that they are in a straight line, tie a string at the bottom and top of the posts to align the posts to. At the same time, check each post with a level as it is set, ensuring that it remains plumb. It may also be necessary to use some temporary braces to hold the fence posts in place, while the concrete is setting.
With the fence posts set, the next part is to attach the horizontal rails that the fence pickets will be attached to. These are clamped onto the fence posts, with a single bolt tightening the bracket and providing the clamping force.
Some people choose to use two fence rails, rather than three. When the fence is first installed, this doesn’t make a difference. But as the fence ages, the pickets will tend to warp. With only two fence rails, it is quite possible for adjacent pickets to warp in opposite directions, leaving gaps between them. Adding that third rail may seem like an unnecessary expense, but it helps to ensure that the fence doesn’t warp in an unacceptable way.
Another choice in installing the rails, which are normally 2”x 4” lumber, is whether they are going to be mounted with the 4” dimension horizontal or vertical. Both are used, but if mounted with this dimension vertically, it resists warping better, helping to keep the top of the fence level.
Finally, it is necessary to decide which side to put the fence rails on, whether on the inside or outside of the yard. Most people mount them on the outside of the yard, so that they can have the more attractive, flat side of the fence facing in. This leaves the fence rails on the outside, where they can be used as a ladder, by anyone wanting to get access to the yard.
Regardless of which decisions are made, the fence rails are normally bolted to the brackets with carriage bolts. Avoid using bolts that are too long, as they can be a point for injury to occur. It is best to avoid cutting off the ends of these bolts, as that will leave a surface visible for rusting that is not galvanized.
To finish off the fence, nail or screw the pickets onto the rails, using a string to ensure that the tops are level and even.
Modifications to the Basic Design
What’s described above is a basic privacy fence design, using cedar fence pickets. There are many ways that basic design can be modified, in order to make a much more customized fence. A few possibilities are:
- Add a horizontal kick panel at the bottom. This not only makes the fence taller, assuming the same size pickets are used, but stronger at the bottom. That might be important if there are dogs in either yard.
- Add a decorative frame around each eight foot section of fencing.
- Add a decorative lattice at the top of the fence, making it taller.
- Cap the fence with a crosspiece, something like a handrail on the edge of a deck or for stairs.
- Cut the top of the fence to scallop it between posts.
Making a Wood Fence with Metal Frame
While most people that use metal posts with a wood fence use galvanized posts and wood rails, it is also possible to make a wood fence using a metal frame or metal rails. There are two ways of doing this. One is to use a square metal tube as the top and bottom rails, screw the fence pickets to it. The other is to use metal C-Channel and set the fence pickets into the channel.
In either of these cases, the fence posts are normally square galvanized steel, not round pipe. The channel or tube is welded to the fence, top and bottom, for the fence pickets to attach to. In the case of C-Channel, the open sides of the channel face each other. The entire thing is painted with oil-based enamel or other paint that’s approved for use on metal, before the pickets are added.
With this design, the fence pickets can actually be bowed and sprung into place, with the ends being captured by the top and bottom channel. The other option is to build the sections of fence as panels, welding the corner of the C-Channel frame together, with the wood in place. Then the frames are welded to the fence posts. Care must be taken in this case, to ensure that the fence pickets are not burnt during the welding process.
Adding Metal Fence Posts as a Repair
An existing fence with rotted posts can be repaired by replacing the rotted posts with galvanized steel ones. In this case, the bad section of fence needs to be disassembled, saving the pickets and cutting or breaking off the existing fence posts flush with the ground. The only part of the existing section of fence which will be reused is the pickets.
The new fence posts will need to be installed in a different location than the originals, as there will probably be a big chunk of concrete in the ground, which anchored the previous fence posts. The new galvanized steel pipe fence posts are set into the ground, just as listed above, and anchored in concrete. Care must be taken to ensure that they are in alignment with the existing fence posts which will still be in use.
With the concrete set, new fence rails need to be installed. Because they will not meet at the fence post, it will be necessary for the new rails to overlap the existing ones by two feet at each end, regardless of how the existing fence rails are mounted (4” dimension horizontal or vertical). Screw the new rails to the old with at least six screws at each end.
In the case where the fence rails are installed vertically, the overlapping rail will need to be mounted to the side of the existing rail, rather than over or under it. Otherwise, it will be nearly impossible to connect the two together. In this case, an additional piece of 2” x 4” rail will need to be scabbed to the new piece, making it so that the face is equal and the pickets can be installed flush with the existing ones.
With the new posts and rails in place, all that needs to be done is to reinstall the pickets on the fence.