How long can I expect my wood fence to last?
Fences can be a large investment! What can I expect to get for my money?
Wood rots, so what does this mean for my fence?
We all understand that wood rots, but do we all understand WHY wood rots? Wood becomes compromised quicker when it is in constant contact with moisture as well as microorganisms that eat away at the dead cells of the wood material. Wood will decay over time, but add either of these two components, or both, and the process can be expedited significantly.
So wood rots... what can we do about it?
Yep! Wood rots. Not only does wood rot, but we guarantee that wood will rot, warp, crack, and split. Doesn't that sound like a great product for your fence project?
In all seriousness, wood is a great product for your exterior wood fence for a few reasons. Wood, here in Metro Atlanta more commonly pressure treated pine, is readily available. A product that is readily available typically means that it is more cost effective as well. You know... supply and demand. There is a steady supply, but also, a steady demand.
If wood is the most available and the cheapest option, is it worth the savings if the product doesn't last as long?
Well, wood is the cheapest option due to it's availability and ease to produce. With everything, there are pros and cons. Fortunately, we have some solutions for the cons...
Where do wood fences fail and why?
We are called out regularly to repair and replace existing wood fences. In our experience, a wood fence will start to fail after about 15 years. The most common repair we are called out for are failing posts, or rotting pickets.
9 times out of 10 we find wood posts have rotted at the point of contact with the ground. In fact, it's typically only the first 3 inches or so. Past that, further in the soil, the wood post is actually, usually, in as good or better shape than the post above ground. Why is this?
Wood posts are set in pre-dug holes, the post put in, and then the hole is filled with concrete. This concrete hardens and then protects the wood post from micro-organisms and moisture from attacking it. Here and there you may find a concrete "slug" that was not placed properly, but even then, the post is typically protected to a certain degree. Where the problem occurs is the wood post is typically set with the concrete a couple inches below the ground. This allows soil to be put back in place and grass to grow up to the fence, covering up the unsightly concrete. Concrete requires a "form" to hold it's shape as well as it cures, which is provided by the sides of the hole.
Those 3 inches unfortunately are where most of your micro-organisms will be found as well as the majority of your moisture. Even if you have well draining soil (our Ga Red Clay does not fit that description) the ground still holds on to moisture for some time that is soaked back up into the post. This then causes the post to decay prematurely.
What about the other 10% of the time wood posts are rotting? If the post is a larger diameter (typically anything above a 4x4), we typically find the posts rotting from the top down. We, and many others, build our 4 rail fences with 4x6 posts. That extra material seems to really combat the rotting at the ground level, however, we then find the rotting to occur at the top.
What this looks like is you walk up to the fence, you will find a hole in the top of the post that appears to have started from the center and worked its way out. From a distance, and from the side, the post looks good, but it can rot over a foot down the posts at times, large enough to put your hand inside. What causes this? When we set our posts for these style fences, you will find that the tops are cut at an angle. This allows water to flow off the top and prevents it from standing. You may also find on agricultural fence, the farmers will attach metal tin to the top of the posts, their version of a cheap post cap that serves the same purpose. Speaking of a post cap, they perform the same function while adding a bit of style.
Wood pickets and rails
Lets clarify our terminology real quick...
Pickets: The vertical face of a wood fence.
Rails: The horizontal boards of a fence. Typically for structure on privacy fences, or the rails of a 3 or 4 rail horizontal fence.
You will typically see fence pickets and rails become compromised for two reasons. First, they are in constant contact with the ground or organic material such as mulch/leaves. Second, the pickets have had a product applied (such as a film-forming stain) that is trapping moisture in the pickets themselves.
We work to leave a slight gap between the soil and our pickets when being installed. This prevents moisture from wicking up the pickets and causing premature decay. Other times, leaves or silt runoff can build up against the fence, again, allowing moisture to wick into the pickets.
Another instance of where we see pickets rotting prematurely, is when a thick, paint-like product is applied to the wood. Wood expands and contracts with moisture and temperature changes. It's just wood doing what wood does. Paint, or other film-forming stains, are not designed to accommodate for those movements, especially as the product ages. What happens is over time, the product begins to fail in the way of micro cracks that may not be visible at first. Water finds the path of least resistance and makes it's way into the wood. Once it's in, it has a hard time getting back out. The fence then begins to rot from the inside out.
How do we protect and prevent this damage from happening?
There are sleeves that can be essentially "shrink wrapped" onto the posts prior to being installed in the ground. These covers then come with a 20 year warranty.
Stain and Seal
We HIGHLY recommend that you stain and seal your exterior wood products. Know that all stains are not created equal. We recommend Stain and Seal Experts Oil-based, penetrating stain for numerous reasons. You can find more information about stain in these blogs, or pull up their site yourself with the link below. Keep in mind, the wood needs to be below 14% moisture content prior to application, as well as a cleaning to remove any existing organics.
Is wood a good option in the end?
Wood is a great option for a fence. It does require some additional maintenance and protective measures, however, when properly protected and maintained, wood can last for years to come and look beautiful too.
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