Should I use galvanized steel or cedar posts?


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Old 02-09-23, 06:35 PM
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Should I use galvanized steel or cedar posts?

Hello community! I am going to build a short fence for a new flagstone patio. The fence will be one of the horizontal slat styles. The size will be roughly 32-feet wide by 40-inches high. The issue I am debating is using galvanized steel vs cedar for the posts in the ground. I have read several pro/con articles on this debate. I plan to bury either one 2-feet in the ground. My soil is very easy to dig in (no clay or rock etc). I live in Austin, Texas and it can get hot/humid here. With all this above known, I do have some questions which I could really use your help with.

1. I talked to a local fence company, and they prefer to do steel for longevity. However, he did say I might be able to do the cedar posts fine as I am not going high like a traditional fence would be. His only concern is wood warp. What is your opinion on using cedar only in a concrete base knowing it is a short fence?

2. If I did use galvanized steel, I would imagine I could custom cut some wood and box them in (hide them). Is this something you see done?

3. Considering I am building a flagstone patio, I am think I should do the posts first. If I do it in this order, and excavate 8-inches after that (road base, decomposed granite, flagstone layer), will the posts still be safe for the most part? I could build the fence out completely to give it more structure before digging.

4. Is there anything else or another way I am not considering?

Thank you so much for any help!
 
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Old 02-10-23, 01:09 AM
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Cedar is rot resistant, not rot proof so eventually they will need replacement. Your location probably helps and certainly the cost and ease of construction makes the wood posts more desirable.

If your willing to do the framing work for steel post PT wood posts would be a more durable option also.
 
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Old 02-10-23, 06:42 AM
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32 feet x 3.3 feet makes quite a large sail. I would be concerned with posts 24 inches below ground and 40 plus inches above ground tilting in a strong wind.
 
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Old 02-10-23, 07:26 AM
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24 inches below ground and 40" above ground is perfectly fine. Half the fence height is 20" so at 24" you have over half the fence height in the ground. Especially when there is concrete around them.

If the fence was 6 feet tall, 24" deep would usually be a little shallow.

You will probably get 20 years out of cedar posts. If you want to use wood to save $ you could use treated posts, and then use cedar above ground.
 
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Old 02-10-23, 11:03 AM
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Marq1
"If your willing to do the framing work for steel post PT wood posts would be a more durable option also."

Are you saying PT posts would be better to use than cedar posts?
 
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Old 02-10-23, 11:32 AM
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The PT posts should have a longer life but their appearance is so-so. Framing them with cedar, above ground would be along the same lines as what you would be doing with the steel posts so you have the best of both.

I build a large arbor at the edge of my deck, 8x8 cedar posts, it's now about 10 years old, last summer I noticed a fair amount of decay just below the dirt line. Not too many years from now that will have to be taken down.

In hind sight it was the easiest (maybe even the most expensive) but the shortest life span!
 
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Old 02-10-23, 12:20 PM
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I think that wood has a nicer appearance than pipe. See if you can locate some black locust posts. Last spring I removed about 20 of them when removing a split rail fence. Except for two, they were literally just as solid as when I put them in 35 years ago. If you decide to go with red cedar make sure you are getting heartwood.
 
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Old 02-10-23, 02:30 PM
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Marq1 I am liking this idea of using PT posts now that you mention it, and thanks. Wrapping it could be a pain, but would look good. The back side of the fence won't be as "pretty" as the front. If I do wrap it I wonder if I should wrap all 4 sides or just the sides and the back? My concern about not wrapping the front as well is you might be able to see the PT through the cedar horizontal slats. Maybe not?
 
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Old 02-10-23, 04:16 PM
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Big box stores now have "cedar tone" treated lumber that is brown than the standard green of treated lumber.
 
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Old 02-10-23, 04:41 PM
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Originally Posted by Marq1
Cedar is rot resistant, not rot proof so eventually they will need replacement. Your location probably helps
Well, it depends on the post.
My grandmother purchased the family farm back in the 40's, and the cedar posts from the prior owner's pastures are still in place, along with some early barbed wire, incongruously running through the middle of a third growth forest of oak and maple.
This is in wet eastern clay soils, and the old cedar post are doing fine.

But, much like all lumber, the newer 'fast growth' wood is not as hardy or strong as the old-growth wood that was harvested in the 1700s, 1800s and into the 1900s.
 
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Old 02-10-23, 04:42 PM
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Be careful of the PT "garden timbers" at big box stores. They do not age well. I used them as supports for a couple of birdbaths and they rotted through in less than 10 years. If you go with PT make sure it is ground contact rated.
 
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Old 02-10-23, 06:57 PM
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"1. I talked to a local fence company, and they prefer to do steel for longevity. However, he did say I might be able to do the cedar posts fine as I am not going high like a traditional fence would be. His only concern is wood warp. What is your opinion on using cedar only in a concrete base knowing it is a short fence?"
The problem with wood is that it rots. I've seen people waterproof the wood with tar or some waterproof material below grade. That way, it protects the wood from rotting. I've not done it. So i don't know how that works out.

"2. If I did use galvanized steel, I would imagine I could custom cut some wood and box them in (hide them). Is this something you see done?"
I've seen people do this. Don't need to cut. 2 x 4 will work. Though i haven't done it myself. I had trouble screwing wood brackets to the metal posts with self drilling metal screws. The head breaks off. If you don't have any trouble attaching wood to metal, then yeah it's very doable. My suggestion? Spray paint metal post with dark walnut and stain the ceder with redwood. They look fantastic.

"3. Considering I am building a flagstone patio, I am think I should do the posts first. If I do it in this order, and excavate 8-inches after that (road base, decomposed granite, flagstone layer), will the posts still be safe for the most part? I could build the fence out completely to give it more structure before digging."
Weather is the biggest factor. You don't want the posts, especially wood, to be exposed to too much water. Keep water away from the posts as much as possible. Doing it is quite easy. Planning it out takes time. My backyard has pavers. My neighbor's backyard has pavers. They have them under concrete slab. I have mine under gravel. Why? because i want water to travel down there because i had a big tree.
 
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Old 02-10-23, 07:16 PM
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"I think that wood has a nicer appearance than pipe."
Maybe but the pipes, they last a long time. Don't know when the pipes were installed in my backyard but they are still good.
 
 

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