Replacing a rusted post base

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Old 08-28-16, 04:37 PM
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Replacing a rusted post base

We have a 4x6 post at the corner of our patio supporting the extending roof. The post is supported at the bottom with a metal post base or strong-tie, whichever you want to call it, which is then on top of concrete.

Problem is that the base is completely rusted out. I'm actually surprised it is still holding the post up. Today I ripped the sides of the post base off to see if the wood was rotted, and it's fine.

So what are my options?

To start, I figured I would need to support the roof/truss with a shoring post / jack post, then remove the old post base (it just crumbles if I poke at it). But then what? Do I actually need to tear up the concrete and have new concrete poured with a new post base?

Here's a picture of a post base like mine:


Any help is appreciate.
 
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Old 08-28-16, 05:04 PM
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It depends on the type of post base that was used. Some are poured into the concrete, others will be attached with a nut and washer on an anchor. No way to tell what kind you have without seeing it or having a model number. But in all likelihood, the post will need to be removed, or moved to the side in order to remove the old and replace it. Hopefully you will just be removing a nut, plopping a new one down, and put on a new washer and nut onto the same anchor.
 
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Old 08-28-16, 05:36 PM
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Ah. So if it's possible the post base isn't one piece, I'll try to carefully inspect what we have to see if I can see a nut under there. Thanks for the input.
 
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Old 08-28-16, 05:49 PM
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Well, it looks like there is something metal sticking up through the bottom, and then something somewhat resembling what used to be a bolt. The problem is that if it was a nut, it too is disintegrating. Now what?
I suppose I might have to just put a jack post in place and then do some investigating. What if I can get the old post base off, but the threaded rod sticking up has become totally useless due to rust? Could I put a new one down and instead of using a washer and nut just attach it with PL Premium or some other concrete adhesive?
 
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Old 08-30-16, 02:03 PM
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I think I figured out what to do. I am going to support the truss with a shoring post, then remove all of the old rusted base.
Then slide in a Simpson Strong Tire 4x6 composite plastic standoff. Finally, I will use a retrofit post base and secure it to the post and anchor it to the concrete with concrete anchors.

Standoff:


Steel strong tie:


Are there certain concrete anchors I should look for that won't corrode as quickly? I don't know why my base rusted in the first place; I'm not in a corrosive environment.
 
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Old 08-30-16, 02:27 PM
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If your wood is pressure treated, its possible that the post base was not z-max, which is zinc plated for use with pressure treated wood. When it got wet there could have been corrosion from dissimilar metals... either CCA or ACQ.

I would probably grind off the old bolt and install 2 new ones offset from the center, and drill new holes in a standard post base.

Construction adhesive can never be used in place of an anchor.
 
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Old 08-30-16, 07:24 PM
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Red Head makes a stainless steel version of their wedge anchor:

Red Head 3/8 in. x 3 in. 304 Stainless Steel Hex-Nut-Head Concrete Wedge Anchor-50104 - The Home Depot

That may not be the right size for you, but it's a good anchor and being stainless you should have no problem with rust. Of course they make it in other sizes. And if you can find your post anchor in stainless, I'd certainly consider going that route.
 
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Old 09-04-16, 12:02 PM
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Well I ended up using the above products. I first supported and lifted the upper beam about 1/8" with a shoring post. This gave me enough clearance to clear out all the rusted metal, and grind down the "threaded" rod in the concrete, which was just a rusted post at this point. I placed the plastic standoff down and eased the shoring post back down ensuring the wood post was plumb.
Then I used the retrofit strong tie I pictured above and drilled 3/8" holes for 3/8" concrete anchors which I bought from a local supplier (stainless steel). Then finally I secured the bracket to the post.

It is very solid now. I appreciate the input from the community here.
 
 

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