My carport has five 4x4 posts with two of them are showing serious signs of rot. I have attached a photo of the worst and 2nd worst looking one, and what the other ones look like. At first I thought the only way to repair the posts was to replace them. However some epoxy’s have incredible bonding stength, load bearing strength and water resistance properties. My plan to repair them with epoxy as follows:

  1. On each side of the post, cut the blacktop a couple inches away from the post, and expose the full length of the post.
  2. Remove as much rotting material from the posts as possible with a small chisel
  3. Liberally Spray a wood preservative solution of copper napthenate (green preservative) to halt the rot’s progression
  4. Prebuild forms that will be put around the posts once the resin mixture is ready, and spray them with silicone spray so they will come away from the resin a little easier.
  5. Mix West Systems 105 Resin with West Systems 206 Slow Hardener, and thicken the mixture with West Systems 403 Microfibers. Note, I may not necessarily use West Systems products, but something similar such as from conserve: http://conservepoxy.com/category/Rot-Repair-Epoxies.htm .
  6. Let the Resin cure for a day or so and remove the columns.
  7. Prime and Paint the posts, including the repaired area.
  8. Repair blacktop and raise the blacktop enough such that rain water will slope away from the posts. I got this idea from a blog here: http://www.westsystem.com/ss/saving-the-deck/

What do you think, is my plan sound?

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  • If footings are questionable, the answer I have below will allow new footings to be dug as well – Jack Sep 10 '15 at 16:38

The plan will make the 4x4s look good. However, you did say they are LOAD BEARING, an epoxy is great for holding things together or protecting things, but terrible at withstanding stress from a load. The posts function is to transfer the weight above it to the ground, so filling in the rotted parts of the wood with epoxy is just hiding the problem. Most epoxy adhesives rely on the stress being directed against thier cohesion to the material. When the stress is in a direction that is contrary to that the epoxy fails. If you wanted to glue two pieces together to double the load bearing capacity it would work great for that, but it can't take the load and replace the structural member yet. Maybe in the near future they will come up with something that can. Sorry to tell you this, but you are going to have to replace the 4x4 posts, or you run the risk of them tipping, or collapsing so that the structure comes down. It aslo would be a good time to bring them up to code. The good news is you can treat them so they are rot resistant for far longer now, and it is far cheaper than having the carport fall on your transportation.

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  • Nice Explanation. I'd just like to echo the fact that it could actually be cheaper to carefully to just replace the posts. Ideally, the footings, etc are sound. Assuming that, and counting using some good bracing, you could take your time and replace one bad post at a time, even a weekend, until it's all fixed. – BrownRedHawk Sep 8 '15 at 19:58
  • I wonder why here then they say their epoxy can be used for structural repairs: conservepoxy.com/… – Off The Gold Sep 8 '15 at 22:12
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    Post replacement really isn't hard. Even if the epoxy is structural (something I've not heard of, but I'll read the info), I suspect you'd spend as much time on epoxy as post replacement. – User95050 Sep 8 '15 at 23:52
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    @User95050 - +1 for the time equate. I would also like to point out that the epoxy materials are going to be expensive. I scoped out one of the half gallon sized containers at the conservepoxy web site and saw a price of like $80. Some of those worst posts could take that much of the epoxy for just one post!! At home depot .com a 10' pressure treated 4x4 is $11.37! The choice is pretty obvious. – Michael Karas Sep 9 '15 at 2:59
  • @MichaelKaras: Replacing a post should take less than 30 minutes each. Blacktop removal and repair, chiseling, pretreating, molding, mixing and spreading epoxy is likely to take several hours per post and provide a suspicious or doubtful result, at least compared to replacement which is pretty much a sure thing. If the OP's time is worth anything plus the certainty of a lasting repair make this also a pretty clear choice. – wallyk Sep 10 '15 at 6:21

I have cut posts off and poured concrete under them to get them above grade. The pics below show a 12" diameter post, but an 8X8" square poured under the cut off post could work with proper anchoring. post 1 post 2

I thought I had a picture of the finished post, but I could not find one, but you might get the picture.

Yours may only need to be 12" tall.

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  • Looks interesting. How did you anchor the post in the cement? How much of the post did you cut? – Off The Gold Sep 11 '15 at 18:36
  • On the upper picture you will see a plate with a threaded rod that is actually holding the bottom of the post off the footing. I left that intact to anchor the new concrete to the existing footing. I power washed the footing cleaned the rust off with a wire wheel on a strong drill and painted the pin with rusty metal primer. I cut of about 16" to get to sound wood. You may not need to cut that much off yours to get to sound wood, and shorter the new concrete base is the better. 12" is ideal. If you need a footing, it would need to be configured differently too. – Jack Sep 11 '15 at 20:04
  • You could drill holes in the concrete footing if you have one and set them with expansive concrete, Clean the holes thoroughly!!!! With in an 8" square form the pins need to be 2" from the form unless you use epoxy coated rebar, then you could get closer. Use a minimum of 2, 4 would not hurt. You could use epoxy too, in this case to set the pins.... Also use a post bottom clip to cast in the concrete. Set it on the post first, bolt it, or nail it, then pour the concrete. – Jack Sep 11 '15 at 20:10

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