Removing Rust on Steel Stumps

simplesierra on 08/10/2023 - 12:30
Last edited 08/10/2023 - 13:50 by 1 other user

Hi,

I'm trying to clean the rust off the steel stumps on my house. I have a few questions:

1. Is this in fact rust?
2. What's the best approach here? Wire brush the surface level rust, treat with Penetrol then use epoxy enamel after?
3. How do I treat the 3 sides that are surrounded by concrete?
4. Should I use a rust converter?
5. Once treated, should put cement in to bring cover it up to surface level?
6. Is this a job too big to do DIY? Have about 8 stumps I need to treat.

Overall, just looking for someone to provide me instructions for the best way to remove this rust and protect going forward.

• 

  Protractor on 08/10/2023 - 12:41

  If it's a keeper and was stumped properly the first time, is it worth having it professionally re-stumped? Or is the concrete part of the floor in the structure?
  Looks to me like the steel part was set into the sand at time of cementing, and if its reactive soil, it may have accelerated the decay. What vintage was the stump set?
  Also looks like holes were drilled to add some sort of internal treatment, so maybe someone else might have had a go.

  • 

    simplesierra on 08/10/2023 - 13:07

    The post is between the driveway and the garage concrete slab. What do you mean by vintage?

    • 

      Protractor on 08/10/2023 - 14:33

      How long ago was that stumped installed.Or How old is that structure it holds up, 'if' the stump is the original.All looks a bit iffy and termite transitory stuff

      • 

        simplesierra on 08/10/2023 - 14:48

        Built in 2000

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  simplesierra on 08/10/2023 - 14:48

  https://pasteboard.co/XohfJZEtbMcE.jpg

  Another photo

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  AngoraFish on 08/10/2023 - 15:48

  +1

  Rust isn't like bacteria, it doesn't 'infect' good steel. In fact, rust can be protective. So long as it's not flaking off and creating voids that trap moisture it's acting as a barrier to prevent oxidization of the steel underneath.

  All you'll be doing by removing the rust is reducing the thickness of the post wall, which is already probably only 1.6mm thick, and exposing what's left of the post to the same issue reoccurring.

  How long has it taken for the posts to get to that point? Odds on you've got twice that again, at least, before it becomes any kind of issue at all.

  A rust converter might improve things a bit, but there's nothing I'm seeing on those posts that you won't see on just about every other post that's been in the ground for a few years.

  Personally, I think you're wasting your time and money. There's more than enough structural redundancy in modern building standards for a couple of posts to completely fail and you'd still have plenty of time to get in there and replace if need be, at which time it's a pretty straight forward job of pulling the failed posts out and putting new ones in.

  • 

    simplesierra on 08/10/2023 - 16:06

    Thanks for your reply. The house was built in 2000 so assume it’s taken 23 years to get like that. Here’s a few photos of one of the other posts that I’ve used the steel brush on:

    https://pasteboard.co/7SomP6J1tHjj.jpg

    https://pasteboard.co/0HmqUqV5oZEr.jpg

    Seems like the steel has slightly worn away but not too much.

    Do you think it’s worth treating the bits I can get to with rust remover, penatrol and epoxy or there’s no point if I’m not treating the whole post? Some bits I’d need to chisel away the concrete.

    Maybe it’s worth replacing the soil with stones in the interim to try reduce further erosion.

    • 

      AngoraFish on 08/10/2023 - 18:13

      I was guessing 20 years, so that looks about right.

      Don't remove any concrete, it's holding the posts in place and you'd just introduce another place for moisture to get trapped.

      It wouldn't hurt to treat the exposed area, particularly now you've cleaned it up.

      In terms of moisture, ideally no water is allowed to get to the area in the first place. Normally one just shapes the soil at the surface so that stormwater drains away quickly.

      The holes in the post are a bit odd. I assume that they're intended to allow condensation to escape. In which case yeah, you might want to back fill the first 200-300mm with 20mm screenings to allow air to circulate. You could probably throw a sheet of HardieFlex over the top, tilt it away from the slab, and keep an eye on it for a few weeks in winter. After a few weeks, if it's doing the job of keeping the area dry you could top it with 100mm of soil and then leave it be.

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  saltypete on 08/10/2023 - 18:22

  The stumps are rusting due to water being trapped between the steel and the concrete. While rust is protective, the constant moisture will be driving rust formation and the post will eventually rust away.
  You need to do 2 things:
  Shape the surface to make sure water runs away from the post.
  Perhaps use cement grout to do this.
  Get something in there that will soak into the rust, coat the steel and keep water away from it.
  Some sort of tar paint

  This will slow things down, but eventually you may need to rest up with something that is less rust prone.

  • 

    Protractor on 08/10/2023 - 19:08

    and it won't be just decomposing on the outside.Those holes are probs for termite barrier chem, or introducing a rust converter, or possibly there was a cladding sheet there if that location of the stump /cement is along a lower wall edge.Or 'maybe' they were where the form-work was attached at the concrete pour for the garage?

    • 

      saltypete on 08/10/2023 - 21:36

      My vote on those holes goes to cladding sheet. So long as water isn’t standing on or in the posts they’ll last a good while.

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  hasselbladsnapper on 08/10/2023 - 22:04

  Pop some rust converter over the affected areas then bitumen paint, stop / drain water from base, pooling is bad!.

  Consider enlarging the hole a bit and inject some sort of cement grout into the lower area of the post, perhaps with some PVA glue added - helps to waterproof the cement and helps internal adhesion and reinforces the post.

  I would still have 1 or 2 holes open above the grout to assist in expeling any water that might come down the stump!. I'm a keen home handyman, but not a professional stumper!! Good Luck

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  tonka on 13/10/2023 - 16:24

  I have a similar problem, but a pergola area where I think the posts are not high grade and are deteriorating quickly. My thoughts were to remove rust with steel brush, then coat with resin. Any thoughts?