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Decks/steel support posts under deck & porch

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QUESTION: The hollow steel support posts (probably from 1960ís construction) under my screened porch are rusting out at the bottom where they have come in contact with the ground and the porch is in danger of sagging or falling down if this isnít corrected.  

The steel posts are embedded in a concrete base about an inch below ground level.  There is a deck under the porch and the steel posts go up through it but donít support it.

The steel posts are encased in fake columns from the lower deck up to the screened porch, so Iím unable to see them without removing (and probably destroying) the cedar boards around it.

Question 1:   From the little I can see, the steel posts appear to be in good shape above ground level.  Is this likely?  Or would the rust have traveled up the length of the beam from the ground?

Question 2:  Is there something I could fill the hollow posts with (like Quikrete 80 lb. Crack-Resistant Concrete)  that would strengthen the rusted area before the deck starts to sag?  If so, would this be a long term fix?    

Related questions:  How big a hole would I need to drill through the pipe to pour in cement (or other product)? What kind of drill bit would I use? Could I drill through the side of the post just under the cap and use a hose to pour the mixture through it?  Is it safe to add extra water to this concrete so that it will be thin enough to pour through a small hole (an inch or less)?  Is there a better product for an application like this?

Question 3:  If the above idea isnít workable, what would you think of jacking up the screened porch, cutting off the damaged steel post at the bottom, digging out the damaged piece, building a new concrete base under the cut off post, putting a cap on the concrete to protect from moisture, then lowering the post onto the capped concrete base?

Iíd like to find a safe way to avoid tearing out all the posts and the decking and railing in that area if at all possible.
Thanks in advance for any help or suggestions you may be able to offer.

bj

ANSWER: Hello, I have seen those steel posts rust out on the bottom many times, I understand you don't want to have to replace the cedar on the columns, but I recommend replacing the posts with PT 6x6, Once they are installed, give them a few months to dry out. With summer coming on it shouldn't take long, after that then you can re-attach the cedar, or just stain the posts and not have cedar. I have never heard of pouring concrete into the posts, and the hole you would need to do it would have to be so big it would ruin the integrity. The idea of cutting the bottoms off would work if you were able to attach another steel plate to the bottom of the posts, but in a few years it would begin to rust again they all do, I also live in Ga. where about are you located? Thanks hope this helped.

---------- FOLLOW-UP ----------

QUESTION: Mr. Clayton,

Thank you for such a quick response.

Iím in Chamblee/Atlanta.  Where are you located?

1.)  I hear you about making a hole in the post.  It makes sense that a large hole in the side of a post would ruin its structural integrity.  I didnít understand that beforeÖ  

Iím still reluctant to tear out so much of the deck and railings to replace the beams with 6x6 PT lumber if thereís any way to avoid itÖ

What if I drilled through the porch floor from above the post, then through the support wood above the posts, and through the ľ inch steel plate at the top of the post and then poured cement into the post from the top?  Could I get cement to pour through a 1 inch hole in the wood ?  If I filled the hole with bondo after the cement was set, would the structural integrity of the wood be OK?

2.) One contractor said that steel set in concrete rusts and pressure treated lumber set in concrete rots, and thereís nothing you can do to prevent it in the long runÖ  It was kind of six of one and half dozen of the other.  Do you agree with that?  

3.) Another contractor said that the steel posts were still good above ground level so I could just build another platform on top of the existing concrete base and poor fresh cement around the steel posts.  But couldnít the steel post continue to rust in the cement and gradually collapse and slide down inside the cement in that situation?

What if I screwed galvanized screws into the good steel above the rusted areas and then poured concrete in the same way?  (Iíd put jacks in before I tried this.) Would the galvanized screws prevent the posts from slipping down inside the concrete even if the bottom of the post continued to rust?  Would they jeopardize the integrity of the steel post?

4.) Also, each post is set into a cement base that is about an inch under the dirt.  One of them appears to only be slightly rusted.  If I gently dug out the cement bases, and dried the steel posts, is there anything I could treat the rust with that might also strengthen the steel?  (something like Rustoleum and Bondo? )

I really appreciate all your help.

BJ

Answer
What if I drilled through the porch floor from above the post, then through the support wood above the posts, and through the ľ inch steel plate at the top of the post and then poured cement into the post from the top?  Could I get cement to pour through a 1 inch hole in the wood ?  If I filled the hole with bondo after the cement was set, would the structural integrity of the wood be OK?

You probably have a double beam above the posts so if you drilled a hole between the beams it should be ok, I would use mortar mix and mix it with a half ratio of portland cement, this will harden like a rock and will be easy to pour, be sure to mix the two very well dry before adding water

2.) One contractor said that steel set in concrete rusts and pressure treated lumber set in concrete rots, and thereís nothing you can do to prevent it in the long runÖ  It was kind of six of one and half dozen of the other.  Do you agree with that?

I agree about the rust but not the rot of the PT, I once dug up a 6x6 that had been buried for 15 years once we washed off the dirt it looked like new. The new treatment process is very good, and if you use " Rated for ground contact" material by the time it rots if ever, we will be long gone from this earth,

3.) Another contractor said that the steel posts were still good above ground level so I could just build another platform on top of the existing concrete base and poor fresh cement around the steel posts.  But couldnít the steel post continue to rust in the cement and gradually collapse and slide down inside the cement in that situation?

Without cutting off the bad area, re-welding a new flat piece on the bottom then re-setting them above ground on a footer it won't last, pour the footer with a slight slope so water doesn't sit on it.

What if I screwed galvanized screws into the good steel above the rusted areas and then poured concrete in the same way?  (Iíd put jacks in before I tried this.) Would the galvanized screws prevent the posts from slipping down inside the concrete even if the bottom of the post continued to rust?  Would they jeopardize the integrity of the steel post?

If they are not above ground, they will eventually rust

4.) Also, each post is set into a cement base that is about an inch under the dirt.  One of them appears to only be slightly rusted.  If I gently dug out the cement bases, and dried the steel posts, is there anything I could treat the rust with that might also strengthen the steel?  (something like Rustoleum and Bondo? )

Get the dirt away from the steel and paint them with rustoleum I live in Cartersville, but work all over, I am currently on a historic renovation in Rome Ga. I still do decks etc.. but now pretty much anything and everything in construction

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Eugene Clayton

Expertise

I would be happy to answer any question reguarding the construction of decks, composites verses natural materials, structure support systems,railing applications,stair design, how to figure stairs etc.. Pretty much anything that has to do with decks and or porches.

Experience

I have been in the construction industry for over 27 years including new home construction, custom deck and screen porches. Most of my expertise is from framing custom homes for over 20 years. I now own and opperate a very successful custom deck and screen porch company in Atlanta Ga.

Education/Credentials
High school graduate

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