Concrete posts for a carport?

[MushCreek]

I just had another crazy thought. I want to build a free-standing carport on our property. I need 8 posts to hold it up. What if I made the posts out of concrete? I could put rebar in them. The only drawback is a 6X6 X 10' concrete post would weigh about 375 lbs. I guess I could form them up in place, if I could figure out how to get the 2-1/2 cubic feet of concrete to the top. I'd make the footings with rebar sticking out, assemble a form, set more rebar in, pour in the concrete, then remove and reuse the forms after it cured. A J-hook could be embedded in the top to attach the roof framing. Am I nuts, or could this work? It would be cheaper and more durable than PT lumber, and I wouldn't have buy post bases. Thoughts?

 

[billconner]

Feels a little fragile. Also hard to replace if a car hit one. Getting rebar - 4 vertical ? - precisely located and held in place seems challenging.

8x8 or 8" round probably.

 

[acer66]

I would only do that if you like the look otherwise I would just have them stick out of ground a foot or so and continue with pt posts or metal posts.

I am using the round concrete form tubes to do that for my deck.

Was just at a house where they did round concrete posts 10’ high to support the entrance deck.

My uneducated guess would be that you need a good wide footing and be sure that you do not create a tower of Pisa.

 

[mike93lx]

How in the world is all that cheaper than a 6x6? A 12' 6x6 is $40

 

[solo machinist]

You could make a concrete base, then stack half block pouring as you go.

 

[acer66]

How in the world is all that cheaper than a 6x6? A 12' 6x6 is $40

Its cheaper because you save so much money on gym membership and workout equipment mixing and bucket the concrete up a ladder.

 

[mike93lx]

Its cheaper because you save so much money on gym membership and workout equipment mixing and bucket the concrete up a ladder.

ah, i knew i was missing something

 

[billconner]

Get pressure treated posts for ground contact - UC4C would be my preference - and skip footings. Last well beyond your lifetime. Minutes compared to hours of work.

 

[acer66]

Get pressure treated posts for ground contact - UC4C would be my preference - and skip footings. Last well beyond your lifetime. Minutes compared to hours of work.

Me personally would not put any wood treated or not in the ground but thats just me.

But I build a deck using composite footing pads for a customer and it was great.

Just dig a hole throw the pad in and build the deck on top.

No concrete hauling, waiting to it cure or waiting for footing inspection.

As a bonus you can move the pads/posts if needed.

Once the deck is done call in inspection and just fill the holes afterwards.

 

[solo machinist]

Get pressure treated posts for ground contact - UC4C would be my preference - and skip footings. Last well beyond your lifetime. Minutes compared to hours of work.

I agree, I don't like working with concrete. OP asked about concrete, but wood post are so much easier.

 

[nadogail]

Why not find some steel beams or water pipe at your local scrapyard and weld up something that will last. I have found that used pallet beams are not hard to work with.

 

[acer66]

Why not find some steel beams or water pipe at your local scrapyard and weld up something that will last. I have found that used pallet beams are not hard to work with.

That sounds like a fun build.

Maybe the OP can let us know if this will get inspected.

 

[MushCreek]

A PT 6x6 is currently $36; less than I thought. But- you need a post base (I don't bury any kind of wood here in SC), and the good bases that are cast into the footing are $40-50 each. I have a hard time believing that a 6X6 concrete post with 2-3 pieces of rebar would be weaker than the light gauge steel tubing they make carports out of around here. I'd like it to look like wood, and of course, the concrete could be painted to match the house. Each post would take 5 bags of concrete, so $25-$30 worth. I have lots of rebar already. I doubt it would be inspected. They don't really issue permits for small structures, but you do fill out a paper and pay a fee. Another idea, as solo machinist mentioned would be to stack half block, and fill them with rebar and concrete as I went. I could cast an 8X8 post, which would be 9 bags of concrete. PT 8x8's are ridiculously expensive, if you can find them.

I've had a lot of trouble with PT posts twisting and bowing. I had to replace one in the basement as it bowed over 1-1/2 inches. Several of the ones in my barn twisted severely. Probably not going to fail, but they look like ****. This carport will be near the front of the house, and needs to look good.

 

[Big Bad Dad]

My dad built a carport when i was a kid, mid 1960's. For posts, he used scrap yard 4" water pipe, and filled each pipe with hand mixed concrete. Short sections of angle iron welded to the tops for bolting the roof structure. I went back by the old home about 10-12 years ago. The posts were still standing. But the tin roof had blown off and the wooden rafters were in bad shape. The current owners had let it go....

 

[billconner]

Just to be clear, the pressure treated posts I suggested - UC4B - and laminated - so not likely to twist - and more expensive for sure.

 

[solo machinist]

I'm looking at building a double carport next year. I also saw how much those post brackets are selling for.
I have a sheet metal shop not far from me, I'm going to check and see what they would cost to bend up a few.
I'll weld pins on the base and paint mine. Galvanizing is crazy these days.
Where your at, do you have that nice red clay that never washes out of your clothes.
I lived in Columbia and Summerville, S.C. We got tired of the grid lock and heat.

 

[billconner]

Just use a plate - maybe 18x6x1/4 - holes with rebar pins in lower half, set in footing; holes for bolts in upper half, and kerf post. Very simple.

 

[Firebrick43]

A PT 6x6 is currently $36; less than I thought. But- you need a post base (I don't bury any kind of wood here in SC), and the good bases that are cast into the footing are $40-50 each. I have a hard time believing that a 6X6 concrete post with 2-3 pieces of rebar would be weaker than the light gauge steel tubing they make carports out of around here. I'd like it to look like wood, and of course, the concrete could be painted to match the house. Each post would take 5 bags of concrete, so $25-$30 worth. I have lots of rebar already. I doubt it would be inspected. They don't really issue permits for small structures, but you do fill out a paper and pay a fee. Another idea, as solo machinist mentioned would be to stack half block, and fill them with rebar and concrete as I went. I could cast an 8X8 post, which would be 9 bags of concrete. PT 8x8's are ridiculously expensive, if you can find them.

I've had a lot of trouble with PT posts twisting and bowing. I had to replace one in the basement as it bowed over 1-1/2 inches. Several of the ones in my barn twisted severely. Probably not going to fail, but they look like ****. This carport will be near the front of the house, and needs to look good.

I would make a form laying flat on the ground, 14' long, and make it all in once pour so you don't have a cold joint. Fiberglass rebar has really come down in price as well so I would personally use that.

I am planning on doing some concrete corner post this way when it gets warmer. To keep the sides of the forms from spreading I am going to use some PVC 1/2 pipe cut to the width that the forms should be apart, and place them in the form with all thread thru them/the form sides and then use the lined holes to pass the electric high tensile wire thru.

I would also keep them covered and moist with burlap or something for a week before breaking them out of a form.

 

[strutaeng]

You can build some 12x12 square columns with nominal rebar. You'll need some spread footings. Then set your carport framing on top.

Getting them formed and poured would be a challenge though.

 

[MushCreek]

12X12 would be too clunky. As for making them one piece, minimum footing size here is 16" square, but only 12" deep. I'm not sure what the rules are on a buried post. I have no intention of going down 4', though. We have heavy red clay, and it's tough digging. I do have a post hole digger for the tractor, though. I have rigged up my engine hoist to connect to the tractor 3 pt hitch, so I could use that to stand the poles up and set them in the holes if I went that route.