Tall Pier-Concrete inside PVC?

[KAllen]

Hello

This is my first of many posts and I'll break this one down. I'm looking at building a pier for my telescope that will need to be about 8' high from the ground. I'm thinking of using PVC 10" or 12" O.D for a finished look versus sono-tubes. I'm not certain on the footer size so I'm guessing about 3'x3'x3' to start with. My question is...

Does this setup sound ok as far as pipe size and footer combination?

What to pour first? I've heard/read to pour the footer first then the pier. I've also seen do the pier then the footer.

For the footer I was going to use a combination of rebar and brick-o-blocks with the pipe 2/3 down inside the footer. Do I need rebar running all the way thru the pipe or just enough in the lower portion with the footer?

I'd appreciate any advice and tips. All this is in the planning stages so my options are open. Thank you.


Kenny J.
Nashville Tn.

[concretemasonry]

Never heard of brick-o-blocks, so I can't comment.

Pour the concrete footing with 2 or 3 rabars each way in it.

Put two "L" shaped bars in the footing and extending about 2 or 3 feet out of the footing in the area of the post.

Set the post and put 2 rebars into the post. It would be best to use wire to lap the "L" bars to the vertical bars before slipping the post over or raise the plastic post to let you tie the bars together.

Get the post vertical and brace it well. Pour the concrete (mix it rather dry) and pour it slowly in lifts taking a couple of hours. Consolidate it with a rod to ensure there are no voids. If you pour too fast, you will have concrete shrinkage and cosolidation and no bond to your plastic.

If you really want stability for your telescope, use the 10" or 12" pipe. I It is not a question of strength, but stability, rigidity and deflection.

Your real rigidity and strength is in the concrete and the plastic is only a pretty sleeve.

[Don_P]

Why the concrete in a sleeve? Wouldn't casting a piece of I beam or pipe as the pier make a better job and give a good mounting plate? Footing first, otherwise you just punch thru.

[concretemasonry]

A tube for appearance.

A steel pipe would work equally as well as a PVC pipe, but is a lot heavier (10" or 12" diameter by 8' long minimum.