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properly installing posts

Posted by v1rtu0s1ty (My Page) on
Sun, Sep 5, 10 at 22:52

I'm including pergola installation as part of my patio project. Post will be a 6"x6". I found this article which claims that cement is not as good as crushed angular gravel.

I'm thinking of going with the method(crushed angular gravel rather than cement) described in this article. I will be digging 42" of dirt as we are required by the village.

Is it true that using this method, the posts will still be very stable?

Here is a link that might be useful: Installing posts


Follow-Up Postings:

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RE: properly installing posts

Installing fence post and post for a pergola are not the same thing. Most wood will rot if installed in concrete, treated pine might not rot, but not a good choice for pergolas due to splitting, twisting, warping ect. that yellow pine does.

Your footings may be required to go down 42" if you live up north, but the pergola post should be attached to the top of the footing with the proper post base.

Simpson makes some post base that are imbedded in the concrete & have sleeved that come up the sides of the post. Those are the ones you'd want to use. I have a welder custom make post base when I built pergolas or pavillions that are more heavy duty than the ones simpson makes. No movement at all when those are used.


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RE: properly installing posts

Sorry deckman22, I forgot to say the it will be a free standing pergola. When I told this to the person at the village, he suddenly changed his suggestion from "installing it on top of concrete footing" to "burying it to the ground".


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pressure treated wood suggested

He also told me to use pressure treated wood.


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RE: properly installing posts

Take it from someone that builds pergolas for a living not some clerk, you don't want to use TP post unless they are going to be covered with stone or wrapped with another wood.

Burying post in the ground to stop lateral movement is the typical thinking of the uninformed layman. The right post base imbedded into the concrete when poured is the right way to do it. Angle brackets/lattice work can help to reduce lateral movement but, does not work as well.


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RE: properly installing posts

Ok, I've decided to use cement then. I'm thinking of renting an auger with a 12" diameter drill. Can I just put the posts then pour the cement? will the cement I found at home depot do the job? It's the one which says "just add water".

I'm a little confused with the terminologies. Am I correct that concrete is the finished product after I mix it water?

What do you think about my plans?


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RE: properly installing posts

If you are going to set the posts in concrete, then dig the hole, tamp the base well, set the post, then add a few inches of gravel back into the hole.

Then fill the remainder of the hole with concrete.

This will give you a concrete "collar" around the post instead of the post bottom being completely encapsulated in concrete.

The quikrete products at the box stores are fine.

Terminlogy:

"Cement" is bagged portland cement. No sand, no stone, just portland cement.

"Mortar" is portland cement, sand, and lime, the amount of lime can vary. Think brick or block mortar for building a brick or block or stone wall.

"Concrete" is portland cement, sand, and aggregate. Aggregate is stone. Sidewalks, foundations, fence posts, etc.

Variations within the above, but that's the nutshell.


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RE: properly installing posts

Does that mean that if I buy Quikrete, I still have to buy sand and aggregate? I haven't seen what Quickrete looks like. I have seen just the outside packaging.

Thanks!


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RE: properly installing posts

the quikrete yellow bag is already premixed with gravel, concrete, etc. just add water and mix it up.

I am a little hesitant to use the 'red bag' which is the one that you pour in the hole, then add water. I prefer to just spend the time mixing the cement so i get the consistency/ratio right.


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RE: properly installing posts

Yes, what funyellow wrote. They have a basic concrete mix, in a yellow bag. Just add water, mix, and fill the hole.


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RE: properly installing posts

Yes, what funyellow wrote. They have a basic concrete mix, in a yellow bag. Just add water, mix, and fill the hole.

6" post in a 12" diameter, 42" deep hole with a little bit of gravel added around the base of the post, plan on roughly three 80-lb bags per hole. I'm sort of guessing there as there are a few variables, how clean the sides of the hole are, etc, etc.

Regardless, it's always better to have extra and return it than to come up short on your last post.


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RE: properly installing posts

If you have a helper, the fastest way to mix concrete bags is to use a piece of 6 mil plastic, about 8' square. Pour the dry mix in the middle, make a little volcano, and add the water measured from a 5 gallon bucket. You and the helper pick up the corners of the plastic and agitate the mixture, back and forth, folding it over itself like you are making bread dough. It takes about 30 seconds to get a uniform mix with this technique. And you keep the weight of the concrete mainly on the ground, so it is not that much effort.


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RE: properly installing posts

I had to fill 8 footing holes myself - 48" deep, 12" wide. renting the mixer was WELL WORTH the $50 or so I paid. we banged it out one Friday night after work - started at 8pm and finished by 12:30am. it took between 5-6 bags per hole - hopefully that gives you a good frame of reference.


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RE: properly installing posts

I would blow the mixer away using plastic. 5 to 10 minutes per hole, no joke. After work, in the dark, no problem.


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RE: properly installing posts

Aidan, that technique sounds like it forms a bag. Otherwise, it seems it would spill out the sides if it was just being folded in half like a piece of paper. I need to mix near 30 bags pretty soon. I'm gonna se if I can use your trick....


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RE: properly installing posts

when did this become a pissing contest?


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RE: properly installing posts

You and the helper hold the corners of the plastic, to form a bowl in the center. The plastic needs to be 6-mil poly (the thick stuff) and the ideal size is about 8' square. It goes even faster if you have 3 people. The 3rd person can open the bags onto the plastic and add water. The piece of plastic makes it pretty easy to pour the concrete into the hole once it's mixed. Piece of cake!


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Who's pissing?

This is a place to exchange ideas and share experience. I have quite a bit of experience mixing bags of concrete. I also have lots of work to get done, but sharing my experience and giving advice over here is a nice way to take a rest break now and then. If it is not appreciated, I will go away. Sometimes I wonder why us contractors give so much for nothing. It is because we enjoy the work we do and we like to help people.

Over and out.


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RE: properly installing posts

Guys, thanks for all the inputs!

funyellow, I am shocked to saw your post that I need 5-6 bags of yellow bag quickrete.

Anyways, we submitted the pergola project papers 2 days to the village. Hopefully, we'll get an approval next weel. I can't wait.


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RE: properly installing posts

Forgot to update this thread.

We completed six 45"-48" deep holes last Saturday. Here is the latest picture. The holes will be inspected tomorrow morning.





And what do you think about my 9.5ft x 20ft pergola design that is perpendicular to the house? I did it this way so I can have more room on the right rather than making it parallel with the wall of the house. Hopefully, I'll get some comments. :)

Any help would be greatly appreciated. Thanks!!!


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RE: properly installing posts

What are your thoughts about this? I want to save $$ from purchasing many bags of concrete.

My original plan didn't have the CA-6 crushed stones.


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RE: properly installing posts

It's good you recognized having gravel under the post as well, not just around it. It allows drainage and lessens the chance for the post to start rotting out at the bottom. You can also brush some asphalt emulsion on the sides of the post up to the point where it wont show at the top, but dont seal the bottom of the post.


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RE: properly installing posts

What do you think about the addition of CA-6 crushed stones around the post? Do you think it will make the post weaker as compared to putting concrete all the way plus the 6" gravel below the post?

I like the ashphalt emulsion. Where can I buy it?


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RE: properly installing posts

Imo, It's going to be hard to get in there to compact the ca unless maybe you do it in one or two inch increments. If it were my project, I would just bite the bullet and go concrete although some fence post setters are just doing all gravel, no crete. I think it would depend on location and extremes concerning freezing, thawing, ground movement, etc.

Asphalt emulsion is a Henry's product and can be purchased wherever Henry's roofing products are sold. They make roofing cements, coatings, emulsions, etc. Home cheapo has it here were we are, you might check in with them or any reputable hardware store such as Ace. If they dont stock it, more than likely they can order as long as they carry Henry's products.


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RE: properly installing posts

I'm going with full concrete. I remember my driveway rose 2" early this year. I don't want that to happen in my pergola.

I want to save $$. Rather than buying the yellow bag of Quikrete, can I just order sand, cement, rocks and make up my own? Will I really be saving if I go that route?


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RE: properly installing posts

Sure, you can save a couple of bucks if you mix all the ingredients yourself. But for 6 holes, that is about what you will save, a couple of bucks. It's not worth the hassle and it's probably messier.


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RE: properly installing posts

Got it! I can't wait. I'll buy all the materials for my pergola tomorrow at 6am. I will also have to suck up the water on the holes. 3 ft of water, bummer :(

We had rain which lasted for days.

Thanks!


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RE: properly installing posts

Here is an update. I'll work on the remaining 3 holes tomorrow. :) OH, it was quite a workout especially I was the only one doing it. It was fun though.

OH, how many days will it take before concrete is ready/cured/solid?


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RE: properly installing posts

More updates...

I started working on the posts yesterday and I completed everything today. Tomorrow will be measuring day again. I will mark the top of the posts for the girders.


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