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-   -   Pouring Patio Slab and Post Footings Question (http://www.diychatroom.com/f19/pouring-patio-slab-post-footings-question-53648/)

average_male 09-23-2009 12:21 PM

Pouring Patio Slab and Post Footings Question
 
Hello All,

I am going to put in a covered patio. Question is, what is the preferred mthod of putting in post footings between the two methods (after the slab pour versus before the slab pour ).

Method 1 (After pouring the patio slab)
Pour the concrete for the patio slab and after the concrete drys for a couple of days, drill and place anchor bolts and place Simpson Strong Ties for your posts. (See image Method 1 Below)

Method 2 (Before pouring the patio slab)
Before pouring the patio slab, create forms for the post(s) and first pour the concrete for just the post footings using "Method 2 Hardware" noted below, and let dry, and then pour the main patio slab. So this method you will have a number of footings set higher than the patio slab that the post will sit on top of.

Method 1 Hardware:

http://i796.photobucket.com/albums/y...ost_Anchor.jpg

Method 2 Hardware before patio concrete slab:

http://i796.photobucket.com/albums/y...6_Post_Set.jpg

Thanks,
Moe

joed 09-23-2009 12:37 PM

#1 But instead of drilling later put the anchor bolts in the slab when it is poured.

average_male 09-23-2009 01:37 PM

Thanks Joed,

Can you expand as to the benefits of this approach versus the other method?

Thanks,
Moe

Willie T 09-23-2009 01:42 PM

Quote:

Originally Posted by average_male (Post 331462)
Thanks Joed,

Can you expand as to the benefits of this approach versus the other method?

Thanks,
Moe

  1. You don't have to drill anything.
  2. The anchor has a 90 degree turn in it for better holding force.
  3. Even if the anchor SHOULD work loose in a wind storm, it's still going to hold things down... whereas a drilled anchor will lose it's effectiveness as soon as it loses any grip on the concrete.

average_male 09-23-2009 01:59 PM

Quote:

Originally Posted by Willie T (Post 331469)
  1. You don't have to drill anything.
  2. The anchor has a 90 degree turn in it for better holding force.
  3. Even if the anchor SHOULD work loose in a wind storm, it's still going to hold things down... whereas a drilled anchor will lose it's effectiveness as soon as it loses any grip on the concrete.


Willie,

Thanks for your input. However, I am not sure which method you are in support of, sounds like method #2. Not sure what you mean by "90 degree turn in it". Can you expand on that?

Thanks,
Moe

Willie T 09-23-2009 03:00 PM

1 Attachment(s)
Yes, #2. These anchor bolts come in many lengths to suit your needs.

average_male 09-23-2009 03:28 PM

Ah, interesting. So that's how it's done.

Thanks Willie!

Willie T 09-23-2009 03:48 PM

3 Attachment(s)
This is how you suspend the bolt in the concrete pour.

Drill a long ( 12") piece of plywood with a hole the bolt will just fit through.

Put the bolt through, and slip on the washer, then run the nut down to give you the height of thread sticking above the form board you desire. (Be accurate here) Remember, you're measuring from the BOTTOM of the plywood.

Nail the plywood to the top of the form board in the correct (measured) position........ (I'm only showing a single form board actually attached for this corner so you can see how the bolt hangs.)

For side form boards, you simply make the plywood a little wider so the bolt is out far enough to be where you want it.

That orange thing in the background is nothing more than an example of how you would drill the plywood.
*********************
There is a slightly more complicated way of suspending that bolt, using two nuts, one above the plywood, and one below it. But this method will do for you. Just be sure the bolt is vertical when the pour is done.

Willie T 09-23-2009 04:40 PM

One thing about doing this "bolt" method is that there is usually some "play" allowed in the hole/s in the bottom of your "method #1" hardware.

"Method #2" insists that you be 100% accurate when you place that bracket in the concrete. That is sometimes hard to do.

itsreallyconc 09-23-2009 04:53 PM

a masterful explanation by a true craftsman, willie :thumbup:

Willie T 09-23-2009 04:58 PM

By the way, some people will tell you to just pour the concrete, then simply poke the bolt down into the wet concrete, and "joog" it around a little till it stays put. This will do fine for very rough work, but not for hitting holes in future bracket installations. Besides, it is not accepted workmanship at all... it has a tendency to create voids down inside the concrete. Best to measure accurately, and hang the bolts.

average_male 09-23-2009 04:59 PM

Willie,

While reading other posts, I found your other postings had a wealth of information laid-out in a very clear and detailed manner. So thank for providding the same level of input to my question. It's greatly appreciated.

Also, where do you get those figures? Did you create those?

Thanks,
Moe

Willie T 09-23-2009 05:00 PM

Quote:

Originally Posted by itsreallyconc (Post 331549)
a masterful explanation by a true craftsman, willie :thumbup:

I learned formwork early... on parking garages and bridges. :wink:

Willie T 09-23-2009 05:02 PM

Quote:

Originally Posted by average_male (Post 331557)
Willie,

While reading other posts, I found your other postings had a wealth of information laid-out in a very clear and detailed manner. So thank for providding the same level of input to my question. It's greatly appreciated.

Also, where do you get those figures? Did you create those?

Thanks,
Moe

Helping is why many of us are here.

The picture of the bolt came directly from a Google "Image" search of the www.

The other stuff is just some simple drawings I throw together with Google SketchUp.

Gary in WA 09-23-2009 05:35 PM

You have to decide what you are looking for in the two different post bases. #1 could be a non-treated post sitting on 1" high plate to protect from water splash (check with your local Building Department), or a p.t. post. This design has little or no resistance to lateral (side) forces. The hold-down in a high wind is rated from 550# to 2100# using nails or bolts. #2 has to be a pressure treated post as it will sit on the metal plate on the slab. This has the advantage of side resistance for stiffening. It has a rating for hold-down of 4200# minimum with bolts. So if you are trimming out the posts, #1 would be much easier than the bolts, washers, nuts and side flanges in #2. Remember to thicken the edges of the slab at the posts for load, possibly using a vapor barrier (6mil. plastic) under slab, possibly 2" insulation at perimeter (cold locales), and good gravel base underneath with the soil sloped for drainage.
Be safe, Gary


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