Securing Posts to Concrete Pylons

[jemmy]

I am man on mission to put up my first structure while using my own circle mill. One of my biggest problems that I am having with the designs, is how I am going to connect the post to the concrete. The majority off my posts are going to be sourced from the dead ash that is on my property. Now, I wasn't planning on cutting these posts down much, due to their lack of size, maybe just square them off on each end so that I can build "L" brackets to secure things. The dead ash will be 6" minimum in diameter at the small end, with the ideal being a uniform 12"x12", but being pragmatic most will narrow to about 6"-10".... My design currently is to pour 2'x2'x5'  concrete pylons acting as the post's footer, anchor, etc. This is where my question resides, how should I secure the posts to the concrete pylon? My idea is to use 6"x12"x.5"/6"x6"x.5" steel plating to create "L" brackets. I know how to secure the metal to the concrete with wedge anchors, and as I see it I have 2 options for securing the post to "L" bracket. 1) 2-4 lag bolts/"L" bracket 5"x.5" or 2) Drill holes through timber and secure "L" brackets with all thread and lock nuts. I do not know if this will work structurally, or if this is a viable option, I am half tempted to try "dipping" the logs in some form sealant, then just sinking them into the concrete hole.... This is all VERY speculative, I am very open to knowledge and wisdom, so please feel free to let me know what you think or know! Btw if you need information for answering this question please let know, I know I left a lot of detail out, but this post could be a book or two...

[Banjo picker]

Trying to sink poles into wet concrete will probably cause you some grief.  In the heat of the battle, it will be hard to get them where you want them or get them plumb.  Putting wood into concrete is usually not a good idea anyway.  I would bolt the poles to the L brackets instead of using lag screws.  You might want to check out using an epoxy to put the bolts into your concrete instead of wedge bolts.  Hilti makes some very good products to do that with.  Banjo

[jemmy]

Thanks banjo, that is what I was leaning towards the most for securing the "L" brackets to the post. I gave some thought to using threaded rod w/ the epoxy for the concrete anchors. I even bought a tube of it, but something just doesn't sit with me right about it compared to a wedge bolt. I read all the math behind it, but I prefer physical over chemical for me in this instance. I can also always add epoxy later if the wedge bolts don't work out, but hopefully that is not the case! I agree that the threaded rod/lock nuts would yield the best result through the post. I am including some of the "L" brackets that I did this year, this is my half way finished mounting brackets for my motor, they still need touched up. I would use wider flat stock, just gives a good visualization.  

 


 

[Don P]

I don't much care for either, loop a big strand of steel down at the bottom of the pier and hook to that. In the top of the pier I either cast a flat plate with long rebar welded to the bottom and hooked or extend a rebar up out of the pour, drill a hole in a steel plate, slip it over the rebar and weld. This is placed flat on top of the pier pour. At your leisure measure from the top of the plate to the final height. Cut a piece of square or round tube about 1" long to create a standoff and weld a plate on top that just tucks under the post, don't make a water catch. Extend a vertical knife plate up from that. Cut a slot in the post and insert the knife plate. Then drill thru the post, knife plate, post and secure with a pair of preferably 3/4" steel or 1' wood dowels.

Now you can measure from the bottom of the standoff to the top of the post and cut to length. Stand the post on the flat plate and drift it around till you're happy, then weld the standoff to the pier plate.

I've used short pieces of pipe welded to the pier plate and standoff to create a hinge that I can slip a long bolt through as a hinge pin. With both legs of a bent secured like that it makes raising easier.

[jemmy]

Don P,

Thanks for the technical knowledge, a couple of questions. How thick should these plates be? And do you have any photos for examples?

[Banjo picker]

 

 

 You could just use anchor bolts like I did on my mill shed and just wield your bracket to the top of the plate to secure your wood post to.  And before you folks jump all over this application, I know those plates should be sitting on jack nuts and then grouted around.  Also to meet ASTM standards now you would need 4 anchor bolts per pier.  I picked up those base plates at a salvage yard along with some of my vertical pipe.  You can see where the 2 x 4 was at the top of the pier that I had the anchor bolts fastened to.  What Don P said about getting something imbeded in the concrete is difinately best.  I could not go into detail last night, because it was 8:00 and Mountain Men came on .... the only show I watch on a regular basis.    Pay no attention to all the clutter in that first picture.  It looks better now.  NOT.  Banjo

[Jim_Rogers]

Here is one way a customer of mine did it for his frame:



 

Here is a drawing of the base:


 

This worked for them.



 

Jim Rogers

[WV Sawmiller]

Happy Birthday Jim.

[curved-wood]

Those plates are really a top job

[Hilltop366]

I have used a ¼" x 2"  flat bar imbedded in the concrete, I don't remember if I bent the end or drilled a hole and put a piece of rod through to prevent pullout from the concrete.

To get the post off the concrete I added a layer of roof shingle and a piece of pressure treated 2x? before installing the post. I kept the treated 2x? a bit smaller than the post so it would not collect water and cause it to wick up the bottom of the post.

I then drilled a hole in the bottom of the post and stood it up up over the flat bar, then drill and bolt through the post and bar.

[Don P]

 This is a 2 piece set, the bottom hook and plate for the pier and the standoff, plate and knife plate for the post. This knife plate is too short and shouldn't be predrilled, I prefer more hook embedment but it is the general idea. These were used by one nearby TF company.






I do this on porches, same idea. I've used a piece of trex cut and slotted to drop over the knife plate under the post to act as a standoff.





This is the tip up base. made from a chunk of 8" I beam and some 3" channel. I didn't use a knife plate here but just ran a couple of 10" lags up into the post... works for lateral but doesn't provide good uplift/withdrawal. a plate cast in the mud, The shiny is where I just welded the center piece of the hinge to the pier plate.






This is fabbing the hinge.




tipping that up

[Jim_Rogers]

Happy Birthday Jim.

Thanks

[jemmy]

Wow, I have now become fascinated. I love studying how to secure things in the proper fashion, especially when it looks good! And those examples are prime time in terms of fit and function. Don P and Jim thank you for the help! These gave me a lot of idea's, and I'm excited to get fabricating! Jim, why did your customer sink the nuts into the wood? Is there a problem if you don't sink them? And happy birthday!

[Jim_Rogers]

Jim, why did your customer sink the nuts into the wood? Is there a problem if you don't sink them?

It was a public place so they didn't want anyone to walk into the fasteners on the side of the post.
Jim Rogers

[Brad_bb]

Post bases like Jim shows are the way to go.  I've drilled and epoxied the anchor bolts into the concrete foundation.  Wet setting in concrete is a nightmare and you never get things to stay in the position you want.  I tried that on the first project with simpson straps wet setting them.  Somehow a lot of them moved and ended up not straight or out of position. From then on, always lay out on a cured foundation with string lines and laser.  This will assure that everything is dead nuts and level.  

[canopy]

Timberlinx is another option. The anchors are hidden in the post, can be set before the pour or after cured, are galvanized, and allow cranking the posts down tight. Downside is they are expensive and require a lot of things to be done perfectly. A lot of people will want their drilling jig which itself costs many hundreds of dollars.

[Stuart Caruk]

I use TimberLinx connectors all the time, and this would be my choice to secure the post to the poured concrete. I'd pour the concrete, let it cure, then drill for a 7/8" rawl bolt. You start by threading their base adapter onto the rawl bolt. Then you drill and 1 1/8" hole in the base of the post and another one up about 5" from one side. Set the post on a moisture break (I use laser cut acrylic plates), tighten it down, and you are good to go. It save the hassles associated with base plates and bolts.

Here's a picture from their installation manual.

 

[florida]

I build and repair a lot of decks using hardware to connect wood posts to concrete piers. There is no point in re-inventing the wheel. Simpson makes many different types and styles of bases to fit almost any need.

https://www.strongtie.com/postbases_capsandbases/category

I quit setting mine in concrete years ago as it's so easy for them to end up slightly out of place. We now use mostly galvanized Simpson UB/WUB bases conected to the concrete with wedge bolts.

Powers Fasteners - Wedge-Bolt® +

Using this method I can get my brackets spot on and they install very quickly. 

[mike_belben]

Pour your bases.  Set some temp stakes and snap your chalk lines. Triple check then Hilti in your holes along the chalk grid.  Insert a wedge anchor or a piece of rebar, pound it in.  Bore mating hole into bottom of post.  lay asphalt shingle over the concrete and putty knife some roofing tar onto the post as a moisture barrier.  Set post onto dowel, if necessary anchor from the side with angle iron and lag bolts into the post, red heads into the concrete.

Never put wood grain onto concrete.

[florida]

Mike

Down here in Florida stopping uplift is  more critical than than holding the post down. Plus pretty much every post I've ever removed with a rebar dowel was badly rotted around the rebar. 

[Plankton]

Not sure I'm following the question completely but if your asking about setting posts on sono tubes we do that fairly often on shed roof additions to barns etc.
We just pour our sono tube set a long section of threaded rod into the wet concrete based on measurements and use a strong tie bracket that has 4 sides and a hole in the center for the rod and bolt the plate to the sonotube. Post goes in bracket and gets timlocked.