# Post attachmets to cement foundations...



## texican (Oct 4, 2003)

Been building on a new home for several years, doing work when I have both cash and time... soon I'll be at the point where I can start raising posts. Love the idea of a cement slab for floor...would have everything 'termite proof' if I could afford/scrounge the materials.

I do have a nearly inexhaustible supply of timber, and already have a lot of large 10x10 (minimum) posts, anywhere from 20 to 32' long. Have no problem 'engineering' posts on the perimeter of the house, but the 'interior' posts, free standing and resting on the cement slabs, are giving me concerns.

Tried asking other websites, but you're shamed if you use incorrect terminology... Consensus seems to be to set 'pins' in the foundation, either during the pour (tricky, because of potential movement), or drilling the foundation, epoxying pins (1" bolt) into the cement, setting a sheet of shingle in between the concrete and wood, and lowering the post onto it.

My fear is that's a lot of wood resting on a foot long pin of steel and if the beam moves at the top while building around it, it will weaken the pin when it's straightened up.

Other option is in the foundation pour, dig a larger hole three or four feet down, set a sonotube (or equivalent) in the hole, pour slab... and have a concrete 'hole' for the post to go in... weatherproof the post going into the hole to prevent rot (possibly use some of my cypress posts in 'those' holes)...

Third option, pin the base, set the post on pin and asphalt, brace it securely, then lay up a foot of stone work (reinforced with rebar sticking out of the floor) four or so feet high... basically giving it more bracing.

Oh, and most all of this work is going to be done with just a front end loader, a 12K truck winch, and gin poles... so, getting a pole up will be 'fun', getting it to pivot over and sit on those pins will be even more fun...

Anyone actually done anything like this?


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## MushCreek (Jan 7, 2008)

You could set heavy galvanized straps into the concrete, leaving enough sticking up to bolt the posts too, but again, location would be tricky. Alternately, you could make a couple brackets out of (very) heavy angle iron, lagging it to the slab, and bolting them to the posts.


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## Dixie Bee Acres (Jul 22, 2013)

My great grandpas barn/crib burned just after they got the corn in, back in 1956.
A couple of days later, he started cutting down trees, and sawing them into posts and lumber.
By spongy, his new barn was done.
He had 8by8 posts at each corner, and a 4by8 ever 8 foot.
He attached these to a 2by8 sill plate, and a 2by8 top plate.
The sill plate was bolted to the cement slab.

Must have been an ok way of doing it, in 2010, my great aunt had me redo the barn. Had the original wood siding and corrogated tin roof. I stripped it to the skeleton, put new purlins on the roof, and shelled the building with new steel siding and roof.

My point is, frame it like a wall, posts attached to top and bottom plates, attach bottom plates to your slab, you should be good to go.


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## homstdr74 (Jul 4, 2011)

MushCreek said:


> You could set heavy galvanized straps into the concrete, leaving enough sticking up to bolt the posts too, but again, location would be tricky. Alternately, *you could make a couple brackets out of (very) heavy angle iron, lagging it to the slab, and bolting them to the posts*.


That's what we did. When I built my 30'x40' shop (10' high walls) on a concrete slab (w/foundation) I didn't want trusses because I wanted the ceiling to be higher than that, so we put 10"x10" posts in the middle and bolted them to the floor through thick angle iron brackets, ran beams from side to side and built braced rafters.


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## wy_white_wolf (Oct 14, 2004)

If you put the posts on a slab it should be thicker at those location. If it's a monolithic slab then it would be the relitive size as the exterior beam.

The pins should be large enough that they will not bend from the wieght of the post. I've used 3/4" chromemoly round stock just so I know they would not bend or rust. 

I've also set 6" wide flat stock into the concrete. Then cut a slot in the post for it to set. That allows you to drill through the post and flat stock to place bolts. Works nice if you are putting together bends like a timber frame. The flat stock keeps the posts from kicking sideways when being stood up.

WWW


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## simi-steading (Sep 27, 2012)

Or... 










or....


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## haypoint (Oct 4, 2006)

I set steel rods in the slab with a foot sticking out. Sure they move some, but I drilled holes in the bottom of each post and simply adjusted where the hole went by where the rod ended up. If the rod was an inch north and 3/4 inch east, I just drilled the post off center that amount. I tarred the concrete and the bottom few inches of the post..
I also have used metal brackets cast into concrete. I made posts, but you could do it differently.


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## jwal10 (Jun 5, 2010)

When I rebuilt a barn into a shop at the farm I used the worn out throwaway plow shares, left the old bolts in where they were buried in concrete. sandwiched the post in between 2 and torched holes to bolt through above the concrete. Set the post on a treated pad on top of the concrete. Plow shares never rot or rot out, made from cast steel....James


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## Space Cowboy (Apr 26, 2008)

It's not pretty, but it works......
(8x24 power center-wood is 4x4x8)

J bolt sitting in sono tube


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## Evons hubby (Oct 3, 2005)

My favorite method is to set a one inch diameter wooden peg into the concrete while pouring concrete. Measure carefully so peg will be in center of post.after concrete is set well drill hole in bottom of post to fit peg.. you want the hole to be a qurter icnch deeper than peg is sticking out of concrete ... cut a slot across peg down to about an inch from concrete. Fit a wedge into top of peg leaving a couple of inches sticking above top of peg. set post down over peg and drive down tite to concrete. This drives the wedge firmly into wooden peg securing everything together.


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## texican (Oct 4, 2003)

MushCreek said:


> You could set heavy galvanized straps into the concrete, leaving enough sticking up to bolt the posts too, but again, location would be tricky. Alternately, you could make a couple brackets out of (very) heavy angle iron, lagging it to the slab, and bolting them to the posts.


I've thought about this, it's just the tricky part of "hulling" out a chunk of the wood, bolting, and then 'replacing' the wood. These posts will be in the grand entrance area, out in the open, and wouldn't want to see the 'connectors' or stub my toe every time I walk by. Guess I could always do stonework around the base...


wy_white_wolf said:


> If you put the posts on a slab it should be thicker at those location. If it's a monolithic slab then it would be the relitive size as the exterior beam.
> 
> The pins should be large enough that they will not bend from the wieght of the post. I've used 3/4" chromemoly round stock just so I know they would not bend or rust.
> 
> ...


May have to end up doing something similar, to keep it in place. Plan on digging out a larger (probably 3x wider) and deeper area under the slab, where these heavy posts rest.

I do have a few large straight cypress that I can use... but I know the wood, for structural purposes isn't that strong. Have lots of dead and dying post oak trees, and have a dozen milled up into beams already. One of my uncles built a barn, down in the 'river bottoms', where it was subject to flooding every few years, back in the 50's... I salvaged some 2x12's that were lying on the ground, still hard as steel. The posts set directly in the ground were solid as ever...


Thanks everyone!


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