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Foundation to post connections

Started by Jim_Rogers, August 02, 2003, 01:30:41 PM

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Jim_Rogers

There were many discussions about proper post to foundation connections, on this forum and others.
Here is a type of connector use in Europe to connect posts to concrete pads. Some are adjustable and hidden, others are fixed and exposed.
I'm not sure if these are readily available here in the US, but you could fabricate your own if you wanted to.
This is a shot of stock items that came with my timber frame cad program. On the top left are the available post connectors, on the left bottom are the concrete connectors, and on the right is an example of one in place. This is an adjustable one with the hidden blade connector being used with the most left concrete connector.
In Europe these are called Column Shoes.
I hope this help you to understand how these connections can be done. Good luck with your projects. Jim


Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

UNCLEBUCK

hello Jim_Rogers, very good topic. Could you tell more about this timber frame cad program ,sounds interesting ok. thanks :P
UNCLEBUCK    bridge burner/bridge mender

Jim_Rogers

I posted a lot of info about it in the thread called "Finding Timber Frame Blue Prints."
You can check that out or ask me a question and I'll tell you more.
What more do you want to know?
Jim
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

JoeyLowe

Just a quick note to show a foundation to post connector that Simpson Strongtie offers. They are kind of pricey, but the entire system seems to work pretty good.

The first drawing is of the actual foundation to post connector.  It retails at Home Depot or Lowes for around $8.50 each.  A box of 100 is about $900.00.


.
This next photo shows a typical connection using the above strap.



The biggest concern when using this type of connection is called "spalling".  Spalling occurs whenever you twist the strap in order to get it to attach where you want it to.  This weakens the strap and reduces the load capacity accordingly.

For those interested, you can go to //www.strongtie.com and peruse their many selections.  You can also download their free connector software that shows you what products will work for your particular application given certain criteria that you enter into their software.  After choosing the particular connector or system you want, you can then print/fax the page directly to Home Depot or Lowes (They seem to get preferred pricing from Simpson).  Both of these stores will tell you that there is a 21 day turnaround on ordering these parts.  This is simply not true.  I called Simpson and spoke with one of their plant managers who told me that it is best to pick out your parts, then call Simpson direct to see if the item is in stock.  Then you can order through the retailer of your choice and if the item is a stock item, turnaround is closer to 2-4 days.

Hope this tidbit helps someone! ;D

--
Joey Lowe

"Working towards perfection has to be a part of anything one does.  You've got to put yourself into it." ... Sam Maloof (chairmaker)

Jim_Rogers

Joey:
Thanks for your input on this subject, nice job.
Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

ARKANSAWYER

  I just make my own and have shorter turnaround time.


ARKANSAWYER

hillbilly

                Those look pretty slick,are you bending them in a bender ,or are they cut out of tubing?
                 hillbilly

logosoluser

Since we are talking about post to foundation connections let me ask this question. I will have a conventional floor what is the best way to connect my post to the foundation? Will they be longer and go all the way to the ground on concrete pillars or something like that or will I make long beams around the outside of my floor and put holes in them for the post to sit down in. I am just wondering what is the most common practice on timberframes like that.

Jim_Rogers

Good questions!
There are several methods of connecting your posts to foundations with the standard stick built flooring system.
The easiest is by using a strap embedded in the concrete and coming up the side of the post as show above.
The way you get support for your post is to have your post sit on your mud sill. A mud sill is usually some width of pressure treated lumber bolted to the top of your concrete foundation wall, with some type of water proof membrane between the concrete and the wood.
I don't know if I have a picture on hand in my computer right now. But I know there are some in books and I can draw one for you to show you, later, not today, as I have to leave soon.
But you would build your regular deck with a rim joist and floor joists and plywood sub-floor. Then where the post is going you cut out a spot so the post slides down beside the rim joist and end joist to sit on the mud sill.
You may have to trim away the sides of the post at the base to keep the outside faces of the posts flush with the outside of the rim joists if that's what you want.
Here I found a picture of what I mean:




In the above photo you see the post bottom has been cut away so that it will fit over the joist, and next to the rim joists. And it will sit down in enough for the bottom of the post to sit on the mud sill. In this location (where the frame was erected) they just drove screws or nails threw the rim joists to fasten the posts to the deck frame, as it was in a low wind load area.

You can also see the decking cut away for the post.
Also you can see the kicker on the outside of the building and it's brace fastened to the stake driven into the ground.

This post was in the middle of the bent and with the corner posts the post bottom was cut away on two sides.

Hopefully you're still in the planning stage, and you can re-enforce your concrete foundation at these points where the posts will sit. This should be done as more load from the roof above will push down at these key spots.
If your foundation is already poured you might have to look at other re-enforcing systems.

I have also seen timber sills sit right on top of the decking around the outside of the deck for the frame posts to sit on.

Here is a shot of that:




This was in a barn. I'm not sure what type of frame you are doing but this may or may not work for you.

Good luck with your frame.
And keep asking questions......

Jim Rogers
Whatever you do, have fun doing it!
Woodmizer 1994 LT30HDG24 with 6' Bed Extension

Engineer

We are building the frame for my house on top of the deck, and putting stub tenons on the end of each post to hold it in place.  Each post will have "squash blocks" going from under the post to the sill or bearing point.  I'll strap the outside of each post to the sill and rim board.

My basement posts are all 8x8 pine and they will be anchored to the floor using a connection similar to Arky's.

Paschale

QuoteA mud sill is usually some width of pressure treated lumber bolted to the top of your concrete foundation wall, with some type of water proof membrane between the concrete and the wood.

This is an interesting thread.  I'm curious about the water proof membrane you're talking about.  I just did some concrete work on my garage, and have to redo some of the trim that will be resting on the concrete pad, outside.  I've been trying to figure out how to protect the wood trim around my garage door, since it's wood that is resting on the concrete.  I'm planning to trim it with cedar, but having some sort of membrane down there sounds like a good idea.  

Thanks!
Y'all can pronounce it "puh-SKOLLY"

ARKANSAWYER

  There are rolls of foam (some 3.5" and 6" wide) that are used between the sill and concrete to keep the wind from blowing through that also keeps water out and from wicking up.  I also use "black mammy" or roofing tar to coat the bottom of the seal but it can be a bit messy.  If you use the wet/dry type it will stick to the pressure treated if it is still wet.
  On my timbers in the connectors I coat the end of the timber with boiled linseed oil twice.  The connectors are tubing I cut the seamed side off to make a U.
ARKANSAWYER
ARKANSAWYER

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