Yes, that was my point exactly. Upon re-reading my post, it wasn't clear that I was trying to point out that there are too many variables to give a simple answer. One must do the math, or hire someone that can.

All the wood I will be using will be treated pine, including the 8x8 posts. I know that treated wood doesn't necessarily preclude rot, but I was thinking of treating them with some additional chemical, for example, some paint/sealer type product. My dilemma is that the footers will be four feet down (frost-line), which makes assembling any type of post-bottom yoke quite difficult, let alone placing it in the correct spot on the footer.

I will be using a 7.5/12 pitch for the roof. There will two bents, the front side gable and the backside gable. The bent spacing is ten feet, on center. The 8x8 purlins will be spaced three feet apart, notched 1" into the rafter.

Please explain how an 8x10 rafter using an 8x12 tie beams, king posts and struts plan is underdesigned. I can do the math, I just don't know how. If you forward me to some resources where I could check some of these loads, I would appreciate it. Better yet, are there any 10'x20' timber frame pavilion plans out there?

Thanks for your help, Tim

Hi all

A very lively topic indeed. I have used a imbedded wrought 3\4" iron rod in the concrete footing which extended up for about 7 ". The top 4" was threaded. In the bottom of the timber pre drill a 1" hole as close to the location of the imbedded wrought iron rod, and about 9" in depth. drill from the side of the timber an access hole that intersects the vertical hole about 7.5" from the bottom, and then chisel out a flat shoulder on the horizontal acess hole, big enough to slide in a 3\4" nut and flat washer. After setting the post over the imbedded rod slide in the nut and washer and tighten down firmly. I suggest some type of moisture barrier between the end of the timber post and the concrete to stop moisture wicking, we used a copper sheet set over the imbedded rod.
best of luck NH

Tim: A good place to start learning "the math" is the Timber Frame Joinery and Design Workbook put out by the guild. It's actually a collection of articles from the journal.

Regarding securing wood posts in concrete, I spoke with a fellow who made the following recommendation:

Wrap the bottom of the with an adhesive water/ice barrier. A brand name that I found is made by a comapny called "Grace." This stuff is like a roll of very thick tar paper, or a shingle without the rough particles on the outside. Through the water barrier, place re-bar into the post that will secure the post in the concrete. Set the post in the hole, and pour in the concrete, enough so it doesn't go over the water barrier.

This is the simplest way to secure a post without having the concrete touch the wood. -- Tim

pouring the concrete after installing the wood is a great option in that you don't have to worry about precision in hardware placement, only getting the foundation forms as close as possible.
it does take extra time to do some temporary bracing and in the case of timberframing the temporary bracing may need to be substantial......

Gib, I would keep the post above ground and dry.

The quick and easy method for post attachment I use is:

1. Pour footing with above ground pier.
2. Bore post on center axis and embed with epoxy, 3/4 stainless all-thread.
3. Fab a p.t. wood base and clad with copper. Mount base to post, allow all-thread to extend 8 inches.
4. Bore pier on center line grid and embed rod with epoxy.

The copper has two roles, stop wicking and inhibit fungi.

Hey Mark, and yes, that is precisely what I want to do in getting the post placed in the four-foot deep hole, THEN moving it around to its exact location. Once it is where it is going to be, I will brace it plumb and pour in the concrete. I calculate that I will need to mix about 5 bags of ready-mix for my 2-foot diameter hole with an 8x8 post in the middle of it.

And Roger, thanks for your input, but there is nothing that sounds quick and easy about pouring a footer and four-foot concrete pier with it. I was really planning on just mixing the crete myself, and making a pier would probably be more than I care to mix by hand. But this would definitely be "PLAN B" if I wasn't so sold on wrapping the bottom with this Vycor stuff. I am going pack the rest of the hole (around the post) with 3/4" rock.

This is going to be an open-frame structure; so uplift because of heavy winds is part of the design consideration. IMO, embedding rebar in the bottom sides of a waterproofed post to secure it in the footer is a much more secure attachment than a "U" strap or a threaded rod.

I am interested in any other thoughts on this subject. -- Tim

In the interest of information, the epoxied rod scenario does have significant uplift values. See this

For a 5/8 rod, average ultimate uplift is 19835 lbs, and allowable design value is 4490 lbs. Seems to me the connection could hold to the point that the footing dislodges.

Tim...

My sense is that ALL of these suggestions are valid. If I were to put a wooden post in concrete, I definitely seal the bottom! But to be honest, I personally would not put wood into concrete. To me, a footing/pier/Strong-Tie plate or equivalent/wooden post would be the preferred approach.

I know many a person who has cut off and replaced the bottom of posts/studs...that were installed in a not-so-great manner and over time feel prey to Mother Nature.

Joel