Can anyone tell me what is the best commercially available anchor/bracket for 8" x 8" timber posts 10' tall, supporting 18' x 22' pavilion roof to anchor to concrete after concrete has set? I need to purchase hardware soon.

Disclaimer: this connection can experience extremely high forces under design criteria, so it should be approved or designed by an engineer.

that being said:

Here is our most common pavilion post foot connection:

HDG allthread epoxied into the concrete. Drill the post foot for allthread and mortise into a non-show face to get in there and put a plate washer and nut on it. Plug mortise if it is in a show face. This connection is pretty good for uplift and some shear.

Size of allthread, plate washer, depth of embed, relish below mortise, and epoxy spec should be determined by your engineer.

Be sure to isolate the wood from the concrete. We usually use 1/2" thick black UHMW plastic.

Gabel, thanks for the info. Isn't there a off-the-shelf engineer tested mounting/anchoring system for 8" x 8" timbers to concrete that I can buy for a 4-post pavilion with 22' x 18' gable roof? The posts to beams will be angle braced.

Gabel, better yet, how much would you sell me what I need for the 4-8" x 8" posts not including epoxy which I have? I have and/or will get the proper tools for the installation.

Depends on the environment that the structure is in. Uplift, seismic, do you need it to be a moment connection, what kind of bracing is in the structure, etc. etc.

If you need a moment connection to keep things rigid, the simple epoxy rod / stand off might not work.

Simpson makes a bunch of off the shelf options - most of them aren't pretty:
http://www.strongtie.com/products/categories/caps-bases.html

You can do this yourself and order plastic for the base part from McMaster-Carr or similar. You can also use a plate of stainless. The rod should be off the shelf at a local supply house. Depending on where you are, stainless rod / connections might be worth the extra $$.

But again, it really depends on the specifics.

Mike, I am 30 miles west of Indianapolis in the middle of farmland. The only windbreak is mature trees to the north and hopefully in 5-10 years the trees I planted west and east of the house will give some relief but for now we really get slammed sometimes with wind. A 15-20 mph wind feels double that. The frostline is 32"

Mike, I will have 4" x 8" braces at 45 degree angles both directions of all 4 corners. Are you saying the thread rod mount is best? What diameter and is one per post sufficient? I've only seen 3/4" diameter available at hardware stores and the big box stores. Also, what size washers for the nut mortise? If 3/4" rod is used, I've only seen about 2"OD washers. Is that enough? Is an epoxied rod better than a bracket imbedded in the concrete? I don't think I need more than the epoxy rod/stand off connection but for my own education, what is moment connection? Is that available prefab or is it cheaper to have something fabricated locally? Unfortunately, I am not a welder and will have to hire any such fabrication out.

I can't comment on whats good enough. You should get a local engineer involved. Or work with someone on these forums (myself and others offer design and review services). Or contact an engineer from the TFEC: http://timberframeengineeringcouncil.org


Thread mount is OK depending on the circumstances. Really depends on what you need for uplift and sustained wind.

Bracing tends to work well in compression only, unless you've designed the braces to deal with tension. Again, I haven't seen a design, nor studied the loading of your site - so I can't comment on specifics.

There may be an off the shelf product that will work. Simpson does have some post foot connectors. I can't really sell you what you need -- allthread, nuts, washers, etc are pretty easy to come by. But really, I don't know what you need for this specific project.

I feel like I should explain why I am hesitant to answer your question with specifics. I do this for a living and I take structural design quite seriously. There is a lot of risk in building or designing something. That's why I have insurance. And that's why on almost all of my jobs I pay an engineer to answer these types of questions for me. In other words, I don't even answer this question myself when I am getting paid to -- I hire a legally recognized expert (licensed engineer).

I don't mean to offend or seem unhelpful -- I just wanted to explain where I am coming from.

Gabel is perfectly right and frankly I winced when you asked him to provide you with the hardware. First of all there are all the potential liability issues, but you should also consider that all of this odds and ends stuff has to be found in these huge hardware catalogs, ordered, inventoried, lost, found, lost again. Its not much different than the local guy that rolls up in his pickup and wants to buy some timbers. Yeah we do it for good community relations, but then you have to reorder, chances are the next week you'll need one of those sticks, and its very inefficient to buy timbers a few at a time you really want to buy trailer loads....

The stick framing market is big enough that manufacturers create load tables, and fastening schedules and so on. Timber Frames are all unique, so the joints are loaded differently every time based on frame design, use, location, and other influences. Like Gabel I have lengths of all-thread in various diameters, nuts, washers and other hardware kicking around for these various conditions, but I hire an engineer to help me spec the material and details. There are lots of variables involved in timber frame engineering, we might be familiar with most of them but you don't know what you don't know, what is a moment connection, unbalanced load condition, do I get a reduction for a steeper roof pitch, and so on. Hire a Specialty Engineer from the TFEC (see Mike's link above), don't assume just any civil or structural engineer can do this. While you might be right, they'll probably be cracking open some old college textbooks and relearning something they haven't done in years, but keep in mind all of these guys charge by the hour.

Gabel and Paul, I understand completely about liability. I just had to ask if anyone had something for sale they knew to be engineered properly for 8" x 8" pavilion posts. I have talked to big name manufacturer's engineer describing all the pertinent details for which he told me what I needed. Now I will have them fabricated stronger for less than that manufacturers price.
Thank you all for your input. I'll post some photos during the project.

Hi TMC,

I almost answered you in the beginning, but Gabel beat me to it, and then continued to give almost verbatim info that I (and 98% of all professional Timberwrights would have provided.) I routinely, scribe fit round and square posts to all shapes and sizes of boulder, rock and other masonry plinth. The modalities of such such meetings of timber to foundation, and their "moment connections," both ancient, contemporary and amalgamated are vast.

Off the shelf...well that is not what most of us do. Each job, even though it may be in the same area, on similar foundation, has its own individual considerations, from bearing soil types, to aesthetic constraints.

The oldest frames in the world are not tied to there foundations at all; haven't been from 500 to 2000 years ago...they just "kinda" sit there. Many ancient forms do have "drift pins" in bronze or copper. Many of these are subjected to Tsunami and other tectonic events way beyond the norm, (including a couple of nuclear blasts that a few decide to share with the world...) So why do we use the many types we now do? That is a long and complicated story, yet in many modern timber frames...it does make sense. The main reason being our frames are much lighter.

So, I suggest that perhaps you contact Simpson, as that is the closest you are going to get to "off the shelf." Or pay the appropriate nominal fee to a PE with TF experience to spec a bracket that someone local to you can weld up. OR, most simple and practical...if you frame actually needs to be tied to its foundation, is follow Gabel's first description...Its really a good one. Let us all know how things turn out and post some pictures for us.

Regards,

j

In addition to Simpson products, there is also TimberLinx.
They specialize in timber to whatever connections. I do know they sell a 7/8" threaded rod with a re-bar end for either cast-in-place or epoxy applications. The top end uses a wedge based cross piece to anchor the post down.
I have never used the concrete anchor they supply but have used a variation where the rod was welded to an I-beam. Worked well.
Check out their website.