Timber Frame Build - Round 2

[EddieWalker]

I never tried to do a two post arbor, but if I had to, I would probably try to drill a hole as far as possible into the post for at least a one inch pipe or rod. Two inches would be better if you get a lot of wind. Then sink the post at least 4 feet into the ground with 6 feet being even better.

 

[jk96]

I never tried to do a two post arbor, but if I had to, I would probably try to drill a hole as far as possible into the post for at least a one inch pipe or rod. Two inches would be better if you get a lot of wind. Then sink the post at least 4 feet into the ground with 6 feet being even better.

I was thinking about fabricating something like this out of steel that could be anchored into a concrete footing. My worry about burying the posts would be ground rot since I'm using doug fir and not pt.

Simpson Strong-Tie 12-Gauge Black Powder-Coated E-Z Base-FPBB44 - The Home Depot

 

[EddieWalker]

I didn't mean for you to bury the post. It needs to be above grade. I don't think an anchor like you posted the link to will do anything. It's too short to give the post stability. You are going to have to have something that's several feet tall, above grade at a minimum.

On my gazebo, I have 5 foot long lengths of channel iron set three feet into the ground, with a 12 inch hole filled with concrete and then a pad 6 inches thick to rest the post on. I ran two 3/4 galvanized threaded rods through the posts and then cut the rod after getting the nuts tight. This is not strong enough to hold the post from being pushed over, it's only designed to hold it in place.

 

[BitChin1]

I was thinking about fabricating something like this out of steel that could be anchored into a concrete footing. My worry about burying the posts would be ground rot since I'm using doug fir and not pt.

Simpson Strong-Tie 12-Gauge Black Powder-Coated E-Z Base-FPBB44 - The Home Depot

Jeremy my concern is the leverage from any side load the arbor would receive (wind? other?). This would anchor the post to the foundation but likely will act as a hinge unless the above/below grade steel is significant - setting light posts (very little wind load) we used 18" bolts tied to rebar in a 4' hole - then the pole is continuous aluminum. In your case the DF will sink/swell with humidity so the steel socket is all that will keep it vertical (your left over DF posts are dry, but mine are a year drier and still shrinking).
If you are confident that the location will not see significant loading (I don't know how to measure that) Connecticut Post and Beam make some AL joints (instead of true timber frame mortise/tenon) including post base - the plate fits into a slot in the post so it is not highly visible - might be an option for something similar to what Eddie was recommending to get a solid connection to the concrete foundation along with a significant connection up into the post to reduce the hinge leverage. Not sure if AL or steel is better in this application, but AL may weather better?

 

[jk96]

Jeremy my concern is the leverage from any side load the arbor would receive (wind? other?). This would anchor the post to the foundation but likely will act as a hinge unless the above/below grade steel is significant - setting light posts (very little wind load) we used 18" bolts tied to rebar in a 4' hole - then the pole is continuous aluminum. In your case the DF will sink/swell with humidity so the steel socket is all that will keep it vertical (your left over DF posts are dry, but mine are a year drier and still shrinking).
If you are confident that the location will not see significant loading (I don't know how to measure that) Connecticut Post and Beam make some AL joints (instead of true timber frame mortise/tenon) including post base - the plate fits into a slot in the post so it is not highly visible - might be an option for something similar to what Eddie was recommending to get a solid connection to the concrete foundation along with a significant connection up into the post to reduce the hinge leverage. Not sure if AL or steel is better in this application, but AL may weather better?

Going to have to give this one some thought. I was thinking 12" tall steel sleeve bolted to a decent size concrete footing, thinking 30" augur bit that I have at 3-1/2' deep. If the post set inside the sleeve 12" deep the only place I can see a failure would be in the sleeve itself or the concrete bolts. I would have to find out what specs for steel thickness and bolts needed would be. But some decent size J-bolts imbedded in concrete should do the trick. In the end it also has to look decent. That may be as hard as the figuring out the specs and load.

 

[EddieWalker]

How big are the posts? Can you get square tubing big enough to fit the post inside the metal tubing? I have five inch square tubing on my fence. It's expensive, it's special order, but it's solid.

Set the square tubing in the post hole and concrete that into place. Have it go three feet above grade and then slide your wood post into it. Paint the metal, or surround it in brick or rock.

 

[Luke'sScreenName]

Have you considered a knife plate? Wide saw kerf then through bolt it. Trim the base to hide the kerf, bolts, and stand-off plate.

 

[jk96]

How big are the posts? Can you get square tubing big enough to fit the post inside the metal tubing? I have five inch square tubing on my fence. It's expensive, it's special order, but it's solid.

Set the square tubing in the post hole and concrete that into place. Have it go three feet above grade and then slide your wood post into it. Paint the metal, or surround it in brick or rock.

Eddie that is my original plan. Posts are 8" x 10". I would fabricate an 8" x 10" sleeve for the post to drop into. The sleeve would be anchored to a concrete footing. Just need to figure out steel thickness needed to support the post under high wind. With this design I don't see how it could topple unless the bolts or sleeve were undersized. I've got a fabricator I use that could easily make these for me.

 

[BitChin1]

Going to have to give this one some thought. I was thinking 12" tall steel sleeve bolted to a decent size concrete footing, thinking 30" augur bit that I have at 3-1/2' deep. If the post set inside the sleeve 12" deep the only place I can see a failure would be in the sleeve itself or the concrete bolts. I would have to find out what specs for steel thickness and bolts needed would be. But some decent size J-bolts imbedded in concrete should do the trick. In the end it also has to look decent. That may be as hard as the figuring out the specs and load.

This is similar to how the light posts I have worked on - the key is getting all components solidly connected (Ground, footing, post) - for 10" x 10" post you gain some support just from the footprint. Checkout the t-rex connectors (you would need a custom one or build it similarly yourself) at ctpostandbeam - seems to me AL might weather better over time and this approach would hide the plate in the post - maybe an "x" plate s it has support in all directions - with your post this would be like 4 4x4's all tied together.
If you do the sleeve I think it would need some sort of trim/cover for long term appearance - steel eventually rusts - my railing is powder coated and in 4 years I am still getting some rust to show up already.

 

[jk96]

A little bit of progress today. I was able to get all of the electrical conduit behind the pergola in the ground and ran to the footing I dug for one of the stone column location where the service panel will be located. Marked out the locations for the remaining column footings that need dug. We also got some trees in the ground for some background landscaping. Plan to dig the other 5 footings for columns tomorrow. I can reach those with my tractor and auger so should make for easy digging I hope.

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