Post holes revisted.

[NutBucket]

Right.

To me, a footing is for a vertical load and a post is for a lateral one (ie a fence).

 

[PowerEngineer]

I agree with NutBucket. What I meant by thinking about your gazebo like a house was to consider a concrete foundation upon which the wooden gazebo would rest above ground level by a few inches (maybe bolted down). It seems to me that your wooden posts in the ground will be the weak point of your gazebo regardless of how you do it.

 

[Humpy]

Not sure what OP is building. When I hear of a gazebo I think of something like this, maybe even 6 or 8 sided.

Those angle braces are what provide all the lateral stability. The structure could just sit there on top of the deck and not be fastened down at all except to stop it from blowing away in the wind.

Another method is to build it like a pole barn.

Unless something like utility poles are used though you are pretty much leaving the longevity up to fate.

 

[paperfist]

I never liked the metal brackets besides it's a dissimilar material situation.

Too late anyway, I already poured a 10" x 24" square pier. So the 6x6 will sit on that below grade wrapped in tar paper then surrounded by crusher run. As soon as it stops raining I'll finish the other piers.

All the posts will be covered by a roof so additional moisture shouldn't be a problem. Though I've read a few other articles that say bugs and mold are what actually breaks the wood down and rots it even if it's treated.

 

[paperfist]

Not sure what OP is building. When I hear of a gazebo I think of something like this, maybe even 6 or 8 sided.

Those angle braces are what provide all the lateral stability. The structure could just sit there on top of the deck and not be fastened down at all except to stop it from blowing away in the wind.

Another method is to build it like a pole barn.

Unless something like utility poles are used though you are pretty much leaving the longevity up to fate.

First pic is exactly what I'm building right down to the hip roof. Mine will be screened in though. We get some pretty crazy winds here. I know it's not the same but every year I buy one of those fabric gazebos and every year the wind shreds them.

 

[PowerEngineer]

Oh, I was thinking something like this:

 

[Todd K]

I don't know nothin' bout nothin', but I wonder if you could sleeve the posts in plastic for the underground portion. Seems obvious to me, so maybe there's a reason that isn't done.

Sleeving or cupping the wood in plastic, metal or concrete just retains water that has seeped into the wood from above and traps that moisture inside, assisting the rotting process. It helps to coat the sides of the post that will be underground in a 50-50 mix of diesel and motor oil (or something similar) to minimize water entering the post. DO NOT cap or in any way seal the bottom end of the post....instead, allow water that has entered to post to seep out the bottom into a bed of packed pea gravel below the bottom end of your wood posts. DO seal and/or cap the top of the post to minimize water getting into the wood.

 

[paperfist]

Sleeving or cupping the wood in plastic, metal or concrete just retains water that has seeped into the wood from above and traps that moisture inside, assisting the rotting process. It helps to coat the sides of the post that will be underground in a 50-50 mix of diesel and motor oil (or something similar) to minimize water entering the post. DO NOT cap or in any way seal the bottom end of the post....instead, allow water that has entered to post to seep out the bottom into a bed of packed pea gravel below the bottom end of your wood posts. DO seal and/or cap the top of the post to minimize water getting into the wood.

I only got to set 2 posts before the snow was too much but on those two I used sill sealer in the bottom and tacked it to the sides.

 

[Ns1]

5' deep hole wtf.

 

[NutBucket]

Frost line, bro. Although 5' is pretty dang deep even for that!

 

[paperfist]

Need to keep 1' of the concrete pad and 6" of gravel under the frost line.

Though at least where I live deep frost doesn't seem to exist anymore.

 

[Scarpozzi]

Eliminate rot? That's funny. YMMV when it comes to treated lumber. Honestly, 4" vs 6"....you go with thicker stuff if you don't want it to rot as quickly. Water typically doesn't go as deep underground as you think. It's more than likely going to rot just above ground than below.

Most of the time, they say to put a few inches of gravel in the bottom of the hole for drainage. The concrete base of 1" won't do anything but crack if it cures before you put the posts in....unless you mean to just put dry concrete in without water....it will harden eventually by soaking up water and when you pour mixed concrete on top, the moisture will help it cure with the green concrete above.

The way most contractors handle posts these days is to pour those tubular forms full of concrete to a particular depth/height above ground...and sink a steel post mount in it. Then you bolt your post to the mount. That keeps the post above ground, making no contact with the masonary (only the steel)...so it lasts longer in theory....but the sun will still cause damage if you don't treat it. Just expect 20-25 years max out of posts. If they last 30+, they'll likely be weathered and have cracks running down them. If they're long 4x4s, expect the to twist....long 6x6s, expect them to bow.

 

[Sukhoi]

My professional project creator (wife) keeps moaning about a pergola. If I want something that will last until North Korea does us in, would it be feasible to embed stainless steel threaded rod in concrete footers and then bolt the posts to the rods via some bracket? 5/8" dia rods 1' long are only about $7.50 for 18/8 and $15 for 316 on McMaster, so it really wouldn't be that much cost for something that lasts forever. Why do I never hear of pergolas being attached to threaded rods embedded in concrete?

 

[paperfist]

My professional project creator (wife) keeps moaning about a pergola. If I want something that will last until North Korea does us in, would it be feasible to embed stainless steel threaded rod in concrete footers and then bolt the posts to the rods via some bracket? 5/8" dia rods 1' long are only about $7.50 for 18/8 and $15 for 316 on McMaster, so it really wouldn't be that much cost for something that lasts forever. Why do I never hear of pergolas being attached to threaded rods embedded in concrete?

I personally don't like brackets, but you can use ancor bolts tied to rebar to secure them in concrete.

https://m.lowes.com/pl/Anchor-bolts-Bolts-Fasteners-Hardware/4294710930

 

[paperfist]

Eliminate rot? That's funny. YMMV when it comes to treated lumber. Honestly, 4" vs 6"....you go with thicker stuff if you don't want it to rot as quickly. Water typically doesn't go as deep underground as you think. It's more than likely going to rot just above ground than below.

Most of the time, they say to put a few inches of gravel in the bottom of the hole for drainage. The concrete base of 1" won't do anything but crack if it cures before you put the posts in....unless you mean to just put dry concrete in without water....it will harden eventually by soaking up water and when you pour mixed concrete on top, the moisture will help it cure with the green concrete above.

The way most contractors handle posts these days is to pour those tubular forms full of concrete to a particular depth/height above ground...and sink a steel post mount in it. Then you bolt your post to the mount. That keeps the post above ground, making no contact with the masonary (only the steel)...so it lasts longer in theory....but the sun will still cause damage if you don't treat it. Just expect 20-25 years max out of posts. If they last 30+, they'll likely be weathered and have cracks running down them. If they're long 4x4s, expect the to twist....long 6x6s, expect them to bow.

Me?

All the builders I talked to don't use Sono tubes anymore.

I don't like using brackets as it presents another point of rot and I like the stability of having 4' of 6x6 post under ground.

I mixed fast set concrete and poured a 24" x 12" thick (w/rebar) slab 5' down with a 6" crushed stone base. There's really no weight on it at this point as just the 6x6 is sitting on the slab.

 

[Greenman]

My professional project creator (wife) keeps moaning about a pergola. If I want something that will last until North Korea does us in, would it be feasible to embed stainless steel threaded rod in concrete footers and then bolt the posts to the rods via some bracket? 5/8" dia rods 1' long are only about $7.50 for 18/8 and $15 for 316 on McMaster, so it really wouldn't be that much cost for something that lasts forever. Why do I never hear of pergolas being attached to threaded rods embedded in concrete?

That would work, though most of the hardware you're going to find will galvanized. Simpson makes all sorts of post bases and hold downs.

 

[Sukhoi]

That would work, though most of the hardware you're going to find will galvanized. Simpson makes all sorts of post bases and hold downs.

Good call - I'll have to browse the Simpson catalog. Depending what brackets are available I might be stuck with using galvanized threaded rod since stainless and zinc are not friends on the galvanic table.