Anchoring pergola posts in 1x1m concrete slabs

[KJD]

trying to understand what's required to secure a couple of pergola posts to the ground slabs I've cast myself, 50-55mm coarse concrete. The roof/posts unfortunately need to be as high as 320 cm because we also want sun shading for the bedrooms above (the basement below creates the height).
I've looked at different attachments but feel unsure if they can withstand all the stresses, and I'm allergic to any wobbly construction. Feel free to convince me otherwise .

I've started leaning towards cutting out holes in the slabs to be able to dig down pillars, but it bothers me a bit to have to do this after getting the slabs in place.

Anyone with experience in this?

 

[roli]

That slab is too thin for you to attach any posts to it. Are your slabs reinforced? If not, they will likely crack if you place a point load in the middle of it, like a post would be.

 

[AXS]

Hole saw, dig, cast. Good luck!

 

[KJD]

Holesaw, dig, cast.
Good luck!

They are reinforced, otherwise, they would probably look like

That slab is too thin for you to be able to attach any posts to it. Are your slabs reinforced? If not, they will likely crack if you place a point load on them, like a post would be.

Good, that confirms what I thought. They are reinforced, I've cast 30 of them, so I know what happens if they even have poor reinforcement.

 

[KJD]

Hole saw, dig, cast.
Good luck!

Good! I actually have a hole saw with dismantling cuts, never thought about that. What size hole do I need for these enormous posts then? (90x90mm x 320cm).

I was thinking angle grinder with concrete cut and a 20x20 hole to lower a ready-made plinth. Is that overkill?

 

[KJD]

Good! I actually have a holesaw with dismantling cut, never thought about it. What size hole do I need for these enormous posts then?? (90x90mm x 320cm).

I was thinking of using an angle grinder with concrete cut and 20x20 hole to lower a pre-made anchor. Is that overkill?

Would need a heck of a holesaw - or several drill holes - if you want to dig as well. And maybe something like this h-anchor? The question is whether a pre-made anchor is preferable.

 

[KJD]

Would need a heck of a hole saw - or several drill holes - if you're going to reach and dig as well. And maybe one of these h-anchors?
The question is whether a prefab foundation is preferable.

Recently made a foundation in the carport, it might be more clean and better concrete quality than what you can achieve yourself... if you also go for types of foundations with better quality.

 

[AXS]

Depending on what the material is, it might be possible to vacuum it up with a vacuum cleaner + cyclone.

More than 10cm, I would probably have chosen 12 or 15 cm myself. Raising the concrete above the slab is probably not wrong; you can also make the part above the plinth wider if you want for aesthetic reasons.

 

[KJD]

What is "Cyklon"?

 

[KJD]

Anyone know how "diamond"/concrete blades handle the reinforcement?

 

[z_bumbi]

A cyclone is a separation device that you attach before the vacuum cleaner to prevent debris from entering the vacuum cleaner.

Now I don't know if there's anything special about the tiles but if you lift one up, cast a substantial plinth underneath and put the tile back, you can drill holes for the mounting.

 

[KJD]

Cyclone is a separation device that you place before the vacuum cleaner so that debris doesn't end up in the vacuum cleaner.

Now, I don't know if there's anything special about the tiles, but if you lift one up, cast a solid footing underneath, and put the tile back, you can drill holes for the fasteners.

got some traction … bought a coring drill for the concrete drill + a concrete blade for the angle grinder to smooth the edges. Dug half the hole but that's almost the hardest part. Cyclone seems fancy, but what's there works passably.

 

[KJD]

There we go