Invisible Support for Pergola Posts - Is this OK

[IJWS15]

SWMBO wants a pergola and I do not want to concrete the posts into holes (rot).

I do not like any of the "concrete in" fixings I have seen (unsightly).

What I am considering is a piece of threaded bar - as big as I can get it (cheaply) so around 12-14mm, set into the concrete (use nuts to stop it pulling out) and with a hole into the base of the post (vertical). Then with a hole through the post 6-8 inches from the end I can use a nut and plate on the threaded bar to take the weight, add the post and put plate and nut onto the top of the bar in the hole in the post to hold it down.

Allows me to keep the post off the ground and almost invisible fixings.

Posts are 100mm square. Posts will be on a paved area.

Any views?

 

[Deluks]

I considered this a few weeks back when planning a pergola on a block patio, location changed to the lawn area so I went with the standard concrete option.


Use thickest bar you can get M16 as a minimum, No need to have another hole part way up the post, use a nut and washer at the base of the post, the post sitting on the washer effectively. You will need 45 deg. bracing between posts and beams though.

but tbh, 4" posts will last for years anyway, and if you bolt the crossbeams to the posts, it will be simple enough to unbolt and change out the posts when they start to go. Which will be ages.

Only worth considering if you can't get long posts to go deep enough in the ground.

 

[Thermo]

just concrete them in, 100mm posts will last years and years

 

[IJWS15]

I don't believe the "years and years".

5 years ago I had to replace a6x4 post in the back fence. Had only been in 5 years!

 

[WabbitPoo]

For my own pergola I used the dreaded metpost spikes (!) but I actually concreted them in so that the posts are just above ground. They are normally rubbish but I had a load from somewhere - they are the bolt type, so could replace the posts later if required.

I agree though, a 4x4 should last flippin ages if done right to begin with.