Concrete -In Swift Clamp Fence (FenceMate) Post Supports for a Pergola

pleuraXeraphim

Hi all,

I am about to start building a Pergola as a DIY project and it will be approx. 10 feet wide by 14 feet long.
I will use 6 100mmx100mm (2.4 metre lengths) treated fence posts to support the rafters.

I was planning to use Concrete-In Post Supports (FenceMates) (pics attached).

The question I have is:
Has any one used these, will they be fit for purpose and what's the best way to use them ?

They are 12 Inches long with 6 inches that go below ground and 6 inches to hold the Fence Post above ground. My concern is that that the 6 inches that go below ground may not be enough ?

Also one other point is that the Fence Posts I received are around 95mm and the Post Supports are 100mm. The Clamps will help but not as snug as would be preferred.

Maybe this approach will be fine but before I start it would be good to get assurances or advice

Thanks for any suggestions
Cheers, Dave

TheBoyConor

The concrete pad under should extend well below the bottom of the steel base. I'd say 450 sq by 500 deep.

pleuraXeraphim

So the they should work as long as I concrete wide enough and deep enough around and below the steel support ?

loyatemu

you can get versions with much longer spiked bases. designed for driving into the ground but I assume you could embed them in concrete as well

listermint

You'd usually want the base to be 1/4 to 1/3 the height of the above ground below ground so that's 600 to 800 mm. As these are a combined support you could probably bring that down a small bit but still looking at 450-600 minimum. Pergolas can catch the wind. Will there be cross bracing or paneled walls at all ?

pleuraXeraphim

If I sink the Post into the Concrete it will rot though right ? If I were to sink it 600 mm, is there any need then for the Support Steel ?
I was only using them to keep the base of the Post out of the ground.

I will brace the posts but the pergola wont be attached to a building. No panelled walls.

pleuraXeraphim

Pic of planned Pergola attached.

listermint

pleuraXeraphim wrote: »

If I sink the Post into the Concrete it will rot though right ? If I were to sink it 600 mm, is there any need then for the Support Steel ?
I was only using them to keep the base of the Post out of the ground.

I will brace the posts but the pergola wont be attached to a building. No panelled walls.

It will rot If there isn't drainage capabilities in the post hole and also of you don't have some form of slope away from the posts at ground level.

Basically pee gravel in the hole so post ends aren't sitting constantly in a puddle. And you don't want a puddle sitting around the post at ground level either

Small things but drastically extend the life

Fine Cheers

Those post supports should be fine once set in enough concrete.
The only issue is that once set, you don't have any wriggle room to tweak.
I learned this from a similar recent diy project.
It it was me I would go with the the flat plate type that you bolt into the concrete pad e.g.
https://www.securallfastenings.ie/product/4-x-4-fence-post-anchor-bolt-down-shoe/
I just think it would be easier installation.
I also had the issue with the 95 x 95 timber vs 100 x 100 plate.
I just shimmed as necessary with some old slate pieces.
Water will get in so drill a few weep holes if not there already and seal over the gap with a tape of some sort of timber quad maybe.
Shim under the posts too slightly to leave gap between bottom of timber and concrete / plate.
Treat all cut edges of timber.

pleuraXeraphim

Thanks for the advice everyone.

DIY KING - Thanks for your thoughts. Good advice on the drilling of water holes. Will definitely do that.

Time to start the Dig

Fine Cheers

Best of luck.
Have to say I enjoy The Restoration Couple on Youtube - here's one you might enjoy:
https://www.youtube.com/watch?v=IGeGou23roM