How to secure a garden pergola against very powerful winds?

[David001]

An old wooden seat with a wooden pergola above it (covered with clematis) has over the last 12 years rotted and has also been shunted forwards by gale-force winds, and perhaps by some earth movement, so I have removed the old wooden structure and bought a metal replacement (for just £70 in a sale at Wayfair).

 

Although strong winds will largely blow through the metal-work unobstructed, once the structure is dressed with clematis there will still be some degree of vulnerability in the face of winds.  The vulnerability will be mainly due to the pergola's height being 2 metres and only 1 metre from side to side.

 

So my concern now is how to secure the four feet of the seat so that future gale-force winds striking the pergola from behind will not drive it forwards. 

 

Also, the position where the pergola is to sit is a small flat area of about 2m x 1.5m, behind which the earth rises up a hillside, and in front of which the hillside falls, meaning that it is possible that over time there may be downward, gravity-led, earth movement.  This movement may explain the crack which appeared recently in the thick stone directly in front of the position where the wooden pergola sat.

 

At the end of each leg is a small round horizontal plate, with 3 holes for insertion of the 4" nails which have been supplied.

 

I thought of embedding the feet but it would be best not to lose any of the height of the 4 legs, otherwise the seat will become lower, in relation to the ground.

 

Once the pergola has been secured, I will move the two planters of clematis close to each side and thread the plants through the metalwork.

 

So, how should I go about securing this pergola so that it is stable and level, and so that it is not pushed forwards either by wind or slight earth movement?  What steps should I take?

 

Thank you.

 

David.

 

 

Below: the pergola with the two planters of clematis which will sit close to each of its two sides.

 

 

 

Below: a top-down view.

 

 

 

Below: a crack in the thick stone in front of the seat, possibly suggesting earth movement.

 

 

 

Below: one of the four feet of the structure.

 

 

 

Below: 4-inch nails have been supplied to fasten the four feet.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

[Mr Punter]

Some tent pegs driven at an angle

[JohnMo]

I would be tempted to dig 4 holes (space width square and deep) get some threaded bar, chemical anchor, and postcrete. Fill holes with postcrete and level. Drill holes for flanges. Chemical anchor threaded bar in place. Tighten nuts - it's going nowhere in a hurry.

[Jenki]

15 hours ago, JohnMo said:

I would be tempted to dig 4 holes (space width square and deep) get some threaded bar, chemical anchor, and postcrete. Fill holes with postcrete and level. Drill holes for flanges. Chemical anchor threaded bar in place. Tighten nuts - it's going nowhere in a hurry.

+1 Do this^^^^^^^.. Before living in the Highlands, I would have read this response and thought that's a bit overkill. I read this now and feel the earned experience of Highland living flowing through the advice.🤣

Edited Saturday at 07:02 by Jenki

[saveasteading]

Tent pegs is plenty.but so should be the nails, on angles. 

Plants will catch the wind bug also anchor it.

[Conor]

I'd pave under the area to meet the stone and just fix the pergola to the paving slabs with short concrete screws.