Corner deck with posts 2.5m tall to hang lights

[DIYpessimist]

Hi all

In the corner of my garden I'm planning to build a ground level deck (it will be raised slightly off the ground but the top of the deck will be 30cm or less from the ground).

I want to have some festoon lights around the area and was thinking how best to hang them around the decking area.

My current thinking is to use the posts that will form the deck supports, and extend these upwards, 2.5m above ground level, and hang the lights over these. I'll only make 3 posts this tall.

So it's not a pergola or gazebo, it's just a deck with 3 corners having the support posts raise up.

Firstly, are there any planning permission issues here? It's not a building. The deck level is no more than 30cm above ground. Could a neighbour object?

Secondly, if the posts are going to be 2.5m above ground, bearing in mind they're also supporting the deck, how deep below ground should they go and what thickness should they be?

Was thinking I'd need to go 70cm below ground and use 10x10cm posts if I can find them long enough!

Any thoughts on this? Any better ways to suspend the lights? Are there any poles that could attach to the deck posts instead? We have lots of strong wind here so need a robust solution.

Thanks for your thoughts.

 

[JohnD]

Wooden posts are best not buried in the ground, as they will rot.

Instead, pour a concrete pad for each support. 1 ft deep, 1ft square, and rising out of the ground by 6 inches (wooden formwork placed in the top before pouring will make it look neat) and use steel post supports, either cast in place or bolted down. Pic below shows example in corner Somebody will complain that they are clumsily done. I got better with practice

Paint the steel thoroughly before placing. I have a example one I dug out that rusted away like tissue paper.

Decking posts are not subject to wind forces trying to blow them over, like fenceposts. The forces are almost entirely weight, downward, and the deck holds them rigid.

 

[DIYpessimist]

Thanks for the quick reply, JohnD.

I should have mentioned, the post will be treated - and when planning to put it below ground, I will first dig out a hole, drop some gravel or bricks at the bottom, pour on 6 inches of concrete (let it go off) and rest the post on this until I get it straight and in the exact position for the deck frame. Once in the correct position for all of the corner posts and attached to the frame, I will then fill the hole around the post with concrete. Before inserting the post, I will also paint it with a bitumen-based paint just up to the ground level. So whilst it will be subject to rot more than something attached above ground, it will be reasonably well protected I think.

I can see securing it above ground like in your example would provide superior protection from rot due to less contact with water in the ground or splash back, but if the post goes up 2.5m above ground as planned, and is only supported by a steel post support at the bottom, and is only attached to the deck joist (2x6 or maybe 2x8 not sure yet), I don't think the tall post will be very secure. But I do take your point about the wind having little impact on it, which is good to know.

With my plan to bury some of it, do you have any thoughts on how deep (70cm? less/more) or how thick the post should be (10x10cm, thicker?)? Are you aware of any issues with planning permission that might arise? Any alternative thoughts on how to hang the lights? The posts seem a bit like overkill to me. I'm still levelling the ground so trying to settle on a final design in my head. Thoughts are appreciated.

 

[JohnD]

I should have mentioned, the post will be treated -

It will still rot.

And all the digging and concreting you did will make it a terrible job to get out.

Another method is to put a concrete spur in the ground, and bolt the wooden post to it (also example in my pic).

People who have had to replace rotten posts set in concrete take great care to avoid doing it again.

You will bolt it to the frame of your decking which will hold it upright.

 

[DIYpessimist]

I'm warming to this idea. So long as I can still keep the deck lower than 30cm with this approach. And I'll need to level up my string line skills, I think, as setting the support in concrete before connecting the joists means they'll need to be spot on, to keep everything square but also at the right height. My original approach gave me loads of wiggle room for lateral and vertical adjustments before committing. This is a big point for me to consider.

And I'm thinking of moving away from having the posts extend up above the deck. My new thinking is to use planters on each of the corners, and cement a pole Into each, and use the poles for hanging the wires.

 

[scbk]

I'm not saying it's something you'd like the look of or not, but scaffold poles buried a couple feet in the ground would be totally fine for hanging some festoon lights off. You don't even need concrete, rammed earth or stone for backfill.

 

[DIYpessimist]

I'm not saying it's something you'd like the look of or not, but scaffold poles buried a couple feet in the ground would be totally fine for hanging some festoon lights off. You don't even need concrete, rammed earth or stone for backfill.

I hadn't considered scaffold poles. Not a bad idea. For the last set, I used a large metal washing line post which is basically the same thing, so why not Cheers