Support posts for decking

[Deanobello]

Hi all,

I have started digging my holes for the support post for my raised deck, I have dug them 700mm deep and 200mm wide, I am going to use 100x100 posts.

Are the 200mm holes wide enough and what is the bext product to concrete them in?

Thanks in advance for your answers

 

[Alarm]

Easiest, postcrete http://www.wickes.co.uk/postcrete/invt/221100/

Dig hole, put in post add postcrete making post vertical, add water done.

 

[imamartian]

i'm a diyer not a pro - IMO your depth is plenty, but your 200mm width for a 100mm post is inadequate. That gives 50mm (or 2inches) either side of the post. I'd say you'd need at least 100mm either side of the post, so a hole of 300mm width.... admittedly, this is not a fence post, but better to be safe than sorry?

 

[ladylola]

Do you even need to concrete the posts in anyway? I feel that this idea that posts should be concreted has become something that is just done out of habit and on decking really isn't necessary.
In my garden I have an arbour and a trellised fence for vines that is held in the ground by nothing more than rammed hardcore, bricks and sand and they don't move.

 

[imamartian]

but as with everything, take it to extremes.... you invite your rugby club mates round for a BBQ, you'll have 20 x 20 stone blokes sat on your decking eating burgers and hot dogs.... fairly sunstantial post footings required !

 

[Alarm]

What is the spacing of the posts?
How high out of the ground will they be?

 

[FDJ]

If a raised deck is more than 300mm above ground, it requires planning permission.
(Well it does according to my local planning office)

For raised deck supports, I would set the posts on 100mm thick concrete pads at the bottom of your holes, then fill up with hardcore. Once connected to the full structure, they won't move.

Frank

 

[Richard C]

If a raised deck is more than 300mm above ground, it requires planning permission.
(Well it does according to my local planning office)

Your correct, it does.

 

[ladylola]

invite your rugby club mates round for a BBQ, you'll have 20 x 20 stone blokes sat on your decking eating burgers and hot dogs.... !

Ooooh martian I do so envy your social circles,

 

[Deanobello]

Thanks Alarm, postcrete sounds great (is it that simple to use?), the posts are 1500mm apart, 700mm deep. I hope this is ok?

I'm in the proscess of planning permission but wanted to get the project started by digging the holes thanks for the advice FDJ

 

[Deanobello]

Do you even need to concrete the posts in anyway? I feel that this idea that posts should be concreted has become something that is just done out of habit and on decking really isn't necessary.
In my garden I have an arbour and a trellised fence for vines that is held in the ground by nothing more than rammed hardcore, bricks and sand and they don't move.

I have seen a video clip showing filling the holes with hardcore/gravel but wasn't sure if that would be ok.

 

[imamartian]

Do you even need to concrete the posts in anyway? I feel that this idea that posts should be concreted has become something that is just done out of habit and on decking really isn't necessary.
In my garden I have an arbour and a trellised fence for vines that is held in the ground by nothing more than rammed hardcore, bricks and sand and they don't move.

I have seen a video clip showing filling the holes with hardcore/gravel but wasn't sure if that would be ok.

in my opinion, that's a bit like saying "oh i'll be alright with third party insurance", or "i don't need to wear a cycle helmet".... and you're probably right 99 times out of a hundred.. but for a little extra effort to get a whole lot more assurance... i think it's worth it.

 

[ABCwarrior]

Suppose a lot depends on soil type and how this may rot the posts long term. Our ground is freely drained gravel/till and I reckon concrete wouldn't be necessary either. Dig it out to say 450mm, put a bit of broken slab in the bottom and put the post on this, backfilling it while keeping an eye on plumb and tamping it well. You'd be surprised what grip it gets and this at least allows the water to drain around the post.
300mm is the legal max eh? Is that just E&W or UK whole? Our front "micro patio" is 1m x 3m, and it's 500mm above ground level. The threshold through the patio is 90mm high so if some poor disabled person wanted to get outside alone they'd have to bump over this and hope they could stop in a metre....
BTW when we bought the house there was not even a step up to this from ground level- surely that couldn't have passed building controls signing off procedure!?

 

[Deanobello]

Fair point, I'll make the holes bigger. Better to be safe than sorry.