casting concrete pillars for a pergola

[Hazelb]

I'd like to try to cast some concrete pillars ( round columns) for a garden pergola. They won't need to take much weight, just some wooden crossmembers.
Can it be done?
What could I use as a mould- ( length of soil pipe?)
Would it need reinforcing?
Would it work?

 

[Thermo]

yes, maybe, give it a try.
you could use soil pipe, but youd need to be able to split it down after, with plenty of mould oil on it. you also need to be able to tamp or vibrate it as you fill it, so pour in a small amount and give it a good poke with a long batten, pour in a bit more, another etc etc. You would need some rebar down the middle but it should take the weight. A fine conrete mix would give a better finish.
would be a bit of trial and error to get the finish you want, but i dont see why not

 

[Hazelb]

I'd use a sharp sand mix for the concrete. Where would I get 'mould oil' from and would I be able to get just a few 8ft lengths of rebar? ( where from?)

 

[Thermo]

most builders merchants sell lengths of it that they will cut to length. You can also get mould oil from them, failing that you can use vegetable oil, its only to help the mould come away from the concrete. I think you might be better of, sawing down the pipe in two before pouring and then clamping it together with some jubilee bands as it will be easier to get off afterwards

 

[breezer]

just a thought, as you will be using soil pipe, it is going to take a very very long time to dry out. I would suggest you "open your pipe" after a few days to let it thoughrly dry out

 

[mcdermottc]

Hi

I am soon to embark on a pergola project and was going to concrete posts into the ground however after reading how the posts would rot I am thinking of making the same concrete pillars and bolting the posts to the top of them using something like these

pic 5

• mcdermottc
• 7 May 2013
• 2

pic 5 bolt down anchors

pic 4

• mcdermottc
• 7 May 2013
• 3

pic 4 concrete pillars

my question is if I was create the pillars using a length of soil pipe why is it necessary to take the mould away afterwards - couldn't I just leave the soil pipe mould on the pillar in the ground ? I assume it has something to do with moisture getting in but would appreciate any advice

thanks

chris

 

[freddiemercurystwin]

Why would you want to insert a pipe into the ground and then fill it with concrete? Just fill in the hole.

 

[mcdermottc]

To be honest im.not sure why but it seems to be what lots of people are suggesting. Maybe it creates a clean concrete column instead of a big lump of concrete ?

 

[freddiemercurystwin]

it seems to be what lots of people are suggesting

They're wrong. foundations work by the concrete being in direct contact with undisturbed earth and the connection. Dig your holes and fill 'em with concrete.

 

[mcdermottc]

freddy can you also then just stick the posts in the concrete or are you best to fill the hole with concrete and then bolt your posts to the concrete using something like the below. lots of people suggested the posts will rot if in thr ground in concrete

pic 4

• mcdermottc
• 7 May 2013
• 3

pic 4 concrete pillars

it seems to be what lots of people are suggesting

They're wrong. foundations work by the concrete being in direct contact with undisturbed earth and the connection. Dig your holes and fill 'em with concrete.

pic 4

• mcdermottc
• 7 May 2013
• 3

pic 4 concrete pillars

 

[freddiemercurystwin]

Eventually timber posts embedded in concrete will rot. How long do you want your pergola to last? If treated they will give you 10-15 years. They are not subjected to the same kinds of wind loads that fence posts are subjected to, which tend to snap.

But mounting your posts on metal shoes such as the ones in this thread sat above ground level on concrete founds would be preferable.

 

[mcdermottc]

Thanks freddy I will go with concrete in the ground and then bolt post feet to it to keep posts above the ground. I plan on having a deck underneath the pergola do you think I could bolt the pergola leg to the cement using the post feet and then use the pergola leg as part of the deck frame. Would the post foot be strong enough to hold the pergola and deck in place or would seperate post feet be advisable for the pergola leg and deck frame post

Thanks

 

[freddiemercurystwin]

Your deck will be fine supported off the pergola legs.

 

[mcdermottc]

thanks freddy that will make things easier because I can...

dig holes
pour concrete
bolt the feet to the concrete
attach the pergola legs to the bolt down feet
create and screw the deck frame to the pergola legs to raise the deck off the ground.

thanks for your advice