Wood forms for concrete deck suports?

[lee171181]

Hi,

Has anyone got any idea of something I could use to help build a concrete support for decking posts?

I have dug some holes for the supports which I now need to full with concrete. The problem is the holes are much too large at the top so I need something to go in the hole that I can fill in with concrete to build the support, maybe 8-10" across?

If not, what about some kind of wood forms that I could make but I'm not sure of the best way to do this or what wood to use?

Thanks

 

[big-all]

shuttering ply is cheap and cheerful or osb /sterling board

 

[lee171181]

...& be made in to the form how? Just by nailing some smaller wood into a square/cube and then fixing the ply around the outside?

 

[skotl]

Sounds like a plan. Make it outside the hole (obviously) and ensure that the form fits the posts well, batten it together.

Then make a larger hole, put the forms in and (continuing to check that the forms remain vertical in both axes) fill the hole around them.

 

[lee171181]

Presume this will still work if filling inside the form so as to create a pillar as that's what I need to do?

 

[r896neo]

DSo you mean your holes are too Wide at the top and you don;t want to waste concrete filling them and want to reduce the concrete needed by using shuttering?

 

[lee171181]

Yes that's correct, the hole is the right size at the bottom but the top is massive where a lot of the loose earth has gone etc & this will take a lot of concrete to fill in so I need to make something that I can fill in with concrete and then back fill the top of the area afterwards with earth etc

 

[r896neo]

thats less than ideal to be honest. You'd be better making lean mix concrete up and filling with that.

Are these going to have masonary built on top to support a raised frame?

 

[lee171181]

They will be supporting a raised deck platform and will have met posts concreted into the top to hold the posts. I want the base to be as strong as possible so if that idea won't work then may have to have a rethink

 

[r896neo]

Having a tall thin bit of concrete, which is essentially what a post hole is, is fine but if its not restrained on all sides by original earth then it may have a tendancy to tilt or shift laterally once loaded. In reality a raised deck will provide almost no lateral force once all bolted together. as there are many posts.

Setting your posts into concrete would be the norm.

If you concerned about them rotting use concrete posts or concrete repair spurs (google it if your not familiar) and the bolt your timber post to that.

 

[freddiemercurystwin]

Concrete foundations work by forming concrete next to undisturbed earth. Forming a shutter around and then backfilling is inappropriate, as mentioned fill them up completely.