Precast Concrete Foundations & columns

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Precast Concrete Foundations & columns

Postby udon74 » Mon Mar 14, 2011 11:11 am

Does anyone have any experience with precast concrete foundations? My builder plans to use precast concrete foundation footings, columns and slabs. They say the cost is considerably cheaper and takes less time. Also because they're factory made they're manufactured under ideal conditions.

I'm not sure whether to go with precast or the standard on-site concrete pour method. The pour method looks stronger to me because there are less joins.
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Re: Precast Concrete Foundations & columns

Postby geordie » Mon Mar 14, 2011 5:12 pm

got to be honest here if he is talking precast colums i do not see an issue with it the precast colums but a precast foundation is a new one so if you would like to post more info on that ?
normally on a single story build for speed you can use pre cast i had the foundation holes dug
and errected the colums using nylon rope as guide ropes we managed to get all the colums up quicker than you could errect shuttering for half of them the ground beams were cast around them and they were drilled with rebar fed through them so little chance of movement and saved a few weeks labour making shuttering and waiting for concrete to set
Also as an added bonus the finish on them is better
come back if you want more as a few people have used them
my comments may be wrong but never deliberately
If it aint broke, dont fix it
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Re: Precast Concrete Foundations & columns

Postby udon74 » Tue Mar 15, 2011 9:37 am

Thanks for the reply.

The precast footings look similar to this:

precast-footing.jpg (162 KiB) Viewed 2689 times

I haven't watched the building process so I can't give an accurate description however it's something like this. A hole is dug, the base is lined with reinforced concrete and the precast footing is placed on top, the hole is then backfilled leaving the top of the footing exposed. Precast foundations are then laid on top, ends are welded to the footing and finally the precast columns are welded to the foundations. The joints are then filled with concrete. I believe precast slabs are then laid to form the floor.
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Re: Precast Concrete Foundations & columns

Postby glennb6 » Sat Apr 30, 2011 6:03 am

I recently had the need to construct the frame of a larger work shed. Used precast columns which were prepared in 7 days. Holes were dug aprox 70cm deep and aprox 1m x 1m square. Concrete base 10cm poured in each, sat for 1 day. Poles "set" on the base and straightened using an M150 bottle on a fishing line hung from tops of each, and temporarily held using 2 eucalyptus trees and stakes. Then aprox 20cm of concrete was poured into the holes.
I told the guys they should fill the holes with concrete. They said "no, thai never do, just fill with dirt"... The look on their faces really was saying that they didn't want to hand-mix and hand tote 4x the concrete. Two days later I had epoxied a few 10cm cut rebar pieces vertical into the cement bases and had our "family worker" proceed to mix and fill all the holes up to desired level.
Not that I've ever seen a house fall over because the poles became wobbly, but I was paying so that's the way it was.
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Re: Precast Concrete Foundations & columns

Postby SKR » Thu Nov 29, 2012 5:55 pm

Hi Glennb6

I have designed a house in insitu concrete and wonder whether there is a precast concrete supplier who could produce drawings and calculations to convert the structure into precast. Or do you perhaps know a contractor who could do this and possible the whole house. The house is very modular, so a precast concrete structure would make sense and presumably be cheaper and faster to build. The plot of land is in Hua Hin.

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Re: Precast Concrete Foundations & columns

Postby thailazer » Fri Nov 30, 2012 9:13 am

Regarding the original post, pre cast items may or not be manufactured properly. Before you commit to a whole project, buy a few items and take a hammer to them. We used a company at first for some concrete rings and one broke being delivered. The rest were like powder. Proper concrete mixing on site will always be better than anything you get from the local supply yard at least in my experience.
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Re: Precast Concrete Foundations & columns

Postby gliffaes » Mon Apr 29, 2013 4:22 am

I plan to use them shortly for a storage shed bike shelter but with in filled walls. Lightweight roof
Is it normal to dig the hole say about -60cm deep then pour in a layer of concrete with a bit of rebar on or how about I have a roll of 6mm road mesh (not the thin stuff) to use to make a cage, when its set drop in the column on top , level up then pour more concrete over it?
Also as mentioned above add a bit of rebar drilled and glued into the base pad.
Then no beams? just a reinforced slab I can lay the blocks onto or must I have beams also, single block about 2.4 m high.
Bearing in mind im on rock not rice paddy
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