The REAL cost of concrete first floor?

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pudzer

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Hi!

We have just started our selfbuild and had budgeted €10,000 toward the cost of putting concrete first floors. however, I would like to hear from anyone that knows anything about the additional costs that I need to factor in e.g. putting in a 9" on the flat wall inside to support the concrete upstairs and putting in a 17" external perimeter wall (4" block, 4" cavity, 9" on the flat block) to support it also?

My pocket is feeling that it's much more expensive than I first budgeted for?

Also, should the precast concrete company or my engineer certify what walls should be what size? My engineer says it should be the concrete company as he doesn't know anything about their slabs.
 
Take your engineers advice, Talk to the company suppling your slabs. I gave my plans to the supplier and they told what orientation I should put my inner leaf and spine wall.
In my case the inner leaf is 4" as normal and the spine wall is a 4" block on the flat to support 2 slabs. You will also need RSJs in places where you have openings on the bearing walls.
Slabs are cheap you shouldn't be paying anything ner 10K my estimate would be about 6K and thats including the RSJs
 
In our case (~1,200 square feet of floor), the cost comes to around €9,000
Breaks down as:
Slabs ~€5,000
Concrete pump ~€400
Core drilling (For Water + electric) ~€400
Labour ~€1,000
Suspended ceiling ~€2,000

We needed a 9" (4" blocks on the side) internal supporting wall for the slabs to sit on (don't know what the additional cost of that is). The inner leaf of the external wall was a standard 4" block.
The steelwork was ~€1,700 but some of the steel lintels would have been needed regardless of the type of floor.
I don't know what the costs were for insulation (UFH upstairs), concrete and reinforcing steel in the floor.

We received recommendations from our builder, the slab company, and the engineer. In the end, I believe your engineer will have to certify that the structure is sound and it will be on his or her indemnity insurance and reputation if not.
 
There are loads of manufacturers out there who only require 4" bearing on external walls, so there is no need for a 9" inner leaf. The only location internally that 9" walls are required is where two slabs meet internally. In my experience the manufactirers design the slabs in such a manner as to requir as little 9" internal walls as possible.

Its my opinion that the 'real cost' of incorporating concrete floor slabs is hugely outweighed by the 'real benefit' of a solid first floor, soundproofing, fire protection and structural stability.
 
Precast floor & stairs for a 3100 dormer set me back about 8.5k. Think it was a surface area of 185sq metres first floor. This included a crane to come out and lay it down. Also other costs were insulation (40mm foil insulation) we had underfloor heating - pouring in a screed on top of this.

The labour of the screed bit was i think around the 1500 figure, this included the screed pump. believe the thickness of concrete was 55-60mm.

insulation - i forget how much i paid for this, layed it down myself.

Hope this helps
Kildare Build

pudzer said:
Hi!

We have just started our selfbuild and had budgeted €10,000 toward the cost of putting concrete first floors. however, I would like to hear from anyone that knows anything about the additional costs that I need to factor in e.g. putting in a 9" on the flat wall inside to support the concrete upstairs and putting in a 17" external perimeter wall (4" block, 4" cavity, 9" on the flat block) to support it also?

My pocket is feeling that it's much more expensive than I first budgeted for?

Also, should the precast concrete company or my engineer certify what walls should be what size? My engineer says it should be the concrete company as he doesn't know anything about their slabs.
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