New offer for floor slab

Hello,

we have now received our second offer for our floor slab. Here there is an additional price of €11,000 (the soil survey was included here). According to the contract, we signed an offer of €16,500 for the floor slab. Now enormous additional costs are coming our way. How can I have these costs checked? The floor slab company works hand in hand with the prefab house supplier. So I have no way to get other offers here, otherwise the warranty for the house construction would no longer be valid.

I'll bet on the most typical of all mistakes.

Soil report before signing the contract!? I don't need that, it's in the offer from the construction company that is building the house. And the slab costs €16,500...

I bet it says something like: "assuming the following soil values..." and "level".

Now a report was made before the start of construction. Apparently, the values came out that are far from the assumptions of the construction company. This makes the matter almost twice as expensive.

A construction company always assumes in the offer "no groundwater", "bone dry" and "level". Anything that deviates from that can only become more expensive.

One can only keep saying: Get a soil report before signing, even if it costs €1,000, and have the contract professionally reviewed. Also get external construction supervision during the construction period. It does cost money, but it's money that you shouldn't save in today's environment of "botched jobs and being taken for a ride".