Rent for construction dryer in final invoice/builder - legal?

Dear house building specialists!

After an eternity of waiting, we have finally received the final invoice from our builder. What is very annoying is that it is 35% higher than the amount the site manager gave us two months earlier, with the note that "it will at most vary by EUR 1,000 up or down." For us, this amount was decisive for scheduling the exterior work.

Now there are some discrepancies where I would like to ask you for advice:

1. The builder is charging us heating-up costs, which is also regulated in the construction and service description (clause: "All costs incurred for the installation, operation, and drying heating during the construction period. This applies to all heating systems, including electrically powered heating systems such as heat pumps and direct electric heating devices").

We understand that we have to pay the pure consumption costs (EUR 418.080). However, the rental costs for the heating device amount to EUR 700 net. We assume that the heating device belongs to the company itself but cannot say this with 100% certainty. Now the question arises whether we also have to pay these rental costs.

2. Furthermore, the builder installed a hot water circulation system even though we said we did not want this, and is now charging EUR 600 net for it. How should we proceed here and can it be simply removed again?

3. How can/may I offset un-tiled areas (only material or also labor?)

Thank you in advance!

Best regards Sony

With tiles, it is like this with us: credit only for material, instead of the tiler the plasterer has more work. At least with wall tiles in the bathroom.

The ww circulation is mandatory to prevent legionella and especially for heat pumps and long pipes.

Regarding the dryer, I would address this sentence directly with him and ask how he now comes to charge for this.

The ww circulation is mandatory to prevent legionella and especially for heat pumps and long pipes.

Regarding the dryer, I would address him directly about this issue and ask how he now intends to charge for it.

On the subject of obligation, we would have liked to have circulation, but unfortunately were not allowed because of KfW40+, according to KfW it is apparently more ecological to run water liter by liter rather than use circulation..... nevertheless, we still have one.

I don't have the explanation on hand right now, but it is repeatedly described in the Lila forum; circulation increases the chance of Legionella. In terms of costs, it is more expensive during operation, mainly due to the heat loss of the constantly circulating water.

It is usually like with such things: with good planning (routes and cross-section) of the pipes, it is not necessary in a typical single-family house, and it is more expensive to operate than without. From a certain size and long pipe lengths, it then becomes more important from a comfort perspective, after all, who wants to wait forever for warm water

1. All costs incurred for the installation, operation, and dry heating during the construction period.

this can be endlessly debated: does the equipment rental belong to it or not?

Try the argument: according to the construction service description, earthworks are definitely extra costs (comparable to heating costs), but you were also not separately charged afterwards for excavator rental or shovel and wheelbarrow rental.

and: demand to see the alleged €700 invoice and then criticize that, for example, the delivery date does not match the start of heating (heating protocol), making the invoice invalid.

2. although we said that we do not want these

you don't have to pay for anything essential without a written order. This does not apply to small parts, consumables, and auxiliary materials, but a circulation system is a clearly defined additional equipment that cannot simply be installed without an order. BUT: if, for example, the heating system comes with a circulation pump and corresponding connections and these are needed for smooth operation, then the argument becomes difficult.

3. offsetting un-tiled areas

unfortunately, this will probably only result in - material only -