Additional positions in house construction: are they useful and reasonably priced?

Good evening,

we have an offer from a general contractor and are wondering whether the following additional items are reasonably priced and make sense:

1. Compensation for fittings and sanitary objects if procured by the client (warranty is only valid up to the raw installation interface; concealed installations remain our responsibility):
Compensation WC ground floor: hand washbasin including fitting, WC including actuation (flush tank remains our responsibility)
Compensation bathroom attic floor: 1 washbasin including fitting, WC including actuation (flush tank remains the responsibility of Bösteinhaus), shower fitting and shower set including rail (connections remain our responsibility)
Compensation: €2,420.00
These sanitary objects would include: brand Vigour series “Derby” or “Derby Style”, alternatively brand Geberit series “Renova Plan” or brand Villeroy & Boch series “O.Novo”, fittings: brand Vigour series “Derby”, alternatively brand Hansgrohe “Talis S” or brand Hansa series “Hansapinto”

2. For double-leaf windows omission of fixed central mullions,
instead installation of special mullion profiles
Additional cost 3 windows x €160.00 = €480.00

3. Installation of a secondary entrance door as a wooden door to the utility room offset against the omitted window, including security fittings and insulation like the front door, with closed door leaf, including locking system matching the front door
Additional cost: €2,020.00

4. Installation of a roof window in the hallway attic floor, approx. 78 x 118 cm according to the Energy Saving Ordinance, brand Velux type GGU MK 06 Thermo (pivot window)
Additional cost: €1,360.00

5. Supply and installation of rough plank flooring in 24mm thickness made of Nordic spruce or fir, dried, laid staggered and screwed to ceiling beams or collar beams
Additional cost: €1,840.00

6. Concrete staircase white plastered with beech steps and risers as white Forex plates (washable), with railing parapet according to building specification and steel handrail or alternatively masonry parapet with internal handrail, with storage room with door under the stairs including light outlet and socket
Additional cost compared to standard staircase: €4,800.00
This staircase would be “standard”: elegantly shaped, open staircase with solid beech wood steps in finger-jointed panels, continuous railing in modern round tube

7. Installation of an additional shower in the guest WC as a barrier-free, tiled design approx. 90 x 150 cm with installation of 1 floor drain and necessary large-area waterproof sealing, wall masonry up to 2.10 m height according to drawing, shower area tiled up to 2.10 m height; shower fitting and shower set including rail supplied by client
Note: a shower enclosure must be provided on site
Additional cost: €1,990.00

8. Creation of a tiled niche in the shower in the WC ground floor, approx. 30 x 60 cm
Additional cost: €340.00

9. Creation of a masonry and tiled shelf behind the washbasin in the WC ground floor, height 1.20 m, approx. 0.8 running meters
Additional cost: €200.00

10. Installation of an additional cold water connection in the WC ground floor next to the toilet (for later client installation of bidet shower)
Additional cost: €290.00

11. Creation of a tiled shelf next to the bathtub according to drawing, height approx. 50-60 cm
Additional cost: €190.00

12. Installation of a laundry chute from the bathroom upper floor to the utility room (ground floor), 300 mm spiral seam pipe with laundry bag and secured throw-in flap
Additional cost: €1,160.00 (alternative: laundry chute provided by client, our scope only ceiling breakthrough 350 x 350 mm additional cost: €180.00)

13. Installation of all switch boxes in a deep construction form for retrofitting of Smart-Home based on radio by client
Additional cost: €560.00

14. Installation of AEROPAC SN (company Siegenia AUBI) demand-controlled ventilators. Draft-free and whisper-quiet operation, individual air regulation, dust filter function, including core drilling and socket
Additional cost: number of bedrooms 4 x €1,100.00 each = €4,400.00

What do you think?
Are there items that are overpriced?
What would you include and what not? (I know some things are very individual. For those, it’s more about whether the additional cost is okay.)
Are there individual things I should initially leave out to commission them later with the respective trade?

We would be grateful for any advice.

Best regards

Reads like average prices. Decision based on mood, whim, and wallet.

Just a note on 14.
Are you planning a house WITHOUT a ventilation system? I wouldn't consider anything over 14 (except for renovation), but rather a central system.

When I compare this with the pricing policy of my general contractor, it sounds plausible, yes. Although, for example, the drywall installer told me... if I had ordered the recessed shelf in the shower and by the bathtub directly through him, i.e. verbally on the construction site, it would have cost me 50 EUR. Via the site manager or general contractor it will probably cost 150-200 EUR, I haven't received the additional invoice yet.

The only thing I find cheeky is the 560 EUR for installing deep electrical boxes. I assume they mean 68mm deep boxes? My electrician installed those everywhere anyway, at no extra cost. That's standard nowadays because no one uses extra junction boxes anymore.

How many square meters of rough-sawn boards do you get for that money?

Sounds like average prices. Decision depends on mood, desire, and wallet.

Just a note on 14.
Are you planning a house WITHOUT a ventilation system? I wouldn't consider number 14 (except in renovations), but rather a central system.

yes, a central ventilation system is supposed to cost €17,300. that's simply too expensive for us... we'd rather ventilate more often

yes, the central ventilation system is supposed to cost €17,300. that's simply too expensive for us... we'd rather ventilate more often

And you believe heating more for 40 years in the end is cheaper than a central ventilation system with heat recovery?

When I compare this with the pricing policy of my general contractor, it sounds plausible, yes. Although, for example, the drywall installer told me... if I had ordered the recessed shelf in the shower and at the bathtub directly through him, i.e. verbally on the construction site, it would have cost me 50 EUR. Through the site manager or general contractor, it will probably cost 150-200 EUR, I don't have the change order yet. The only thing I find cheeky is the 560 EUR for installing deep boxes. I assume this refers to 68mm deep boxes? My electrician installed those everywhere anyway, without extra charge. It's standard nowadays because no one works with extra junction boxes anymore. How many m² of rough planking do you get for that money?

The thing with the drywall installer is a good point, can someone else confirm this price-wise? For us, possibly a recessed mirror cabinet instead of the shelf is an option. Does that cost about the same? Yes.. I assume that the 68mm boxes are meant. Should I possibly remove it again? It should be about 64m2 of rough planking.