ᐅ Costs for Shell Construction and Roof Covering/Insulation – Is a Fixed-Price Quote Acceptable?

I am trying to assess whether the price offered to me for building a house is reasonable.
Model: An architect builds houses at a fixed price through his company. He purchases a plot of land, demolishes the existing buildings, and constructs two semi-detached houses on it. I am being offered the plot + demolition of existing structures + shell construction + roofing/insulation/gutters + garage at a fixed price (notary basis). The interior finishing will be contracted separately by me; for this, I have price quotes per trade, executing company, and scope of work from the architect. The architect does not earn any profit from the interior finishing (I only pay a flat fee of €5,000 (approx. $5,400) for his construction manager), meaning his profit is fully included in the “notary basis.”
After deducting the market price of the land, passed-on purchase-related costs + 50% of demolition costs (including basement) + subdivision, approximately €400,000 (approx. $430,000) remain for the fixed price covering planning + shell construction + roofing/-insulation + garage + profit.
Here is my estimated cost breakdown based on my research (I am not an expert) and I would appreciate your review for general accuracy:
Details: 1.5-story semi-detached house, 8 x 13 m (26 x 43 feet), attic converted into living space, reinforced concrete basement, built according to the 2016 Energy Saving Ordinance, about 1000 m³ (35,300 ft³) enclosed volume (my calculation based on sections).
1) Earthworks + shell construction: approx. €150,000 (approx. $161,000)?
(Basement: 36.5 cm (14 inches) masonry or concrete, party wall made of sand-lime brick; load-bearing masonry: sand-lime brick + 120 mm (5 inches) core insulation + facing bricks (€0.5 per brick), non-load-bearing: sand-lime brick/brick/plaster walls; ceilings: reinforced concrete, stairs from basement to attic: reinforced concrete)
2) Masonry + facing bricks garage 9 x 5 m (30 x 16 feet): approx. €30,000 (approx. $32,000)?
3) Roofing + insulation + gutters: approx. €50,000 (approx. $54,000)?
(approx. 160 m² (1,720 ft²) roof area (my calculation based on sections), roof frame made of softwood, quality concrete tiles on roof membrane, gutters + downspouts in zinc, insulation meets requirement for living attic and attic conversion)
4) Architect and engineering services: approx. €35,000 (approx. $38,000)?

Subtotal costs: €265,000 (approx. $284,000)
Remaining amount (€400,000 - €265,000): €135,000 (approx. $145,000)
- of which VAT: €22,000 (approx. $24,000)
- of which profit/margin: €113,000 (approx. $121,000)

a) Does this allocation of the fixed price seem realistic?
b) Is the margin/profit typical for the market, considering that no additional profit comes from the interior finishing?

Thank you in advance for any feedback!

That is extremely expensive. The profit margin is very, very high. We are only talking about the shell construction here, without windows, plaster, or interior finishes.

You need to budget roughly another 250,000 euros for the rest. Are you aware of that?

Bookstar schrieb:

You need to budget around 250,000 euros more for the rest. Are you aware of that?

I didn’t want to overload the thread with this topic: For the remaining work, I have a breakdown of €150,000 divided by trade and company. This also seems very low to me. The scope of work sometimes reflects a rather basic standard. I have sent change requests to the architect asking for pricing. Still, the architect must have exceptionally good prices if he intends to source the rest for €150,000. For example, the design includes a large amount of window area and high ceilings (ground floor with a clear height of 2.90 m (9.5 ft)) with correspondingly tall windows, all with wooden frames.

You see, that will never work. Your cost estimate above is accurate and shows how high the contractor’s offer is. 150,000 for the remaining work is therefore more than unrealistic.

50 for heating/plumbing, 20 for electrical, 40 for plastering, 5 for painting, 30 for windows, 10 for shading, 30 for flooring, 5 for garage doors, 4 for front doors, 7 for interior doors, 7 for screed, 10 for stairs, 20 for extras such as stove, ventilation, roofing, etc.

The profit margin for property development should not fall below 15%, and is usually around 20-22%. Since you have no clear idea of the actual costs, you cannot make any reliable statement about the price or the architect’s profit here.

This means that with production costs of €550,000 (as you estimated), the purchase price of the house should be around €450,000 so that the architect can make a reasonable profit.

I will now share the cost estimate from a preliminary discussion with a general contractor:
1,000 m³ x 400€ = 400,000€
A turnkey house, additional costs not included: fees, landscaping, garage, special requests, etc.
Ready-to-build plots are currently being sold at around 50-100% above the standard land value in our area. :-o
Now you can do the math yourself.