Wow, I didn’t expect so many comments in such a short time. Thanks already for that. I will try to address the points.
But painter, stairs, cistern tiles, floors I think are set way too low.
Yes, I also found the painter a bit low, but I had read it several times that way and left it at that for now. For the cistern, I have a quote including all connections for under €2500. Sure, mounting will add costs, but would it cost about the same again?
Regarding the floors, I think I calculated quite generously. When I look at parquet prices, many are up to €40/m². We have now calculated €70 + €5 miscellaneous materials per m². So I cannot quite understand that it should be too low.
I think you underestimate the KfW requirements regarding a 40+ house in terms of “we want to build monolithically”. [...] It’s not timber frame construction where you kind of get the 40er almost for free.
Who said we want to build monolithically? We are clearly planning with sand-lime brick plus external insulation (ETICS). Timber frame construction has no direct advantage here, right? Only ETICS will be applied here.
But I also think that a KfW40+ house is significantly more expensive if you think monolithically. We want KS + ETICS and the slab is already a very well insulated slab. Naively, I then only think of the windows and the roof insulation.
Regarding your numbers: Many positions are estimated off by €500-2000. Off the top of my head, I’d say add another €40-60k, then you’re in the right range.
Could you maybe name the positions and justify them if necessary?
Also, the exterior landscaping is completely missing. The costs for the groundwork only add up if the plot is completely flat from the street edge like a mirror.
The exterior landscaping is intentionally not included. Just like the kitchen, etc. But it’s on the radar and thanks a lot for the hint. You never know.
The building plot is in a new development area, where the civil engineering work is currently underway. Can you not assume a flat building plot then? Friends built nearby and the plots were similar and flat in my eyes. So no slope or anything, or do you always have to consider this generally?
Do you have the figures from the fee table of the municipal utilities?
No, but soon. Thanks for the hint.
Regarding individual items, I picked out the photovoltaics. Who plans 2.600kWp on a 200sqm house with later 4? residents? In my opinion, the full 9.99kWp belong on there. And the battery only if you really want it. Economically it has never really been worth it.
I made a typo here! I meant €2600/kWp and we are calculating with 8kWp. That would be €20,800. But we chose the costs from Sonnenbatterie and therefore budgeted €25k. You need the battery for KfW40+, but in any case, in our opinion, it makes sense. For example, with 8kWp from SonnenCommunity you get 5,500kWh free annually if you provide 3% of your battery for grid balancing. Also, your self-sufficiency increases (e.g. at night). You are also the first who does not recommend a battery. You can do without the battery if the PV system does not cover the demand at all.
Construction water and electricity €500 each: are those connection costs or consumption?
Consumption, and according to several blogs, that should be fine. Some consumed more water than electricity or vice versa, but generally both were under €1k.
An architect’s house also takes a bit longer to build, so add generous rent and connection fees.
Yes, I was thinking about including double burdens and the commitment interest. I wasn’t sure whether to include it (like the garden), but I will probably add it.
Then things like containers, construction toilets, scaffolding, and cranes are missing.
We forgot container and construction toilet. Thanks! The scaffolding is included in the façade. For the crane, I have to check if and for what we need it.
What about the mentioned expert? Then the energy saving ordinance expert for your 40+?
It is planned in the budget of €31k. There is also a KfW subsidy of up to €4k. So, €35k would be available.
I think such all-around cost calculations, which are extrapolated from a lump sum price per sqm found on the web to the whole area of a house, are very dangerous and not accurate.
We also don’t trust these costs blindly, but as reference points they are very good. If you want to get information about costs, these sqm prices are often referred to in forums.
Regarding development costs: The municipality may ask you to pay development costs 0-2 years after completion; these are derived from a price per sqm of living space (divided into €12.30 for wastewater and €0.50 for electricity – at least in our area).
Interesting... just read that this is necessary in case of secondary development measures. Now the question is whether this is an exception or the rule.
We also covered a concrete staircase with natural stone. With €5000 we didn’t get there including railing.
How expensive was it for you? We are planning to use a concrete railing.
Exterior landscaping is completely missing. It’s easy to get that wrong. House entrance platform (2 steps) cost us €2000.
Curbstones (gravel strips), terraces, paved yard, lawn → Depending on size, €15,000 to €25,000 disappear quickly.
Yes, we are estimating about €20k for the garden, but we don’t have exact data yet. Your €15-25k fit well there. But from your other costs/comments I see we are not that far off after all.