ᐅ Demolition and New Construction, Basement, Sloping Site

Sparclou? There was no mention of a Sparclou.
In the area where we would like to live and build, most properties are on slopes, so we have to accept generally higher construction costs. Even if you were to buy a comparable vacant plot, it would still be more expensive than this one, including the demolition of the existing house. Especially since there is already a house with a basement on the site, it is at least clear that the soil conditions allow for that.
The slope is probably around 15%. Accordingly, it would make little to no sense to build on a building platform / pad, especially since a basement excavation is currently present. The necessary earthworks for that would likely be just as extensive as constructing a new basement. And we want to have some usable basement space anyway.
Of course, it’s clear that you can’t avoid earthworks entirely. However, it is quite difficult to estimate potential costs under these existing conditions. Basically, it only states that for sloped sites, a basement is hardly more expensive than a building platform / pad, and that the earthworks represent a significant portion of the costs.
Therefore, my question is whether it would be more practical to add a prefabricated basement as usable basement space and then build a house on top, or to build the basement so that it is partly used as living space on the downhill side, reducing the number of floors by one. What is roughly the cost difference between a living basement and a usable basement? And what is the typical cost range for earthworks, etc.?

Basement for utility purposes, for what use + living area
is more expensive
than a habitable basement + reduced above-ground living area
both have the same living area

Dartfan schrieb:

If you were to buy a comparable plot of land empty, it would still be more expensive than this one including demolition of the existing house.

This statement makes little sense.
That might be possible, but it is generally very unlikely. I don’t know how many times I have read something like this here already. Why would the seller accept less? Or to address your specific example, why would other interested parties offer less for this exact property? You simply cannot know what they are offering. The starting price does not say much. They also know what the prices are in the surrounding area. Accordingly, the final price will reflect that.
Plot costs from the surrounding area minus demolition costs at best.

Dartfan schrieb:

It is relatively difficult to estimate potential costs given the current conditions. It basically says that with a sloped lot, a basement is hardly more expensive than a semi-basement, and that earthworks make up a significant part of the costs.

Yes, and here additional costs come into play for disposing of the old basement. Depending on the construction year and condition, it might even be classified as hazardous waste?

Dartfan schrieb:

That’s why my question is whether it would be more sensible to add a prefabricated cellar as a utility basement and then build a house on top of it, or to build the basement so that part of it is used as living space on the downhill side and thus reduce the number of floors by one. Roughly, what is the price difference between a living basement and a utility basement? What is a typical ballpark figure for earthworks, etc.?

You can’t really generalize. It depends on many factors, such as location, soil conditions, size, to name just a few. Below is an example post. I would just recommend using the search function and browsing through related threads. There are several discussions about similar houses here. A standard basement on an average plot should cost around 70,000 Euros (about $75,000) — but as mentioned before, this reference might not help you much.
My layman’s opinion, shaped over time here, is that with a sloped lot, a living basement becomes much more affordable than it would be otherwise. For that “small” extra cost, it is therefore worthwhile for many. If the budget does not allow it, then it simply isn’t possible.
However, if you can save an entire story by having a living basement, it is probably cheaper to build with a living basement. But keep in mind that you will lose the corresponding square meters. I mean, it is quite a difference whether you build two living floors plus a basement, or just two living floors.

Here is a post from a user, just to give you a rough idea.

Harakiri schrieb:

Since we are currently also building a living basement similar to what you plan (around 155 m² (1668 sq ft), 28 cm (11 inches) waterproof concrete exterior walls, 14 cm (5.5 inches) insulation outside as well as under the screed, except in the garage area of about 25 m² (269 sq ft), which is outside the thermal envelope), here is what we have to invest:

Shell construction (prefabricated elements, including interior walls and 3 basement windows): 102,000 Euros
Sanitary plumbing for drinking water and sewage: 7,000 Euros
Underfloor heating (everything except garage and utility room): 9,000 Euros
Controlled mechanical ventilation (pipes only, ventilation unit separate): 7,600 Euros

That already brings us to about 125,000 Euros, and costs for screed, flooring, electrical installation, wall smoothing/painting, possibly suspended ceiling, staircase from basement to ground floor, as well as extra earthworks and possibly disposal compared to a semi-basement, are not included yet.

That’s why I think 150,000 Euros is quite realistic, while 200,000 Euros is probably rather too high – but of course it also depends on the region (we are in a relatively affordable area).

The prices for the basement were given to you as rough estimates – there’s not much more that can be said based on the information available. The cost depends on the location, soil conditions, and overall slope of the site. So, no one can give you a precise figure. However, if you plan on around 2,000 to 2,500 €/m² (approximately 185 to 230 USD/ft²), you should be in a reasonable range.

That said, I would recommend paying closer attention to the demolition phase. You’re planning to tear down an entire house, right? Are you fully aware of that? How have you planned this? Will you be doing the stripping out yourselves to save money? Do you know what materials were used in construction? There was a time when asbestos facade panels were popular and widely used. If you have to dispose of something like that today, it can be very costly and troublesome.

You can estimate the cost of the basement reasonably well, but I would be much more concerned about the potential surprises the demolition might bring.

danixf schrieb:

This statement doesn’t make much sense.
It might be possible, but is usually very unlikely. I don’t know how often I’ve read something like this here. Why would the seller want less? Or to address your specific example: why would other interested parties offer less here in particular? You can’t possibly know what they are bidding. The starting price doesn’t say much. They also know the local market prices. That’s how the final price will be set.
Land costs in the area minus demolition costs at best.

I may have expressed myself unclearly. Of course, it could happen that bids go that high, but in that case, we would drop out. Our limit would be if, after demolition and clearing costs, we end up at the land value. Otherwise, we won’t pursue it. This is not our first auction; last time it didn’t sell. The creditor’s claim is well below the market value, so it’s possible to get it cheaper. Someone is still living there, and as mentioned, it would need to be demolished and cleared out, which doesn’t bother us much since we wouldn’t start building immediately anyway. But for others, this might make it less appealing.

danixf schrieb:

Yes, and here you also have additional costs for disposing of the old basement. Depending on the construction year and condition, it might even be hazardous waste?

Yes, we are currently trying to clarify that. The appraisal does not provide much information on this. We will review court files again to see if there is more detailed information.
Also, @Climbee: the appraisal included estimated demolition costs. However, I don’t know to what extent the materials were specifically examined. We certainly wouldn’t do the demolition ourselves, but hire professionals. Naturally, that would add costs, especially if asbestos is involved. The house dates from the 1950s, so there is a risk, but also a chance that asbestos was not used.

danixf schrieb:

You can’t say that in general terms. It depends on so many factors: location, condition, size, to name just a few. Below is an example post. I’d suggest using the search function and browsing similar threads. There are several about similar houses. A standard basement on a typical plot should be achievable for about 70,000 (70k). But as mentioned, this benchmark alone won’t help you much.
My layman’s opinion, formed over time reading here, is that building a living basement on a sloped site becomes much more affordable than without a slope. For the relatively small additional cost, it’s worthwhile for many. If the budget doesn’t allow it, then it’s simply not possible.
But if you can save an entire floor by having a living basement, it’s probably cheaper to build that way. Just keep in mind that you lose corresponding square meters. I mean, it’s quite a difference whether you build 2 full floors plus a basement or just 2 floors.

That already helps a lot, thank you!
Basically, it’s about the following:
If we consider a desired living area of around 160–170 sqm (square meters), I could (simplifying the calculation here) build a basement of 80–85 sqm and then add 2 full floors above it.
Or I build a 100–110 sqm basement, of which 60 sqm would be living space and 40–50 sqm utility basement, and then build only one floor above it with 100–110 sqm. The living area would remain the same. We actually don’t need an 80 sqm basement. That would be for house technology, laundry room, tool storage, and some storage space.
In total, that would be 200 instead of 240 sqm, which should be cheaper—or would the savings be offset by larger excavation and the partly living basement being more expensive than a purely utility basement?
We generally have a relatively large budget margin. But of course, before potentially bidding at auction, we want to have a rough feeling about it, since the effort to make the plot buildable is quite considerable.

Dartfan schrieb:

That already helps a lot, thank you!
Basically, it’s about the following:
If we assume a desired living area of around 160–170 sqm (1720–1830 sq ft), I could (simplifying the calculation here) build a basement of 80–85 sqm (860–915 sq ft) and then place two full floors of corresponding size on top.
Or I build a basement of 100–110 sqm (1075–1185 sq ft), using 60 sqm (645 sq ft) as living space and 40–50 sqm (430–540 sq ft) as utility/storage basement, and then only build one floor above with 100–110 sqm (1075–1185 sq ft). The living area remains the same. We don’t really need an 80 sqm (860 sq ft) basement; it would be for building services, laundry room, tool storage, plus some additional storage space.
So overall, it would be 200 sqm (2150 sq ft) instead of 240 sqm (2580 sq ft), which would be cheaper—or does the saving balance out because a larger excavation and partially finished basement used as living space might be more expensive than just a utility basement?
We basically have quite a flexible budget. But, of course, before potentially bidding on something, we want to have a rough idea, since the effort to make the plot suitable for construction wouldn’t be insignificant.

Could you explain what exactly you mean by “quite a flexible budget”?

Have you reviewed the building plan / zoning regulations? You can’t build just anywhere as you like. Option 1 can quickly become irrelevant because of that.
But option 2 still seems like the more practical approach here. Depending on the plot size and amount of excavation, you can distribute it across the site and save on disposal costs. Those are usually a major cost factor in earthworks.