ᐅ Asked four people, got five answers...

Created on: 17 Nov 2013 20:28
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Dipl-WiING
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Dipl-WiING
17 Nov 2013 20:28
Dear forum members,
we are about to purchase a hillside plot of around 1000 m² (approximately 16° slope, west-facing). It is actually larger than what we are looking for, but otherwise it fits our needs quite well.

Of course, as building beginners, we have many questions, which we have asked various “experts.” From our two potential architects to different prefabricated home builders. Naturally, everyone gives advice from their own perspective, but the statements are so contradicting that I can’t move forward with planning based on them.

So I’m trying here to get a clear overview 😉

Is a flat roof on a 90 m² area the same cost as a hipped roof (10 m by 8 m (33 ft by 26 ft) at 15°)?

Is it cheaper to fully finish a basement as a living space (with a large window front) rather than leaving it as a dark (insulated) utility basement with a wooden cladding on the visible part and instead build an upper floor equivalent in quality to the living basement?

Is it generally more cost-effective to use part of the front basement ceiling (possibly 3 m by 4 m (10 ft by 13 ft)) as a terrace rather than having a terrace on the upper floor using part of the ground floor footprint?

In summary, we need about 130 m² (1400 sq ft) of living space, 15 m² (160 sq ft) of terrace (at least at basement ceiling height), and about 30 m² (320 sq ft) of utility space for a workshop, storage, etc. We originally planned to skip the upper floor and instead build a fully usable living basement. We cannot reduce the floor plan too much since we want a living and kitchen area of 10 m by 6 m (33 ft by 20 ft) to take advantage of the hillside view. The terrace was meant to connect to the living room (ground floor, above the living basement) as a wooden structure attached to the side or front. Now we were told it’s common to “simply” use the surface of the basement ceiling for this. We are not planning anything special—a shoebox floor plan with a flat or open hipped roof.

Thanks for any tips, and maybe someone knows a similar house matching our requirements?

Best regards
Pit
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Bauexperte
17 Nov 2013 21:26
Good evening Pit,
Dipl-WiING schrieb:

We are about to purchase a hillside plot of about 1000m2 (ca. 16° slope, west-facing). It is actually larger than we are looking for, but otherwise everything fits.
You must have a lot of time 😀
Dipl-WiING schrieb:

Is a flat roof on a 90m2 area roughly the same cost as a hip roof (10*8m @ 15°)?
No. A properly executed flat roof (FR) is more expensive.
Dipl-WiING schrieb:

Is it cheaper to fully finish a basement as living space (with large windows) than to keep it as a dark (insulated) utility basement (cladding the visible parts with wood) and instead build an upper floor of equivalent living quality?
No – but the question is not that simple to answer. In my opinion, a basement only makes sense if it is actually used as living space. This is generally recommended if the plot has a slope.

A purely utility basement is the most expensive way to gain floor area you can imagine. This is also because, with a large garden available, it tends to become an expensive storage area. First just a box, then maybe furniture you don’t want to part with, etc. In the end, nearly every utility basement ends up filled with what I consider useless clutter, which you will never effectively use again anyway.

80m2 (860 sq ft) of utility basement with partially exposed exterior walls should cost about EUR 50,000**. If it is converted into living space – aside from a utility room – you should budget additional costs of around EUR 15,000** (insulation, upgrading the heating system, underfloor heating, screed, etc.).

A detached house 10.00m x 8.00m (33 x 26 ft), two stories, KfW 70 standard, with a flat roof, should cost about EUR 172,000**, with the utility basement about EUR 50,000** (with exposed masonry, plus further conversion to living space).

A bungalow (single-story) with the same parameters costs about EUR 172,000** plus the cost of the utility basement and its conversion to living space.

Since you will have a basement anyway, in my view it makes little sense to put more money into an upper floor you don’t need. Better to convert the basement into proper living space.
Dipl-WiING schrieb:

Is it generally cheaper to use part of the front basement ceiling (possibly 3*4m) as a terrace rather than using part of the ground floor as a terrace?
Why the basement ceiling? Do you mean you want the basement ceiling to cantilever?
Dipl-WiING schrieb:

I actually wanted the terrace to extend from the living room (ground floor above the living basement) as a wooden structure on the side or front. But someone told me it is common to simply use the surface of the basement ceiling for this.
That would only be “common” if the basement floor area is larger than the floor above it.

** In Bavaria, you should calculate 3-5 times higher costs depending on the district you want to build in.

Regards, Bauexperte
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Dipl-WiING
20 Nov 2013 11:47
Hello building expert, first of all, thank you very much for your detailed response!

Can you roughly estimate how much more expensive the full basement would be compared to the walk-out basement or even a half-basement with about 15°?

If I understand you correctly, you think we will need a basement anyway because of the slope, so it also makes sense to fully finish it rather than use it just as storage. I completely agree with you here, but I still see two advantages to having a second floor: 1. It will be brighter upstairs and the view would be nicer, 2. The basement can be converted into living space later more easily, whereas adding a second floor after the fact is probably much more complex!?

Why do you think the basement in Bavaria could cost 3 to 5 times more? Are you thinking of the excavation? We are not really in Bavaria 😉 we are in Franconia on a vineyard – does your assessment stay the same here?
Why basement ceiling? Do you mean you want to cantilever the basement ceiling?

Yes, exactly, we were thinking of making the basement ceiling somewhat larger than the ground floor, but not along the entire length, since we don’t want to block the view (we are planning floor-to-ceiling windows) too much with a balcony. Here, we are rather thinking about adding a kind of corner terrace on the side, accessible from the ground floor.

If I understand you correctly, you are calculating around €240,000 for a finished basement plus a second floor – so if we forego the basement renovation, we would only save around €15,000 to €20,000? How much would you estimate additional construction-related costs to be (the plot already has all connections to the property line)?

And the last question, who would build the described house for this price?

Many thanks in advance!!

Greetings from Franconia!
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klblb
20 Nov 2013 11:55
Instead of a flat roof, consider a shed roof with a 3° pitch. Covered with roofing felt or metal sheets. This is very similar to a flat roof and is one of the most cost-effective roof options due to its simple construction and low material use.
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Bauexperte
21 Nov 2013 07:16
Hello,
Dipl-WiING schrieb:

Can you roughly estimate how much more expensive a full basement (FD) would be compared to a walk-out basement (WD) or even a half-basement (SD) with about 15° slope?
Certainly in the range of approximately 5,000 to 8,000 thousand euros.
Dipl-WiING schrieb:

2. It's easier to convert a basement into living space later, while adding a second upper floor later is probably more complex, right?
In my opinion, both are about equally challenging — although converting a basement into living space later becomes difficult if you haven’t already considered raising the building height, insulation, and a larger heating system during planning.
Dipl-WiING schrieb:

Why do you think the basement costs would be 3 to 5 times higher in Bavaria? Are you referring to excavation? We’re not exactly in Bavaria 😉 we are in Franconia on a vineyard — does your assessment remain the same here?
I’m not speculating — I know. In Bavaria, which includes Franconia, construction costs are simply higher.
Dipl-WiING schrieb:

How much additional ancillary building costs would you estimate here (the plot is developed up to the property boundary).
Sorry, but I cannot provide a reliable estimate. I don’t know the soil conditions, nor the plot itself, or the costs for gravel or whatever the geotechnical engineer may require.
Dipl-WiING schrieb:

And the last question, who would build the described house for that price?
Ask here in the forum and request responses via private message. I’m sure you will receive numerous suggestions.

Best regards, Bauexperte