ᐅ Building on the Plot – To Include a Basement or Not?

Created on: 6 Feb 2022 10:39
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SandyBlack
Hello everyone,

maybe this thread is a bit early since we don’t have a planned floor plan yet. But we would still appreciate your advice. First of all, because this is probably the most important information: We are planning with a budget of 600,000 euros for the house plus additional building-related costs. We have received approval to purchase the plot shown here. We will sign the purchase contract at the end of next week. Now to our problem:
We are very uncertain about which is the better decision for our plot: a (partial) basement with a smaller floor plan (about 130 – 140 m² (1400 – 1500 sq ft)) (Option A), or a slab foundation with a slightly larger floor plan (about 170 m² (1800 sq ft)) (Option B).
I will list the pros and cons as we see them for each option.

Option A:
+ Utility room in the basement frees up space on the ground floor; no noise issues
+ More usable space overall
+ Hobby room can also be used flexibly for gatherings
+ Storage space!
+ Possibility of a double parking space
- Expensive (a full basement is probably unrealistic with our budget; is a partial basement more sensible?)
- Less space on the ground and upper floors

Option B:
+ More living space on the ground and upper floors
+ High potential for cost savings!
+ Possible to use the attic for storage?
- Is there still enough space for a double parking space?
- Possible issues with the plot ratio? If we understand correctly, the footprint of the house may be limited to 143 m² (1540 sq ft) plus 70 m² (750 sq ft) for driveway, garage, etc. My feeling is that the developed area might easily be underestimated and reach the limit quickly.

We would be interested in your opinion on how you would build on this plot. I have made a very rough sketch of how we imagine the orientation of the house and placement of parking spaces, etc. I have also attached the site plan and development plan. The questionnaire is mostly filled out, but a “final” floor plan is still missing, as mentioned. This will also largely depend on the question of whether to have a basement or not.
I hope I haven’t forgotten anything...
Best regards

Development Plan / Restrictions
Plot size 477 m² (5130 sq ft)
Slope Minimal
Plot ratio (ground coverage ratio) 0.3
Floor area ratio 0.8
Building envelope, building line, boundary 14 x 14 meters (see image)
Edge development see image
Number of parking spaces unknown
Building height up to 2 full stories
Roof type Hip roof or gable roof 30-40 degrees
Architectural style unknown
Orientation unknown
Maximum height / limits unknown
Other requirements unknown

Homeowners’ Requirements
Architectural style, Roof type Gable or hip roof (open to either)
Basement, number of floors Basement yes/no is the big question. 1.5 – 2 full stories
Number of occupants, ages 2 adults (32 and 33), 1 child (1), 1 more child planned
Room requirements on ground and upper floors Utility room, guest toilet with shower, guest room, study (a study nook might also be sufficient), 2 children’s rooms, master bedroom, bathroom
Office: family use or home office? Both
Overnight guests per year Parents-in-law should be able to stay regularly (about once a month)
Open or closed layout Open kitchen / living / dining area
Conservative or modern design Exterior should be clean and simple – relatively straightforward
Open kitchen, kitchen island Yes, at least a peninsula
Number of dining places in the kitchen No dining space needed in the kitchen; the dining room should have space for a large table
Fireplace If budget allows; not mandatory
Music / sound wall 11.2.4 sound system + TV to be integrated into the study (or guest room)
Balcony, roof terrace Not necessary
Garage, carport Double carport or double garage would be nice if space allows; otherwise 2 parking spaces in tandem
Utility garden, greenhouse Not planned
Other wishes / special features / daily routine, including reasons why some options are preferred or rejected Smart home with KNX (or Loxone); controlled ventilation system, photovoltaic system (+ possibly battery storage), air-to-water heat pump

House Design
Who did the planning:
- Planner from a construction company
- Architect
- Do-it-yourself
What do you especially like? Why?
What do you dislike? Why?
Estimated cost according to architect/planner:
Personal budget limit for the house, including equipment:
Preferred heating technology: Air-to-water heat pump + photovoltaic system (+ possibly small battery storage)

If you have to give up something, which details or features
- can you do without:
- cannot do without:

Architectural floor plan of a building complex; green-highlighted interior area in the center.


Parcel 6802 marked green on cadastral map; neighboring parcels 6803, 6811.


Plot plan: house 14×14 m (46×46 ft), terrace at bottom, garage to the left, driveway, distances 2.5 m / 5 m.
K a t j a6 Feb 2022 16:25
The building plot and site are sufficient for a double carport and a house on a slab foundation. I don’t see a compelling reason to build a basement. Including a basement would, in my opinion, make the budget quite tight, and there are always concerns about moisture (this also depends on the construction location and standards). Without a basement, it should work well, and you won’t have sleepless nights.

For a family with two children, a house on a slab foundation is completely adequate. If needed, the attic could be reserved for future conversion.

It is often said that the smaller the lot, the more reason to build a basement to preserve some garden space. But first and foremost, the budget for the house must be sufficient.
11ant6 Feb 2022 18:10
SandyBlack schrieb:

We are very uncertain about which option is better for our plot: a (partial) basement with a smaller floor plan (around 130 – 140 m² (1400 – 1500 sq ft)) (Option A) or a slab foundation with a somewhat larger floor plan (around 170 m² (1830 sq ft)) (Option B).

I don’t yet see the basic criteria to apply my basement rule here, or any indication that this decision is truly open to you. For partial basements, use the search function with "partial basement" "from: 11ant." Assuming the difference between 170 and 130 m² (approximately 40 m² (430 sq ft)) represents the space requirement of the proposed basement, that would correspond to a 31 (46)% partial basement beneath a one-and-a-half or two-story house. We are talking about roughly 60 to 70% of the costs of a full basement (possibly plus site preparation costs if the plot would favor a basement).
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
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Wugler1978
6 Feb 2022 18:34
Two years ago, we built a single-family house with 150 sqm (1,615 sq ft) of living space and a basement, and we would do it the same way again.
All the technical equipment, including the washing machine and dryer, is located in a room larger than 20 sqm (215 sq ft), providing plenty of space.
In the storage room (over 25 sqm / 270 sq ft), we have a foosball table as well as a play area for the children (Lego, slot car racing, etc.). We chose laminate flooring for this room.
Additionally, there is a study (15 sqm / 160 sq ft) and a guest room (13 sqm / 140 sq ft) in the basement.

All of this could certainly have been accommodated on the upper floor as well. However, with our small plot of land (less than 600 sqm / 6,458 sq ft), I would have lost too much garden space.
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SandyBlack
6 Feb 2022 19:43
@WilderSueden Our site plan says "Excerpt from the land register," but unfortunately, I don’t see any contour lines on it. I think I’ll try my luck with a water level hose.
@hanse987 The development plan doesn’t specify any required parking spaces, so I assume that won’t be an issue. But we would definitely prefer a double parking space anyway.
@K a t j a Thanks for your assessment. I think the garden area would be sufficient for us. The garden would also wrap around the house.
@11ant I don’t quite understand. Why wouldn’t the decision be up to us? Do you mean because the geotechnical report isn’t available yet? Thanks for the tip about the partial basement. We weren’t aware of that. Does that mean a partial basement isn’t really worthwhile from a cost-performance perspective?
@Wugler1978 Thanks for sharing your experience 🙂 What ceiling height do you have in the basement?
11ant6 Feb 2022 20:07
SandyBlack schrieb:

@11ant I don’t quite understand yet. Why wouldn’t the decision be up to us? Do you mean because the soil report isn’t available yet? Thanks for the tip about the partial basement. We weren’t aware of that. Does that mean, conversely, that a partial basement isn’t really cost-effective considering price versus performance?
You’re not making the decision alone; the plot of land more or less speaks for itself—how strongly, I can’t tell without more information as I said. From a business perspective, partial basements are textbook examples of inefficiency in cost per square meter.
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
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SandyBlack
6 Feb 2022 21:07
Okay, the idea of a partial basement is off the table then 😉.

I found your basement formula: "for every 20 cm (8 inches) difference in ground height within the building plot, add ten percent of the basement cost, even if you don’t build it." So, you’re missing the information on whether there are differences in ground height, right?

My excerpt from the property cadastre unfortunately doesn’t show contour lines, but I found something in the development plan.

In the explanation to the development plan, I see:

Technische Zeichnung mit Höhenlage, Tangentenpunkten und Gefälleangaben, Textauszug


and in the development plan directly for our plot, the following data:

Nahaufnahme eines Bauplans mit Maßangaben und Zahlen


I know it’s unfortunately very hard to read... but maybe this helps?