Is the basement cost estimate realistic?

2021-09-13 07:35:36

Hello forum,

for our single-family house, we are currently planning a basement. In addition to the building services, a laundry room (washing machine + dryer), the basement will also include a gym and a study.

The four rooms cover an area of about 65 sqm. The soil is suitable for this (from about 2.5m medium-density gravel layer according to soil report - load class 2 according to WU guideline). The basement will have perimeter insulation (outside, floor slab, basement ceiling) - planning is currently (and following advice from the forum ;) ) for Kfw 40, which requires thicker insulation. The study and gym will have underfloor heating. The study will also have a light well. The gym and laundry room will have a light shaft. The technical room will have no windows. Anhydrite screed will be laid throughout. Then a floor covering. Electrical installation will be mounted on the walls.

The incidental construction costs (especially the creation of the batter board and excavation) are not included in the costs. I am currently planning with a price of €1250 per sqm, i.e. about €81,000 for the basement. Now everyone looks at me like a car and says that this is way too expensive and that around €35,000 would be more than enough? What is your assessment?

Regards Andy

2021-09-13 07:42:16

Hello forum,

for our single-family house we are currently planning with a basement. In addition to the building services, a laundry room (washing machine + dryer), a fitness room and a study are to be set up in it.

The four rooms are spread over an area of about 65 sqm. The ground is suitable for this (from approx. 2.5m medium density gravel layer according to soil report - load class 2 according to WU guideline). The basement is to receive perimeter insulation (outside, floor slab, basement ceiling) - planning is currently (and following advice from the forum ;) ) for KFW 40, which requires thicker insulation. The study and fitness room are to have underfloor heating. The study additionally a light well. Fitness room and laundry room a light shaft. Technical room without window. Flowing screed laid with anhydrite screed in each case. Then a floor covering. Electrical installation to be mounted on the wall.

The ancillary construction costs (especially creation of the batter boards and excavation of the construction pit) are not included in the costs. I am currently planning with a price of €1250 per m2, i.e. about €81,000 for the basement. Now with this price everyone looks at me like a car and says that is way too expensive and that about €35,000 is more than sufficient? What is your assessment?

Regards
Andy

We are building without a basement, however it has often been mentioned in the forum that the costs for a living basement are the same as for normal living space.

2021-09-13 07:48:00

The ancillary construction costs (especially erection of the batter board and excavation of the pit) are not included in the costs. I am currently planning with a price of €1250 per m2, i.e. about €81,000 for the basement. Now with this price, everyone looks at me like a car and says that this is way too expensive and that about €35,000 more is more than sufficient?

If a basement is planned, I would definitely obtain a soil report for cost estimation. Problem areas: - partially rocky ground - groundwater depth - contamination (asbestos, WWII remnants)? If basement, I would definitely set it >2.0m high

2021-09-13 08:52:24

Now everyone looks at this price like it's a car and thinks that it's way too expensive and that just under €35,000 more is more than enough?

These "everyone" probably haven't dealt with construction costs for at least 5 years. Or is there even one who has built recently?

I think your assessment is already much more realistic.

And even if it would be that cheap (which it won't) - what's better? Having €45,000 left over or having to refinance €45,000?
;)

2021-09-13 09:01:23

What do you think is missing for an above-ground created m2? So why should the civil engineering, which is already more expensive than building construction (among other things due to securing, waterproofing, a lot of reinforced concrete instead of cheap stones, disposal of excavation), then be cheaper? Because of the slightly missing exterior plaster and surface-mounted installation? Simple windows, by the way, cost about the same as masonry.

For the 35 TE, ten years ago you might have gotten a nicely calculated masonry potato cellar in the raw state, the excavation distributed for landscaping in the garden - your acquaintances will probably compare with something like that.

2021-09-13 09:01:58

Although we are building without a basement, it was often mentioned in the forum that the costs for a residential basement are the same as for a normal living area.

I have also read that, but I just can’t get the numbers to add up. For our basement, that would mean construction costs of around €162k. Maybe someone could explain where these costs are supposed to come from? Are wet rooms, etc. taken into account here?

if a basement is planned, I would definitely get a soil report for cost estimation. Problem areas: - partially rocky ground - groundwater depth - contamination (asbestos, WWII remnants)? if basement, I would definitely set it >2.0m high

This was already examined through a geotechnical report. The ground is mainly sandy and gravelly with partially silty layers in the upper area and medium dense to dense gravel layers from about 2.5m depth. Groundwater appears at around 5m depth, above which water is found from approximately 1.1m depth that was classified as perched and seepage water. No other contamination was found since the entire site was excavated to about 1.5m depth due to a suspected archaeological ground monument (not confirmed in writing).

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Is the basement cost estimate realistic?

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