ᐅ Removing existing material or adding gravel: which is more cost-effective?

11ant schrieb:

This is a planning mistake. According to 11ant’s basement rule, the avoided basement here would cost about three-quarters of a built basement. Keep searching for a plot of land suitable for this building project. Or, if the land has already been purchased, plan for a partial livable basement instead. Half a meter (20 inches) of elevation difference under the house footprint is still a "gentle" slope – three half meters (1.5 meters / 5 feet) clearly no longer.

Thank you

Does the basement rule include that the floor area of a built basement can be smaller? If not yet, that would mean it might eventually come down to roughly the same costs. Or is that already included in the three-quarters calculation?

KaraiKa schrieb:

Does the cellar rule imply that the floor area can be smaller when building a basement? If not, that would mean the costs might end up being about the same. Or is that already factored into the 3/4 ratio?

This compares the costs of a usable basement beneath the entire ground floor (corresponding to the considered slab floor area) with the measures taken to "avoid a basement, even though the plot requires one." In this context, "usable basement" refers to a non-residential basement (regardless of whether it is used for anything other than storage) built to the simplest standards with surface-mounted electrical wiring, and so on. While it is true that using this basement for living purposes compensates or saves above-ground living space proportionally, that is a separate matter. The cellar rule only deals with the question of whether, in a simplified example, "L-shaped concrete blocks instead of basement rooms" makes economic sense or is a foolish idea. Although even the simplest storage basement would have more than two meters (6.6 feet) of floor-to-ceiling height, the price parity effect is fully achieved at two meters (6.6 feet) of height difference. One and a half meters (5 feet) is three-quarters of two meters (6.6 feet), which corresponds to the value in this example. I myself can hardly believe how accurately such a rough general estimate can serve as a prediction. Likewise, a living basement compensates 1:1 for above-ground living space.

In terms of your initial question, the "moral of the story" is that, if you have one and a half meters (5 feet) of height difference under the building footprint, you would be well advised to build a full basement and use it for a mix of living and storage spaces. Using it exclusively for living space (hypothetically, since you will need storage anyway) would require daylight windows with standard sill heights, which in turn would necessitate excavation pits that would make these basement living rooms somewhat more expensive than the above-ground space they replace. Hence my advice for mixed use. At two meters (6.6 feet) of height difference, even "empty" basement rooms are economically "free," while at just one meter (3.3 feet), it may still be worthwhile to consider a partial basement.

Excavating the house so deeply that you then have to "re-excavate" parts of it is basically as foolish as raising the building and trying to "flatten" the terrain. The cellar rule will tell you to what extent this is a smart move or just nonsense.

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And my tip: If the builder calculates that filling in is cheaper, please also get a quote from a landscaper to find out what additional costs may arise in the transition area afterwards. A colleague just received the quotes for landscaping the garden area, and for that amount, she could have had a cellar converted into a living cellar. Currently, her house is practically sitting on a nearly 2 m (6.5 ft) high cliff above the garden.

Schorsch_baut schrieb:

And my tip: If the contractor calculates that adding fill is cheaper, make sure to also get a quote from a landscaper for any follow-up costs in the adjacent areas. A colleague just received quotes for developing her garden area, and for the same amount, she could have converted a basement into a living space. At the moment, her house basically sits on a nearly 2 m (6.5 ft) high cliff above the garden.

Thanks, great tip. I think to keep the construction project affordable, does it make sense to continue hoping for a plot without a slope and simply build on a slab foundation without having to make major adjustments to the land?

KaraiKa schrieb:

I think to keep the construction project affordable, it makes sense to hope for a plot without a slope and then simply build on a slab foundation without having to make significant adjustments to the site…..

Well, in a way, waiting for Godot might be shorter than waiting for a cost-optimized plot that, together with the house, won’t end up more expensive overall. Hoping is too passive a strategy.

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KaraiKa schrieb:

Thanks, great tip. I think to keep the construction project affordable, does it make sense to keep hoping for a plot without a slope and then simply build on a slab foundation without having to make significant adjustments to the site?

It also depends heavily on your region, both in terms of geography and availability. It’s not worth paying an extra €50,000 for a flat plot. And remember, not everything that looks flat actually is flat.