ᐅ What is the recommended length for an underground garage?

Hello,
we are quite close to purchasing the plot, and the meeting with the architect is scheduled for next week.

In advance, we have a few "ideas" where I might briefly ask for your opinion (or experience):

Our plot has a 5m (16 ft) wide driveway, but it goes up a slope about 2m (6.5 ft) high right away.

The garage entrance should be at ground level, so the garage (located to the right of the basement) will be partially underground on two sides (the back and the right side) up to the top edge of the garage.
What kind of costs should be expected for such a garage?
It will have to be waterproofed against ground moisture and structurally more stable than a freestanding garage.
The necessary earth excavation for the garage should be done with the excavation from the basement, so the cost should be "only" about 3000 euros (?) roughly.

---

And another question: if we wanted to also park our motorhome in the garage (which would save the need for a separate parking space or carport next to the house),
what would be the approximate cost for a garage about 12m (39 ft) long and 2.7m (9 ft) high (clearance height)? Two sides would again have to be protected against moisture and earth pressure.
Or is this "idea" completely unrealistic?

Martin

darksun schrieb:

The driveway to the garage should be level with the ground.

I assume you mean level with the street. Are you imagining a “three-quarter buried” garage? What would be above the garage or on the “garage roof”?

The cost depends on the region, local conditions, and the design. I would set aside about €35,000 and see what can be done with that. I first think of building it together with the basement – that way it becomes one unit. You should ask about that. It is also possible to build two concrete foundation walls to support the soil, and then cover the space between the basement outer wall and the foundation wall as a parking area. That would be a kind of sunken carport – which can also have a gate and is completely adequate for vehicles. Whether that is significantly cheaper is questionable.

Having space for an RV sounds good; for example, we built our carport with extra height for that purpose. Make sure to have a power outlet for maintaining the onboard battery, because if you have a roof over the solar panels on the RV, you won’t get any electricity from them there… 😳.

darksun schrieb:

Or is this “idea” completely unrealistic?

The only thing that is unrealistic is something that violates natural laws. Sometimes limits are set by budget or regulations – I can’t judge that from here. Unreasonable? Possibly, but is “reason” really a practical decision criterion when building a private house from scratch? Uneconomical? Probably every garage is uneconomical. The protection of the vehicle and thus avoided depreciation only compensates for the construction costs in very few cases.

darksun schrieb:

And another thing, if we also wanted to park our motorhome in the garage (saving the effort of building an extra parking space/carport next to the house), what would be the approximate cost of a 12m long and 2.7m high (drive-through height) garage?

More than a separate parking space.
I think the setback regulations would be violated by the 12 meters.

ypg schrieb:

I think the setback rules are being violated by the 12-meter (39-foot) distance.

That could be the case if the garage is placed right at the property boundary — which would probably also argue against integrating the basement. I sometimes forget how small plots have become nowadays. What is the distance to the neighboring property?

I assume a setback of 3 meters (10 feet) for a basement. Whether it becomes a garage or a habitable basement does not matter.

For garages on the property boundary, compliance with the maximum height (on average) and length limits applies. It doesn’t matter if part of the structure is partially buried due to a slope. However, the finishing is up to the architect. Personally, the cost factor that has already emerged would discourage me.

ypg schrieb:

Personally, I would be put off by the price factor that has already emerged.

Constructing a driveway also costs money. Developing a slope access from the bottom is often somewhat more complex than from the top.