ᐅ Adding an Additional Floor vs. New Construction – How to Get Started?

Hello everyone,

I’m new to the forum and hope this is the right place to discuss my issue (please feel free to move it to the appropriate subforum if not – thank you).

I need to give a bit of background.
My husband and I want to own a home. We both grew up in houses with gardens, and it quickly became clear to us that we are not fans of apartments and long for a house.
After our wedding, we started researching new builds. The plot of land was already decided — a gift from my parents (right next to their house). We quickly agreed that we wanted a prefabricated house and scheduled appointments with various suppliers.

In the meantime, my mother unfortunately passed away suddenly and unexpectedly. Suddenly, my father was left alone with a large house, and the original plan to build next door became uncertain. You should know that my father’s house was built in 1982 and is in top condition (new roof, photovoltaic system, energy certificate with good ratings, etc.). It is a flat-roofed house that, due to changes in building regulations, could now also be extended upwards. My father has now offered that we could move into the house and have the entire ground floor (approximately 100sqm (1,076 sq ft)) plus the attic (after the extension) — he would move into the existing granny flat.
According to a known structural engineer who has reviewed the plans, an extension upwards is likely possible.

We have thought this through and could now see this as a good alternative to building new. We know that legally a lot still has to be arranged beforehand (we won’t invest blindly in a house that legally wouldn’t belong to us, etc.).

To finally decide between a new build (offers are already in) and an extension upwards, what we lack is a sense of the costs involved and how to get quotes.
Who is the right contact for this? An architect, a carpentry company?
Who should we approach first? Or do we have to contact each contractor individually?

Additionally, we probably need to submit a building inquiry/request for early approval to find out if our idea for the extension (knee wall height > 1m (3.3 ft)) would even be approved. Should an architect, a structural engineer, or a construction company handle this?

I think you can see that we feel a bit lost regarding the extension, and I would be very, very grateful for any advice.

Good day,

herann schrieb:

To finally decide between a new build (we already have offers) and adding an additional floor, we simply lack a clear understanding of the costs and how to obtain a proper quote.
Who is the right contact for this? An architect, a carpentry company?
Should we approach someone first? Or do we need to contact each individual tradesperson separately?

In any case, the usual system providers are not the right choice for you!

herann schrieb:

Additionally, we would actually need to submit a preliminary building inquiry to find out if our idea of the additional floor (knee wall > 1m (3.3 ft)) would even be approved. Does an architect, a structural engineer, or a contractor have to handle this?

Your first step should be to consult a structural engineer, who needs to finalize and put their initial assessment in writing. In the next step, find an architect you trust to discuss the additional floor and develop the draft plans based on the structural requirements.

Further steps depend on the professional field and are often debated; if you ask two experts, you will get at least three different answers. I would send the architect to the building authority to clarify the draft planning: is there a reasonable prospect for approval? If you want absolute legal certainty, only the preliminary building permit (“Bauvoranfrage” / preliminary planning approval) will suffice.

Regardless of how you obtain confirmation regarding the building permit, you basically have two options to carry out the project once you have the permit without conditions. The first, and most common, is to hire the architect to manage the individual subcontracting of trades. This implies that you will need to engage with every necessary step and, sensibly, contact at least three companies per trade. This approach is not suitable for every client because it can easily overwhelm someone without experience. Many (husbands/partners) naturally see this differently—once a hunter and gatherer, always an unwavering head of the household with a tendency to overestimate. If this happens, it is a good idea to entrust the architect with the project management as was done during selection and retain only veto rights regarding the finishes.

The other, less known option is to approach a local builder during the planning approval phase, one who can demonstrably handle renovations. Here, as with a standard new build, you can relax and only need to familiarize yourself with their construction specifications before work begins; the builder takes care of the rest.

In terms of cost, I always see the advantage of a fixed price, which only the builder can provide—pay attention to guarantees! An architect cannot and will not provide this, as they would then be liable like a builder/general contractor/ construction manager. This also means you will only have full cost transparency after receiving the tender documentation. Until then, the architect's cost estimate and final price often differ by 20% or more, which is entirely normal.

Best regards, Bauexperte

Hello,

I just wanted to briefly update on our current situation. We first went to the building authority with our architect, and unfortunately our plans have already fallen through there. The zoning plan was very open to interpretation but, unfortunately, not in our favor.

Therefore, we are now continuing with the construction of a prefabricated house.
Thank you very much for the helpful response!