ᐅ Is it practical to build a prefabricated house using a solid construction floor plan?

How is the hillside construction planned? If the basement is built into the slope, then one floor is already solidly constructed, and only the rest is framed with timber studs.

If you like the design except for a few minor details, go ahead and use it. If major changes are needed, in my opinion, it’s better to start over completely. Yes, a sloped lot does impose certain constraints, but even there the architect can be creative.

Skya2020 schrieb:

We are just at the very beginning of our house-building journey, so I apologize in advance if this question sounds completely silly... We simply don’t know the best way to get started now.

Then read my posts here on the keyword “house-building roadmap” (or “A house-building roadmap, also for you: the HOAI phase model!” directly on “Building now”). The basement question seems to have been answered in your case, apparently resulting in a “living basement” with a correspondingly smaller house above.
Most of the planning from the architect provided by the seller will not be reusable for you, mainly due to differences in your requirements. If I were you, I would carefully evaluate where real changes to the already approved plan are truly necessary. If the plan suits you, accept the “gift horse” for a reasonable price. Check the HOAI to see if roughly one-third (or generously: 40%) of the “new price” (for full entry into the architect contract) would be a fair deal in your specific case. For the seller, this effort without this property would be completely wasted, but for you, the approved plan is a huge time-saving milestone secured. Hence my suggestion of a “third to 40%” fee, subject to a fair architect’s remuneration. $50,000 for service phases 1 to 6 sounds like a large and/or luxury project.

Why did you plan to use “prefabricated construction”? At your current level of building knowledge, this is probably based mostly on myths and assumptions. I always advise those seeking guidance to make a “decision point” during the dough resting phase (see roadmap) by sending an initial inquiry — based on the results of Module A — to usually three masonry builders and three timber builders. Then, based on their feedback, decide whether the architect should develop the preliminary design into a masonry or timber draft. In your case, this approach would differ somewhat because the sloped site practically dictates a masonry basement (as an exception, I only recall the “Shrub Carpenter”).

Not for you, but for other readers (about ninety percent of readers in a thread remain “silent”), and for the sake of completeness, here is the answer to the question in the headline: no, it is generally strongly discouraged to implement a house plan originally designed for another construction type.

For you, the former owner’s architect’s plan is only valuable insofar as the originally non-customized house would also “fit” your needs (provided the fee is not excessive). Changing the construction method — especially after the building permit / planning permission has been granted, which already sounds very unwise — would devalue the usability of the plan, particularly affecting the most expensive parts. This would be a perfect example for a guide called “How to be dumb?”

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11ant schrieb:

Then read my posts here using the keyword "house construction schedule" (or the "A house construction schedule, also for you: the HOAI phase model!" directly on "Building now"). The basement question in your case has already been answered, apparently with the result being a "residential basement, and accordingly a smaller house above."

Thanks for the tip, I will search the forum using that. We are actually still a bit undecided because the situation means we don’t have to follow a fixed procedure. On one hand, we chose the plot because the architect’s plan helped us visualize the house quite well; on the other hand, the pre-made plan kind of interferes with the discovery phase.

11ant schrieb:

Most of the parts of the seller architect’s plan that are the most expensive won’t be reusable for you, mainly due to deviations. If I were you, I would carefully consider where changes are really necessary in the already approved design. If it works for you, then accept the "free horse" at a reasonable price. Look at the HOAI to see if, say, about one-third (or generously: 40%) of the "new price" (for full entry into the architect contract) would be a fair deal in your specific case. For the seller, this effort without the property would be totally wasted, but for you, the approved plan is a major time-saving milestone. Hence my suggestion of one-third to 40% under the reservation of a reasonable architect fee. $50,000 for phases 1 through 6 sounds like something grand and/or luxurious.

The architect estimated the cost at around 1.4 million (including the land) back in 2022. However, he also said the fittings were very luxurious. So we hope to come out somewhat cheaper. The house is about 100 square meters (1,076 square feet) per floor with a double garage in the basement.
But you would only pay 33% if you mostly adopted the plans (including the construction method)?
If I have to commission my own design plan afterward anyway, it would actually be a loss.

11ant schrieb:

Why did you plan to build "using prefab construction"? At your current level of building knowledge, this is very likely based mainly on myths and similar assumptions. I always advise those I consult to take a "resting phase of the dough" (see the schedule) to make a "decision point," meaning that at the end of Module A, they send a preliminary inquiry to usually three masonry contractors and three timber builders to decide based on their responses whether the architect should develop the preliminary design as masonry or timber. In your case, this approach would be somewhat different since the slope location nearly dictates a masonry basement (as an exception, I only recall the "shrub carpenter").

Actually, we have only heard positive things from acquaintances about that, and we are considering, if possible, a YouTube collaboration with a prefab home provider. Such advertising naturally makes more sense for larger nationwide providers than for a local builder.

11ant schrieb:

For you, the previous owner architect’s plan is valuable mainly to the extent that the originally not custom-tailored house "fits" you (assuming the fee is not excessive). Changing the construction method—especially after the approval!, which sounds really foolish—would devalue the usefulness of the most expensive parts of the plan to such an extent that it would warrant a guidebook titled "How to be stupid?"

At least the approval is helpful in that we can refer to it with the building authority (there is no development plan), and we know what height and size we are allowed to place on the plot. But for that, we don’t have to buy the plan.

Skya2020 schrieb:

On one hand, we chose the plot because the architect’s plan helped us clearly envision the house. On the other hand, having a pre-designed plan somewhat limits the discovery phase. [...] In 2022, the architect estimated the costs at around 1.4 million (including the plot). However, he also mentioned that the specifications were very luxurious. So, we hope to come in somewhat cheaper. The house is about 100 sqm (1,076 sq ft) per floor.

Although the discovery phase has no inherent value, it starts with you—that is, your needs, wishes, and so on. Does the budget fit your financial framework, and does the size meet your requirements?
And did I understand correctly: you fell in love with the plot mainly because this house fits on it and would be approved there?
1. Have you known the sellers longer than since they stepped back from their own planning? 2. What is the reason for this withdrawal?

Skya2020 schrieb:

and a double garage in the basement.

Is it really a “basement” if the garage is accessed from the downhill side? Would the entrance then also be located on the lower ground floor (or is that the plan)?
The plan

Skya2020 schrieb:

But you would only pay the 33% if you largely adopt the planning (including the type of construction), right? If I still have to commission my own design afterwards anyway, it would basically be an added cost.

I think the option to purchase the plans makes the most sense exactly if and to the extent that the approved house suits you. Meaning, if the labels “Child 1,” “Child 2,” “Office,” and “Guest” could mostly be swapped around, the bathroom door and storage room placed differently, and so on—in other words, if all stakeholders or residents would achieve an upgrade over the current state. The architecture seems to be already broadly acceptable, if I understood correctly.

Skya2020 schrieb:

At least the approval is helpful in the sense that we can rely on it with the building authority (since there is no zoning plan), and we know what height and size we can place on the plot. But we obviously don’t have to buy the planning for that.

As a preliminary building inquiry, the approved plans are at least usable—as long as you submit your application during their validity period, yes.

Skya2020 schrieb:

Actually, we’ve only heard positive things from acquaintances about this, and we are considering, if possible, a YouTube collaboration with a prefab home manufacturer. Such advertising naturally makes more sense for nationwide large providers than for regional builders.

Are you seriously dreaming of an influencer discount as reference customers if you pick a house from a prefab home manufacturer? Aside from the fact that this would be equally attractive for any regional builder regardless of construction method, I give this idea five LOL stars. By the way, (as a title, not as a link!) could you share the name of the post where your acquaintances already did this? I think companies will value it much less than you hope—maybe they’ll offer a free wallbox and fingerprint upgrade for the front door, possibly even the facade spotlights. But when it comes to gabions or the garage door, they will probably brush you off.

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11ant schrieb:

Just as the discovery phase is not valuable in itself, it does start with you—that is, your needs, wishes, and so on. Would the budget match your means, and would the size meet your requirements?
And did I understand correctly: you fell in love with the plot mainly because this house fits on it and would be approved?
1. Have you known the sellers for a long time before they stepped back from their own planning project; 2. where does this withdrawal come from?

No, we have only known the sellers since the purchase. They apparently withdrew from building for professional reasons because they now spend more time abroad. In fact, we liked the house and the plot immediately. With a few modifications, it fits our wishes and needs very well and is financially manageable for us.

11ant schrieb:

Is it really a "basement" if the garage is accessed from the downhill side, and the entrance would also be located on the lower ground level?

Exactly, the entrance would be in the "basement," next to the garage. There is also a separate apartment, which we would use as an office. The main living floor is then at garden level, so it’s on the same floor as the garden.

11ant schrieb:

I find the option to buy the planning to be especially useful if and how the approved house would suit you. Meaning, if the labels like "Child 1," "Child 2," "Work," and "Guest" could simply be rearranged; if the bathroom door and storage room could be relocated; and so on—basically if all stakeholders/residents would get an upgrade from the current state. From what I understand, the architecture is already likely to get approval.

We actually considered whether we could add a bay window. But since that would increase construction costs further, we would prefer to keep the current floor plan. The roof is currently planned as a hipped roof, but we are also considering a flat roof as an alternative. The architect said that would not be a problem.

11ant schrieb:

Are you seriously hoping for an influencer discount as reference customers if you buy from a prefab house manufacturer?
Besides the fact that this would be equally attractive for any regional provider, no matter the construction type, I give this idea five LOL stars. Please share (just the title, not a link!) the post where your acquaintances already pulled this off. I think companies will value this far less than you hope—maybe a free wallbox and a fingerprint upgrade for the front door, possibly some facade spotlights. But they will definitely dismiss requests for gabions or the garage door.

We don't have any direct acquaintances who have done this. But for example, Weberhaus recently cooperated with a football player. It's a very different industry, but my husband is also a public figure. So we considered this possibility. If it’s not interesting for the companies, that’s no problem. Asking doesn’t cost anything. We will also document the construction a bit on YouTube anyway.

Skya2020 schrieb:

No, we only got to know the sellers after the purchase. Apparently, they stepped back from the construction for professional reasons because they are now traveling abroad more often. Actually, we liked the house and the plot right away. With a few modifications, it suits our wishes/needs very well and is also financially manageable.

Then you would be crazy to want to build a different house than the one already approved (as long as the architect’s fee is not significantly inflated).

Skya2020 schrieb:

We actually considered adding a bay window. But before the construction costs rise any further, we’d stick to the existing floor plan. The roof is currently planned as a hip roof; alternatively, we are thinking about a flat roof. The architect said that would not be a problem.

... and 11ant says that, in this case, is nonsense.

Skya2020 schrieb:

We don’t have any acquaintances who have done something like this. But, for example, Weberhaus recently had a cooperation with a football player. Although it’s a completely different industry, my husband is also a public figure. So we gave it some thought in that regard.

So the acquaintances who have a good personal experience with a (which?) prefab house company are not the same as the example of the advertising partner (?)
By the way, I don’t know Reiner Calmund personally either, but I also wouldn’t follow Alexander (whether Zverev or Bommes) in choosing where to buy their houses. The developer whose main shareholder is married to the former national coach is insolvent, by the way.

Skya2020 schrieb:

If the companies aren’t interested, that’s no big deal. Asking doesn’t cost anything. We will follow the construction a bit on YouTube anyway.

For a masonry-built house, I would actually see even more potential sponsors as possible.

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