ᐅ Prefab House or Traditional Built Home—and Which Heating System?

Good morning dear community,

My wife and I are considering building a house on a gently sloping plot of land. Whether we need a basement or not is still undecided and under discussion. The plot is family-owned and still needs to be connected to utilities.
My wife (a lawyer) and I (an engineer) both have limited practical skills and no experience with housebuilding.

This week, we had an initial consultation with Streif Haus about a prefabricated house to get a sense of the costs and process. Everything we heard sounded very promising and definitely affordable. The consultant recommended the Proxon air-to-air heat pump. The concept also sounds promising—heating and electricity costs are low, and if you build to KfW 40+ standard, you can even receive additional subsidies. These are all new terms for us that we are hearing for the first time.

When researching a bit further, we found that you can apparently save a lot of money by outsourcing services such as the foundation slab or possibly the basement. Whether this approach fits well with project management, I can’t assess at the moment. From what we have seen so far, a solid masonry house (also called a masonry or concrete house) isn’t necessarily more expensive or cheaper. Is it possible to achieve the KfW 40+ energy efficiency standard with a masonry construction?

At the moment, we don’t know where to start. Should it be masonry? Which heating system? Air-to-air heat pump, or perhaps the vertical ground collector / trench collector we have also read about? Maybe we should first have a site and elevation plan drawn up to see what is possible?

We are still at the beginning with many questions, and the house is meant to last a lifetime.

Perhaps you have some tips, answers to our questions, or personal experiences to share.

Thank you very much

Good morning Fetzerino,

nice that you found your way into our community. Welcome! One of the best features of such a forum is the gradually growing availability of all kinds of information on all kinds of topics. You will find plenty of content here related to the questions you asked. Although the forum’s search engine might not always reveal it easily (Google usually works better for that), the information is definitely available. Therefore, I can only recommend investing a few hours here to browse through it.

In brief:

• Whether a prefab or timber frame house or a solid construction (these can also be prefab), it mainly comes down to personal preference and attitude. I am still firmly convinced that typical prefab houses (made of wood) are generally more expensive than solid ones, but otherwise, they are at best the same price.
• An air-to-air heat pump is only suitable for houses with very low energy demand; this usually means a passive house, which requires significantly less energy than a KfW 40(plus) standard, so from a long-term cost perspective, this would probably not be a good recommendation.
• KfW 40 (with or without Plus) can be achieved with both construction methods.
• Whether it is cheaper to contract individual services yourself depends a lot. Many providers offer good inclusive prices due to their volume of work and contracts, which also include project management (which also has costs). My opinion: unless you can save a medium four- to low five-figure amount, I would advise against it. A construction project benefits most from routine procedures, which can be severely disrupted by “external” tradespeople.
• A horizontal trench collector is related to the field of ground-source heat pumps, which generally are more expensive but very efficient and reliable sources of heat. This is one of the decisions (choice of heat generation: air-to-air heat pump, air-to-water heat pump, ground-source heat pump, gas, etc.) I would make in advance—but please based on solid information and specific characteristics of your property, since, for example, geothermal energy does not work equally well everywhere.
• Separate from the heating system, I would recommend visiting a model home park first to get an idea of “your” house. However, this does not mean that a specific construction method is fixed. Instead, also speak to providers not represented at the park.

One more tip: a building project is always more expensive than initially expected, so I hope you have a bigger financial buffer (in the five- to six-figure range) beyond the numbers you already know—just as a general rule.

I’ve written more than I intended, but I don’t want to stop you from reading through the forum.

Best regards

K1300S

Fetzerino schrieb:

At the moment, we don’t know where to start. Should it be a solid construction?

Not committing to a specific “silver bullet” for the wall structure is not a lack of information but the foundation for a more flexible range of options. Honestly, you can build excellent houses using most building materials, despite all the scare stories salespeople tell about competing products. There are even satisfied owners of plastic windows—just don’t tell anyone.
You already have the real start, and if more than the completed site development is not missing, that’s already great. The rest will come together.

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11ant schrieb:

There are even reportedly satisfied owners of plastic windows, but don’t spread the word haha.

Phew! *wipes sweat from forehead*

Yes, plastic windows work... I still find them unattractive. If your budget doesn't allow for anything else.

It probably does not in an estimated 80 percent of all construction projects in Germany.