ᐅ Consultation on House Type

Hello everyone,

We have the opportunity to purchase a plot of land from a municipality and would not be paying an excessive price.

We now have two offers: one for a solid masonry house on a slab foundation and one for a prefabricated house, also on a slab foundation.

Both are priced about the same, each fully turnkey. Therefore, price isn’t a deciding factor. The only difference is that the solid masonry house provider’s offer seems more transparent because it includes a price range for floor coverings, etc., rather than having to choose solely from a model home showroom.

Now to the main question. Each provider naturally criticizes the other’s approach—for example, the prefabricated house provider claims “only with us do you get a mold-free house, which is not possible with solid masonry.”

Is this true, or does a solid masonry build simply require a longer drying time?

Since we are somewhat affected by mold (we currently have slight mold issues in our solid masonry apartment), this sounds appealing, especially because, according to the consultant, no ventilation is necessary in the prefabricated house due to an integrated ventilation system. In my parents’ prefabricated house, there is still no mold after 45 years.

The solid masonry house would be built from 36cm (14 inches) Ytong blocks. The prefabricated house would have exterior walls about 34cm (13 inches) thick.

As far as I understand, KfW55 energy standard is now mandatory and both options comply.

Heating would be either gas with solar or an air-to-water heat pump for the solid masonry house, and an air-source heat pump for the prefabricated house.

What are your opinions on this?

If I forgot anything, I’m happy to provide more information.

Best regards

It is mandatory to comply with the Energy Saving Ordinance 2016. KfW 55 standard is not mandatory. Whether to choose solid construction or timber frame construction is largely a matter of personal preference. Each method has its advantages, although timber frame construction tends to be slightly more expensive than solid construction. I would consider a ventilation system to be very sensible. Providers who speak badly about other providers are, in my opinion, not good advisors. One should highlight the strengths of their own company and, if applicable, the advantages compared to others, but not disparage other companies.

After the construction moisture has dried out, problems only occur due to misuse—except in cases of very poor workmanship. A ventilation system helps significantly in this regard.

Am I mistaken, or do prefabricated houses also have screed? The only issue we had was after the screed was laid, combined with the three-day ventilation ban following its installation—this could have been completely avoided with a better sequence of work (installing drywall after plaster and screed). Since then, we haven’t had any mold problems, and the issues weren’t that severe to begin with.

The consultant is completely unreliable.

Painkiller schrieb:
In my parents’ house (prefabricated house), there has been no mold even after 45 years.

45 years ago, houses were not as airtight as they are today. This allowed for natural ventilation. There are also many solidly built houses that are just as old and just as dry 😉.

Regarding the plot, is it true that there is slightly more moisture in a solid house compared to a prefabricated house? In the latter, moisture mainly comes from the screed.

KfW 55 is not mandatory. Does the solid house have a ventilation system? If not, you should seriously consider this, unless you spend a lot of time at home and can ventilate thoroughly (not only because of moisture but also for air quality and thus overall living quality). Mold is not an issue with any house type if it is properly ventilated.

Then consider the heating system. Whether an air-source heat pump makes sense in a prefabricated house is debatable. It depends on your location and prevailing outdoor temperatures. After all, you first need warm air inside the house to “feed” the heat pump. In cold conditions, heating with electricity could become very expensive.
An air-source heat pump has the advantage for the homebuilder that it is considerably cheaper than the solid builder’s option (e.g., no underfloor heating!). So both types of houses might cost about the same, but with differences in performance 🙁 .
Personally, I would build solid only, but skip the combination of gas and solar. I would prefer a heat pump and perhaps photovoltaics. But that is just my personal opinion.

A disadvantage of a prefabricated house may be that although it can be assembled quickly, you might have to wait a year for delivery. The order books are full… Maybe you already live in a solid house before the prefab house is even delivered.

Hello,
to compare the two offers, you need to do much more than that:

Painkiller schrieb:
Both are priced the same, each fully turnkey. So that does not matter.

You are only looking at the price at the bottom right and the term "turnkey." However, this does not help you because "turnkey" is not explicitly defined. You need to compare the detailed scope of work carefully.

It is clear from your two examples that the houses are not equipped the same way:

Painkiller schrieb:
No ventilation is needed in the prefab house since there is an integrated ventilation system

Painkiller schrieb:
The heating for the solid house would be either gas with solar or an air-to-water heat pump, and for the prefab house an air heat pump.

If you do not have the knowledge or time yourself (which I assume at the moment) to compare the two scopes of work, you should seek external expert advice.

Many local carpentry companies also build complete wooden houses, which would be a third option. We chose this route because we like wood and felt the selected company was the most trustworthy (no “sign today for super special prices” offers or annoying calls) and we have not regretted it so far.