Costs for our house construction

Hello everyone,

we are currently in the process of having offers made by various prefabricated house providers (2 offers are already available, 2 offers will follow. Unfortunately, we have no experience and cannot really assess whether the offers are reputable. Therefore, I would be pleased if someone has experience and could roughly estimate the costs for the following project (only the costs for the house, we already have the land and can estimate the costs for the building permit...):

2-family house
2 floors each about 110m2
Passive house
Gable roof (therefore the apartment upstairs can also be somewhat smaller)
Without basement
Including EVERYTHING except floors (carpet, laminate, tiles), walls (painting, wallpapering), installing doors, bathroom
Everything else should be included, meaning heating, base plate, windows, gutters, electricity, gas, water up to the construction toilet

Can someone estimate our costs? I am very confused and can hardly compare the offers, because you can never be sure whether everything is really covered or if we will experience unpleasant surprises later. As a layperson, it is almost impossible to know what services must be provided.

I would be happy if someone can help me. Thank you very much.

Regards

Hello,

Passivhaus

Real Passive House, so only 15% energy demand?

Kind regards

Well, that's where it starts. An offer states Passivhaus, now another company told me that a Passivhaus is also a Kfw70 house. I would have to inquire about that now or can you help me. Anyway, it should not be the most expensive option. Regards

Hello Kati,

In an offer it says Passive House, now another company told me that a Passive House is also a kfw70 house. I would have to inquire about that now or can you help me. It should definitely not be the most expensive option.

At the moment (end of 2010) there are the following definitions; we will leave the statement of the provider aside for now:

- KfW Efficiency House 70
- KfW Efficiency House 55
- KfW Efficiency House 40

The decisive factor is the annual primary energy demand Qp. Here the maximum value of a building may be, for example, max. 70% of the value for the reference building according to the Energy Saving Ordinance 2009 (corresponding to 55% or 40% for lower efficiency classes). And the transmission heat loss HT' may be max. 85% of the value for the reference building according to Energy Saving Ordinance 2009.

A Passive House, on the other hand, is a building in which a comfortable temperature can be achieved both in winter and summer without a separate heating or air conditioning system. It offers increased living comfort with a heating demand of less than 15 kWh/(m²a) and a primary energy demand including hot water and household electricity of under 120 kWh/(m²a).

...could roughly estimate costs for the following project (only the costs for the house, we already have the land and can estimate the costs for the building application):
Two-family house, 2 floors each approx. 110m2, Passive House, pitched roof (therefore the apartment upstairs can be somewhat smaller), without basement, including EVERYTHING except floors (carpet, laminate, tiles), walls (painting, wallpapering), installing doors, bathroom. Everything else should be included, i.e. heating, base plate, windows, gutters, electrical, gas, water up to the construction toilet. Can someone estimate our costs

I am not sure if I correctly understand your list above, therefore the following data as a base value for a solidly built two-family house:
The house – as a KfW 70 efficiency house – completely without painting and flooring work should be in the range of EUR 260,000 on the base plate. If, in addition, the interior doors and the bathroom are to be done as self-performed work (EL) – attention: the trades for tiling usually also include the interior window sills – the price should settle in the range of EUR 240,000. Both prices are approximate values and can vary in the range of +/- €5,000–10,000; also the respective scope of services offered plays a significant role and can represent the above-mentioned figures differently!

In the conventionally built sector these prices increase by the amount of EUR 25,000 for a KfW 55 efficiency house, in the Passive House range you can add about 70%; alone the windows required according to the Energy Saving Ordinance for a Passive House cost significantly more

For a qualitatively high-quality prefabricated house – which by the way is not cheaper than a solidly built house – the different price levels for the respective efficiency classes are similar.

Kind regards

Hello construction expert,

thank you very much for the detailed answer - that has really helped me a lot. I will take a closer look at the offer regarding the passive house, because something might be wrong there.

But one thing puzzles me - we actually planned to build a prefab house (have already requested offers), as we thought it would be cheaper than a solid house. Is that rather not true and both options can be about the same price? Where is the advantage then? Which option should one choose, as both have advantages and disadvantages.

Regards

Kati

Hello Kati,

But one thing puzzles me - we actually planned to build a prefabricated house (have already requested offers), because we thought it would be cheaper than a solid house. Is that rather not true and both options can be about the same price? Where is the advantage then? Which option should one decide on, since both have advantages and disadvantages.

Basically, it is a very personal decision which building system is used. The prefabricated house industry likes to say that their houses are built faster. That is true, but only after the building permit has been granted, production of the prefabricated house begins ... by then, most solid construction builders already have the shell completed. When it comes to interior finishing, both are then equally fast.

A good prefabricated house - for example Büdenbender, Gussek Haus, Hufhaus or comparable providers - generally costs more than a conventionally built single-family house, which is due to the production process. Your banker can tell you the pros and cons regarding financing and resale; this depends decisively on the provider of the prefabricated house.

In my opinion, the advantage of the prefabricated house lies solely in the wall construction, which not only gives you more living space but also – although relatively thin – good insulation properties. However, most prefabricated house providers are limited concerning changes to their standard plans. If, on the other hand, a prefabricated house is not produced professionally, problems can arise, for example, with subsequent electrical additions, etc.

In my personal opinion - so subjectively - the solid house has the edge; this is also supported by statistical figures concerning the construction of prefabricated houses in recent years. If done seriously, they simply have a longer service life and also allow changes without great effort; for example, subsequent insulation, extensions, etc. It just came to mind. In the prefabricated house industry, there is a nice saying: "Just take a look at the old houses in the open-air museums; all prefabricated houses!" What they don’t say is that back then, construction was completely different, actually with visible timber framing. So no comparison to today, where more Styrofoam is built in than I want around my house. To be fair, I must admit that many solid house providers also work with external thermal insulation composite systems ... not exactly health-promoting, if I may say so.

Be that as it may, you have to make the decision for or against a prefabricated house or a solid house entirely on your own.

Kind regards