Additional costs new build vs. old building

Hello everyone,

we are currently wavering back and forth between a new build Kfw40 or 55 in timber frame construction through a prefabricated house provider and an existing property.

When we then look at the monthly costs, of course one has to take into account that an old house causes more incidental costs – but I really struggle with the actual costs. When I hear something about the incidental costs of a new build somewhere, they also say that you have to build up reserves directly and that you shouldn't underestimate all of that... but roughly where are the differences?

What exactly is more expensive? Building up more reserves for possible repairs is clear, but otherwise, heating costs can only be higher due to insulation, right?

Are there benchmark values?

We are currently comparing 160 sqm new build including heat pump or solar for domestic hot water and then a heating boiler in Kfw55 standard with a renovated house from 1951 - energy class C (which sounds very low, around 98 or so). The most important things like roof, heating, etc. are all less than 5 years old.

What additional costs should I factor in when calculating the incidental costs?

We also live in a fully renovated detached house with 150m² from that time. Energy efficiency according to the certificate (calculated and based on consumption) is also within your range. Despite quite high heating and laundry needs due to a baby, the additional costs are absolutely reasonable. IIRC we pay about €150/month for electricity and gas. Heating would be somewhat lower in a new building, the washing machine doesn’t benefit from a new building. However, you probably have higher maintenance costs for all the systems like heat pump, solar, controlled residential ventilation,... I occasionally have the plumber service the gas boiler. With €150/year, that's taken care of. Ultimately, I wouldn't make it dependent on that. Much more, the question is in what environment you want to live and what is available.

We are currently comparing 160 sqm new build including heat pump or solar for domestic hot water and then a boiler in KfW55 standard with a renovated house from 1951 - energy class C (which sounds very low, around 98 or so). The most important things like roof, heating etc. are all younger than 5 years.

98 kWh/sqm/a is not bad.

Especially for the construction year - but it must have been heavily core-renovated.
Roof/heating etc. <5 years: good.

The purchase price is probably interesting. And as I said - 98 kWh/sqm/a for the construction year - many buildings are significantly worse, that is indeed quite a usable number.

The additional costs - apart from the fact that a KfW 70,55 or 40 has less, but that is not much per month - are the same for new builds and existing properties. The whole fuss with property tax etc. is more or less the same.

Let's say your property has 100 kWh/sqm/a and 150 sqm.
That would be 15,000 kWh/a.
The KFW-55 of the same size would roughly have 35-40 kWh/sqm/a, let's say 40 to stay pessimistic. That would be 6,000 kWh/a (I have a KFW-70 with 135 sqm and was at about 5,000 kWh, so this calculation here is pessimistic)
Difference 9,000 kWh. If I calculate with gas heating and a high price of 6.4 cents/kWh I come to about 600,- additional costs compared to the energy-saving house. In other words, about 50 euros more per month. For that you don't get the world financed, other costs in a house are much higher.

If the property has charm, you like it, the location is good, no appraisal speaks against it, the renovation was done properly: why not? I think there is nothing against buying the renovated old building then.

If you get something really good used (rare, but possible): you save yourself all the new build hassle and stress. A bit of remodeling for 6 weeks - move in, done. It's got something, honestly.

Best regards
Thorsten

If possible, have a look at the heating cost statements of the existing building. If it was thoroughly renovated, you probably won't have to/can't do much more with insulation, or it’s not worth it. Here, in the end, we also tore out 10-year-old windows and replaced them with new ones, but only to achieve a uniform appearance, especially regarding the color (mahogany vs. dark gray wood look – that simply doesn’t match) and also because we changed many window sizes. From an energy perspective, however, it would never have been worth it. 1000 euros for a new window – you won’t recover that through heating costs in this lifetime (Uw 1.5 versus 0.8). The same should apply to insulation. Except perhaps for things that haven’t been done yet, e.g. ceiling insulation between floors, but that can often be retrofitted quite cheaply.

I agree with my predecessors. Nothing will change with electricity unless hot water is heated in the existing building using an instantaneous water heater or under-sink device. Basically, this depends on one's own consumption behavior. Heating costs will vary. The basic structure and other fees depend on the location of the property.

Can almost 100% agree with that, primarily the heating costs are higher and the costs for hot water generation can be higher. A "minimal" additional point can be the building insurance, as you often get a discount for a new building in the first few years. Of course, that does not make a new building worthwhile...