Costs for renovation and extension of a single-family house from the 70s

500k unfortunately exceeds our budget (about 100-150k lower) and to be honest, we do not need the space that would result from the previously planned extension. How about increasing the roof pitch from 26* to 35* only? Then insert a knee wall and thus create less new space? For the stairs, a dormer would be necessary, I think. Could this generate two rooms on the upper floor and thus reduce costs? Is there any other idea that we currently do not see?

to be honest, we do not need the space that would be created by the currently planned extension.

So why then a 100% solution?

Is there another idea that we currently do not see?

What is, for example, standing in the way of converting the existing basement rooms? Why bother with the roof? In my opinion, a different roof pitch is much more complicated. Why not simply put a long dormer at the top and thereby create space for two rooms? Simply a dormer across the entire roof side is, to my knowledge, not just allowed like that, but an architect knows how to convince the building authority to get it approved.

A carpenter says that the extension will roughly cost between 100-150k.

Then talk to him about your options, financially and structurally. For that money, he should present you with some cool solutions. PS, in terms of space you basically have a town villa, just buried.

Why then a 100% solution? What, for example, stands in the way of converting the existing basement rooms? Why the effort with the roof? A different roof pitch is, in my opinion, much more complicated. Why not simply put a long dormer at the top and thereby create space for two rooms? As far as I know, a dormer over the entire roof side is not just allowed like that, but an architect knows how to present it to the building authority to get it approved.

We thought it’s either all (adding a floor) or nothing at all (just the too small ground floor). We have also considered dormers, but that would cost us a lot of space for the photovoltaics. However, we are keeping an option open for an OOrion. Regarding the basement rooms, we have also considered it, but it only protrudes 90 cm from the ground and is therefore quite dark. It would be possible to replace the small basement windows with larger ones and dig a light well. It is still unclear whether it would be approved as living space. We also didn’t agree on which room would be down there. An office is acceptable, but a bedroom or children’s room was ruled out so far.

It would be possible to replace the small basement windows with larger ones and to dig a light well.

yes, that would be a solution.

Then it remains open whether it will be approved as living space.

Why? Do you want to enlarge to sell? You don’t have to ask the building authority if you are allowed to stay there. If you can get light and ventilation in there and – I assume the basement is heated – then you can create nice living spaces. At least an office and bedroom could be developed there.

And dormers could also be placed on the other side, opposite the sun…

yes, that would be a solution.

Why? Do you want to enlarge in order to sell? You don't necessarily have to ask the building authority if you are allowed to stay there. If you can get light and ventilation in there and - I assume that the basement is heated - then you can create nice rooms to stay in there. At least an office and a bedroom could be developed there.

And dormers could also be on the other side, opposite to the sun...

No, enlarge to move in :) Good point that we don't necessarily have to ask. It is partially heated. Let's see how it would be with conversion to underfloor heating and heat pump. But I think an electric heater would also do for the office.

Regarding dormer. Currently there is only a pull-out staircase. If we were to use the attic, we would need a staircase that ideally runs above the basement staircase. But then you can't go up because the roof is right there :D so two dormers

What we are also considering is an extension toward the street. So to extend the whole house by x meters