because much less can be done with large machines
Like what, for example? I can’t think of anything typical that would be done and require large machines that you couldn’t regularly use on the property.
I find the 650k or 500k pretty steep even by southern German standards; there must be more than just a bit of "playing around" in there and probably also more "outdoor facilities" than is usually associated with a new build. Or is that including the purchase price?
We’ve (almost) finished the little 185m² shack from ’39. Terrible backlog of renovations and completely "botched" with various unauthorized extensions on the house and the property.
The demolition produced about 180 cubic meters of construction debris, wood, and waste (and some asbestos) and was carried out step by step in parallel with the planning by ourselves with active help from friends in volunteer work (the last debris container is still there).
Inside, we turned a bit over 16 rooms into 9 (sometimes steel beams or concrete lintels were necessary), enlarged all window and door openings and equipped them with new lintels, and excavated and poured a new slab in the part of the house without a basement. We restructured and re-roofed part of the roof and replaced the wooden beam ceiling. The sewage system on the property was renewed and the "garden" superficially redesigned.
Costs for this: about €5,000 for tools and "miscellaneous" (food, respiratory protection, chisels, sandpaper, garbage bags, etc.), another €9,000 for disposal (including €1,500 for night storage heaters), and ~€35,000 for craftsmen and materials. Estimated time for own work about 1,200 man-hours.
Professionals would probably have done it much faster; we were dumb and inexperienced (and drank too often on the job ). But apparently, especially for desk workers, it triggers some kind of happiness if you hand them a sledgehammer.
In the end, only the remaining masonry was left with a fortunately only 15-year-old roof on it (and the staircase stayed intact). Of course, we also thought about (even in between) just tearing everything down but decided against it because we wouldn’t have been allowed to rebuild the house in this form and size and it probably would have cost a lot more.
On the one hand – and here I have to contradict – the KFW funding for old buildings is already pretty generous, at least for builders who plan to tackle everything anyway. We insulated the basement ceiling and the screed, the sloping ceilings on the upper floor, and the top floor ceiling and will soon have blown insulation added to the cavity walls. Together with a new gas condensing boiler, new windows, and controlled residential ventilation, that’s enough for a KFW Efficiency House 100.
Since the boiler, windows, and controlled ventilation were planned anyway and we would have insulated something in any case, the actual extra costs for the basement ceiling and doubling the rafters on the upper floor amount to just ~€3,500 and 3 long Saturdays. Admittedly, the cavity wall insulation was luck for us.
For that, we got €100,000 at 0.75% interest and a €15,000 repayment grant. Additionally, we were able to have a bunch of already pending measures like the new front door, driveway, or barrier-free shower funded via the "Age-Appropriate Renovation" program, which gives up to another €5,000 "cashback." And the highly recommended energy consultant’s costs are subsidized by 50%.
On the other hand, if I compare our fittings with those of friends in new builds with a similar budget, I would say that overall we could afford a bit more (30m² more living space, parquet with underfloor heating throughout the house, central vacuum system, water softener, ridiculously expensive bathrooms, fireplace, 40m² veranda with large whirlpool, technical gadgets, various built-in furniture, etc.) and on top of that sit right in town on 1,000m² of land (property tax about €150).
All in all, by the end, we will have spent €430,000 for purchase and renovation but, of course, did a lot of work ourselves and saved on an architect (the latter should be considered carefully!). And naturally, craftsmen here in the countryside are still a bit cheaper than in metropolitan areas.
It was (is!) sometimes quite a stressful affair, but I would do it again that way. Demolition and new construction without own work I would have estimated at all in at around €600,000, and paying that off in the long term would have come at the expense of our family time and wouldn’t have been as much fun.