Renovation of an old building from 1969

Hello So the facade is clinker brick and there is a 7cm gap between the clinker and the masonry. Two test drillings with camera inspection have already been done. That’s why I thought about blown-in insulation, because I don’t want to visually alter the facade. Two craftsmen told me I should rather take double glazing instead of triple glazing because of mold. But I think there is a lot of myth involved. An energy consultant (not commissioned) said I should take triple glazing. The roof is a hip roof. It should only be walkable up to the chimney. The height there is only 2m and therefore not usable as living space. The basement height is 2.10m That’s why I thought about basement ceiling insulation. I got an offer for milling. It was for 100sqm including material and sealing at 2500€ incl VAT. The current floor structure is only 4cm thick. If I tear it out and remake it, I will certainly be a good deal higher with insulation and underfloor heating. And then the doors would have a lower clearance height. That’s why my thought with milling. And probably it is also 10k cheaper. My cousin is responsible for the heating design. He is a plumber. His statement was: Leave the oil heating as it is. It will easily last another 20 years. In the meantime, heat pumps will get cheaper or might no longer exist. (He is not a big fan of those things because he thinks that defective heat pumps have to be replaced from time to time and it always gets quite expensive for the customer). Photovoltaic system on the roof is not planned for now, because the money is a bit tight ;)

So the facade is brick-clad and there is a 7cm air gap between the brick and the masonry. Two test drillings with camera inspection have already been done.

So from outside to inside: 115mm brick, 70mm air layer, and only 118mm load-bearing masonry? Rather unusual for the time. I’ll believe it when I see it (my own house is also that old with brick, but it wouldn’t stand if there were also 70mm air layers present).
But then blown-in insulation makes sense.

Two craftsmen told me I should rather use double glazing instead of triple glazing because of mold. I think there is a lot of myth involved. An energy consultant (not hired) said I should use triple glazing.

Not much myth. Pure myth. The connection is not between the glazing and mold, but rather new and airtight windows and mold. With proper work, you also consider the reveal, which you can insulate, for example, with a thin reveal board (if the plaster is off anyway).

The cellar height is 2.10m, so I was thinking about cellar ceiling insulation.

Ok. Still don’t use styrofoam. If you can’t insulate on the ceiling, then at least from below in the cellar. 12cm PUR should be the minimum.

I received an offer for milling. It was for 100sqm including material and sealing at €2,500 including VAT.
The current floor structure is only 4cm thick. If I tear it out and redo it, I will certainly be quite a bit higher with insulation and underfloor heating. And then the doors would have a lower passage height. That’s why I thought about milling. And probably it’s also about 10k cheaper.

What exactly does "including material" mean?
At 4cm floor structure, I personally wouldn’t have it milled. The raw floor is probably not perfectly even, so you might have only 3cm in places. If milled, then at least 16mm deep with a minimum screed thickness of 40mm. You take a big risk that it can or will crack in several or many places.
By the way, 120sqm screed (60mm) only cost me €2,500 (including accelerator so the screed was ready for covering after a few days). Removing it took a Saturday and a helper. But everything was new— you’ll have to remove the floor covering anyway. If it’s really only 40mm, then you have to keep your fingers crossed tightly!
Oh, and the spacing of the pipes is quite wide with milling; with normal installation you can lay the pipes much closer together so that the heating runs more efficiently (also with regard to heat pumps).

My cousin is responsible for sizing the heating. He’s a plumber.

Nothing against plumbers. But with milling, there is not much planning involved. And you don’t have a normal underfloor heating designed by a plumber, because they usually work roughly by rule of thumb or "we have always done it this way." For that, you go to a specialist (costs only €200).

Actually, the floor would be done by an external company. The offer includes the piping system and then a flowing screed. It would be milled at intervals of 12.5 cm. Who else does such a planning? I had an offer for pouring screed with the material for underfloor heating (insulation and pipes) for 11,000 euros. And then there is the disposal.

So actually, the floor would be done by an external company.
The offer includes the pipe system and then a flow screed.
It would be milled at intervals of 12.5cm.
Who else does such planning?
I had an offer for pouring screed with the material for underfloor heating (insulation and pipes) for 11,000 euros. And then there’s the disposal.

12.5cm as an average is not up-to-date, especially in not so well insulated old buildings. But sure, it fits with oil heating at high temperatures.
An offer for screed + underfloor heating is already steep...

Who does such planning? A MEP planner or an engineering office does that. You don’t just need the heating design. Beforehand, of course, a room-by-room heating load calculation has to be done (results primarily depend on building fabric, insulation measures, floor covering, desired temperature). Based on that, the heating is designed (with possible supply/return temperatures) and you get a laying plan for the underfloor heating pipes.

DIYers often go to engineer Heckmann. Just google for him – links are forbidden here under threat of the death penalty.

P.S. Disposal at the recycling center or similar is often free of charge.

Currently, there are still different options for funding renovations. 1. KfW 261 Renovation to energy-efficient house, low-interest loan and repayment grant, energy consultant required who is funded with 50 percent 2. Depending on which federal state you live in, there are also low-interest promotional loans for modernizations (e.g. NRW.Bank). Just Google it

In addition, there is funding for individual measures, which is currently widely discussed as the "Heating Act" or part of the "BEG". With these, you receive part of your investment back as a grant. The conditions for next year still need to be finally decided. Apparently, applications will be possible from 02/27/24...

That’s what immediately comes to mind regarding funding. Otherwise, energy consultants always have an up-to-date overview of funding.

2 trial drillings with camera inspection have already been carried out.

I can't help but point out again that this is rather not the approach of a seasoned expert ;-)

So the facade is tiled and there is 7cm of air between the brick and the masonry.

That may well be the case, although it puzzles me here. With a construction masonry shell of around 175, as is modern today with ETICS, that is indeed possible. Well, if the fact is certain, then blown-in insulation may be acceptable here.

I have received an offer for milling in. This was for 100sqm including material and sealing at €2500 incl. VAT.
The current floor construction is only 4cm thick. If I tear it out and rebuild it, I will certainly be a good deal higher with insulation and underfloor heating. And the doors would then have a lower passage height. That’s why I am thinking about milling. And presumably it would also be about €10k cheaper. [...] I had an offer for pouring screed including materials for underfloor heating (insulation and pipes) for €11,000. And then there is the disposal.

The providers of such alternatives know the prices for classical procedures exactly, and their most convincing argument is that they want only a fraction of that cost. Regarding the height, I follow your line of thought. However ...

With a 4cm floor buildup, I personally would not have milling done. The raw floor is probably not perfectly level, so you might sometimes only have 3cm. If milling is done, then at least 16mm deep with a minimum thickness of 40mm for the screed. You are creating a high risk that it may break in several or many places.

... I tend to think (myself a construction consultant almost exclusively for new builds, but my master craftsman has built a lot on existing buildings) more like this: screed can be 4, maybe in some spots only 3 cm thick. After milling, what remains is a moderately stable layer, which only regains stability through grouting. Overall, this is usually questionable, viable as an emergency solution in special cases, but then not cheaper!

My cousin is responsible for the heating design. He is a plumber. His statement was: Just leave the oil heating as it is.
It will easily run for another 20 years. In that time, heat pumps will get cheaper or might no longer even exist. (He is not a huge fan of those things because he thinks that they always need to replace a defective heat pump from time to time and it always gets quite expensive for the customer).

I certainly would not have this person plan my heating if the measure is supposed to be sensible. Personally, I have no special expertise in heating, ventilation, and air conditioning and refer my clients to the corresponding experts – but never to those whose statements about certain technologies sound like hearsay. Of course, a professional always has, alongside knowledge, an opinion, and indeed not all technologies are equally good. Heat pumps currently enjoy a much higher popularity than the number of competent installers available. Naturally, these units often do not operate optimally—already because, in connection with the skilled labor shortage, they are often calibrated by plumbers who are only moderately familiar with them. Go to two other heating engineers and ask them—openly stating that there is a tendency for the contract to be awarded within the family—for their second opinion. The only point where I agree with him is not to prematurely retire the boiler. But precisely for that reason, you need a heating system that is planned neutrally. Have an alternative developed that does not require the switch to underfloor heating.

Do you have a (experienced in existing buildings!) planner for your renovation?
From the community, I call in ( is already here) also ( unfortunately I haven’t read in ages).