House made of concrete without additional insulation - monolithic

House made of concrete without additional insulation - monolithic

Hello everyone,

We would like to develop a hillside plot (18m * 70m). The plan is to build a single-family house over two floors (basement and ground floor) with about 200 sqm plus an approximately 100 sqm granny flat in the attic. The building will have an almost 100% south orientation.

We have looked at show homes in Bad Vilbel. However, due to the "extreme" hillside location (in combination with the narrow plot), we decided to hire an architect. The first floor plan is already available.

My question specifically concerns the construction method. We prefer a house with exposed concrete. Both the exterior and most of the interior concrete should remain untreated. For example, the living, dining, and kitchen areas should only have a wooden floor, and the walls and ceilings remain concrete, whereas the children's rooms will be plastered or wallpapered.

One proposed option is that the exterior walls are constructed as follows: concrete / insulation / concrete. The alternative is a monolithic concrete wall. This is made of lightweight concrete containing expanded clay balls to increase thermal insulation and storage. The walls are therefore very thick (50-60 cm). Searching online, you can find this under terms like insulation concrete, Liapor concrete, lightweight concrete, etc.

In single-family house projects found, the following was used for the exterior walls:

a) Liapor lightweight concrete LC8/9 of the density class D1.2 and exposure class XC4, XF1 / wall thickness 50 cm / U-value 0.68 W/m²K

b) Liapor lightweight concrete LC8/9 with the density class D1.1 and exposure class XC4, XF1 / wall thickness 50 cm

This house was also shown on TV (Stefanie and Boris Alexy in Bad Kohlgrub)

c) Liapor insulation concrete with grain size 0/8 millimeters with F3 4/8 millimeters and Liaver expanded glass 1-4 millimeters / wall thickness 45 cm / formwork work in four days / lambda 0.32 W/mK

(Urs Sigrist "maison art" in St. Erhard)

What I unfortunately cannot find are costs for this construction method. I hope this is not a bad sign J.

What costs can be expected? To me as a layman, it seems like a relatively inexpensive construction method. The formwork is done in a short time, no additional insulation, no plastering or brick facing necessary outside, and inside partly no plastering, wallpapering or painting of walls and/or ceilings.

Thank you very much!

Where do you want to build? In Seligenstadt there is such a house, built by architects from Aschaffenburg. Concrete inside and out, narrow and long. A real eye-catcher, more details via DM.

Construction is to take place in the beautiful Rheingau
Thank you very much for the tip. Seligenstadt is not too far away and a visit could be worthwhile.

Hello! Is there any news about the project? We have exactly something like that planned as well and mentioned it at our appointment with the architect... he is very impressed by it. Regarding costs, I believe I heard that it is not more expensive than with bricks.... I would be happy to hear something..

We basically built exactly the design with the architect that you planned. Except for the fully plastered children's rooms, the entrance area as well as all ceilings are in exposed concrete. In the living/dining/kitchen area, it is a mix of plaster and large exposed concrete walls. As a contrast, large wood-aluminum windows and oak parquet have been installed. Partition walls are made of brick. However, we have a normal exterior insulation with plaster.

I would not claim that concrete is cheaper than brick walls. Rather the opposite. Processing concrete correctly in exposed quality is very difficult and above all requires a company that masters it 100%.

For exposed quality inside and outside, there are so many factors to consider with concrete that higher costs are to be expected. These include, for example, test runs to see whether the concrete surface corresponds to what one imagines. The formwork elements and boards must or should be new/nearly new. The concrete should come from one batch if possible. The climatic conditions as well as the duration the concrete remains in the formwork influence the final result.

Any savings brought by the faster construction method with concrete quickly disappear if the concrete is given its final coating. This is called hydrophobing (water-repellent). Especially sensible on the outside. The agents do not change the feel or appearance but cost quite a lot of money. Also, rework such as light sanding and cleaning must be factored in.

Exposed concrete is great and an excellent material – no question. But the complexity of processing must not be underestimated.

Very interesting in this regard is the information sheet for exposed concrete buildings from betonsuisse. Just google it. In this otherwise quite good forum, for some shady reasons, links to other sites are apparently not welcome. Otherwise, I can gladly send the link via PM.

Best regards

Thank you very much for the detailed response and the reference to the information sheet from [betonsuisse]! Can you specify how high the production costs per m² were in your case? Best regards