ᐅ Concrete house without additional insulation – monolithic

Concrete House Without Additional Insulation – Monolithic

Hello everyone,

We are planning to build on a sloped plot of land (18m (59 feet) * 70m (230 feet)). The project is a single-family house over two levels (basement and ground floor) with about 200 sqm (2,153 sqft), plus an approximately 100 sqm (1,076 sqft) secondary apartment in the attic. The building will face almost 100% south.

We have visited model homes in Bad Vilbel. However, due to the “extreme” slope of the site (combined with the narrow plot), we decided to work with an architect. The initial floor plan is already available.

My question is specifically about the construction method. We prefer a house with exposed concrete. Both outside and mostly inside, the concrete should remain uncovered. For example, the living, dining, and kitchen areas would only have a wooden floor, while the walls and ceilings remain concrete. On the other hand, the children’s rooms would be plastered or wallpapered.

One proposed option for the exterior walls is as follows: concrete / insulation / concrete. An alternative is a monolithic concrete wall made of lightweight concrete that contains expanded clay pellets to improve thermal insulation and heat storage. These walls are quite thick (50–60 cm (20–24 inches)). Searching online, you find related terms such as insulated concrete, Liapor concrete, lightweight concrete, etc.

For the exterior walls in some single-family house projects, the following materials were used:

a) Liapor lightweight concrete LC8/9 with a bulk density class D1.2 and exposure classes XC4, XF1 / wall thickness 50 cm (20 inches) / U-value 0.68 W/m²K

b) Liapor lightweight concrete LC8/9 with bulk density class D1.1 and exposure classes XC4, XF1 / wall thickness 50 cm (20 inches)

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

c) Liapor insulated concrete with aggregate size 0/8 millimeters (0/0.3 inches) with F3 4/8 millimeters (0.15/0.3 inches) and Liaver expanded glass 1–4 millimeters (0.04/0.15 inches) / wall thickness 45 cm (18 inches) / formwork work completed in four days / Lambda 0.32 W/mK

(Urs Sigrist “maison art” in St. Erhard)

What I cannot find are the costs associated with this type of construction. I hope this is not a bad sign J.

What kind of costs should be expected? As a layperson, this seems like a fairly affordable method: quick formwork, no additional insulation, no plastering or cladding required on the exterior, and partially no plastering, wallpapering, or painting needed indoors on walls or ceilings.

Thank you very much!

Where do you plan to build? In Seligenstadt, there is a house like that, designed by architects from Aschaffenburg. Concrete inside and out, narrow and long. A real eye-catcher, more details available via private message.

The house will be built in the beautiful Rheingau region.
Thank you very much for the tip. Seligenstadt is not too far away, and a site visit might be worthwhile.

Hello!
Is there any update on the project? We are planning something similar and mentioned it during our meeting with the architect... he is very enthusiastic about it.
Regarding costs, I believe I heard that it is not more expensive than building with bricks...
I would be glad to hear any news.

We basically built exactly the design with an architect that you planned.
Except for the fully plastered children’s rooms, the entrance area and all the ceilings are exposed concrete. In the living/dining/kitchen area, there is a mix of plaster and large exposed concrete walls. As a contrast, large wood-aluminum windows and oak parquet flooring were installed. Interior partition walls are made of brick. However, we have a standard external insulation with plaster.

I wouldn’t say that concrete is cheaper than brick walls. Rather the opposite. Properly achieving a high-quality exposed concrete finish is very difficult and requires a company that fully masters the process.

For exposed concrete quality both inside and out, many factors need to be considered, so higher costs should be expected. These include, for example, test runs to check if the concrete surface matches the desired look. The formwork elements and boards should be new or in like-new condition. The concrete should preferably come from a single batch. Climatic conditions and the duration the concrete stays in the formwork also influence the final result.

Any potential savings from the faster construction method with concrete quickly disappear once the concrete receives its final coating. This process is called hydrophobizing (water-repellent treatment), which is especially useful on exterior surfaces. The products used do not alter the feel or appearance but can be relatively expensive. Also, follow-up work such as light sanding and cleaning needs to be factored in.

Exposed concrete is great and an excellent building material—no question. But the complexity of the processing should not be underestimated.

A very interesting resource on this topic is the information sheet for exposed concrete structures by betonsuisse. Just search for it online. In this otherwise quite good forum, links to other sites seem to be unwelcome for some unclear reasons. If needed, I can also send the link by private message.

Best regards

Thank you very much for the detailed response and the reference to the information sheet from betonsuisse!
Could you specify the construction costs per m² (square meter) in your case?
Best regards