ᐅ Aerated concrete solid roof designed as a pyramid roof on an urban villa

Hello everyone,

I have been following this forum for a while, and now we are finally starting our house construction. Currently, we are planning a townhouse (external walls made of 42.5cm (17 inches) aerated concrete, interior walls of sand-lime brick) with two full floors on a plot located in the second row, about 100m (328 feet) straight line from the pedestrian zone.

Townhouses are usually built with a 22-degree roof pitch and a hipped roof. Our idea for the roof is a 35-degree pyramid roof with a solid aerated concrete roof structure and 2 to 3 roof windows. Why this choice?

Firstly, we want to keep the option open to expand the attic in about a year to add an office and another child’s room, which is why we prefer a 35-degree pitch instead of 22 degrees. Secondly, due to the dense development around us, sound insulation is an important factor, and a photovoltaic system is firmly planned. According to a friend who is an architect, when the roof type can be freely chosen, a solid roof is preferable for both soundproofing and radiation protection reasons (especially regarding the photovoltaic system).

According to Ytong, any roof shape can be constructed as a solid roof. So far, in my research, I have mostly only found solid roofs as gable roofs. Does anyone here have experience with a solid pyramid roof and could possibly share photos? And does this approach make sense as we have imagined it?

If it matters, we are still undecided about the upper floor ceiling, whether to go with a wooden beam ceiling or a concrete ceiling.

Greetings from the Ruhr area

We are not familiar with your planned house and therefore lack many details that you might be underestimating in their importance. A hip roof combined with photovoltaic panels initially sounds like a less than ideal combination—or maybe not? This largely depends on whether this design actually creates pitched roof surfaces on the sides that are well positioned for solar panels. An aerial photo would be helpful, as well as cadastral maps or similar documents. How much knee wall height is possible or planned?

Amel_NRW schrieb:

If it matters, we are still undecided about the upper floor ceiling: either a wooden beam ceiling or a concrete slab.

Regarding the structural engineering of a roof frame, you don’t seem to have extensive knowledge—at least you realize it could be important. It would be sensible to provide much more information about the house and the plot. Without that, it is neither possible to give useful advice nor to answer the seemingly simple question of how a solid hip roof could be constructed here. What is the reason against a more expandable gable roof or a shed roof, which are often much more amenable to future extensions?

---

https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/

In my opinion, an architect who wants to build a concrete roof for radiation protection reasons belongs in a mental institution.

apokolok schrieb:

In my opinion, an architect who wants to build a concrete roof for radiation protection reasons belongs in a madhouse.

I think that's good. At least as a resident, you can take off the tin foil hat at home

apokolok schrieb:

An architect who wants to build a concrete roof for radiation protection reasons, in my opinion, needs professional help.

Hahaha, that made me laugh too. I’ve been following this forum for about 1.5 years and have learned a lot, but the whole radiation argument struck me as odd as well.
My first thought was: With so many photovoltaic systems in the country, either most people would have concrete roofs, which is definitely not the case, or the risk is exaggerated, which seems to be the situation here.
In any case, even considering possible radiation protection aspects, I wouldn’t pay extra for a solid roof.
What about other factors like sound insulation and airtightness with a solid roof?
As an amateur, I would guess there are advantages in airtightness compared to a conventional roof construction, but I lack experience to assess the sound insulation.

11ant schrieb:

We don’t know your planned house or many details that could be relevant and maybe are underestimated by you. A hip roof with photovoltaics sounds like an unwise combination at first—or maybe not? That largely depends on whether this creates suitably angled roof surfaces on the sides that receive good sunlight. An aerial photo would be helpful, as well as cadastral maps or similar. How high is the knee wall or what is planned?

Regarding the roof structure’s statics, you don’t seem to have extensive knowledge—at least you realize it might matter. It would be sensible for you to share significantly more about the house and the plot. Without that, it’s impossible to offer optimized advice or even answer the seemingly simple question of how to construct a solid hip roof here. Why not choose a gable roof or a shed roof, which are not only simpler but also much more suitable for future expansion?

Regarding the gable roof, we also see the advantages of easier expansion and simpler roof construction.
What spoke against it: The appearance of a city villa with a gable roof does not look good with a square footprint of 10 x 10m (33 x 33 ft), and we have to stay within a 10 x 10m (33 x 33 ft) building envelope.
The same “tinfoil hat” architect said that distributing the photovoltaic system on east, south, and west sides of a hip roof would provide a steady daily energy yield.
Attached is the requested aerial photo showing the approximate arrangement of the building. We have no information yet about the knee wall; only that the planned hip roof has a 50 cm (20 inch) roof overhang. The development plan allows 2 full stories and pitched roofs (GD = geneigte Dächer), with no specified ridge or eaves heights.

Amel_NRW schrieb:

And the same conspiracy theorist architect said that distributing the photovoltaic system over the east, south, and west surfaces of a pyramid roof would ensure a consistent daily yield.

I agree that the yield is indeed nicely even. The 70% rule doesn't really hurt either.