ᐅ Building with different types of bricks than those specified in the approved plans and structural calculations

Hi, I have the following question:
We originally planned to build our new house using T9 Poroton bricks, 36.5cm (14.4 inches) thick, which would be approved, and the structural engineering and thermal insulation calculations would be prepared accordingly.
Now we have received a proposal to build the house using aerated concrete blocks ytong.

My question is, would the structural engineering and thermal insulation calculations need to be redone in this case?

Hi,

yes.

The bricks are obviously important for structural stability and thermal insulation. Other properties require a new calculation.

If the wall thickness, strength class, and thermal conductivity are the same or better, in my opinion this should be possible without structural calculations or a new thermal insulation assessment.

Usually, the documents state "or equivalent."

RomanRot schrieb:

Originally, we planned to build our new house using T9 Poroton bricks, 36.5cm (14 inches) thick, which would also be approved, with the structural engineering and thermal insulation calculations prepared accordingly.
Now we have been suggested to build the house with Ytong aerated concrete blocks.

Who even makes such a suggestion—some random colleague at the lunch table who enjoys unsettling others with their amateur knowledge?
There is no "philosopher’s stone" or "devil’s stone." In absolute terms, no brick has properties that would require warning against it or make you particularly lucky for discovering the "secret solution." However, relatively speaking, every brick is "problematic" if the builder has little experience with it. Differences in other properties mean that connections to other building components have to be made differently than what is practiced a thousand times over, and with that, the seemingly minor advantages of the other brick come at the cost of potential defects arising from less practiced workmanship. Often, changing the brick also involves changing the contractor. What’s your expert’s answer to that?
Be glad that you have received the building permit/planning permission, and don’t let well-meaning distractions throw you off course.

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icandoit schrieb:

If the wall thickness, strength class, and thermal conductivity are the same or better, in my opinion this should be possible without structural engineering or a new thermal protection calculation.

Usually, the documents say "or equivalent."

Great, that’s exactly how our energy consultant and structural engineer responded to me.

Thank you all.