ᐅ Interpreting Structural Calculations for a Garage (Reinforcement…) Correctly

Created on: 11 Aug 2025 14:51
I
Ilchbart
Dear all,

We have an old house (built in 1924 with an extension from 1994) and always too little space (5–6 people)!
Therefore, a second garage is planned, which I want to build together with my neighbor (a mason).
The structural calculation is available; I wanted to order the materials tomorrow, but unfortunately, the structural engineer is now on vacation.
Could you please tell me based on the photos how many reinforcement mats I need for the ceiling and exactly where they should be placed? Neither the mason nor the building materials supplier could give me a definite answer. So I hope you can help me.

Thank you very much!
Technische Seite Stahlbetondecke Feld 1 mit Auflagern A/B Länge 3,50 m Diagramm und Tabellen

Technische Berechnungsseite mit Tabellen zu Biegung, Querkraft und Bewehrung (Feld 1: Q335A).

Technische Zeichnung: Längsbewehrung (Q335A) mit Diagramm oben/unten und rotem Bewehrungsbereich.

Grundriss einer Garage mit Bewehrung, Stahlbetondecke, Abmessungen ca. 3,5 m, Neubau Garage.
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Ilchbart
18 Aug 2025 04:44
…I’m not sure what to make of your statement if you don’t explain how it is supposed to be. Tiles will be installed on the ceiling, as it will be walkable. Maybe that’s why it was written that way?
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ajokr2025
18 Aug 2025 08:13
The critical area is the underside, where the structurally required reinforcement is located.
Here, XC3 - applicable for open halls and garages - applies. Therefore, an additional one centimeter (0.4 inches) of concrete cover should be provided on the underside.
However, the reinforcement is still sufficient because the calculation was done for one-way bending, while the slab actually rests on all four sides, and a Q-mat was chosen instead of an R-mat.
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HWTIGGER
20 Aug 2025 14:47
The answer regarding the Q-mats could indeed be correct (not recalculated), but this only applies if the joints of the mats are designed as load-bearing joints (approx. 3 mesh overlaps), which has not been specified.
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Ilchbart
12 Sep 2025 20:11
Ok, thank you. We will take your suggestions into account.