Introduction and first question!

Hello everyone, I would like to introduce myself before my first question. My name is Athuro and I live with my wife and our children in Hamburg. We are about to start building our single-family house (without a basement) in Bauhaus style and are facing an important decision. Two days ago, we had an appointment with the surveyor and our general contractor's site manager. The height of the finished floor (top edge of the finished floor) was defined in relation to the center of the street. The street is slightly sloping, meaning at the higher end we would be 20 cm above the street, and at the lower end about 38 cm above the street, always referring to the top edge of the finished floor. The garage at the lower end would stand slightly lower than the house because it is not allowed to be built higher than 2.75 m due to the boundary construction. My question is: Is 20 cm enough for the house? It would be nice because the plot slopes to the back as well, and otherwise we would have problems with garden landscaping, but the most important thing for me is a permanently dry house (foundation). If I understood the site manager correctly, then the ground/foundation will probably be constructed as follows: floor - 17 cm screed - 20 cm base slab - 10 cm insulation - approx. 80 - 100 cm sand. The thickness of the base slab might be slightly increased because the structural engineer still wants to wait for a second soil report. I hope I was able to express myself somewhat clearly, and I hope you have an idea about this. Best regards and happy Easter [Athur0]

It is the same with us, our finished floor level is also "only" 20" cm above street level. Everything is properly sealed and has been working without any problems so far.

Hello Athuro,

Two days ago we had an appointment with the surveyor and our construction manager of the general contractor. The height of the finished floor (top edge of the finished floor) was defined in relation to the center of the street. The street slopes slightly, i.e. at the higher end we would be 20 cm above the street, and at the lower end about 38 cm above the street, each time referring to the top edge of the finished floor. The garage at the lower end would be slightly lower than the house because it may not be built higher than 2.75 m due to the boundary development. My question is: Is 20 cm sufficient for the house?

Why 20 cm? Is this already the result of the weighted average or does it still need to be calculated from both values? Then the house would stand 29 cm “high” in the middle and then less towards the higher and lower ends. And why is this average determined on the property and not in the construction plan discussion before the start of construction?

It would be nice because the property slopes to the back as well, and otherwise we would have problems with the garden design, but the most important thing for me is a house that stays dry in the long term (foundation).

20 cm means roughly one step; that is enough to lead water away from the house, i.e. past the floor slab.

If I understood the construction manager correctly, the floor/foundation will probably be constructed as follows: floor - 17 cm screed - 20 cm base slab - 10 cm insulation - approx. 80 - 100 cm sand. The thickness of the base slab might be a little thicker as the structural engineer still wanted to wait for a second soil report.

The construction manager certainly mentioned gravel or crushed stone; sand would be bad because it is not load-bearing ;) Why a second soil report?

Regards from the Rhineland

: many thanks for the quick response! @ Building expert: the angle brackets are now all at the top edge of the finished floor, 20 cm above street level, measured at the highest point of the street. If I understood correctly, the top edge of the finished floor, as you described, is 38 cm above the street at the lower end of the house and 29 cm in the middle. On-site appointment, because we wanted to assess the entire site at once, as we want to have a lowered living area at the back. Now you are making me a little worried: I am pretty sure about the sand, but I also read something about a fine grading by the earthworks contractor! Can that work well with good compaction? Unfortunately, I realized too late that a studded membrane is supposed to be used as a cleanliness layer! Does that work in combination with the insulation? Or is it better to accept extra costs for concrete? 2. Soil report because the first one was done before the demolition, and now more points should be measured, but it is included in the price, so no price gouging! Many thanks for the effort, best regards from the North