Hi,
I've been googling and reading various forums for several days now without finding an answer to my question.
What I'm wondering about is the load-bearing capacity of a concrete floor slab in residential buildings. There are many threads about this, and new ones keep appearing. Most of them have similar questions, and the key point I've gathered is that 200kg per sqm is the standard.
But from where is this 200kg per sqm measured? For example, if you compare houses from the 1950s versus the 2000s, the construction is a bit different.
Modern homes are often built with prefabricated elements that are prestressed and then leveled with a thin layer of self-leveling compound to create an even surface for the finished floor.
Houses built in the 1950s were cast in place, and to achieve an even floor (and perhaps to soundproof against neighbors?), several cubic meters of sand were spread out, or a lighter fill material was used, followed by another non-load-bearing concrete layer on top.
In my view, the floors in 1950s houses are more heavily loaded from the start, which would mean that these 200kg per sqm do not apply. Or is it factored into the design that it should handle several cubic meters of sand/concrete? And then be able to support an additional 200kg per sqm in live load (people and furniture).
Or do older houses simply have less load capacity compared to new ones being built? What happens when self-leveling compounds are used in old apartments to lay new floors? Have we then eliminated the chance to have a family Christmas dinner because half of the people weight has been replaced with compound weight?
I've been googling and reading various forums for several days now without finding an answer to my question.
What I'm wondering about is the load-bearing capacity of a concrete floor slab in residential buildings. There are many threads about this, and new ones keep appearing. Most of them have similar questions, and the key point I've gathered is that 200kg per sqm is the standard.
But from where is this 200kg per sqm measured? For example, if you compare houses from the 1950s versus the 2000s, the construction is a bit different.
Modern homes are often built with prefabricated elements that are prestressed and then leveled with a thin layer of self-leveling compound to create an even surface for the finished floor.
Houses built in the 1950s were cast in place, and to achieve an even floor (and perhaps to soundproof against neighbors?), several cubic meters of sand were spread out, or a lighter fill material was used, followed by another non-load-bearing concrete layer on top.
In my view, the floors in 1950s houses are more heavily loaded from the start, which would mean that these 200kg per sqm do not apply. Or is it factored into the design that it should handle several cubic meters of sand/concrete? And then be able to support an additional 200kg per sqm in live load (people and furniture).
Or do older houses simply have less load capacity compared to new ones being built? What happens when self-leveling compounds are used in old apartments to lay new floors? Have we then eliminated the chance to have a family Christmas dinner because half of the people weight has been replaced with compound weight?
I think you're worrying unnecessarily; from the 1950s onwards, the sizing is so substantial that there are no risks. For example, if you use self-leveling compound and lay parquet, you might add 20-30 kg, and if it's during new construction, that weight is included in the sizing.
200 kg/m2 is not a breaking load but just the limit for suitable deflection.
Additionally, both materials and loads have safety factors that make them significantly oversized.
How do you plan to reach those loads?
Take a typical living room, for example, 25 m2. It can withstand 5000 kg in a serviceability limit state; the furniture might weigh 1000 kg if you have a piano and oak cabinet.
That means there is 4000 kg left for live load, which equates to about 50 people. That's quite a party
) on 25 m2.
200 kg/m2 is not a breaking load but just the limit for suitable deflection.
Additionally, both materials and loads have safety factors that make them significantly oversized.
How do you plan to reach those loads?
Take a typical living room, for example, 25 m2. It can withstand 5000 kg in a serviceability limit state; the furniture might weigh 1000 kg if you have a piano and oak cabinet.
That means there is 4000 kg left for live load, which equates to about 50 people. That's quite a party
) on 25 m2.Ok, I understand the weight added during leveling, but considering that there might have been several cubic meters of sand before, which weighs a lot, wouldn't that put you in a worse starting position? It's not often you level on sand, but consider a case with non-load-bearing concrete. Such a slab over 25 sqm might weigh somewhere between 2-4 tons? Then there isn't as much left over for other useful loads, or am I wrong?larsbj said:I think you're worrying unnecessarily if you're considering from the 1950s and onwards, the construction is robust enough that there are no risks. For example, if you use self-leveling compound and lay parquet, you might add 20-30 kg, and if it's new construction, that weight is already included in the design.
200 kg/m2 is not a failure load but just the limit for appropriate deflection.
In addition, both materials and loads have safety factors, which result in significant overengineering.
How do you plan to reach those loads?
Take a standard living room, for example, 25 m2. It can handle 5000 kg in serviceability limit state, and the furniture might weigh 1000 kg if you have a piano and oak cabinet. That leaves 4000 kg for people, which means about 50 people. That would be quite a party