What Is This Concrete Material

72chevy4x4

some apartment buildings in my area were built with standard wood construction with a ~1.75" cement based product over the floor. The material was very light with no aggregate. A guy at my local concrete plant told me it was grout (1.3 or 1.4 mix).

Does anyone here know what it may have likely been?

Bob Kovacs

Sounds like gypcrete or one of the other self-leveling systems.

finehomes

yup...its gypcrete....required to meet fire code. Not sure why it would be so thick though. I've never had to do it more than .75".

72chevy4x4

have you noticed on older installations (this one about 20+ years) severely negatively effect the flooring system? I didn't pull a string on the floor, but the one area I checked parallel to the rim joist, had a 3/4" in 8" dip-not even close to the center of the room.

I quickly looked over the Gypcrete installation instructions, which calls for 3/4" installation. If this stuff is Gypcrete and it's installed at 1.5"+, I wonder if the floor system was designed for double the load? It sounds as if 1" is typical based on what you guys said.

One more question, if they use 3/4"-1" of gypcrete for fire protection, does it have to be a continous pour in the apartment or is it only poured inside of the partition walls? The installation I repaired, was inside the partition walls. Seems like a fire might burn out the partiation bottom plate/subfloor before breaking down the gypcrete.

kyle

here in FL i've seen the gypcrete used to level on top of precast hollowcore concrete slabs, i think some people call them hudi. The jobs i've seen it on, its poured over everything but after the drywall is up. is this common?

Dan_Watson

I just found it poured at 1 1/2" thinck in a 8 unit condo complex down at the Jesey Shore. It was used for "sound deadening".

CaliDesigns

They pour it 1 1/2" also when they incorporate radiant heat systems.

stevensmth89

I think it's gypcrete too.