ᐅ Looking for lightweight screed for underfloor heating – any experiences?
Created on: 5 Oct 2018 15:18
M
MarkusW.Hello everyone,
I hope you can help me as I’m currently stuck in a dead end.
We are carrying out an extension to the upper floor of our house and have completely gutted the top floor and rebuilt it with a higher knee wall. Dry screed was used originally, but we have removed that entirely because we want to install a water-based underfloor heating system.
The house was built in the 1980s, and unfortunately, the ceiling wasn’t made very strong back then. In our case, it is a hollow block ceiling.
My problem lies with the floor construction—namely the screed, underfloor heating, and floor covering—because according to the structural engineer, I am only allowed to load the ceiling up to 100kg/m² (20.5 lb/sq ft) for the floor build-up.
My initial plan was to first apply a layer of lightweight screed (a mix of Styrofoam and cement) to level the floor completely. Then install the underfloor heating and finally cover it with cement or anhydrite screed at the appropriate pipe coverage.
Unfortunately, this results in a weight of about 120–130kg/m² (24.6–26.7 lb/sq ft) for the floor construction, and my structural engineer won’t approve this.
There are options to make the screed mix stronger with additives so that the pipe coverage above the underfloor heating can be reduced, but I have already maximized this.
My argument to the structural engineer that we won’t use tile covering but rather glued vinyl flooring throughout the apartment (which saves about 23kg/m² (4.7 lb/sq ft) of weight) didn’t convince him either.
So now I need a lighter alternative…
One thing is important to us—a good impact sound insulation to the floor below. This was also a reason why we removed the already installed dry screed—the impact sound insulation was terrible.
Here is what I have been thinking, and I’m curious to hear your opinions:
Question: Has anyone had experience with this? It seems to me this thin-layer screed is very expensive!
I don’t want to work with leveling aggregate myself, so I want the lightweight screed professionally applied for leveling—this way I won’t have problems with an uneven floor and can simply lay the dry screed on top.
Question: I’m concerned that the impact sound insulation might be poor again. There are special insulation mats made of a Styrofoam-like material that can be placed between the lightweight screed and the underfloor heating, but I’m unsure how effective these are.
General question:
What are your experiences with lightweight screed (e.g., Thermozell Rapid or Thermobound Rapid) in terms of impact sound insulation?
Thank you very much for your help.
I hope you can help me as I’m currently stuck in a dead end.
We are carrying out an extension to the upper floor of our house and have completely gutted the top floor and rebuilt it with a higher knee wall. Dry screed was used originally, but we have removed that entirely because we want to install a water-based underfloor heating system.
The house was built in the 1980s, and unfortunately, the ceiling wasn’t made very strong back then. In our case, it is a hollow block ceiling.
My problem lies with the floor construction—namely the screed, underfloor heating, and floor covering—because according to the structural engineer, I am only allowed to load the ceiling up to 100kg/m² (20.5 lb/sq ft) for the floor build-up.
My initial plan was to first apply a layer of lightweight screed (a mix of Styrofoam and cement) to level the floor completely. Then install the underfloor heating and finally cover it with cement or anhydrite screed at the appropriate pipe coverage.
Unfortunately, this results in a weight of about 120–130kg/m² (24.6–26.7 lb/sq ft) for the floor construction, and my structural engineer won’t approve this.
There are options to make the screed mix stronger with additives so that the pipe coverage above the underfloor heating can be reduced, but I have already maximized this.
My argument to the structural engineer that we won’t use tile covering but rather glued vinyl flooring throughout the apartment (which saves about 23kg/m² (4.7 lb/sq ft) of weight) didn’t convince him either.
So now I need a lighter alternative…
One thing is important to us—a good impact sound insulation to the floor below. This was also a reason why we removed the already installed dry screed—the impact sound insulation was terrible.
Here is what I have been thinking, and I’m curious to hear your opinions:
- Apply about 80mm (3 inches) of lightweight screed to reach the required floor build-up height. Then install a thin-layer underfloor heating system and cover this with a special thin-layer screed. This screed requires a pipe coverage of only 5–10mm (0.2–0.4 inches).
Question: Has anyone had experience with this? It seems to me this thin-layer screed is very expensive!
- Apply about 60mm (2.4 inches) of lightweight screed to reach the floor height. Then install an underfloor heating system designed for dry screed, and lay the dry screed on top.
I don’t want to work with leveling aggregate myself, so I want the lightweight screed professionally applied for leveling—this way I won’t have problems with an uneven floor and can simply lay the dry screed on top.
Question: I’m concerned that the impact sound insulation might be poor again. There are special insulation mats made of a Styrofoam-like material that can be placed between the lightweight screed and the underfloor heating, but I’m unsure how effective these are.
General question:
What are your experiences with lightweight screed (e.g., Thermozell Rapid or Thermobound Rapid) in terms of impact sound insulation?
Thank you very much for your help.
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