ᐅ Screed with a "liquid" insulation layer—can a bathtub be installed directly on screed?
Created on: 6 Feb 2018 20:30
H
hyadenHello everyone,
we are building a semi-detached house through a developer and are currently working on the interior construction. During yesterday’s inspection, I had two major questions regarding the screed, and maybe someone here has some experience:
1) They plan to install a floating heated screed. So far, I know the screed build-up as:
- raw subfloor
- insulation layer as boards, e.g., extruded polystyrene boards
- tack coat layer, etc.
According to the company responsible for the interior work, instead of insulation boards, some kind of liquid insulation layer will be poured in (they couldn’t recall the name), which should be better than the boards because it spreads more evenly. However, when I searched for “screed build-up,” I couldn’t find any comparable construction methods. Can anyone comment on this, especially regarding impact sound insulation?
2) In the bathroom, where the bathtub will be installed, there are quite a few cables and pipes coming out of the floor, so there is little space. Therefore, the bathtub frame is planned to rest not on the raw subfloor but on the screed, which wouldn’t be a problem in terms of weight. Is that common practice? The air heat pump boiler and the equipment for the solar panels were oddly placed on extruded polystyrene boards as well, supposedly for sound insulation reasons, but I already find this a bit unusual.
Best regards
hyaden
we are building a semi-detached house through a developer and are currently working on the interior construction. During yesterday’s inspection, I had two major questions regarding the screed, and maybe someone here has some experience:
1) They plan to install a floating heated screed. So far, I know the screed build-up as:
- raw subfloor
- insulation layer as boards, e.g., extruded polystyrene boards
- tack coat layer, etc.
According to the company responsible for the interior work, instead of insulation boards, some kind of liquid insulation layer will be poured in (they couldn’t recall the name), which should be better than the boards because it spreads more evenly. However, when I searched for “screed build-up,” I couldn’t find any comparable construction methods. Can anyone comment on this, especially regarding impact sound insulation?
2) In the bathroom, where the bathtub will be installed, there are quite a few cables and pipes coming out of the floor, so there is little space. Therefore, the bathtub frame is planned to rest not on the raw subfloor but on the screed, which wouldn’t be a problem in terms of weight. Is that common practice? The air heat pump boiler and the equipment for the solar panels were oddly placed on extruded polystyrene boards as well, supposedly for sound insulation reasons, but I already find this a bit unusual.
Best regards
hyaden
Hello "hyaden".
The topic you are addressing here is a special one.
Liquid insulation layers, as you describe, are suitable for retrofitting insulation between rafters in the roof area or in double-layered lightweight wall systems.
Holes are drilled into the building component, and then a (admittedly effective) material (I will not go into detail here) is injected into the cavities.
However, these systems—regardless of the manufacturer—are not suitable as a compressive load-bearing base. Therefore, they must not be used under floor screeds! Please do not allow this procedure! The proposed construction method is non-compliant, as it does not conform to the generally accepted rules of the trade.
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The (excuse me) incompetence in planning and attempted execution is now evident in part 2.
A bathtub is always installed directly on the structural slab so that the load is transferred via a static building element. Floating screeds are not structural components!
In residential buildings, screeds on an insulation layer (for which I refer to the minimum thickness of 45mm (1.8 inches)) are suitable for loads up to approximately 250kg (550 lbs). However, in edge areas where the bathtub is to be placed, very different stress conditions occur within the screed layer under load.
This means that the screed will very likely crack sooner rather than later (provided you actually use the bathtub).
This planned approach is also unacceptable and should under no circumstances be carried out!
------------------------------------
Regards, KlaRa
(Expert office for floor damage)
The topic you are addressing here is a special one.
Liquid insulation layers, as you describe, are suitable for retrofitting insulation between rafters in the roof area or in double-layered lightweight wall systems.
Holes are drilled into the building component, and then a (admittedly effective) material (I will not go into detail here) is injected into the cavities.
However, these systems—regardless of the manufacturer—are not suitable as a compressive load-bearing base. Therefore, they must not be used under floor screeds! Please do not allow this procedure! The proposed construction method is non-compliant, as it does not conform to the generally accepted rules of the trade.
--------------
The (excuse me) incompetence in planning and attempted execution is now evident in part 2.
A bathtub is always installed directly on the structural slab so that the load is transferred via a static building element. Floating screeds are not structural components!
In residential buildings, screeds on an insulation layer (for which I refer to the minimum thickness of 45mm (1.8 inches)) are suitable for loads up to approximately 250kg (550 lbs). However, in edge areas where the bathtub is to be placed, very different stress conditions occur within the screed layer under load.
This means that the screed will very likely crack sooner rather than later (provided you actually use the bathtub).
This planned approach is also unacceptable and should under no circumstances be carried out!
------------------------------------
Regards, KlaRa
(Expert office for floor damage)
B
Benutzer 100326 Mar 2018 13:01Hello Forum,
regarding the bathtub installation, I fully agree with the previous poster.
Concerning the "liquid insulation," I assume this refers to a bound loose-fill insulation, such as Thermodur or Airmix 500. In this process, insulation beads are mixed with sand, cement, and water to create a thermal insulation screed, which is installed as a homogeneous component and forms the thermal insulation layer after curing.
This method represents the current state of the art and is intended to prevent thermal bridges. Loose-fill insulation is no longer acceptable in this area.
After installation, the surface is very sensitive and must be protected until the screed is installed.
Despite the pressure distribution cone under loads on the screed, a statically durable construction is still achieved, which is also used in highly loaded areas.
During screed installation, it is important to follow the manufacturer’s specifications regarding build-up height and mortar quality, as failure to do so may result in damage to the screed.
Best regards,
Kristof
regarding the bathtub installation, I fully agree with the previous poster.
Concerning the "liquid insulation," I assume this refers to a bound loose-fill insulation, such as Thermodur or Airmix 500. In this process, insulation beads are mixed with sand, cement, and water to create a thermal insulation screed, which is installed as a homogeneous component and forms the thermal insulation layer after curing.
This method represents the current state of the art and is intended to prevent thermal bridges. Loose-fill insulation is no longer acceptable in this area.
After installation, the surface is very sensitive and must be protected until the screed is installed.
Despite the pressure distribution cone under loads on the screed, a statically durable construction is still achieved, which is also used in highly loaded areas.
During screed installation, it is important to follow the manufacturer’s specifications regarding build-up height and mortar quality, as failure to do so may result in damage to the screed.
Best regards,
Kristof
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