Hello everyone,
We are considering using a calcium sulfate self-leveling screed instead of a conventional cement screed. According to our screed installer, this allows for about 20% less installation thickness, which improves the efficiency of the underfloor heating. It is also said to help save on heating costs. I don’t have a cost estimate yet.
What do you think? Are there any disadvantages to calcium sulfate self-leveling screed compared to conventional cement screed?
Thank you!
We are considering using a calcium sulfate self-leveling screed instead of a conventional cement screed. According to our screed installer, this allows for about 20% less installation thickness, which improves the efficiency of the underfloor heating. It is also said to help save on heating costs. I don’t have a cost estimate yet.
What do you think? Are there any disadvantages to calcium sulfate self-leveling screed compared to conventional cement screed?
Thank you!
No, there are no disadvantages.
The advantage of flowing screeds is simply that the encasement of the heating elements by the screed mortar is better with flowable materials. This also improves the heat transfer from the pipe casing to the screed mortar, making it more efficient.
However, anyone who tries to calculate the savings down to the last penny (excuse me: cent) will have a hard time finding an objective basis for their calculations (e.g., in tables).
Calcium sulfate flowing screeds (CAF) can be installed in thinner layers than cement screeds, but their material costs are somewhat higher. So, it mostly balances out!
An additional benefit is the faster response time of CAF compared to conventional installation, due to better heat transfer and reduced layer thickness.
Regards, KlaRa
The advantage of flowing screeds is simply that the encasement of the heating elements by the screed mortar is better with flowable materials. This also improves the heat transfer from the pipe casing to the screed mortar, making it more efficient.
However, anyone who tries to calculate the savings down to the last penny (excuse me: cent) will have a hard time finding an objective basis for their calculations (e.g., in tables).
Calcium sulfate flowing screeds (CAF) can be installed in thinner layers than cement screeds, but their material costs are somewhat higher. So, it mostly balances out!
An additional benefit is the faster response time of CAF compared to conventional installation, due to better heat transfer and reduced layer thickness.
Regards, KlaRa
M
Mastermind115 May 2018 10:28KlaRa schrieb:
No, there are no disadvantages.
The advantage of flowing screeds lies simply in the fact that the casing of the heating elements is better encased by the screed mortar thanks to the flowable mixture. This also results in a better, more effective heat transfer from the pipe sheath to the screed mortar.
However, anyone crunching the numbers with a calculator, trying to save a few pennies (sorry: cents), will hardly find an objective basis for their calculations (e.g., from a data table).
Calcium sulfate flowing screeds (CAF) can be installed at thinner layers than cement screeds, but their material costs are somewhat higher. So, everything more or less balances out!
An advantage is the faster response time of the CAF compared to conventional installation due to the better heat transfer and thinner layer thickness.
Regards, KlaRa We were advised against "flowing screed" at the time because in the event of water damage it swells and then has to be completely replaced—that means both the damaged area and the additionally affected surrounding area. In contrast, with cement screed only the damaged section needs to be replaced (for example, around a pipe burst), and the rest can dry out.
Of course, with cement screed the floor must first be sanded down so that the tiler is satisfied.
Is this correct, or did we misunderstand this (eight years ago)? :-)
K
Knallkörper15 May 2018 10:30Mastermind1 schrieb:
Of course, with a cement screed, the floor first needs to be sanded down so that the tiler is satisfied.Uh? Why is that?
M
Mastermind115 May 2018 10:50The tiler insisted because our tiles were considered large at the time (60cm x 60cm (24 inches x 24 inches)). I have to add that our tiler was 110%.
There were indeed tiny lumps in the cement screed. This is naturally a downside of cement screed. However, the tiler finished grinding the entire ground floor in less than half a day (almost 90m² (970 ft²)).
There were indeed tiny lumps in the cement screed. This is naturally a downside of cement screed. However, the tiler finished grinding the entire ground floor in less than half a day (almost 90m² (970 ft²)).
Knallkörper schrieb:
Uh? Why is that?
Sorry, but this is one of those industry pieces of information where I have to hold myself back!!
Half-knowledge only creates uncertainty.
It is correct that calcium sulfate-based screeds are fully suitable for both residential and commercial areas.
It is also true that calcium sulfate screeds are sensitive to penetrating moisture and wetness.
In residential areas, level-access shower trays are therefore always made from cement screeds. When using prefabricated shower trays, the bathroom floors (as well as the wall areas) are sealed with an alternative waterproofing system.
A water damage event is not "normal use," but—as the name implies—an incident that cannot be expected.
For cement screeds, which are also suitable for wet areas, there is no need to "replace" anything. After all, concrete structures with cement as a binder are even built underwater without any issues.
Neither cement nor calcium sulfate screeds require "grinding." Grinding always means: defect correction.
A light cleaning grind, however, is mandatory before installing any floor covering, regardless of the screed binder!
This serves to remove dirt residues, fine sediments, etc., from the screed surface so that subsequent layers (on the primer) can properly adhere.
Yes, there is indeed a lot that has been misunderstood (or incorrectly communicated) about floor screed technology.
-------------------------
Regards, KlaRa
Half-knowledge only creates uncertainty.
It is correct that calcium sulfate-based screeds are fully suitable for both residential and commercial areas.
It is also true that calcium sulfate screeds are sensitive to penetrating moisture and wetness.
In residential areas, level-access shower trays are therefore always made from cement screeds. When using prefabricated shower trays, the bathroom floors (as well as the wall areas) are sealed with an alternative waterproofing system.
A water damage event is not "normal use," but—as the name implies—an incident that cannot be expected.
For cement screeds, which are also suitable for wet areas, there is no need to "replace" anything. After all, concrete structures with cement as a binder are even built underwater without any issues.
Neither cement nor calcium sulfate screeds require "grinding." Grinding always means: defect correction.
A light cleaning grind, however, is mandatory before installing any floor covering, regardless of the screed binder!
This serves to remove dirt residues, fine sediments, etc., from the screed surface so that subsequent layers (on the primer) can properly adhere.
Yes, there is indeed a lot that has been misunderstood (or incorrectly communicated) about floor screed technology.
-------------------------
Regards, KlaRa
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