ᐅ Screed and tiles have already been installed, but there is no heating system yet.
Created on: 8 Oct 2019 20:45
A
AD1988
Hello everyone,
I am currently in the final phase of building my house and would like to get some other opinions on the topic mentioned above.
In our case, the screed was installed on July 24th. Tiling began on August 20th. However, the tiles were laid with a decoupling membrane because we have still not been able to turn on the heating. This week, our gas meter is finally scheduled to be installed, so we can start using our underfloor heating. The tiler told us that we are only allowed to turn it on at the earliest four weeks after the tiles are installed, and even then, only gradually.
My question is whether this is correct and what exactly is meant by heating up slowly. Does this mean a few days or several weeks? Also, I would like to know if it is a problem that the screed was not dried by the underfloor heating, or if this still needs to be done later. What do the experts among you think about this?
I would appreciate your responses.
I am currently in the final phase of building my house and would like to get some other opinions on the topic mentioned above.
In our case, the screed was installed on July 24th. Tiling began on August 20th. However, the tiles were laid with a decoupling membrane because we have still not been able to turn on the heating. This week, our gas meter is finally scheduled to be installed, so we can start using our underfloor heating. The tiler told us that we are only allowed to turn it on at the earliest four weeks after the tiles are installed, and even then, only gradually.
My question is whether this is correct and what exactly is meant by heating up slowly. Does this mean a few days or several weeks? Also, I would like to know if it is a problem that the screed was not dried by the underfloor heating, or if this still needs to be done later. What do the experts among you think about this?
I would appreciate your responses.
Let me reassure you. We received the screed at the end of June 2017. No heating. We ventilated and used dehumidifiers, also called drying units, for about a week. From around early August, the tiles were installed without this mat. From mid-August, vinyl flooring was laid. Gas and heating were only installed on September 1st. Nothing happened. No tiles cracked, no silicone joints broke, no bubbles in the vinyl. Nothing.
Hello questioner.
In technically complex matters like this, you should not rely on half-knowledge! Therefore, here is the technically correct information:
"For us, the screed was laid on 24.07. The tile installation began on 20.08."
Answer:
After not even 4 weeks, the hope that the screed has reached the required readiness for laying only exists if a fast-drying screed or a calcium sulfate flowing screed was used.
Determining readiness for laying (in this case the dryness) is the responsibility of the floor or tile installer!
They must perform this test according to the CM method, as a standard procedure!
If the underfloor heating was not in operation at the time of tile installation, the risk of excessive residual moisture in the screed is very likely.
------------------------------
"However, the tiles were installed with an uncoupling membrane because we still cannot heat."
Answer:
An uncoupling membrane has nothing to do with residual moisture! It is used for critical screeds, meaning those prone to cracking. In this case, it only served to add an item to the contractor’s invoice.
-----------------------------------
"The tile installer told us that we should not switch on the (Note: the underfloor heating) earlier than 4 weeks after tiling, and then only gradually."
Answer:
This is incorrect and makes no sense!
First, a heated screed is gradually warmed up, then a CM measurement is carried out, and only after sufficient drying does tile installation take place!
The heating process follows a specified protocol according to the "interface coordination for heated floor constructions", so not vaguely described as "gradually"!
You can download the protocol at
bfse.de/assets/Uploads/buecher/BVF20Schnittstellen1.pdf
----------------------------------------------
"Also, I would like to know if it is a problem that the screed was not dried by the underfloor heating?"
Answer:
In principle, screeds dry out regardless of the binder used, even without heating.
However, with heated screeds, the upper screed edge zone—which is exposed to the air—is usually drier than the lower edge zone.
Moisture collects there and is only transported out of the screed structure during the second heating phase.
But only if the screed surface allows it.
In your case, moisture-proof tiles were installed, which significantly hinder drying.
This cannot be corrected anymore!
What will happen in the next 6 to 15 months?
If there was still a sufficiently high moisture content in the screed at the time of tile installation, the screed will dry out very slowly.
However, this drying-related shrinkage of the screed, which otherwise happens unnoticed without any floor covering, will now cause considerable warping of the screed slab(s), which will cause the tiles (bonded firmly) to bulge.
Due to compression stress (from use), the tiles will crack! No joke.
This first appears as fine cracks spreading across the entire surface.
-------------------------
What should be done?
Document everything!!!!!!
Record what happened or did not happen during the construction process (such as the missing CM measurement).
----------------------
You may realize at this point that non-binding answers in a network do not always reveal what really matters or what is truly important.
In any case, I wish you much success on your future path: KlaRa
In technically complex matters like this, you should not rely on half-knowledge! Therefore, here is the technically correct information:
"For us, the screed was laid on 24.07. The tile installation began on 20.08."
Answer:
After not even 4 weeks, the hope that the screed has reached the required readiness for laying only exists if a fast-drying screed or a calcium sulfate flowing screed was used.
Determining readiness for laying (in this case the dryness) is the responsibility of the floor or tile installer!
They must perform this test according to the CM method, as a standard procedure!
If the underfloor heating was not in operation at the time of tile installation, the risk of excessive residual moisture in the screed is very likely.
------------------------------
"However, the tiles were installed with an uncoupling membrane because we still cannot heat."
Answer:
An uncoupling membrane has nothing to do with residual moisture! It is used for critical screeds, meaning those prone to cracking. In this case, it only served to add an item to the contractor’s invoice.
-----------------------------------
"The tile installer told us that we should not switch on the (Note: the underfloor heating) earlier than 4 weeks after tiling, and then only gradually."
Answer:
This is incorrect and makes no sense!
First, a heated screed is gradually warmed up, then a CM measurement is carried out, and only after sufficient drying does tile installation take place!
The heating process follows a specified protocol according to the "interface coordination for heated floor constructions", so not vaguely described as "gradually"!
You can download the protocol at
bfse.de/assets/Uploads/buecher/BVF20Schnittstellen1.pdf
----------------------------------------------
"Also, I would like to know if it is a problem that the screed was not dried by the underfloor heating?"
Answer:
In principle, screeds dry out regardless of the binder used, even without heating.
However, with heated screeds, the upper screed edge zone—which is exposed to the air—is usually drier than the lower edge zone.
Moisture collects there and is only transported out of the screed structure during the second heating phase.
But only if the screed surface allows it.
In your case, moisture-proof tiles were installed, which significantly hinder drying.
This cannot be corrected anymore!
What will happen in the next 6 to 15 months?
If there was still a sufficiently high moisture content in the screed at the time of tile installation, the screed will dry out very slowly.
However, this drying-related shrinkage of the screed, which otherwise happens unnoticed without any floor covering, will now cause considerable warping of the screed slab(s), which will cause the tiles (bonded firmly) to bulge.
Due to compression stress (from use), the tiles will crack! No joke.
This first appears as fine cracks spreading across the entire surface.
-------------------------
What should be done?
Document everything!!!!!!
Record what happened or did not happen during the construction process (such as the missing CM measurement).
----------------------
You may realize at this point that non-binding answers in a network do not always reveal what really matters or what is truly important.
In any case, I wish you much success on your future path: KlaRa
B
boxandroof9 Oct 2019 13:33Install baseboards only after 1-2 heating seasons.
Also, don’t overdo heating and drying now, to avoid any warping or buckling—that was the case for us, at least.
Also, don’t overdo heating and drying now, to avoid any warping or buckling—that was the case for us, at least.
H
hampshire9 Oct 2019 14:51Contact your builder or tiler (depending on who your point of contact is) and ask the following question:
"What are the results of your CM measurement? Please provide me with the measurement values."
At this point, they may respond in one of the following ways:
If they have conducted the measurement and provide you with the values, you can use these to check (or have checked) whether everything is in order.
If they conducted the measurement but do not provide you with the values, you will know that you need to follow up further.
If they did not conduct the measurement, their response will serve as documentation of this.
If they do not respond at all, you should become more firm in your request.
"What are the results of your CM measurement? Please provide me with the measurement values."
At this point, they may respond in one of the following ways:
If they have conducted the measurement and provide you with the values, you can use these to check (or have checked) whether everything is in order.
If they conducted the measurement but do not provide you with the values, you will know that you need to follow up further.
If they did not conduct the measurement, their response will serve as documentation of this.
If they do not respond at all, you should become more firm in your request.
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