Hello forum,
Short version
The screed is too thin, and the company will probably try to fix it rather than remove and redo it.
Long version:
Our construction is not going as planned. We now have the issue that our screed is too thin.
The situation is as follows: We are building a single-family house with a general contractor on a slab foundation. It’s not completely turnkey, but the screed is still the responsibility of the general contractor. On the slab, there is insulation (polystyrene boards), on top of that the underfloor heating is installed, and the cement screed was poured over it. There is no screed under the shower tray. I could see the side and measured the total screed thickness at only 45mm (1.8 inches). However, the relevant standards specify that the screed must be 45mm (1.8 inches) above the heating pipes, so we definitely have too little thickness.
I contacted the site manager, who filed a complaint with the screed subcontractor. He also acknowledged that a greater build-up over the pipes is needed. He said he spoke with the screed company, and there are ways to add another layer (with a bonding layer, etc.). Allegedly, he experienced this once before without problems.
I have now searched forums and found statements suggesting that repairs are only possible if there are already 45mm (1.8 inches) of screed above the heating pipes. In our case, it is definitely not. I also found out that the screed company doesn’t believe we only have 45mm (1.8 inches) and wants to inspect the site. They are welcome to do so; a meeting with the site manager and subcontractor is scheduled.
However, I am very concerned because it sounds to me like the screed including the heating pipes will need to be removed entirely and redone to be defect-free. I do not want to accept a repair that might cause the large tiles and parquet flooring to crack in 15 years. In my opinion, removal and replacement would be better. I am considering getting one or two expert opinions from other screed companies or, if necessary, a surveyor.
Are there any screed experts here, and what do you think about the situation?
What options do I have?
We also face additional costs because we only discovered the problem on the day the construction company left for their winter holiday, and we were only able to report it afterwards. The tiler was supposed to start now. The rental apartment has already been terminated. Several deliveries have to be rescheduled or temporarily stored. On top of that, the full loan repayment is starting now.
Short version
The screed is too thin, and the company will probably try to fix it rather than remove and redo it.
Long version:
Our construction is not going as planned. We now have the issue that our screed is too thin.
The situation is as follows: We are building a single-family house with a general contractor on a slab foundation. It’s not completely turnkey, but the screed is still the responsibility of the general contractor. On the slab, there is insulation (polystyrene boards), on top of that the underfloor heating is installed, and the cement screed was poured over it. There is no screed under the shower tray. I could see the side and measured the total screed thickness at only 45mm (1.8 inches). However, the relevant standards specify that the screed must be 45mm (1.8 inches) above the heating pipes, so we definitely have too little thickness.
I contacted the site manager, who filed a complaint with the screed subcontractor. He also acknowledged that a greater build-up over the pipes is needed. He said he spoke with the screed company, and there are ways to add another layer (with a bonding layer, etc.). Allegedly, he experienced this once before without problems.
I have now searched forums and found statements suggesting that repairs are only possible if there are already 45mm (1.8 inches) of screed above the heating pipes. In our case, it is definitely not. I also found out that the screed company doesn’t believe we only have 45mm (1.8 inches) and wants to inspect the site. They are welcome to do so; a meeting with the site manager and subcontractor is scheduled.
However, I am very concerned because it sounds to me like the screed including the heating pipes will need to be removed entirely and redone to be defect-free. I do not want to accept a repair that might cause the large tiles and parquet flooring to crack in 15 years. In my opinion, removal and replacement would be better. I am considering getting one or two expert opinions from other screed companies or, if necessary, a surveyor.
Are there any screed experts here, and what do you think about the situation?
What options do I have?
We also face additional costs because we only discovered the problem on the day the construction company left for their winter holiday, and we were only able to report it afterwards. The tiler was supposed to start now. The rental apartment has already been terminated. Several deliveries have to be rescheduled or temporarily stored. On top of that, the full loan repayment is starting now.
Somehow, my recently written text seems to have disappeared into thin air, so here it is again:
It is correct that under point 8 of DIN 18560 part 2, a covering of 45mm (1.8 inches) over heating elements is required in residential construction. This also means that a screed nominal thickness of 65 to 70mm (2.6 to 2.8 inches) should have been specified.
If a covering of 43mm (1.7 inches) is present, then, assuming proper compaction of the mortar during installation, this would not be a major issue—provided the screed thickness is maintained evenly throughout the entire room.
To increase the thickness of an insufficiently thick screed: with a maximum aggregate size of 5mm (0.2 inches), the new minimum thickness should be 15mm (0.6 inches). The existing screed surface must be ground down, dust vacuumed, and primed with a dispersion-based bonding agent.
However, we probably do not have this build-up height available, making the use of a standard mortar impossible. What other options do we have?
It would be wrong to apply a high-strength leveling compound directly onto the existing screed following the notion “now the thickness is correct.” The risk that the bond zone will fail due to higher shrinkage stresses (from the higher mortar strength) is quite evident—to me at least.
What options besides full removal and replacement can be considered?
First, as the client, I would request an extension of the warranty period by 2 years beyond the existing warranty. Then, the surface of the existing screed can be properly ground, dust vacuumed, primed with epoxy resin, and while still wet, broadcast with kiln-dried quartz sand. After curing, loose sand is vacuumed off, and over a fully laid stabilization mesh, a high-strength leveling compound is applied to the required thickness.
Granted, this approach is not compliant with DIN standards. But at least it would function without full removal.
------------------
If the responsible contractor does not agree to extend the warranty period: full removal of the screed should be demanded, as the service was not delivered and further work cannot be carried out in compliance with DIN standards.
I think this should be a reasonable (and more cost-effective) solution for the contractor, which they could accept.
----------------------
Best of luck, KlaRa
It is correct that under point 8 of DIN 18560 part 2, a covering of 45mm (1.8 inches) over heating elements is required in residential construction. This also means that a screed nominal thickness of 65 to 70mm (2.6 to 2.8 inches) should have been specified.
If a covering of 43mm (1.7 inches) is present, then, assuming proper compaction of the mortar during installation, this would not be a major issue—provided the screed thickness is maintained evenly throughout the entire room.
To increase the thickness of an insufficiently thick screed: with a maximum aggregate size of 5mm (0.2 inches), the new minimum thickness should be 15mm (0.6 inches). The existing screed surface must be ground down, dust vacuumed, and primed with a dispersion-based bonding agent.
However, we probably do not have this build-up height available, making the use of a standard mortar impossible. What other options do we have?
It would be wrong to apply a high-strength leveling compound directly onto the existing screed following the notion “now the thickness is correct.” The risk that the bond zone will fail due to higher shrinkage stresses (from the higher mortar strength) is quite evident—to me at least.
What options besides full removal and replacement can be considered?
First, as the client, I would request an extension of the warranty period by 2 years beyond the existing warranty. Then, the surface of the existing screed can be properly ground, dust vacuumed, primed with epoxy resin, and while still wet, broadcast with kiln-dried quartz sand. After curing, loose sand is vacuumed off, and over a fully laid stabilization mesh, a high-strength leveling compound is applied to the required thickness.
Granted, this approach is not compliant with DIN standards. But at least it would function without full removal.
------------------
If the responsible contractor does not agree to extend the warranty period: full removal of the screed should be demanded, as the service was not delivered and further work cannot be carried out in compliance with DIN standards.
I think this should be a reasonable (and more cost-effective) solution for the contractor, which they could accept.
----------------------
Best of luck, KlaRa
B
Bierwächter26 Jan 2026 00:24Thank you for the response!
The deadline is now behind us, and at the moment it looks like we will leave the screed as it is. A few areas were broken up and remeasured. At the spot near the shower where I originally measured, it has settled; however, at the test holes there was slightly more screed. Not as much as the DIN standard requires, but definitely more than 45mm (1.8 inches). I think it was around 55-58mm (2.2-2.3 inches). According to the screed installer, our screed averages 60mm (2.4 inches), but he did measure somewhat too deeply. Realistically, the average is closer to 55mm (2.2 inches), maybe a bit more. They also mixed in something for faster drying and, according to him, for strength as well. I don’t put much trust in that but just wanted to mention it.
The site manager and screed installer initially argued about who had marked the reference line on the floor—I doubt anyone wants to admit it. The site manager was definitely not responsible, though. Anyway, we don’t expect the screed to crack, but of course, we can’t be sure. The alternative looks like a legal dispute to us. We prefer to take some risk with the current screed rather than that. A legal battle would mean long delays, stress, and money. In the current situation, we don’t want to accept that.
It seems to me, however, that screed like we have is not uncommon. In general, construction work seems to be done quite imprecisely everywhere, based on the time I’ve spent on site and conversations with others. The screed company also poured some leveling compound on a bonding primer near the front door—about 5mm (0.2 inches).
Next, our tiler (not from the general contractor) will apply self-leveling compound where the parquet flooring will go. Rooms with tiles will be leveled using tile adhesive. That’s our current plan.
Yesterday, we noticed another issue: the water connection for the washbasin in the WC needs to be much lower. So far, there have been quite a few problems—not disasters, but annoying things that didn’t fit, which is slowly wearing on our nerves. I have been unable to be satisfied with almost any of the subcontractor workers on site so far. Friends of ours built with the same company in 2019, but a turnkey project. They had no complaints but were not really present at the construction site and only had a general idea of what was done below the surface. I have spent a lot of time on site and have seen everything firsthand.
The deadline is now behind us, and at the moment it looks like we will leave the screed as it is. A few areas were broken up and remeasured. At the spot near the shower where I originally measured, it has settled; however, at the test holes there was slightly more screed. Not as much as the DIN standard requires, but definitely more than 45mm (1.8 inches). I think it was around 55-58mm (2.2-2.3 inches). According to the screed installer, our screed averages 60mm (2.4 inches), but he did measure somewhat too deeply. Realistically, the average is closer to 55mm (2.2 inches), maybe a bit more. They also mixed in something for faster drying and, according to him, for strength as well. I don’t put much trust in that but just wanted to mention it.
The site manager and screed installer initially argued about who had marked the reference line on the floor—I doubt anyone wants to admit it. The site manager was definitely not responsible, though. Anyway, we don’t expect the screed to crack, but of course, we can’t be sure. The alternative looks like a legal dispute to us. We prefer to take some risk with the current screed rather than that. A legal battle would mean long delays, stress, and money. In the current situation, we don’t want to accept that.
It seems to me, however, that screed like we have is not uncommon. In general, construction work seems to be done quite imprecisely everywhere, based on the time I’ve spent on site and conversations with others. The screed company also poured some leveling compound on a bonding primer near the front door—about 5mm (0.2 inches).
Next, our tiler (not from the general contractor) will apply self-leveling compound where the parquet flooring will go. Rooms with tiles will be leveled using tile adhesive. That’s our current plan.
Yesterday, we noticed another issue: the water connection for the washbasin in the WC needs to be much lower. So far, there have been quite a few problems—not disasters, but annoying things that didn’t fit, which is slowly wearing on our nerves. I have been unable to be satisfied with almost any of the subcontractor workers on site so far. Friends of ours built with the same company in 2019, but a turnkey project. They had no complaints but were not really present at the construction site and only had a general idea of what was done below the surface. I have spent a lot of time on site and have seen everything firsthand.
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