ᐅ New cement screed flexes on top of new underfloor heating and insulation
Created on: 16 May 2023 19:57
W
Winniefred
Hello!
We are doing a complete renovation of our ground floor. The house was built in 1921.
Work done so far: Removal of floorboards and clinker slag. The vault was uncovered. On top of that, an insulating concrete/lightweight concrete layer was applied as a height adjustment, thickness between 0 and 20cm (0-8 inches). We allowed it to dry according to the manufacturer’s instructions. The concrete contains many small beads; due to further work and because we continue to live in the house, small indentations have formed along the walking paths in the hallway. All work up to this point was carried out by a construction company. Next, the plumbing contractor installed 4cm (1.5 inches) insulation boards without leveling out the indentations and then installed the hydronic (water-based) underfloor heating. Under the black dimpled membrane, there was another insulation layer; the underfloor heating pipes lie within this membrane. Last Friday, a 5cm (2 inches) cement screed was poured onto the underfloor heating. It couldn’t be thicker due to space constraints. A modifier was added for better hardness and faster drying. Right at the front door, this screed now rocks a few millimeters. The screed is only about 110cm (43 inches) wide there (narrow hallway).
Now the critical question: Who is at fault, and above all, how can this be fixed? Planned (and already purchased for 2500 EUR) are wood-look plank tiles, 120cm (47 inches) long and 20cm (8 inches) wide, for the entire ground floor. This was known to all trades and is especially important to us, particularly in the entrance area. Discussions with the two companies have yet to take place.
My question: Does anyone have suggestions or ideas? Primarily for how to solve this issue. You can cut the screed and remove it at the affected spot, but underneath is the underfloor heating with long pipes running directly to the door. Presumably, you can’t just lift it and level underneath again, since the pipes run through the entire hallway and are all connected. We are now worried this will turn into a bigger problem, where no one wants to take responsibility, and above all, it will cost us a lot of time. We live in the house with our children, and everything was on schedule until now. I estimate this will cost us at least two weeks’ delay, in the best case. The tiler and kitchen installation depend on this, so it’s quite complicated.
Any input would be much appreciated. This issue is keeping us up at night, and nothing will be resolved before the long weekend.
We are doing a complete renovation of our ground floor. The house was built in 1921.
Work done so far: Removal of floorboards and clinker slag. The vault was uncovered. On top of that, an insulating concrete/lightweight concrete layer was applied as a height adjustment, thickness between 0 and 20cm (0-8 inches). We allowed it to dry according to the manufacturer’s instructions. The concrete contains many small beads; due to further work and because we continue to live in the house, small indentations have formed along the walking paths in the hallway. All work up to this point was carried out by a construction company. Next, the plumbing contractor installed 4cm (1.5 inches) insulation boards without leveling out the indentations and then installed the hydronic (water-based) underfloor heating. Under the black dimpled membrane, there was another insulation layer; the underfloor heating pipes lie within this membrane. Last Friday, a 5cm (2 inches) cement screed was poured onto the underfloor heating. It couldn’t be thicker due to space constraints. A modifier was added for better hardness and faster drying. Right at the front door, this screed now rocks a few millimeters. The screed is only about 110cm (43 inches) wide there (narrow hallway).
Now the critical question: Who is at fault, and above all, how can this be fixed? Planned (and already purchased for 2500 EUR) are wood-look plank tiles, 120cm (47 inches) long and 20cm (8 inches) wide, for the entire ground floor. This was known to all trades and is especially important to us, particularly in the entrance area. Discussions with the two companies have yet to take place.
My question: Does anyone have suggestions or ideas? Primarily for how to solve this issue. You can cut the screed and remove it at the affected spot, but underneath is the underfloor heating with long pipes running directly to the door. Presumably, you can’t just lift it and level underneath again, since the pipes run through the entire hallway and are all connected. We are now worried this will turn into a bigger problem, where no one wants to take responsibility, and above all, it will cost us a lot of time. We live in the house with our children, and everything was on schedule until now. I estimate this will cost us at least two weeks’ delay, in the best case. The tiler and kitchen installation depend on this, so it’s quite complicated.
Any input would be much appreciated. This issue is keeping us up at night, and nothing will be resolved before the long weekend.
There is no specific "screed program," but there is the "interface coordination for underfloor heating and cooling systems in buildings," which essentially covers every conceivable step involved in installing a heating/cooling screed.
Afterward, the screed undergoes a slow functional heating phase, followed by finishing the drying heating after 2-3 days of rest without temperature input.
At this point, the screed should have reached sufficient drying maturity—but this is not mandatory.
Therefore, residual moisture testing using the CM method must be carried out. For heated screeds (I will exclude cooled screeds here, as this form of temperature control has not gained practical acceptance), appropriate (safe) sampling points must be marked with plastic flags during the screed installation.
If the floor still feels springy after the parquet installation, the flooring installer will have to deal with consequential damage.
This is because they hold the responsibility and duty of care for the installation surface.
What may be happening here is a deliberate shifting of risk onto the following trade.
If that is the case, it is an unprofessional approach (by the previous contractor and in relation to both the client and the subsequent trade).
-----------------
Regards, KlaRa
Afterward, the screed undergoes a slow functional heating phase, followed by finishing the drying heating after 2-3 days of rest without temperature input.
At this point, the screed should have reached sufficient drying maturity—but this is not mandatory.
Therefore, residual moisture testing using the CM method must be carried out. For heated screeds (I will exclude cooled screeds here, as this form of temperature control has not gained practical acceptance), appropriate (safe) sampling points must be marked with plastic flags during the screed installation.
If the floor still feels springy after the parquet installation, the flooring installer will have to deal with consequential damage.
This is because they hold the responsibility and duty of care for the installation surface.
What may be happening here is a deliberate shifting of risk onto the following trade.
If that is the case, it is an unprofessional approach (by the previous contractor and in relation to both the client and the subsequent trade).
-----------------
Regards, KlaRa
Winniefred8 Jun 2023 12:53Thank you for your responses! Unfortunately, they do not answer my questions. Could cutting or wetting the surface have any chance of success?
Tiles in plank format will be installed, not hardwood flooring. I would be less worried if it were hardwood, but for 120cm (47 inches) long tiles, the substrate simply has to be stable. As it is now, the tiler will not install anything in that area, and I wouldn’t want them to, because the tiles would definitely break.
The screed heating program was carried out exactly as instructed by the screed installer. It finished today, and there are still at least 7 days before the tiler comes. So that should definitely be fine.
Tiles in plank format will be installed, not hardwood flooring. I would be less worried if it were hardwood, but for 120cm (47 inches) long tiles, the substrate simply has to be stable. As it is now, the tiler will not install anything in that area, and I wouldn’t want them to, because the tiles would definitely break.
The screed heating program was carried out exactly as instructed by the screed installer. It finished today, and there are still at least 7 days before the tiler comes. So that should definitely be fine.
Winniefred9 Jun 2023 20:45So, pouring water on it – surprise, surprise – did not work.
Winniefred4 Jul 2023 05:48Not sure if anyone here is still interested. But I’ll share how it turned out anyway. A cut was made in the screed, then the loose section was removed and new screed was poured in its place. Now it is stable.
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