ᐅ New cement screed flexes on top of new underfloor heating and insulation
Created on: 16 May 2023 19:57
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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.
Good morning, questioner.
There have already been some good answers to your question(s) in this forum.
Why would a "plumbing company," experienced with gas and water installations, install a screed?
Quote: "(...) plumbing company that laid 4cm (1.5 inches) insulation boards without leveling the depressions "
But this is not the question currently under discussion.
The correct approach was to contact the contractor who installed the trade (in this case: screed and substructure).
After the height leveling screed dried, a load distribution layer should have been applied first, for example made of HDF boards. Only then should the insulation layer have been installed.
But now the damage is done.
It is true that a wobbling screed slab is neither proper nor professional work. The question remains when the screed will crack due to constant bending stress.
One solution will be to inject grout beneath the base plate, or in this case, the insulation layer.
The "wobbling" area is a good indication of where to apply the measure.
Breaking up the construction and reinstalling the screed there is not recommended, as the underfloor heating system would then also require extensive repairs due to the intervention.
I suggest injecting an expanding resin.
But beware!
This specialized work should only be done by companies experienced in this process!
Why?
Expanding resins can actually lift entire buildings (case study: Burg Linn in Krefeld); the force involved must be carefully controlled.
Anyone considering filling the void with construction foam may be crossing a line.
I do not want to dismiss that solution entirely on a personal level, but I certainly would not officially recommend it.
-----------
It may not reassure you, questioner, but in fact, the preliminary work was not sufficiently checked or executed for flatness and possibly compressive strength (keyword load distribution).
Therefore, any so-called "sympathy factor" towards the responsible party must be set aside.
Because that would mean taking full responsibility as the client (to put it bluntly).
I can only wish you good fortune in resolving this!
Best regards and good luck: KlaRa
There have already been some good answers to your question(s) in this forum.
Why would a "plumbing company," experienced with gas and water installations, install a screed?
Quote: "(...) plumbing company that laid 4cm (1.5 inches) insulation boards without leveling the depressions "
But this is not the question currently under discussion.
The correct approach was to contact the contractor who installed the trade (in this case: screed and substructure).
After the height leveling screed dried, a load distribution layer should have been applied first, for example made of HDF boards. Only then should the insulation layer have been installed.
But now the damage is done.
It is true that a wobbling screed slab is neither proper nor professional work. The question remains when the screed will crack due to constant bending stress.
One solution will be to inject grout beneath the base plate, or in this case, the insulation layer.
The "wobbling" area is a good indication of where to apply the measure.
Breaking up the construction and reinstalling the screed there is not recommended, as the underfloor heating system would then also require extensive repairs due to the intervention.
I suggest injecting an expanding resin.
But beware!
This specialized work should only be done by companies experienced in this process!
Why?
Expanding resins can actually lift entire buildings (case study: Burg Linn in Krefeld); the force involved must be carefully controlled.
Anyone considering filling the void with construction foam may be crossing a line.
I do not want to dismiss that solution entirely on a personal level, but I certainly would not officially recommend it.
-----------
It may not reassure you, questioner, but in fact, the preliminary work was not sufficiently checked or executed for flatness and possibly compressive strength (keyword load distribution).
Therefore, any so-called "sympathy factor" towards the responsible party must be set aside.
Because that would mean taking full responsibility as the client (to put it bluntly).
I can only wish you good fortune in resolving this!
Best regards and good luck: KlaRa
Winniefred31 May 2023 11:23KlaRa schrieb:
Good morning, questioner.
There have already been some good answers to your question(s) in this forum.
Why would a plumbing company, which handles gas and water installations, lay screed?
Quote: "(...) plumbing company that laid 4cm (1.5 inches) insulation boards without leveling the hollows "
But that is not the current issue at hand.
The correct approach was to contact the contractor responsible for that trade (here: screed and substructure).
After the height-leveling screed dried, a load distribution layer should have been applied first, for example, HDF boards. Only then the insulation layer.
But now the damage is done.
It is correct that a bouncing screed slab is not properly and professionally done. The question remains when the screed will crack due to ongoing bending stress.
One solution would be to inject beneath the supporting layer, or in this case, the insulation layer.
The "bouncing" area is a good indicator of where the repair needs to be focused.
Opening up the construction and breaking up the screed to re-lay it is not advisable, as the underfloor heating would then also require extensive repairs due to this intervention.
I suggest injecting an expanding resin.
But be careful!
This specialized work should be reserved exclusively for companies experienced in such applications!
Why?
Expanding resins can literally level entire buildings (practical case: Burg Linn in Krefeld), so the force exerted behind it must be carefully controlled.
Anyone thinking of using foam sealant to fill the void risks exceeding acceptable limits.
I personally would not fully condemn that solution but would not officially recommend it either.
-----------
It may not reassure you, questioner, but the fact is the prior trade was not sufficiently checked for flatness and possibly compressive strength (keyword: load distribution) and/or was not properly installed.
Therefore, any sympathy factor for the responsible party should be set aside.
Because that would mean taking full responsibility as the client (to put it bluntly).
I can only wish you good luck in solving this!
Regards and best wishes: KlaRa Hello! The screed was poured by the screed layer, a subcontractor of the general contractor. The plumbing company (which we hired separately) installed insulation boards over the lightweight concrete and then laid the underfloor heating. The plumbing company wants to implement the resin injection solution, which they have done before. However, it has not yet been done.
To avoid damaging the underfloor heating, the screed must be removed in that area (otherwise they don’t know where to drill and risk hitting the pipes). How else could the resin be injected?
I have not read anything about a load distribution layer so far; for example, the manufacturer of the lightweight concrete does not describe this either. They state that the concrete can be covered directly with wood panels, insulation, or similar. At least, that is how I remember it and would have to check again.
So far, unfortunately, nothing has happened. We definitely need to be more emphatic about this. It is already very frustrating because everything else has worked perfectly until now, and then this problem arises.
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WilderSueden31 May 2023 11:26The pipes can be fairly easily located while the heating is running using a thermal imaging camera or thermal film.
Winniefred31 May 2023 11:27WilderSueden schrieb:
The pipes can be quite easily detected with a thermal imaging camera or thermal foil while the heating is running. Very interesting! I will bring this up. That would definitely be helpful. The screed drying is almost complete now, and reopening it, even if it’s just for 1 square meter (11 square feet), would be frustrating and cause delays.
Winniefred7 Jun 2023 09:17So far, nothing has happened. However, two possible minimally invasive solutions have been discussed with the screeding contractor:
1. Pour water onto the affected areas, apply weight for 2 days, and hope that the section settles.
2. Cut the screed behind the affected area and hope that the part in front then settles.
Is there any chance of success with this? I am quite skeptical. The screed is perfectly level—I checked it with a 2-meter (6.5-foot) spirit level. There is no traditional sagging; none of the corners have lifted. And where there are no uneven areas, in my opinion, nothing can settle, right? By now, the screed has dried completely—the curing process ends tomorrow.
1. Pour water onto the affected areas, apply weight for 2 days, and hope that the section settles.
2. Cut the screed behind the affected area and hope that the part in front then settles.
Is there any chance of success with this? I am quite skeptical. The screed is perfectly level—I checked it with a 2-meter (6.5-foot) spirit level. There is no traditional sagging; none of the corners have lifted. And where there are no uneven areas, in my opinion, nothing can settle, right? By now, the screed has dried completely—the curing process ends tomorrow.
Winniefred schrieb:
And by now the screed is dry, and the program ends tomorrow.I think those are two different things. According to our builder, the screed still has residual moisture even after the screed drying program. It may be "ready" for some types of flooring, but I know for sure that they will still carry out moisture measurements before installing the wooden floor. Because for that, the screed really has to be completely dry.Similar topics