Hello, during the renovation of our house, the following issue came up today: after removing the carpet in the attic room, we noticed that the floor is uneven and flexes. We would like to install laminate flooring there. Does anyone have experience with whether laminate can be installed in such conditions, or is there a risk that it will crack? We were planning to level the unevenness with self-leveling screed. Any advice would be greatly appreciated! Many thanks in advance and best regards
guckuck2 schrieb:
How uneven is the floor? There are leveling compounds for that. Screed has minimum thickness requirements (see processing instructions) and wouldn’t be suitable here.Good morning...thank you very much for your response. The unevenness is sometimes more than 1 cm (0.4 inches). We will get advice regarding leveling compounds. Do you have any experience with laying laminate flooring on a floor that flexes or moves — after the leveling compound has been applied?
guckuck2 schrieb:
If, then floating, I would say.Great – thank you very much!!!
Hello Sabine.
I hope you have not put into practice the "good advice" given in this forum so far, to simply apply some kind of filler compound onto a wooden subfloor that flexes up to 1cm (0.4 inches) deep?!
This does not work, even without load (in this case meaning without use)!
Laminate floor panels, as they are correctly called in professional terminology, require a flat and pressure-resistant subfloor.
Flat means in this case that when a straightedge is laid down with and without pressure over a distance of one meter (between the front and rear support of the straightedge), there must be no more than 3mm (0.1 inches), maximum 4mm (0.15 inches), of deviation under the straightedge.
Applying filler means increasing the scope of future repairs by adding the need for removal later on.
Apart from the fact that a wooden surface must first be sanded, dust vacuumed, and primed before a filler compound suitable for wood subfloors can be applied in a thin layer.
What happens if you proceed as "recommended" in this forum?
An unsuitable filler (e.g., one intended for mineral subfloors) will separate from the subfloor during drying due to the inevitable tensile stresses within the material. Visually, cracks will appear on the surface. Even the slightest foot traffic will cause the structure to crumble, and you can sweep up the broken pieces of the filler with a broom.
At the latest, when the floor deflects the amounts mentioned during walking, the entire surface will collapse.
Even hypothetically, if the filler could withstand these deflections, and the laminate is installed as a floating floor, the deflections will inevitably cause gaps in the locking joints between the laminate floor panels. In summary, when walking on laminate floor panels with significant gaps between the long edges and end joints, the filler will crunch and indicate that it has crumbled.
A complete renovation would then be necessary.
The correct approach is either to remove the existing floorboards and level the subfloor so that it is pressure-resistant enough for installation, or better, to lay a vapor-permeable layer on the existing floorboards and stabilize the entire surface with 22mm (7/8 inch) thick OSB panels fastened only with Spax screws (these have continuous threads; otherwise, there may be creaking later if they loosen by even half a millimeter (0.02 inches)).
All other solutions, where something is apparently rushed and consumer-friendly applied onto the existing subfloor, are doomed to fail!!
Good luck with your future renovation: KlaRa
I hope you have not put into practice the "good advice" given in this forum so far, to simply apply some kind of filler compound onto a wooden subfloor that flexes up to 1cm (0.4 inches) deep?!
This does not work, even without load (in this case meaning without use)!
Laminate floor panels, as they are correctly called in professional terminology, require a flat and pressure-resistant subfloor.
Flat means in this case that when a straightedge is laid down with and without pressure over a distance of one meter (between the front and rear support of the straightedge), there must be no more than 3mm (0.1 inches), maximum 4mm (0.15 inches), of deviation under the straightedge.
Applying filler means increasing the scope of future repairs by adding the need for removal later on.
Apart from the fact that a wooden surface must first be sanded, dust vacuumed, and primed before a filler compound suitable for wood subfloors can be applied in a thin layer.
What happens if you proceed as "recommended" in this forum?
An unsuitable filler (e.g., one intended for mineral subfloors) will separate from the subfloor during drying due to the inevitable tensile stresses within the material. Visually, cracks will appear on the surface. Even the slightest foot traffic will cause the structure to crumble, and you can sweep up the broken pieces of the filler with a broom.
At the latest, when the floor deflects the amounts mentioned during walking, the entire surface will collapse.
Even hypothetically, if the filler could withstand these deflections, and the laminate is installed as a floating floor, the deflections will inevitably cause gaps in the locking joints between the laminate floor panels. In summary, when walking on laminate floor panels with significant gaps between the long edges and end joints, the filler will crunch and indicate that it has crumbled.
A complete renovation would then be necessary.
The correct approach is either to remove the existing floorboards and level the subfloor so that it is pressure-resistant enough for installation, or better, to lay a vapor-permeable layer on the existing floorboards and stabilize the entire surface with 22mm (7/8 inch) thick OSB panels fastened only with Spax screws (these have continuous threads; otherwise, there may be creaking later if they loosen by even half a millimeter (0.02 inches)).
All other solutions, where something is apparently rushed and consumer-friendly applied onto the existing subfloor, are doomed to fail!!
Good luck with your future renovation: KlaRa
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