ᐅ Optimal solution for installing HDF laminate flooring over existing wooden floorboards
Created on: 10 Nov 2025 18:05
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tayfun6519T
tayfun651910 Nov 2025 18:05Hello dear experts,
I am deciding on a floor covering for my renovation and have settled on a design/laminate floor with an HDF core (wood-based panel). The critical subfloor is an old wooden plank floor that may have unevenness and some movement.
1. Current condition of the subfloor
I am torn between two rigid click floors (rigid vinyl is deliberately excluded) and would like to know which you would choose.
Option A: HDF floor WITH integrated cork impact sound insulation
Option B: HDF floor WITHOUT integrated impact sound insulation
I prefer the look of the floor with cork, so I want to install Option A with the 1mm (0.04 inches) cork underlayment plus my 150kPa underlayment. How high is the risk that this double, soft underlayment will compress too much, causing the click joints to break or gaps to form? Is this an absolute no-go?
On the upper floor, there is a screed subfloor. Since this subfloor is solid, I am considering skipping the underlayment completely.
Thank you very much for your clear assessment of the different subfloors!
I am deciding on a floor covering for my renovation and have settled on a design/laminate floor with an HDF core (wood-based panel). The critical subfloor is an old wooden plank floor that may have unevenness and some movement.
1. Current condition of the subfloor
- Subfloor: Old wooden plank floor (planks on joists, no screed) from 1960.
- Background: A laminate floor (8mm (0.3 inches)) with impact sound insulation (>45kPa) has been installed for 5 years without major issues.
- New underlayment (UL): An impact sound insulation with 150kPa compressive strength (CS value). This can be returned if needed.
I am torn between two rigid click floors (rigid vinyl is deliberately excluded) and would like to know which you would choose.
Option A: HDF floor WITH integrated cork impact sound insulation
Option B: HDF floor WITHOUT integrated impact sound insulation
I prefer the look of the floor with cork, so I want to install Option A with the 1mm (0.04 inches) cork underlayment plus my 150kPa underlayment. How high is the risk that this double, soft underlayment will compress too much, causing the click joints to break or gaps to form? Is this an absolute no-go?
On the upper floor, there is a screed subfloor. Since this subfloor is solid, I am considering skipping the underlayment completely.
- Should I completely skip the impact sound insulation on the screed floor? Of course, a vapor barrier must be added.
Thank you very much for your clear assessment of the different subfloors!
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nordanney10 Nov 2025 18:19I see Option A as a no-go. The risk is simply too high for me. What does the flooring manufacturer say? They usually specify how pressure-resistant the subfloor needs to be and often exclude any warranty if the subfloor doesn’t meet these requirements.
Option B would be my choice. But with a different subfloor, for example, more pressure-resistant wood fiber boards with a suitable permeability coefficient (PC) value to compensate for unevenness.
For the upper floor, please use an underlay as well. Preferably a 2-in-1 or 3-in-1 system (then you don’t need a separate vapor barrier; the vapor retarder is less relevant since the screed should be dry after 60 years, and there is heated living space below). It’s not just about impact sound (which might, with some luck, work without an underlay), but more about footfall noise within the room. That’s where the underlay is much more important.
Option B would be my choice. But with a different subfloor, for example, more pressure-resistant wood fiber boards with a suitable permeability coefficient (PC) value to compensate for unevenness.
For the upper floor, please use an underlay as well. Preferably a 2-in-1 or 3-in-1 system (then you don’t need a separate vapor barrier; the vapor retarder is less relevant since the screed should be dry after 60 years, and there is heated living space below). It’s not just about impact sound (which might, with some luck, work without an underlay), but more about footfall noise within the room. That’s where the underlay is much more important.
Hi,
your approach is well thought out, and you have the right key points in mind – especially the combination of a “floating” plank floor and HDF substrate is critical, because HDF hardly flexes but quickly develops micro-cracks at the click joints under point loads.
If your plank floor is reasonably flat and stable (no loose support, no excessive movement), option A with integrated cork insulation is basically feasible – but not with an additional underlay underneath. Cork already provides enough cushioning. If you add another layer of insulation below, it creates an overly soft composite that slightly stresses the click joints with every movement. You won’t notice this immediately, but after one summer/winter cycle, the joints start to show movement. In short: double insulation layers = not a good combination.
If you definitely want to use your 150 kPa underlay, choose the HDF floor without integrated insulation instead (option B). This gives you a more defined, firmer build-up, which is more stable in the long term, especially with slightly flexible wooden floors.
On upper floors with screed, the opposite applies: here, due to the solid base, you don’t need high compression resistance but rather some impact sound decoupling. A thin layer of insulation (1–1.5 mm (0.04–0.06 inches) PE or PU) is sufficient. I would not do it without an underlay, mainly because of noise and the minimal tolerance for small unevenness. As you said, a vapor barrier is mandatory – but only on mineral substrates, not on wood.
Have you checked the old plank floor with a straightedge to see if there is more than 2 mm (0.08 inches) deviation over 1 m (3.3 feet)? That would be the decisive point for your choice.
Good luck!
your approach is well thought out, and you have the right key points in mind – especially the combination of a “floating” plank floor and HDF substrate is critical, because HDF hardly flexes but quickly develops micro-cracks at the click joints under point loads.
If your plank floor is reasonably flat and stable (no loose support, no excessive movement), option A with integrated cork insulation is basically feasible – but not with an additional underlay underneath. Cork already provides enough cushioning. If you add another layer of insulation below, it creates an overly soft composite that slightly stresses the click joints with every movement. You won’t notice this immediately, but after one summer/winter cycle, the joints start to show movement. In short: double insulation layers = not a good combination.
If you definitely want to use your 150 kPa underlay, choose the HDF floor without integrated insulation instead (option B). This gives you a more defined, firmer build-up, which is more stable in the long term, especially with slightly flexible wooden floors.
On upper floors with screed, the opposite applies: here, due to the solid base, you don’t need high compression resistance but rather some impact sound decoupling. A thin layer of insulation (1–1.5 mm (0.04–0.06 inches) PE or PU) is sufficient. I would not do it without an underlay, mainly because of noise and the minimal tolerance for small unevenness. As you said, a vapor barrier is mandatory – but only on mineral substrates, not on wood.
Have you checked the old plank floor with a straightedge to see if there is more than 2 mm (0.08 inches) deviation over 1 m (3.3 feet)? That would be the decisive point for your choice.
Good luck!
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