ᐅ Floor construction over an existing wooden beam ceiling – how to build it up
Created on: 4 Jul 2020 14:38
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Speedy1985S
Speedy19854 Jul 2020 14:38Hello forum community,
A few years ago, we completely renovated the ground floor of a single-family house built in 1965. During this work, the wooden beam ceiling to the attic was fully opened and insulated with 8cm (3 inches) of mineral wool plus about 6cm (2.5 inches) of loose gravel filling between the beams. On top of the beams, we first laid coconut fiber strips (about 8mm (0.3 inches)) for decoupling, followed by 25mm (1 inch) OSB panels that were glued together and installed as a floating floor over the beams and coconut strips. Now the question is how to proceed most effectively, especially to improve impact sound insulation. About 90% of the floor will be covered with vinyl.
My idea is as follows:
- A second layer of OSB, either 12.5 or 15mm (0.5 or 0.6 inches), screwed to and glued over the first layer (with half-offset joints when laying). This should ensure that the joints of the first layer remain tight and improve the overall stiffness of the floor.
- Then the vinyl with a separate impact sound insulation layer installed as a floating floor on top.
Is this approach reasonable? Currently, you can still feel quite clearly that the 25mm OSB floating on the coconut strips gives slightly under load. Will a click-lock vinyl flooring hold up under these conditions, or could this cause problems? Alternatively, the vinyl could be glued down, but I would prefer to avoid that if possible.
Thanks for your tips and opinions
Regards
Michael
A few years ago, we completely renovated the ground floor of a single-family house built in 1965. During this work, the wooden beam ceiling to the attic was fully opened and insulated with 8cm (3 inches) of mineral wool plus about 6cm (2.5 inches) of loose gravel filling between the beams. On top of the beams, we first laid coconut fiber strips (about 8mm (0.3 inches)) for decoupling, followed by 25mm (1 inch) OSB panels that were glued together and installed as a floating floor over the beams and coconut strips. Now the question is how to proceed most effectively, especially to improve impact sound insulation. About 90% of the floor will be covered with vinyl.
My idea is as follows:
- A second layer of OSB, either 12.5 or 15mm (0.5 or 0.6 inches), screwed to and glued over the first layer (with half-offset joints when laying). This should ensure that the joints of the first layer remain tight and improve the overall stiffness of the floor.
- Then the vinyl with a separate impact sound insulation layer installed as a floating floor on top.
Is this approach reasonable? Currently, you can still feel quite clearly that the 25mm OSB floating on the coconut strips gives slightly under load. Will a click-lock vinyl flooring hold up under these conditions, or could this cause problems? Alternatively, the vinyl could be glued down, but I would prefer to avoid that if possible.
Thanks for your tips and opinions
Regards
Michael
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pagoni20205 Jul 2020 23:07We experienced something similar nearby, and the OSB boards were also floating.
I would fasten this layer of OSB directly onto the joists from below; otherwise, the layer above will float again.
The idea of placing sand or gravel in between was suggested by my former construction expert— I still think it’s clever because it’s simple, though probably not state of the art.
We used cork infill before, but mineral wool works well too.
The cork strips are also useful when fastening with screws.
For 30 years, I had a floor like this, with 28mm (1 inch) solid pine or larch planks screwed directly onto the joists. Simply great!
If you’re particular about gaps, this might not be for you, but I would do it that way again immediately. You can get affordable planks and then treat them with, for example, OSMO finishes. Very easy to apply with a roller. We used hard wax oil and later, after changing preferences, applied decorative wax coating without sanding. I thought it was fantastic, and it’s very durable—even with a dog.
Never install it floating—screw the boards onto the joists.
I would fasten this layer of OSB directly onto the joists from below; otherwise, the layer above will float again.
The idea of placing sand or gravel in between was suggested by my former construction expert— I still think it’s clever because it’s simple, though probably not state of the art.
We used cork infill before, but mineral wool works well too.
The cork strips are also useful when fastening with screws.
For 30 years, I had a floor like this, with 28mm (1 inch) solid pine or larch planks screwed directly onto the joists. Simply great!
If you’re particular about gaps, this might not be for you, but I would do it that way again immediately. You can get affordable planks and then treat them with, for example, OSMO finishes. Very easy to apply with a roller. We used hard wax oil and later, after changing preferences, applied decorative wax coating without sanding. I thought it was fantastic, and it’s very durable—even with a dog.
Never install it floating—screw the boards onto the joists.
HausiKlausi6 Jul 2020 00:01I’m not a structural engineer, but here are my initial thoughts: Our house is 35 years older, and I recently completed a similar project. Since you live in a single-family home with no tenants, I believe the current setup is sufficient in terms of impact sound insulation. Maybe I’m being too cautious, but it’s important to remember that there is already a significant weight on the surface—6 cm (2.4 inches) of gravel plus OSB. Adding another layer of OSB seems excessive, at least for what you expect. In my opinion, you can go ahead and lay the vinyl flooring now.
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