Background
I am going to lay a new floor (oak parquet with waterborne heating) and have opened up the joists. I haven't experienced any issues with bounce with the previous floor, a pine floor from the 30s, but now when walking on the floor joists, the bounce is visible with the naked eye. Now I want to do what I can to minimize the bounce.
The floor joists are about 8 meters with support in the middle where the load-bearing wall runs. The room I am working in takes up half the width of the house, approximately 4 meters.
The new floor needs to build about 55 mm to align with the hallway floor level. My plan has been to level the floor joists, then lay floor gypsum on them, and then screw glue slotted chipboard through the gypsum down into the floor joists. This would build 13+22 mm = 35 mm. Additionally, there would be plates, acoustic panels, and parquet flooring, about 22 mm extra, totaling 57 mm.
The alternative, placing gypsum on top of the plates doesn't appeal to me, partly because full bonding seems tedious, and screwing 30 sqm with the risk of puncturing the pipe doesn't sound fun either.
Question
Will it result in a worse installation concerning bounce if I do as planned, compared to, for example, skipping the gypsum and raising the floor joists by 13 mm and screw-gluing chipboard to it instead? Or should I also screw glue the gypsum? The advantage I see with gypsum is its sound-dampening properties.
Or should I use another sound-dampening sheet material instead? 13mm plywood?
All good advice appreciated.
I am going to lay a new floor (oak parquet with waterborne heating) and have opened up the joists. I haven't experienced any issues with bounce with the previous floor, a pine floor from the 30s, but now when walking on the floor joists, the bounce is visible with the naked eye. Now I want to do what I can to minimize the bounce.
The floor joists are about 8 meters with support in the middle where the load-bearing wall runs. The room I am working in takes up half the width of the house, approximately 4 meters.
The new floor needs to build about 55 mm to align with the hallway floor level. My plan has been to level the floor joists, then lay floor gypsum on them, and then screw glue slotted chipboard through the gypsum down into the floor joists. This would build 13+22 mm = 35 mm. Additionally, there would be plates, acoustic panels, and parquet flooring, about 22 mm extra, totaling 57 mm.
The alternative, placing gypsum on top of the plates doesn't appeal to me, partly because full bonding seems tedious, and screwing 30 sqm with the risk of puncturing the pipe doesn't sound fun either.
Question
Will it result in a worse installation concerning bounce if I do as planned, compared to, for example, skipping the gypsum and raising the floor joists by 13 mm and screw-gluing chipboard to it instead? Or should I also screw glue the gypsum? The advantage I see with gypsum is its sound-dampening properties.
Or should I use another sound-dampening sheet material instead? 13mm plywood?
All good advice appreciated.
If you want to eliminate the bounce, it's important to increase the stiffness of the floor structure. You can do this by adding joists between the existing ones or glue-screw the chipboard directly to the joists. The latter requires careful execution to ensure good integration.
So you advocate not putting gypsum between them? There will also be an additional joist between the gypsum/floor particleboard and the floor joist as we need to level the floor. The alternative is not to level the joists but to even out with self-leveling compound.B bossespecial said:
Yes, I should have skipped the plaster. The problem is already today that the floor joists are somewhat too weak and the thin distance that is intended to lie on the rule makes no difference. What is required to get a stiffer floor is to add additional joists between the existing ones. Simply using self-leveling compound instead of leveling can unfortunately only worsen the deflection.
I think it is unnecessary in this case. As mentioned, the floor is already a bit flexible, so a screw-glued homogeneous chipboard directly on the joists would also contribute to increased rigidity.
It sounds quite noisy down in the basement, I should add, hence there will be a bonus with an extra layer of floor gypsum.
And screw-glued floor chipboard would be used in both of my alternatives, the difference is that in one scenario there is gypsum in between. If the gypsum does not reduce stiffness, I should add it if I want better sound insulation? Did I understand you correctly then? Or are you also suggesting that to maximize stiffness, the chipboard should not be screw-glued to the gypsum/floor joists but directly to the floor joists?
Your answer is ambiguous, hence this nagging.
And screw-glued floor chipboard would be used in both of my alternatives, the difference is that in one scenario there is gypsum in between. If the gypsum does not reduce stiffness, I should add it if I want better sound insulation? Did I understand you correctly then? Or are you also suggesting that to maximize stiffness, the chipboard should not be screw-glued to the gypsum/floor joists but directly to the floor joists?
Your answer is ambiguous, hence this nagging.
Add extra beams between existing beams. Glue and screw 22mm flooring chipboard (non-grooved) onto the floor beams. What is done on top of this does not matter. The stiffness of the floor framework has a significant impact on the sound.
While you are reinforcing with noggings and double sheathing, you can take the opportunity to fill the spaces with rock wool. It can provide some dampening of certain sounds, though not footstep sounds if the floor structure becomes very stiff.
If you want to get rid of footstep sounds, it might be better to hang a new gypsum ceiling in the basement.
If you want to get rid of footstep sounds, it might be better to hang a new gypsum ceiling in the basement.
The proposal from @bossespecial is the only right one: New floor joists between the existing ones and glued and screwed unspiked chipboard on top. The additional joists ensure that the impact of point loads (e.g., someone walking) is distributed over a larger area. The chipboard also contributes to increased rigidity. The original joists are probably 3x7 inches (75x175 mm) on c/c around 750 mm. With a span of 4 m, it is insufficient for an acceptable deflection. The stiffness of the floor structure is significant for sound transmission, especially of bass sounds. You don't need to fill the cavities, a 70 mm ground slab (high volume weight) of stone wool is sufficient.