How to sound insulate upstairs wooden floor

[StephenStephen]

Hi all,

We've an upstairs wooden floor which we want to reduce noise coming down to the room below.
We want to reduce both the sound of footsteps and the sound of speech

Currently there are spotlights in the ceiling below, so we're going to remove those and fill the holes in the plaster.
There is currently insulation between the joists - some kind of foam bats
I don't think I'll get agreement to overboard the ceiling below, or reduce the ceiling height at all

We're planning to keep the current underlay and carpet and put more carpet on top

so a couple of questions:

-Are there products we can put over the joists to reduce impact noise - any recommendations?

-What's the best sound insulation to put between the joists?
-Is acoustic underlay worth going for?

Many thanks for your thoughts, Stephen

 

[big-all]

you have 3 sorts off sound transmission
airbourn structural thrid one escapes me
with structural insulation in the structure can often count for little iff you have outer surfaces that act like sounding boards as in a large non absorbent surface connected to the structure connected to a large non absorbent surface will transfer a massive amount off sound as there is no mass to stop the surfaces vibrating
you either need to add a absorbant surface or two that will greatly reduced vibration through the structure or fixings with insulation to to disconnect the surface from the structure in a way that stops vibration transmitting

 

[Deleted member 174758]

Currently there are spotlights in the ceiling below, so we're going to remove those and fill the holes in the plaster.

Good idea

There is currently insulation between the joists - some kind of foam bats

Do you mean Cellotex or similar? That actually isn't brilliant at noise attenuation - mineral wool batting of the same thickness performs noticeably better

We're planning to keep the current underlay and carpet and put more carpet on top

If your floor is planked it can help to over clad the floor with a layer of thin plywood or hardboard with taped joints (which need to be staggered from the floor joints). Using one or two layers of tradinional heavy felt underlay is also an effective sound dampener

Is acoustic underlay worth going for?

It can be, but only after you've dealt with the main sound insulation issue

As B-A says noise is transmitted through air (and round corners) so having doors which shut properly in the openings is a help and is why some modern schools use acoustic drop seals and brush strips on classroom doors. Noise can also be transmitted through materials such as floors and the ways to mitigate that include blocking-up openings, having a diffuse (not smooth/reflective ) ceiling surface, having a diffuse floor covering (so not laminate), using sound blot ceiling panels and possibly mounting them on resillient bars and filling voids with well-fitting, dense insulation materials such as mineral wool batting. Another problem is that some frequencies will continue to travel up through walls from downstairs to upstairs. Then you can start getting into other things like not having furniture touching walls.

 

[wwwebber]

I am doing the same in my house and after some investigation I have chosen 100mm Rockwool RW3 which I will put under the floorboards upstairs over the weekend . This is for sound & thermal insulation.

 

[endecotp]

We want to reduce both the sound of footsteps and the sound of speech

Are you hearing actual impact noise, or squeeks?

There is currently insulation between the joists - some kind of foam bats

Post a picture and someone will try to work out what it is.

We're planning to keep the current underlay and carpet and put more carpet on top

Two layers of carpet is.... unconventional.

Are there products we can put over the joists to reduce impact noise - any recommendations?

What is the construction of the floor? Chipboard? Floorboards?

There are pads that you can put between the joists and the boards but of course they raise the floor level, which is not ideal at the doorway.

 

[StephenStephen]

Thank you, much appreciated

Are you hearing actual impact noise, or squeeks?

We're hearing both, but mainly impact (the squeaks are in specific areas)

Post a picture and someone will try to work out what it is.

It's some kind of quite dense foam - a bit like you might find in a firm foam mattress - I think it's doing a good enough job, and seems to have been cut and fitted in a suitably persnickety fashion. Further discussions have also identified that airborne noise is less of a concern than impact

Two layers of carpet is.... unconventional.

Yes - though I'm wondering if there are good reasons not to leave it in place - any thoughts?

What is the construction of the floor? Chipboard? Floorboards?

Wide old floorboards, quite gappy, with a thin layer of hardboard on top.

There are pads that you can put between the joists and the boards but of course they raise the floor level, which is not ideal at the doorway.

I can't seem to find a name of these to search for or find to buy - can you help with that?
Also - I'm thinking that it would be less than ideal to glue floorboards down on pads?

Our updated plan is:

-remove spotlights from ceiling below and fill holes in plaster
-leave the foam between the joists in place (it ain't broke)
-check and fix the floorboards down solidly, sort out any squeaks
-use sealant in the gaps between and around the edges of the boards - is acoustic sealant really worth the money?
-replace the thin hardboard layer, sealing all gaps
-some kind of acoustic foam mat or underlay to reduce/absorb impact - any recommendations on this would be really appreciated
-put the old underlay and carpet back down, with new carpet on top

We're resigned to planing off the bottom of doors to accommodate foam layer/carpet

I'm very much appreciating all your help and any further thoughts you might have...[/QUOTE]

 

[endecotp]

I can't seem to find a name of these to search for or find to buy - can you help with that?

https://www.soundstop.co.uk/ZMJCAP50.php