Smoking neighbours flat below - Underlay solution?

[Fredde87]

Hey guys,

So I have a new downstairs neighbour who has moved into the flat below mine. Unfortunately they sometimes smoke indoors (when they come home at 2am) and the smell comes up into my flat, specifically into the bedroom.

There are no windows in my bedroom (just a uPVC terrace door which is on the opposite side of building from my downstairs neighbour's window), so I dont think the smell is going out of their window and then into my bedroom, I think it must be coming through the floor.

I have a hardwood floorboards that are relatively well interlocked (no major gaps between them), but I guess maybe not air tight. They sit on chipboards (with no underlay) which sits on top of the joists.

Further there is no insulation in the floor, so the joists have just an open void around them and then of course underneath them sits the the neighbours plasterboard for their ceiling.

My question is, would adding a type underlay be a potential solution to blocking the smell/smoke from reaching my bedroom from the neighbours below me?

What I am considering doing is opening up the floor, filling any voids around the edges (under the wall) and adding some sort of underlay that can block smoke/smells and then putting the floorboards back.

If that is a suitable solution, can someone advise if there is a suitable underlay that I should be using?

Or shall I start smaller, because lifting the floorboards is not easy. Shall I first seal up any small cracks between the floorboards and the skirting for example?

Or would you recommend some other solution?

Another option I read about online is you can maybe add a positive pressure ventilation system to push the smoke/smell the other way, but not sure how well that would work and I have limited space to install something like that. But open to hear any recommendations!

Thanks in advance!

 

[Wayners]

Cloud 9 underlay.
Mastic around joints and under skirting.

Problem will be stud walls as smell may get up there and in

 

[catlad]

If you are going to lift the floor boards then I would put rockwool in between the joists.

 

[foxhole]

So they don’t have a ceiling?You share a chimney ?

 

[Fredde87]

Cloud 9 underlay.
Mastic around joints and under skirting.

Problem will be stud walls as smell may get up there and in

Thank you. The Cloud 9 underlays I can find online seems to be for Carpets though, is this the right stuff and can be used under floorboards too?

They look breathable looking by the pictures. Should I not use something plastic that will block the smell? Or this stuff is efficient at blocking smells?

 

[Fredde87]

If you are going to lift the floor boards then I would put rockwool in between the joists.

Yes for sure. I was planning to do this for noise and thermal insulation as well (they like to play loud music until 5am on Monday nights as well).

But I figured rockwool is a bit breathable and will allow the smell through? So I was thinking maybe a underlay as well on top?

So they don’t have a ceiling?You share a chimney ?

We dont have a shared chimney. They have a plasterboard ceiling. (I previously had the floor up years ago when a joist failed so I remember how its built)

 

[foxhole]

Yes for sure. I was planning to do this for noise and thermal insulation as well (they like to play loud music until 5am on Monday nights as well).

But I figured rockwool is a bit breathable and will allow the smell through? So I was thinking maybe a underlay as well on top?

We dont have a shared chimney. They have a plasterboard ceiling. (I previously had the floor up years ago when a joist failed so I remember how its built)

So smoke can’t penetrate a plasterboard ceiling will just be floating up thru your front door . And into room with biggest ventilation to outside ( your external bedroom door).

 

[catlad]

If it was my flat I would lift the floor, install dense acoustic slab rock wool between the joists, and then lay cement board over the joists as thick as practical ( starts at 6mm ) then relay the floor.

 

[DaveFix]

I had this problem in a flat, it was coming from the cupboard where water services rise/fall between flats. If you opened the cupboard door you could clearly hear every word the neighbour below was saying.

Your neighbour might not be keeping their service cupboards closed.

Also check around your fusebox. My fusebox had its own built-in cupboard, but inside the door was a huge 100mm service hole in the cavity wall, which my neighbour also had.

 

[Fredde87]

Thank you all for your advice. Sorry for the late reply, been away over Easter.

So smoke can’t penetrate a plasterboard ceiling will just be floating up thru your front door . And into room with biggest ventilation to outside ( your external bedroom door).

Sure but they have cutouts for their spotlights which I guess have gaps in them.
I went around with some silicon as an emergency fix and filled the gap between the floorboards and the pipes for the radiator. That has thankfully removed I would say about half the intensity of the smell. It now smells like they are smoking in the room next door and not in the same room.

It’s unlikely to come through the terrace door as it would have to wrap around the building and I’m on 5th floor so the winds or breeze would take it away and not around the building in that way. Further you can’t smell it at all from the terrace itself.

If it was my flat I would lift the floor, install dense acoustic slab rock wool between the joists, and then lay cement board over the joists as thick as practical ( starts at 6mm ) then relay the floor.

Thank you, not heard of cement boards before but will look into that! I presume you would fill the gap between the cement boards with something to make it air tight?
What’s the noise insulation properties like for cement boards?

I had this problem in a flat, it was coming from the cupboard where water services rise/fall between flats. If you opened the cupboard door you could clearly hear every word the neighbour below was saying.

Your neighbour might not be keeping their service cupboards closed.

Also check around your fusebox. My fusebox had its own built-in cupboard, but inside the door was a huge 100mm service hole in the cavity wall, which my neighbour also had.

Thank you. Yes I found out a lot of as coming through the holes in the floor for the radiator pipes. Will check around the boiler too as that is just outside the bedroom. The rest (gas and water) enters through the kitchen but here the smell is not as bad.

 

[foxhole]

You misunderstood , your terrace doors created a chimney affect drawing air up the stairs and thru you home.