Severe vibrations and noise from neighbouring property - joists issue??

[JackieBrecken]

Our neighbours (3-bed 1930s semi) can somehow generate severe vibrations in our property that travel across the party wall, up from the floor into bigger items (e.g. the sofa, bed, etc) and make you jump/move uncontrollably. I know it sounds crazy but it happens numerous times daily as they enjoy terrorising us (waking us up, etc). It seems they get some kind of indication where we are in our property so they can always target us successfully.

The noise is everything from conversations to foot steps to sockets to crockery in cupboards to doors closing (these can be like explosions). It started after their water tank burst and flooded down the party wall for days as they were on holiday.
Prior to this the soundproofing was nearly 100%. Very rarely heard a thing and felt nothing. It developed into vibrations after their building work (2 years after flood) but those vibrations were in response to heavy footsteps or door slams next door - nothing like it is now.

I have talked to surveyors, noise consultants, builders - nobody has been able to help. I know nothing about building, DIY etc but from years of research, etc it sounds like we have shared joists and maybe these have become loose or something (at the party wall - flood? building work?) so weight on our side cause them to rise (e.g. floorboards slightly?) in the neighbouring property (see-saw type effect?) ? Then they stand/jump on this making them knock our floorboards causing these vibrations? No idea if this is even possible but desperate to find out what is happening in order to stop it!!

So - sorry for the long post - if anyone has any ideas, come across this kind of thing before or could recommend what kind of expert we need to investigate (e.g. structural engineer?) it would be very much appreciated.
Thanks.

ps
There seems to be some similarities with this post :

(...joists span both hallways ... impact noise transmits straight across the shared joists into my house ... whole of my hall floor creaks really loudly when they walk about...)
https://www.diydoctor.org.uk/forums/joist-problems-joists-through-party-wall-t25196.html

 

[Deleted member 174758]

Which way do your floor boards run? Front to rear or side to side?

In terms of floor noise, after their flood did your neighbours install laminate flooring? Do you have laminate flooring? Did your neighbours strip the walls back to the brick on the party wall and leave it that way (I am told it is fashionable.... but it isn't good for noise attenuation)

In terms of dealing with this I have had the first hand experience of having in the past lived in a terrace house with deliberately noisy neighbours on both sides. I am also a working joiner with a bit of experience. But to pinpoint the issue takes a bit more information than your posts have given so far.

In all probability the joists do not go through the wall, but what might be the case is that the joist tails might be sitting in contact with each other

One thing I suspect is that the flood may have washed debris down into the cavity in your party wall, turning it in effect into a sort of solid wall in effect. Was your side of the wall soaked as well?

 

[foxhole]

Have you tried a psychiatrist?

 

[Deleted member 174758]

Have you tried a psychiatrist?

It's actually no joke when you live next door to vindictive, noisy neighbours, Foxhole. It can have a very negative effect on your well being

 

[HERTS P&D]

Do you drive a Vauxhall?

Andy

 

[Deleted member 174758]

OK, Andy. What do you know that we don't?

 

[HERTS P&D]

We had a Poster on here about a year ago who would post questions about his car, everything was wrong with it, when he was given an answer he would just argue the point.

Just wondering if he is back.



Andy

 

[foxhole]

It's actually no joke when you live next door to vindictive, noisy neighbours, Foxhole. It can have a very negative effect on your well being

Naturally sceptical about somebody who joins and this is his first post.
He mentioned crazy .

 

[JackieBrecken]

Hi JobAndKnock

Thanks for your reply.

Our floorboards run front to rear everywhere except in the downstairs front room where they run side to side.

I’m pretty sure the neighbours did install laminate flooring but we don’t, we have carpet. In terms of stripping the walls back to the brick on the party wall I don’t know I’m afraid. They did remove a chimney breast from the rear room.

That sounds horrendous having deliberately unpleasant neighbours on both sides. Just one side is driving us insane! Sorry about the lack of info - it’s not my area at all. Pulling back the carpet to check the floorboards is a big deal

That’s interesting about the joists. I wonder if they could still effectively move as one (maybe if they were tight) - in terms of giving some kind of indication to next door as to where we are in our house at any point in time. It just seems so baffling. The joists were the only thing I could think of.

Our side of the party wall wasn’t soaked but we were/are concerned that it might have seeped in via the subfloor or similar as our floorboards that were perfect became separated and buckled in places and there was no other source of moisture. Difficult to tell I guess with the age of the property.

I think ultimately we’d like to get someone in to do some investigating. Do you think our issue would come under a structural engineer’s area of expertise?

Thanks,
Jackie

p.s.
foxhole/Andy - Yes I am new to this forum and this is a genuine post about a nightmare issue. Just trying to see if we can get some advice from those with more knowledge in these areas

 

[Deleted member 174758]

I doubt a structural engineer will be much help - and they will cost a lot of money.

Simply lifting a couple of the floorboards nearest the party wall will allow you to see how the joists are fixed at the wall.

Personally I think you'd benefit from a "decoupled wall" in your alcoves (basically a stud wall with no mechanical connections to the party wall and which is faced with sound proofing materials). You lose 2 to 4 inches depth of alcove, but you potentially gain 30dB of sound deadening (like putting on a pair of ear defenders). There may be other things you need to look at, such as sound deadening carpet underlay, but sound deadening false walls are a start. Sound proofing firms can install these, but they aren't cheap and much of the work can be done by a competent DIYer

 

[JackieBrecken]

Thanks JobAndKnock that’s really helpful.

I’d seen structural engineers mentioned by people with similar-ish problems so was just wondering. They were talking about cutting joists and things though. I’ve never used one but yes I imagine they are not cheap.

You are right, I will do a bit (lot ) of moving by the party wall and have a look under the floorboards. Have ordered necessary tools from amazon. It will definitely be interesting to see up close how the joists are connected.

The “decoupled wall” sounds interesting but is way out of my depth and I don’t know any competent DIYers.

I’ll see what the under the floorboards inspection turns up and let you know, if that’s ok.

Thanks again,
Jackie

 

[Deleted member 174758]

Before talking about cutting anything there is a need for investigation. Because joists are structural I think that cutting them without first exhausting other possibilitites is plain ridiculous.

In many cases much of the noise is coming through the wall and can be reduced by installing resilient bars and soundbloc plasterboard in front of the affected walls (a decoupled wall), possibly with mineral wool batting in the void between the back of the PB and the original wall. The wall is installed onto a layer of acoustic sealant (such as AC50), the plasterboards are fitted so as to stop short of the floor, walls an ceiling by 3 to 5mm (with those gaps filled using acoustic sealant, as well as the PB joints themselves) and the second layer of PB is installed so that the joints are staggered from the first layer. Screws are selected to be just long enough

This is potentially a DIY task

Noise transmitted through the floors can be reduced by simply adding a layer of the old-fashioned, thick, heavy felt underlay beneath your carpet which has excellent soundproofing properties, or alternatively a layer of thick, heavy rubber underlay. At home I have the former.

There is quite a bit of info about soundproof walls on the British Gypsum website

 

[JackieBrecken]

Don’t worry I’m not planning on cutting anything I’m with you - investigation first and even then I’d need some convincing to cut anything! No, I was just guessing that the plan to cut things under the party wall may have been why those other posts were talking about getting advice from structural engineers.

Thanks for the decoupled wall and soundproofing advice. I appreciate the detailed info and knowing there is a workable solution available to try. Even though it sounds pretty scary to a DIY newbie like me

I will have a look under the floorboards and let you know what I find.

 

[JackieBrecken]

Well that wasn't as easy as the man in the B&Q video said it would be!

Unfortunately I have looked twice, on either side of the fireplace, but need to go back and (clear both sides of furniture to) look directly in front of the fireplace now. The joists either side of the fireplace do not go through the PW but from what I could see, the ones beneath the fireplace do. Just wasn't a totally clear view hence the need to revisit.

Looks like these joists were left exposed somehow/touching neighbours joists/etc or just in some way accessible to neighbours after their building work and instead of getting it fixed they have used it to harass us and make our lives a misery. Thinking about it, we need to get this central issue resolved irrespective of sound proofing solutions otherwise they will still be able to do this vibration thing to harass us in all rooms as they do currently

Hmmmm this is a bit tricky. Am thinking I need to go to my home insurance to see if we can claim against them for leaving our joists exposed/accessible/etc after their building work and the subsequent damage from their continued years of harassment. Just not sure what category it might come under and whether or not we are covered. It certainly would explain all the extreme vibrations we experienced after their building work. The flood probably loosened the joists initially causing the extreme noise issue.

What a pain!

 

[Deleted member 174758]

I believe I did say that the joists were extremely unlikely to go through to next door - if only because 25ft long joists are a tad difficult to source, not to say ruddy expensive (and they were in the 1930s)

The solution as far as the joists go might be to fix a treated timber ledger to the party wall with the top, say, 25mm below the underside of the joists. That 25mm is where a 25mm thick rubber acoustic strip goes. The joists are then solid strutted, the ends inside the wall are sawn off and finally the floor is reinstated taking care to ensure a 10mm gap betwen the floor boards and the wall. This gap is filled with Compraband (a super compressecd expanding thermal and sound sealant tape - a bit like closed cell foam rubber) before the skirting boards are replaced.

A party wall agreement is required but I'd just tell them you have dry rot and need to deal with (possibly caused by their flood) as it can affect both houses