Shared joists in a semi

[Peter_ST16]

I live in a semi from mid 1990s, and joists over the internal garage go into the party wall. How likely is it that they're shared with next door? My neighbours are really quiet, but their floor isn't - creaking noise whenever they're in the bedroom.
If the above is the case, is there anything I can do (apart from installing new joists and cutting the old ones)?

 

[tell80]

Unlikely in a 1990's build - BCO's were well alert to fire risks & sound transmission from fully penetrating joists.
First thing to do is to establish exactly how yours and your neighbour's joists are supported at the party wall in question.
Getting in a joiner for a paid investigation might help but you & the neighbours would have to work together for any possible resolution.

 

[blup]

They’ll be in a pocket or on a joist hanger.

Is the creaking noise from their side, in which case it is just noise.

Blup

 

[tony1851]

Unlikely in a 1990's build - BCO's were well alert to fire risks & sound transmission from fully penetrating joists.
First thing to do is to establish exactly how yours and your neighbour's joists are supported at the party wall in question.
Getting in a joiner for a paid investigation might help but you & the neighbours would have to work together for any possible resolution.

I think timber joists and beams are allowed to go through a compartment wall as long as they are properly fire-stopped.

 

[tell80]

Thanks for that tony - do you happen to have a reference?

 

[^woody^]

In practical terms, builders won't be humping about 7 or 8m long joists to span two front rooms.

 

[^woody^]

Thanks for that tony - do you happen to have a reference?

Ask him to post some photos. Lol

 

[^woody^]

I think timber joists and beams are allowed to go through a compartment wall as long as they are properly fire-stopped.

What about sound stopped?

 

[tony1851]

In practical terms, builders won't be humping about 7 or 8m long joists to span two front rooms.

As it's a room over an integral garage, it's likely it won't be much more than 2.5m wide on both sides, which makes the length of joists around 5.2m - more manageable.
Besides, structurally it enables them to use smaller joists because of the continuity over the party wall.

 

[tony1851]

Thanks for that tony - do you happen to have a reference?

 

[^woody^]

Besides, structurally it enables them to use smaller joists because of the continuity over the party wall

LOL

Does the span magically change when you use a longer joist?

Or are you adding a 2.7m bearing to the span to get an effective length of 5.2 for a 2.5 span?

 

[Peter_ST16]

They’ll be in a pocket or on a joist hanger.

Is the creaking noise from their side, in which case it is just noise.

Blup

When I had a look the joists were just going into the wall - definitely no hangers, the pockets were cut in breeze blocks but no joist caps were visible.
It is the "just noise" that bothers me though
Just trying to understand if adding some sound barriers to the wall is worth it...

 

[tony1851]

LOL

Does the span magically change when you use a longer joist?

Or are you adding a 2.7m bearing to the span to get an effective length of 5.2 for a 2.5 span?

When you signed on for your course on Building Construction, are you sure you didn't go to the wrong room and signed on for the Cake Decoration course instead?

 

[tony1851]

When I had a look the joists were just going into the wall - definitely no hangers, the pockets were cut in breeze blocks but no joist caps were visible.
It is the "just noise" that bothers me though
Just trying to understand if adding some sound barriers to the wall is worth it...

Are you sure that the joists continue through the full thickness of the wall?

 

[^woody^]

When you signed on for your course on Building Construction, are you sure you didn't go to the wrong room and signed on for the Cake Decoration course instead?

No, although with some of the doughnuts I come across, I may as well have.