Wooden floor makes "booming" noise

[Alpha456]

Hello

• On the first floor, I have a corridor that is 2.6m wide and 10m long.
• The joists run across the corridor (and are therefore just over 2.6m long) and sit on the solid stone walls of the similar-sized ground-floor corridor.
• The joists’ cross-section is 10.5cm deep (ie vertically) by 6cm wide.
• The joists are 46cm apart (centre to centre).
• The floor sitting on the joists is cheap, thin, interlocking floorboarding.
• There is no insulation between that floor and the plasterboard ceiling below.
• When you walk on this floor, even with quite a thick rug laid on top of it, the floor makes a “booming” noise, which sounds very loud at night and which I would like to stop.

I would be interested to know how such a floor SHOULD have been constructed but, more importantly, what I can do to fix the problem. All suggestions very gratefully received.

Thank you

 

[ivixor]

Are the floorboards properly screwed down to the joists? Can you make the sound by stepping on the joists themselves?

 

[John D v2.0]

The problem is they're under sized so they are bouncing when you walk like a drum. You need to damp them some how. That span doesn't meet modern regs for deflection.
I don't think strutting or blocking would really help with such shallow joists but you could give it a go.
If you remove the floor boards and replace with 18mm ply in as few pieces as possible it would help slightly.

 

[Alpha456]

Thanks for the replies. I am now wondering... If I wanted to replace the joists but without changing the depth of them (to avoid changing the floor height etc), is there some material better than wood that would solve the problem?

Thanks in advance.

 

[Notch7]

Thanks for the replies. I am now wondering... If I wanted to replace the joists but without changing the depth of them (to avoid changing the floor height etc), is there some material better than wood that would solve the problem?

Thanks in advance.

To keep the same floor height maybe you could sister the existing joists with say 125 x 75 material ripped down to 110mm.

That would give you each joist 110mm deep x 135mm thick.

If you want to go further, you could screw 32mm x 32mm battens to each joist towards the bottom, then screw 18mm plywood in tight in between. Just do say about 1.2m strip in the middle. That will lock the joists together like noggins.

Then fit 18mm pkywood on top.

Then high density acoustic underlay.

Then carpet underlay and carpet.

I suppose its possible sound deadening underlay on the existing floor might silence it enough for you. Unfortunately, only 1 way to findmout.

 

[Alpha456]

Thank you. Can I ask, with apologies for my ignorance, a couple of follow-ups...

1. Are you suggesting I could do both the Sistering AND the battens+plywood? Or should I do EITHER the Sistering OR, for more effort but better result, do the battens+plywood?

2. If I do the sistering, how should I fixed the new wood to the joists (ie nails? screws? bolts? what sort? how many in a 1.2m length?). I don't want to do the wrong thing and go from a booming floor to a squeaking one.

Thanks in advance.

 

[Notch7]

Thank you. Can I ask, with apologies for my ignorance, a couple of follow-ups...

1. Are you suggesting I could do both the Sistering AND the battens+plywood? Or should I do EITHER the Sistering OR, for more effort but better result, do the battens+plywood?

2. If I do the sistering, how should I fixed the new wood to the joists (ie nails? screws? bolts? what sort? how many in a 1.2m length?). I don't want to do the wrong thing and go from a booming floor to a squeaking one.

Thanks in advance.

Sistering would be my first option, plywood as an extra.

It is to some extent a compromise as the depth of the joists is not increasing, however you would be effectively more than doubling their strength.

Fixing: I would screw and glue. Use PU glue, probably from a mastic gun and plenty of screws, a double row probably every 600mm.

In theory you could create flitch beams by fitting a steel plate between the joists, but that would be an awful lot of work and weight.