Ceiling Acoustic insulation solutions, Iso-Max, GenieClip etc.

[Michaelsf90]

Possibly won't make much difference. I'd check out the price. If knauf is cheaper then get that. Are you ripping your old ceiling down completely?

 

[pls1]

Possibly won't make much difference. I'd check out the price. If knauf is cheaper then get that. Are you ripping your old ceiling down completely?

Yes, it was lath & plaster overboarded (badly) with a single layer of plasterboard. There was no access from above to put RW3 between the joists and can't lose any ceiling height so pulling it down was the only option.

 

[Michaelsf90]

Have you done it now? My plan is to cut the ceiling in the middle like a slot to get me on between joists and push the batts down with some wood. That way I just need board a slot down the middle. Then batten it out and board onto that. Downstairs is fine it's 7x3 joists by the looks of it. When I do upstairs I don't know what I'm gonna do. The loft is only done in 3 by 1.5 inch. The joys of diy and the joys of houses. By the way do you think overboarding a wall would need a vapour barrier?

 

[pls1]

Ceiling is down yes, not a difficult job just very messy due to the amount of sh*t accumulated between the joists over 100 years! (gas mask essential)
If your joists are spaced evenly and you know there isn't much in the way (noggins, old pipes, wiring etc) then you might get away with pushing the insulation along through a gap. You won't be able to get a tight fit on the insulation batts otherwise they won't move along the joists. I wanted a tight fit so there wasn't any weak points for airborne noise to get through.

 

[Michaelsf90]

Yer I get you. I'm thinking take a whole section down to address the flanking noise and the rest of the ceiling which I'm not too fussed about the insulation cut it so I can push it. If it's tight I could use a 2x1 to push it down. I ordered the stuff today so that's me busy for the next few weekends. Have you finished the project yet?

 

[pls1]

Quite a way to go yet as I'm only doing it in the evenings. I've nearly finished cutting & fitting the RW3 between the joists. I decided to cut the RW3 on the short length to minimise wastage, more work but it will save money.
I ordered a load of resi-bar from the local builders merchant, they had two types available: Gyproc RB1 and one manufactured by a company called 'Superior'. The Superior was half the price of RB1 at about £4 a length so went for that! Hopefully it will do a decent job once its all installed, flat above has vinyl floor glued to 9mm ply on floorboards so a shed load of noise is coming through

 

[pls1]

One thing I'm thinking of doing as well is getting a solid rubber strip and cutting small bits to put between the joist and resi-bar before screwing to the joists to help with impact noise. Whether it makes and difference remains to be seen!

 

[Michaelsf90]

You can get isolation tape to put between the joists and resilient bar. It's like a 5mm foam. Jcw acoustic isolation tape or something like that. Price varies depending on the thickness and it comes in ten metre rolls. Looks good tho. It's got to help with all that insulation packed in

 

[endecotp]

One thing I'm thinking of doing as well is getting a solid rubber strip and cutting small bits to put between the joist and resi-bar before screwing to the joists to help with impact noise.

There’s no point doing that as the solid screw bypasses it.

This is exactly the issue that things like the genie clips are addressing.

 

[Michaelsf90]

You are right but surely it's better having that than the whole thing being pressed up tight against the joist or wall etc. It's how far you want to go with it, how much you expect and how much you want to pay

 

[pls1]

That seems to be the whole thing about soundproofing after endless nights of research! Bit of a grey area with so many variables, differing claims of DB reduction and installation methods.

My next thought is whether to put anything between the sheets of plasterboard when double boarding. I've seen Green glue mentioned elsewhere and this is an interesting thread as I was thinking about using AC50 as its cheaper!
https://www.johnlsayers.com/phpBB2/viewtopic.php?f=6&t=21516

 

[Michaelsf90]

I don't think the AC50 would do anything to be fair. Green glue is some kind of miracle product that turns the sound waves into heat. Dont ask me how it does it or how it works but through some research that's what I've figured out. AC50 is just a silicone that stays permanent flexible so as sound hits it it vibrates with the sound rather than transmitting it. You could try it but I don't think it would make much difference. My soundbloc board came today. A hefty 44kg a sheet. I'm thinking can resilient bar take the weight of two of those!

 

[pls1]

Should do, I read somewhere that with resilient bars spaced at 400mm, maximum loading is 35kg per m2. Have you got a plasterboard lifter to get them up to the ceiling?

I think I'll ditch the green glue idea, too expensive. Mass Loaded Vinyl (MLV) is my next thought, a 2mm thick layer is 5kg/m2 so that sandwiched between two different thicknesses of acoustic plasterboard would give a good mix of materials & densities to reduce the noise from above.

 

[Michaelsf90]

Soundbloc is 14.5kg per m2. So two of those is 29 plus the five your at 34. So it's on the limit. MLV will work and is probably amazing stuff but it's very pricey! Like I said it's how far you go isn't it. Probably be a good six weeks before my project is finishing. Most of the stuff has come today and the missus is already moaning. Haven't even started yet!

 

[endecotp]

A hefty 44kg a sheet. I'm thinking can resilient bar take the weight of two of those!

Yes. The limitting factor is the screws from the bars to the joists. There is a danger of the screws pulling through the holes in the RB, according to someone who posted here previously when I was doing this. If the holes align suitably, consider two screws; maybe consider washers. But it will probably be fine without.