JonBATConsult

Sounds like something is off. Lets talk more

Standard rockwool pipe lagging works quite well. Upgrade this to a mass loaded vinyl around the lagging

That really is a right old Cock up isnt it. Without figures I cant help you but normally. I would not expect to see more than 8l/s being force down a 75mm duct. One problem is you will end up with a large oressure drop on your grille and it will regenerate noise.. Reducing your your fan duty below what has been advised is not reccomended and woudnt comply with part F. If you have go to the effor of sealing up its important to follow through with the correct MVHR setup. (15 years working in building acoustics and air permeability)

A little bit more context needed. Is this new to you, age of property etc?

I find a jumper is the most eco thing. Some people's houses are so hot and then they complain to me their gas bill was £200 a month..

Yeah i often find if you go and talk to your local you can get a price that is good. Maybe not with travis perkins though

If its a creaky floor you have then to prevent this all the floor amd orginal deck has to come up. The joists should be checked for being flat and not moving. I see too many dodgy conversions where ceiling joists have become the structural floor. Once checked, joista shimmed if needed, lay mineral or glass wool between the joists (its an irritant, just wear a dust mask). Use expanding polyurethane glue to put down a new chipboard floor. Use the glue between the board and joist and you will have a very quiet low creak floor.

Pictures will help

Hi if your phone is fairly new there are some decent sould lever meter apps that are pretty decent. Carefully measure the unit at a distance of 1m and let me know what you get.

The weight of the frame is negligable in this scenario. Make sure you plasterboard and system achieves your fire requirements. Make sure speakers have a fire rating so they dont compromise the ceiling.

https://www.walls-and-ceilings.co.uk/metal/britishgypsum1.html?_=1684877947009&p=2 Great prices for the metalwork on here.

Thats a decent gang

What he said. A decent gang could install, tape and joint it all in a day it the lights a terminated in advance. Resilient hangers, bit of 25mm insulation in the void will improve sound insulation by a significant amount.

Surely just use 215 wide block or blocks laid flat single blocks or hollows or discuss windframes. Im sure he is doing this for a very valid reason but important to have a bit of back and forth in design development with se

Regarding plaster i bet that board will suck like crazy on the first coat. Prime prime prime