Along with building the 4th wall and loads of other stuff to do along the way.
Time to make a list of things that need to be remembered before we seal the walls for good:- Electrics need to be in place or at least main feeds should be (there will be two distribution boards in DR3, one for the HiFi, one for ‘everything else’) . Water – nope, not needed thankfully, but there are two condensate drains to make certain are fully functional and leak free, one from the A/C – Heating (heat pump) and the other form the mvhr unit in the loft (Mechanical ventilation & Heat Recovery). There are also the feed and return pipes to the A/C unit.
Wiring for the lights, alarm, ethernet & ring main all need to be ready, probaly for second fix.
The ‘soundproofing’ thing. Not so easy, nothing to do with acoustics, and generally ‘expensive’ There are two imperative things with soundproofing. Mass & total, complete and utter sealing. If air can get in – so can sound. That equates to a lot of acoustic intumescent sealant (think 200 odd tubes in this room, if not more) and an equally large number of silicone (sikkaflex in my case) seal. Sealing a room totally obviously presents issues with air supply. This is why, many moths ago, I had installed a mechanical vent and heat recovery unit in the loft. This pulls in outside air, passing it through 18 activated charcoal filters, two pollen filters, and finally 2 hepta filters. this then goes into a heat exchanger which heats up / cools down that air with the air being evacuated from the room. It then passes through two huge ‘silencer’ units before being fed into the room. So the incoming air should be of a fairly reasonable grade.
There are loads of ready made items that can be used to add mass and help make a room soundproof. They all have one thing in common. Cost – lots of it. From MLV (mass loaded vinyl) to various grades of plasterboard, to hybrid boards made of wood/plasterboard and foam type material all stuck together. In a room of the size I am looking at – that is many $$££K’s and somewhat more than I was willing to pay.
They all really needed to be hung off another ‘fully floating wall’ as well, and to achieve that was going to be challenging.
After much research I found some panels that quoted superior figures than most other varieties, were 15mm thick, and weighed, well, a lot. more research showed that they were sold under various trade names, but were all basically the same.
15mm thick, very strong, tri wall corrugated cardboard. Filled with, erm, dry sand. Yes, cardboard with sand, and all edges sealed with brown paper tape that has a rubber glue on them. Effectively 100% biodegradable and environmentally friendly. All of this I sourced at trade, from large sheets of corrugated, to ultra fine, high silica content water worn, kiln dried sand. To hang them from the floating wall, the cheapest I could find was ‘Genie clips’ and their associated furing channel. Once the cardboard was filled with sand, screwed to the channel with screws of correct size (imperative NOT to go and touch the back wall as that would effectively ‘earth out’ the floating wall and give noise a channel to get to it) a further layer of Gyproc ‘Plank’ boards are then screwed to them and that gives the highest proofing I have yet found. More than just double platerboard by some margin.
So that became the plan. Plenty of extra work for me & the machine shop, but a very considerable saving on ready made product. Make that VERY considerable.
Thanks to Covid & Brexit cardboard sheeting had become nigh on impossible to purchase, with strict limits imposed on quantity. I was in need of some 60 sheets, not the 10 allowed . Breamfold Packaging came up with the goods, their final run, with all the product they had left – arrived and I was very thankful to them.
Sand – I figured that the ultra fine version would be good as its finer particle size would get more mass in per sheet, and also be easier to work with (it flows like water as it turns out). A ton arrived, followed slightly later by another 500Kg, which should finish the job..
It didnt, still needed another 100kg 🙁
Some 200+ panels were filled, mostly 600×600, some bigger, some smaller, and more than a few had to be very custom due to the building being, well, the building.
Gyproc Plank – again a thing in short supply. 25 arrived, stored ready for use (I now need a further 52 to finish the job)
Rockwool. So much Rockwool, I think I have shares in it. Since 2008 I have used many, many tons of the stuff, but as a building, and nigh on 275 yrs old, it is now incredibly heat efficient. that much insulation and sealing has allowed heat pumps to work effectively, whereas before they would not have been viable.
Storing it is fun though, it takes a huge volume of space. As does pretty much everything else I need.
Timber. From memory to date now we have used 480 linear Mtrs of 150 x 45mm in joist format. I go with 150mm as the rockwool and wall is 100mm thick. 4×2 these days is just not 4″ – its usually circa 95mm. So I go with 150 and cut it down to exact 100mm, and have plenty of uses for the off cuts.
Rockwool comes in shrunk wrap plastic for protection. It’s 600x1200mm batten size. So I made the first wall to have these fit right in. Nope – they fell straight out, despite my ruler telling me the studwork was exactly 600×1200.. The shrink wrap has effectively shrunk the batt sizes to somewhat below 600×1200, noted for next three walls, so that studwork was all made to 595x1190mm, and hey, rockwool batts stay exactly where they are put.
The acoustics? Well, thats going to be rockwool once again, and plenty of it. For now, lets get building the 4th wall and get soundproofing..
Building th 4th wall can be the next part – thats enough to take in for now.