I want light and sound isolation

#31

The room is coming along - see photo. The wood inner structure is done, wood fiber insulation is in place, the rest is on it's way...

I haven't yet decided what to do with the floor. And I'd like to decide before putting up the drywall, in case I decide to do a screed, which might warp the drywall. The existing floor is a slab that's not very level. In one corner I have 4cm difference with the highest point.

I had originally thought of just putting down an underlay underneath a laminate floor. Something like this: https://www.leroymerlin.fr/produits/rev ... 67108.html

But now I'm thinking maybe I should level the floor once and for all. For this I see 2 options:

Option 1 - install a screed (self leveling cement) between 0-4cm. Then follow with the original idea, a thin underlay and laminate floor. This would be a cheaper option with less isolation.

Option 2 - a dry vermiculite screed for leveling, with a layer of something hard, such as OSB on top, then finished with stratified flooring. If you search for fermacell dry screed you'll see what I'm refering to. This is a more expensive option with (I believe) better isolation.

I have two questions:

I would like thermal as well as acoustic isolation. I believe the weakest part in my design is the double glass doors. As I believe that sound isolation is a "weakest link" kind of thing, would the extra sound isolation from option 2 be of any use?

I believe most types of insulation sold for use on floors with thermal and acoustic properties are meant to dampen mainly foot noise between floors. Because in my case I would want to prevent as much flanking as possible escaping the room through the slab (for example drumsets or bass amps sitting on the floor) Would any of these products actually be doing me any good?

#32

the fermacell approach looks like an option if it's in your budget (https://www.fermacell.com/en/flooring) as is the self-leveling compounds. either way you could put a hard layer (e.g. OSB) then your finish flooring.

on the isolation question - i'd recommend you use isolation platforms for the drums and amps.

for the doors - if you need more isolation - adding a second set of doors can address the isolation level as well as increasing mass and lamination for damping to reduce resonances.

#33

Hi Again,

I've got a 2 random questions:

1. My electricity/internet is coming into the room through 2 plastic conduits - one for high voltage (230v - 2 outlet circuits, one light circuit) the other for an internet cable. As I was closing up the inner leaf, I attached the two conduits with zip ties, thinking that I don't want them to vibrate against each other, then I closed the wall (insulation and vapor barrier - drywalling not yet done). Then of course, I remember that high voltage and internet need to be seperated (in France, the code specifies 20cm of distance between them) So these two conduits are side by side for about 4m between my two leaves. Do I need to reopen the wall and rectify this ? Or is 4 meters not such a big deal?

2. I'll be doing the drywalling soon - two layers of acoustic drywall. Every indication for drywalling in normal constructions tells me that you're supposed to leave a 1cm gap between the floor and the drywall, to avoid the drywall absorbing any humidity or spills, and also to avoid any cracking of the drywall in case of movement in the structure or floor. However the 1cm gap from a sound isolation perspective is clearly not ideal. I don't have any plumbing in the room, except the condensation tube from my heat pump.

My electrical will be in a plastic base board that will cover the potential gap, and could be caulked to seal the inner leaf.

Do I leave the 1cm gap and use the plastic base board and caulk to create a seal ? or do I put the drywall up against the floor ? Or is there some other solution ?

#34

#1 - they are in conduit, so most codes would see that a wholly separated. the main reason would be potential interference from the digital circuits or mistakenly plugging your internet gear into 230v... if you have proper grounding (star grounding etc) then the possible interference from the network is very low. and just don't plug network things into AC outlets :-)

#2 - i'd suggest you go to 0.5cm-0.6cm on the drywall to floor gap and using backer rod and caulk to seal it up. then leave a 2mm gap under the trim (avoiding hard contact with the floor).

#35

Hi Glenn - Thanks! I always appreciate your clear responses!

Backer rod and caulk sounds like a good solution. But what is the logic on leaving 2mm under my baseboard?

#36

the 2mm on the trim is my habit. i leave it off the floor and seal it with caulk before painting. it matters slightly if you have decoupled the walls from the floor (e.g. Kinetics Noise Wallmat etc).

#37

I have a new question. I've just finished my first layer of drywall, getting ready to seal the joints and start the second layer.

Here's the pertinant info:
2 layers of BA 13 acoustic drywall attached to wood studs (walls and ceiling). First layer was screwed to studs. The studs are about 63cm apart, instead of 60cm, which means I had a lot of wasted scraps of drywall. No plan to use green glue, because my sliding glass doors will be the weakest link in the sound isolation.

I was intending on screwing the second layer as well. But I've recently learned that hanging the second layer of drywall to the first with an adhesive is a possibility. The advantages for me would be that the sheets don't have to align with studs, so it would be much easier to stagger the joints, and I would have much less wasted drywall.

Is this a good idea from a sound isolation point of view?

#38

And from a building point of view, there seem to be different types of products. Does anyone have any recommendations?

#39

i would use screws. the problem with adhesives on drywall is it's gluing the paper together, not bonding the gypsum. why did you go with 63cm instead of 61cm or 60cm? also, if the first layer is vertical, rough finish on tape and mud, then horizontal on the second layer. or vice versa.

#40

63cm was a mistake. 60cm was the intention so that 120cm drywall sheets would fit. Big mistake! So now, the drywall is hung horizontally. If I screw the next layer, it will also have to be hung horizontally so that the edges of the drywall sheets land on a stud. This is why I was exploring the idea of adhesive, as it would allow me to hang vertically.

Do you think that drywall isn't securely attached when done with adhesive?

#41

i know there are plenty of folks who use construction adhesive to attach drywall and panel layers in homes. however, unless you're using paperless gwb, then you're simply bonding paper to paper and there is a risk. whilst i'm sure it comes too late - you could have "sistered" the studs to create the 60cm spacing... ok, next studio build ;-)

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