another garage conversion

[gullfo]

yes, the wall can sit on the concrete floor, however, the rest of the structure should be decoupled from the existing walls and ceiling. if necessary or required - use isolation bracing (check Mason Industries and Kinetics for products) which are used to stabilize walls and stabilize/suspend ceilings esp in seismic areas, high winds, etc.

[anodivirta]

I made few rough options:
yellow is insulation and red is gypsum. cavity always filled with insulation
a)inside-out walls
b)normall walls
c)combination of them

I understand that symmetry plays also big part of what the final outcome is, so should start to focus on it allready at this point before any acoustics is designed?

Does it matter much what kind of insulation I use between the walls?

I'm hoping to eventually have my speakers(genelec 8260, yeah shaped lovely) soffitted and use Johns small studio examples from here:
http://www.johnlsayers.com/phpBB2/viewtopic.php?t=5457

[gullfo]

inside-out has some nice features because it adds an absorption layer into the room. the only downside comes from the amount of air gap between the mass layers - with normal MAM, on 2x4 walls with a 1" air gap between frames, you're at 8" of air. if you flip that, you're at 4 1/2", so depending on the isolation needed, you could bring the inside-out walls in 3 1/2" or use the normal MAM. with mass enhancement on the exterior walls and a full set of mass on the interior, most times the 4 /1/2" gap can be enough. lot's of drums and loud amps, i'd opt for the regular MAM and larger air gap.

so i'd pick A. the insulation on the exterior side can be regular pink wall insulation. on the inside - use semi-rigid 703 type or equiv.

[anodivirta]

slooooowly learning sketchup

[John Sayers]

When dealing with Sketchup make sure you create everything as a group. Make a wall and group it, you can then move it, copy it, and alter it.

cheers
john

[anodivirta]

When dealing with Sketchup make sure you create everything as a group. Make a wall and group it, you can then move it, copy it, and alter it.

cheers
john

thank you, good point!

[anodivirta]

slow progresss

[anodivirta]

I have a small gap between the wall and floor slab, what would be the best filler for this?
I would think there would be better things than normal acryllic caulk, but is silicone, butyl-sealant etc good for this?

this will not face the full spectrum of outside temperatures we see here (-30 to +30 ish 'C) but definitely bigger changes in tempereture than in normal drywall etc.

edit: I think some of the brands I see mentioned alot in this forum are not easily available in Finland ie.Big stretch or that glue that is not really a glue.

[gullfo]

look into concrete slap joint mixtures. pretty sure someone in Finland must seal concrete joints with products that are designed for the weather maybe swing by a construction product lot and ask. might be an 80lb bag you need to mix, but the key would be to have something which will stay flexible even during deep cold.

[anodivirta]

look into concrete slap joint mixtures. pretty sure someone in Finland must seal concrete joints with products that are designed for the weather maybe swing by a construction product lot and ask. might be an 80lb bag you need to mix, but the key would be to have something which will stay flexible even during deep cold.

thanks! sometimes I just ignore the most obvious solutions thinking that this is now totally different game

[anodivirta]

slow progress again. now I managed to make my final measurements before building.
so this will be my baseline and hopefully I get better results later:)

Green line is measurement taken inside.
Blue line is SUM of measurements taken outside.

once I had taken my first measurement(green line) I moved microphone to outside and measured all 4 walls, mic 1m from wall.
Biggest sound leaks came from window and air conduit and on the side sound leak measured a lot lower.

there was birds chirping and flying around and all normal noises from the neighborhood that messed up the measurement in the kHz range,
but now I have atleast something to compare.

[anodivirta]

wanted to share my progress but first sorry to see these sad news about mr.Sayers!
glad to see that the future of this forum is good hands.

[anodivirta]

I now have empty room (inner measurents 4.1m x2.9m)
sidewalls are made from 10mm OSB+13mm gypsym
frontwall 13mm gypsum (and will add a layer of OSB)
ceiling 13mm gypsum
backwall 2x13mm gypsum.

attached picture or the room and sound leakage test

[anodivirta]

generally I'm guite happy with the isolation i got,
but empty room sounds the even worse than I did expect

In measurements I noticed this ~10dB difference at ~95hz and that is buzzling me:
mic was 1.61m (39% of room lenght) from front wall, ear hight (120cm)
used one genelec 8020 placed symmetrically with lasers and tape measure as I could first L then R position.

is this something that comes from difference in walls (right wall is "damped" by old existing wall while left wall is facing center of garage)?
and is this something that should be adressed ie.making stiffer walls or parts of the existing walls stiffer etc?
or can few mm difference in speaker placement couse measurement error in this low frequency?

or is this something so minor that it can be ignored?

[gullfo]

maybe move the listening mic a bit to see how stable that 95hz is. it may be a mode function based on the room width. or room height. moving back and forth, side to side over (say) a 1m circle should tell you.