build or just treat?

Hi all After reading for few years many forums and books while sharing a studio with a friend of mine I decided to start my own little mastering studio and I want to start treating the cellar/garage above that I bought last year(I know dimensions are far from ideal but that's what I can afford). Dimensions:H 2,70 meters W 4,20 meters L 5,70 What I'm looking for with this post is to solve my doubts about the isolation. I made some rough tests few days ago keeping the speakers at 85 dbspl(that is most of the time the way I work) and I discovered from the area above uninhabited for now, that I could just hear something.I do not have numbers on my hand but I could say that reducing that transmission of 10-20db would be perfect. I have always been temped to construct in the inner space of the hollow concrete walls(attachment above) a single leaf wall as J.Sayers suggest for little room,but I'm tied by my doubts about a 3rd leaf build. As you can see the concrete structural wall run parallel next to 2 inner walls 70cm far. The Hollow space around between the inner actual room and the structural wall is ventilated with a perforated grid door. The inner room is concrete Hollow blocks for walls, concrete floor slab and the ceiling is concrete-pot-concrete. My my question then is: What is the best way to get 10-20 db of TL? (I will try to post some photos very soon) Thanks in advanced Alessandro

Photos and Measures: H 2,70 meters W 4,20 meters L 5,70 cheers Alessandro

Hi Alessandro, and welcome! :)

(I know dimensions are far from ideal but that's what I can afford). Dimensions:H 2,70 meters W 4,20 meters L 5,70

Those dimensions are actually not bad at all! If you plug them into a mode calculator, such as Bob Golds', you'll see that the modal distribution is fairly good, it passes all three critical tests, and the Bonello chart is also good.

I discovered from the area above uninhabited for now, that I could just hear something.I do not have numbers on my hand but I could say that reducing that transmission of 10-20db would be perfect.

That should not be too hard to do. It is a reasonable goal.

The Hollow space around between the inner actual room and the structural wall is ventilated with a perforated grid door. ... The inner room is concrete Hollow blocks for walls, concrete floor slab and the ceiling is concrete-pot-concrete.

The reason for the lack of isolation is very likely due to the "perforated grid door". Please post a photo of that. With the structure you already have, you should be getting very good isolation, so the cause of poor isolation is almost certainly because the two leaves are not sealed properly, and there are holes or cracks where air can get through. The photos show that the mortar work on those concrete blocks is very poorly done, so there are very probably multiple air paths through that wall. So before you build anything, I would suggest that you first seal all of the walls and the ceiling. I would plaster over that side of the wall, then seal the plaster with masonry sealant once it is fully cured. You also need to replace that "grid door" with a solid door that has good seals all around, and check carefully all around the room for any other cracks, holes or passages for air, such as through the electrical system, for example. Then check your levels again, to see how much it has improved. - Stuart -