Flanking transmission in dense blockwork

midgeybin · Post by **midgeybin** » Sat Jun 05, 2004 11:09 am

I have a ground floor industrial unit with blockwork walls which I intend to subdivide into 5 rooms.Given the mass of my proposed walls and as the floor is concrete will flanking transmission via the new walls to existing floor be a problem.What do you think of the wall isolation solution provided by www.kineticsnoise.com. If possible I want to avoid the added expense of building a timber stud wall with r/c and Gyproc.

knightfly · Post by **knightfly** » Sun Jun 06, 2004 6:42 am

I resized your dwg so reading text wouldn't require scrolling sideways, which is time-consuming and irritating to most people (there's a comment on the design forum, you probably missed it) - when you post drawings/pix, try to resize them to no more than 800 pixels wide, thanks -

I'll have to catch your question a bit later though, I'm out of time for right now - at first glance, it looks as if your first wall plan is a quad-leaf (not good) - what are your individual rooms to be used as; will this be a studio, or 5 separate practice rooms, ?? Steve

midgeybin · Post by **midgeybin** » Sun Jun 06, 2004 12:27 pm

Apologies for the widescreen post.The rooms will be used for rehearsals.I had planned to build as shown in attachment using 150 mm dense block for all walls.Only the outside wall in the diagram is existing.I had thought that given the density of the walls coupled with the wide air cavity that each studio was a seperate entity, a room within a room with negligible effect on its neighbour.On reflection I see I have in fact created a quad leaf wall.I may just butt the walls together with standard ties giving me 300mm walls either side of the cavity and build a plasterboard studwall from floated floor to ceiling.What do you think of the adapted r/c as shown in picture,it claims to stop joiners screwing through to stud.I would like to achieve decent isolation as most studios here fail in this respect.There are a lot of dodgy acoustic experts this side of the water.Thank you for an excellent informative site.

midgeybin · Post by **midgeybin** » Mon Jun 07, 2004 12:15 am

I have based my plans on avaress post-under 100hz,april 9 2004 and your advice on mass as the way to go.I also agree with those views just on a gut feeling leaving stc charts etc aside.I have built timber stud in my studios before and found those frequencies troublesome.How can I best achieve mass airspace mass when building rooms alongside each other and avoid triple/quad leaf construction.Lastly what do you think of the floating floor solution as detailed,better than the joist route?

midgeybin · Post by **midgeybin** » Mon Jun 07, 2004 8:15 am

The whole 2 leaves is best mantra is true - but thats all things being equal - ie it's the best reduction for the cost - particularly in the troublesome low end. It's still certainly possible to get a better reduction with 4 leaves if you add enough mass. ie if you were having to work with something existing and didn't want to tear stuff out. In fact more mass on a 4 leaf wall is just going to be the best in the end.[quote] Andrewmc June 14 2003.Just read this from previous discussion.As the block is much cheaper to buy and lots of brickies in the family I may revert to plan A with aesthetic finish to blockwork and suitable traps etc.

AVare · Post by **AVare** » Mon Jun 07, 2004 9:10 am

It's still certainly possible to get a better reduction with 4 leaves if you add enough mass. ie if you were having to work with something existing and didn't want to tear stuff out

I don't understand you. Have you seen this drawing at the bottomt?

http://www.domesticsoundproofing.co.uk/tloss.htm

midgeybin · Post by **midgeybin** » Mon Jun 07, 2004 12:32 pm

The point I was trying to make, somewhat crudely, granted ,is as follows.If you build 2 adjacent studios based on the room within room method its impossible to adhere to the mass/airspace/ mass theory.I wish to seperate my rooms with dead air then build an exterior masonary wall for each room with a timber stud decoupled inner on a floated floor(or masonary from existing concrete floor) which is in effect a four leaf partition=doubt = sadness.

AVare · Post by **AVare** » Mon Jun 07, 2004 1:33 pm

Thanks for the clarification.

Have you studied the BBC report on actual studio isolation measurements?

[url]http://www.bbc.co.uk/rd/pubs/reports/1987-01.pdf

I hope I got the url right. Key thing to this case is that the inner walls are also floated (figure 9).