A bit of a strange one

hi ive been lurking around this forum for a good while and i thought it about time to sign up. im a guitar maker by trade (luthier if you want the fancy word for it) and ive recently moved workshop to a new building. its far larger than i need and my immediate thoughts were to stick a live room and a control room in there. ive built studios before but this building offers some interesting challenges. its built in two parts, The part with the space for the control room is 2 bricks thick 3.4 meters by 3 meters and is built on a concrete slab, this is fine i can deal with that there's no problem ... the problem is that the part where i want to put the live room is built on a timber frame over a 16" cavity lined with bricks. i have no idea how to isolate the live room floor over this and i cant cut the floor. im worried that if i just build a floating floor over this the cavity underneath will resonate and amplify the sound of drums guitars etc. The building is on a seperate plot of land but it is in a residential area with the closest neighbour being about 50 feet away. could anyone please offer any ideas to try solve this as its driving me mental. thanks guys Gareth.

Location, Location, Location.

sorry im in the uk i should have included that :? id like to manage to do it without having to get underneath and filling it with concrete if possible, but isolation and getting the sound down as much as possible is the key here.

and....pictures, pictures, pictures :) Might be the only thing you can do is going to be a basic damped type flooring system. This would mean installing something similar to 2 inch rigid owens corning insulation on the entire floor area, and add two layers of 3/4 inch plywood over the top of the is insulation. But this method will change the door elevations...so as they say, there is the rub. Then again, you might be able to simply add mass directly to the existing floor and have that work, more understanding of how this floor leaks into the surrounding environment would help some. Still, the door elevations are going to be modified. But you did not mention the overhead, the ceiling/roof area...this is often the weak area and may still prove to be as such. Please update your profile to reflect your geographical area so we can keep up with where you live globally...thanks :)

Hi thanks for the fast response. raising the floor level is not an issue at all as i will be sectioning everything off as it is. as for the celling its timber framed with 1" pine as the outside skin then 22mm osb on the inside (this was installed by the owner.) i will be strengthening this part with new framing made from 4x2 and filling the void with rockwool. (ive worked on construction sites and i know i have to beef the wall structure up to take the extra weight) as i then thought to add 3 layers of plaster board to the inside offsetting everything and joining the walls of the room below sealing all the gaps. the next step was to be the room within a room part which would follow the same methods using 4x2 as the structure and plasterboard on both sides (3 layers and a 6" air gap with rockwool in between) the floor is my main concern as i don't want to build a floating floor over the timber framing if its not going to help and in fact make it worse. construction method of the floor as far as i can tell is brick foundations and lined with bricks spanned by large timbers 8x2 from the look of them. i will do my best to get under the floor (means cutting an access hatch) and taking some pictures tomorrow. ive updated my profile hope thats better :D Thanks for the help guys Gareth.

ok so ive checked under the floor and its not as bad as i thought. the floor is 1x4 planking over 8x2 beams that rest on rows of bricks that run across the building widthways every 4 feet. they are 4 courses high and are very stable. i can upload pictures if people want to see but it is literally a shot of some beams on bricks. what would be the best bet for isolating my first leaf floor then ? would you guys sugest the plywood beef up or the rigid insulation route? thanks for all your help. Gareth

"i can upload pictures if people want to see but it is literally a shot of some beams on bricks." Beams and bricks in the UK are much different from beams and bricks in the US...pictures plz :)

hi heres a couple of pictures of the beams on the bricks. like i said this is repeated every 4 feet. i gave the "floor" under there a good "tap" with a hammer and i think its concrete. any suggestions on how to procede? thanks guys. gareth

having read (deep voice with much reverb) THE BOOK!!! it would seem that a sand filled frame would work to both isolate and add mass to the floor. would anyone advise against this? the floor will take the weight. thanks guys

"the floor will take the weight." You do not know that...we have not the first measurement to work with, so we do not know that as well. :) I would venture to say that you currently have a mass/spring/mass system in this floor. You have the upper layer of the floor, the air space and the damped Earth. Kind of a good thing, maybe more mass on the upper side of the above floor would help, depending on HOW much leakage is available in the brick perimeter with coupling vents. But, will the floor take the weight of the sand and the additional framing has yet to be determined. With a center support under the floor joists this option could be doable...need some measurements to work with.

Iv'e spoken to an architect about the size of the beams the surface of the floor and the supporting bricks and she has told me that the floor would take the weight of the sand plus the walls roof of the isolated room. the thing im worries about is the hollow portion under the building amplifying the sound and transmiting everything to the rest of the building. is there a better way to add mass other than the sand ie the plywood (mdf?) option? ive never worked with a wooden suspended floor before everything else ive done has been on a good thickness reinforced concrete slab. im fairly certain that the floor underneath that the bricks are on is a concrete slab. what measurements do you suggest i get? i can get them tomorrow and post them up as soon as i get back ? thanks Gareth

"the surface of the floor and the supporting bricks and she has told me that the floor would take the weight of the sand plus the walls roof of the isolated room." Well that might be an accurate statement, but in terms of isolation it is incorrect...and let us both remember you said an Architect...not an acoustics technician. The problem you run into will be the flanking of the structure..ask her about that...

hi thats what im asking for help with. she has no idea about sound so she isn't even going to comment. i know it will take the weight i just want some help with making sure that the sound is as atenuated as possible, sorry if that sounds like a moan but it's what ive said from the start. i bow down to 99% of the people on this forum's knowledge. i dont care if i can hear anything inside the building thats not a problem. its outside the building im interested in. and this part of the building is unfortunately a glorified shed. 4x2 framing with 1/2 concrete board on the outside covered with metal sheeting. my plan was to add 2-3 layers of plasterboard between these studs (sealed off with acoustic sealant) and then some rock wool, a 6" air gap and then an isolated room constructed from 4x2 framing with 3 layers of plaster board on the inside wall. rockwool in the cavity obviousely, its the floor that im not sure about. i spoke to an accoustic company yesterday http://www.cmsacoustics.co.uk/ (these guys) and they reccomended adding a layer of ply to the floor then a sheet of there sound matting and then building a frame on top of that using there flanking packs that they sell. Does anyone have any opinions on this ? http://www.cmsacoustics.co.uk/c-acousti ... dlay_E.htm (this is the stuff he was talking about) thanks guys.

"...a 16" cavity lined with bricks. i have no idea how to isolate the live room floor over this and i cant cut the floor." Ok, do you have a sketch up model or something that gives the dimensions of the rooms in question? It seems that we are at a disadvantage here since this information was never given to us...

Hi im really struggling with sketchup at the moment. the room itself is 4.8 meters by 4.2 meters without the room within a room. sorry for taking so long to reply, i had a bit of a run with guitars so i had to concentrate on those for a good while. any suggestions for the floor? thanks guys