Solid Wall

Hi, I have read the FAQ on walls about double leaf and single leaf etc. My idea is to build a wall that consists of Concrete Block > Concrete > Concrete block. The blocks are 100mm and the gap of concrete would be large enough to make the total wall width 12" (excsue the measurement changes). I understand this would be classes as a single leaf wall. The room is for a drum practise room and nothing else. At a drum shop near me they had a wooden wall, loft insulation and another wooden wall. You could only just hear the bass drum and snare, this would be plenty of insulation for me. So would this solution work well enough, it doesnt need to be totally silent as I shall be a good 20ft away from any houses, maybe 30ft. I hope my intentions are clear. Thanks Nick

It probably would work "well enough" - but I suspect it would work better if you were to leave an air gap between the two layers of concrete block. The effect of a mass-air-mass system will be more significant than that of just adding the mass to a single leaf. Why do you want to fill the gap?

Nick, IR-586 shows massively better performance of two separate walls separated by 2 inches of airspace versus 1 thick wall at all frequencies above 63 hz. see chart below. of course below 63 the double wall will perform a little worse, because of the resonance frequency. the data isn't there but that's for sure what will happen. how bad will it be i can't say. insulation will make the problem less. at 630 hz the difference is about 30db better for leaving a gap! not sure what is about to happen above 6300 hz, probably the two lines will converge ... anyway i'd say if you really want the best iso at 40 or 50 hz at any cost then do the single wall, but if you want the best overall performance go with the double wall with air in between. on the chart, 90-60-90 means 90mm block wall separated by 60mm insulation and another 90mm block wall. the 190 refers to just a 190mm block wall. so the double wall is slightly less mass, and still performs better over most frequencies. intersting, huh? Dan

Thanks for the help, Ill look into the double wall with an air gap, the reason I was going to fill it with concrete is because its going to be about 8/9ft tall and I didnt think a single wall that tall would be strong enough. What would happened if I were to slide a 2X4 every 600mm in the air gap to keep the wall slightly sturdier, would this damage the t&l at all?

Yup; essentially you'd have a very heavy, but SINGLE frame, wall - rough calculations are as follows 300mm solid concrete - STC 68, worst TL 40 dB @ 50 hZ 100mm block, 100mm insulated,, NO STUDS, 100mm block - STC 80, 53 dB @ 63 hZ Add studs that contact each 100mm block leaf - STC 54, 34 dB @ 63 hZ. Both walls without concrete in center, resonance is around 20 hZ - solid wall, 300mm, resonance is around 42 hZ. HTH... STeve

By insulated do you mean roof insulation or an air gap?

I meant 1 to 3 PCF (density) fiberglass or mineral wool... Steve