Plastering soundproofed ceiling

[kateangela]

When soundproofing our ceiling we left a 5mm gap between the plasterboard and wall. We filled the gap with acoustic sealant. We want to plaster the ceiling. Can we take the plaster to the walls or do we need to leave a gap here also to stop sound transmitting through the walls to the ceiling via the plaster?
Any help would be apppreciated.
Thanks

 

[roughcaster]

Can't really help you much here on the soundproofing issue, but i don't think the 5mm gap would make that much difference, and as you said, you've filled the gap up with an acoustic sealant anyway. I'd just go ahead and plaster the ceiling. Are you going to plaster the walls too?? if you are, you would need tape all around the wall/ceiling line anyway.

 

[JohnD]

add coving?

 

[roughcaster]

Great idea!! You wont need to tape then either, unless you wanted too.

 

[padsman]

out of intrest how did you soundproof the ceiling.

 

[ajrobb]

When soundproofing our ceiling we left a 5mm gap between the plasterboard and wall. We filled the gap with acoustic sealant. We want to plaster the ceiling. Can we take the plaster to the walls or do we need to leave a gap here also to stop sound transmitting through the walls to the ceiling via the plaster?
Any help would be appreciated.
Thanks

I want to learn too. I think you are right to worry about bridging the isolation gap affecting the noise insulation (I worked in engine/vehicle noise and vibration analysis for 15 years). Also, rigid plaster over a flexible gap spells CRACKS to me. The application brochure for Soundbloc plasterboard is not much help either.

 

[padsman]

to truly soundproof anything you need to isolate, the sound will always transmitt through the walls and ceiling until you break the path. sound will travel through anything that is connected to each other "flanking". whilst overboarding a ceiling will help a little, you ideally need to add another ceiling or walls with as little or nothing touching the original ceiling or wall. this will stop the sound flanking as it has no where to go as it hits "fresh air" but in the common house this may add up to 50mm lose in room size .
i agree with ajrobb plasting over flexible gaps will CRACK. Soundblock will help a little more the normal wallboard but if soundproofing is a major problem then isolate. i hope this makes sense.

 

[padsman]

another option thinking about it is to google "british Gypsum" pertend you are a builder and call the techincal department for good advice.

 

[ajrobb]

another option thinking about it is to google "British Gypsum" pretend you are a builder and call the technical department for good advice.

They provide both Soundbloc and resilient bars so surely they must have a Robust Detail solution.

 

[padsman]

ajrobb, you in the trade?

 

[ajrobb]

ajrobb, you in the trade?

Not yet - but looking around for property renovation guidance. With my history in noise, I have a keen interest in building solutions.