Spinny Posted February 28 Share Posted February 28 My warm roof with PVC membrane is quite noisy when it rains. Almost seems to leave me inside a drum as the noise comes through the 150mm PIR and plywood deck beneath. I am also having recessed downlights and speakers in the ceiling beneath. So my plan is to stick a layer of tecsound mass loaded vinyl to the underside of the ply between the joists. Then a layer of 50mm rock wool. This will leave me enough ceiling void for the recessed lights. Does this seem a reasonable approach (as I really don’t want to mess about with resilient bar/clip systems) ? Link to comment Share on other sites More sharing options...
Moonshine Posted February 28 Share Posted February 28 I don't think that the mass loaded vinyl will do a significant amount. 100mm acoustic insulation between the joists will be a better solution paired with resilient bars. However you need to be careful of the risk of interstitial condensation. This was our roof type I got a couple of insulation firms to do a interstitial condensation risk analysis based on my geographical location, which showed no condensation in the lower layers (below the vapour barrier) 2 Link to comment Share on other sites More sharing options...
Mike Posted February 28 Share Posted February 28 An alternative could be to upgrade to a sedum roof. Logically, even a thin layer of sedum should have a useful impact in breaking up the raindrops, though can't give you a figure for the as most of the academic studies are focused on cutting traffic noise and therefore use heavyweight solutions). You'd need a structural engineer / existing roof designer to advise on any strengthening required, but the additional weight can be relatively modest (from around 40kg/m² when wet, for the thinnest). Link to comment Share on other sites More sharing options...
Andehh Posted February 28 Share Posted February 28 Sedum would make a massive difference as it would cushion the rain dramatically. Weight and cost would be a headache though. We have a warm roof, 150mm PIR and a wood deck.... Can't say it's a biggie. You do hear heavy rain, but that's the Named storms everyone hears! Wind is louder then expected, but i think as part of the room has solar panels stood 150mm up off the roof, so it's probably the wind ripping through them. Not sure what noise you're worried about if I'm honest! Hearing the rain falling is no different to it blowing against a window which you'll never class as an irritant! Link to comment Share on other sites More sharing options...
Iceverge Posted February 28 Share Posted February 28 9 hours ago, Spinny said: My warm roof with PVC membrane is quite noisy when it rains. Almost seems to leave me inside a drum as the noise comes through the 150mm PIR and plywood deck beneath. I am also having recessed downlights and speakers in the ceiling beneath. So my plan is to stick a layer of tecsound mass loaded vinyl to the underside of the ply between the joists. Then a layer of 50mm rock wool. This will leave me enough ceiling void for the recessed lights. Does this seem a reasonable approach (as I really don’t want to mess about with resilient bar/clip systems) ? 1. Block air paths. Acoustic sealant around the edges. Block all gaps. Get rid of the downlights and speakers. 2. Add mass. Just adding more standard plasterboard is the cheapest way. Soundbloc or OSB is similar £/kg. Mass loaded vinyl is much dearer as is insulation. 3. Stop resonance. Add something fluffy in the void to stop sound bouncing around. Id be happy with up to 150mm of Rockwool there with 150mm of PIR on top. 4. Stop sound transferring through the structure by breaking the physical link. eg resilient bars. Link to comment Share on other sites More sharing options...
Andehh Posted February 29 Share Posted February 29 It's trickier as the noise would be a lower frequency dull drumming! Like I said doesn't bother us, and I am pretty twitchy about sound..... The water dripping off the wall onto the window cills. .. That annoys me!!! (but I get over it) Link to comment Share on other sites More sharing options...
Tom Posted February 29 Share Posted February 29 Our roof is corrugated steel sheets over 150mm thick PIR/composite panels and the rain was quite loud. We've now finished the internal pitched ceiling with 200mm thick rockwool (just standard stuff, not acoustic) behind PB and can't hear anything anymore. Just the slight echo of my empty bank account. 1 Link to comment Share on other sites More sharing options...
Moonshine Posted February 29 Share Posted February 29 40 minutes ago, Tom said: We've now finished the internal pitched ceiling with 200mm thick rockwool (just standard stuff, not acoustic) behind PB and can't hear anything anymore. That sounds like its getting into the relms of a Hybrid roof, did you have a look at interstitial condensation risk? Link to comment Share on other sites More sharing options...
Tom Posted February 29 Share Posted February 29 yep, but BC insisted we use a vapour barrier to be sure Link to comment Share on other sites More sharing options...
Moonshine Posted February 29 Share Posted February 29 1 hour ago, Tom said: yep, but BC insisted we use a vapour barrier to be sure interesting, does that mean that there are two vapour barriers, one below the PIR and one below roof joists / rafters above the plasterboard? 1 Link to comment Share on other sites More sharing options...
Tom Posted February 29 Share Posted February 29 Well I guess the composite sheets form a vapour barrier too, so guess so Link to comment Share on other sites More sharing options...
Kelvin Posted February 29 Share Posted February 29 6 hours ago, Andehh said: The water dripping off the wall onto the window cills. .. That annoys me!!! (but I get over it) This is the only sound we hear when it rains too and just on one cill which is the downstairs bathroom. I suspect with the doors on a shut we’ll probably not hear it. I do aim to fix it though by adding a drip to the window head somehow. Link to comment Share on other sites More sharing options...
Spinny Posted March 1 Author Share Posted March 1 Thanks for all responses. It is a definite drumming or pattering noise. At present with no plasterboard up it can seem like standing inside a shed. Yes a lot of rain is only drizzle, but when you are building something you want to get it right for the decades to come. I don’t really get why interstitial condensation should be an issue and nor did my architect. It’s a warm roof with its own built in vapour barrier. The whole point is the temp underneath will essentially be room temp ? I am not going to get rid of the recessed downlights and speakers because I want that aesthetic. This does mean the plasterboard will have some 25 apertures which compromises its use as an acoustic barrier. I can put 100mm rock wool between joists where there are no downlights. Maybe some acoustic hoods but they seem expensive. Link to comment Share on other sites More sharing options...
Moonshine Posted March 1 Share Posted March 1 7 minutes ago, Spinny said: I don’t really get why interstitial condensation should be an issue and nor did my architect. It’s a warm roof with its own built in vapour barrier. The whole point is the temp underneath will essentially be room temp ? In a warm roof there is no issue, but by starting to put insulation under the vapour barrier between the joists your are creating a hybrid roof. Acoustic Insulation has thermal properties too. You can create a temperature differential in that cavity under the vapour barrier which can cause condensation if the upper surface gets cold enough. The key is to make sure that the thermal properties in the cavity aren't too high to limit that temp difference. Link to comment Share on other sites More sharing options...
Dave Jones Posted March 1 Share Posted March 1 delink the roof from the new plasterboard. https://www.ikoustic.co.uk/products/isolation-clips/muteclip/ Link to comment Share on other sites More sharing options...
Spinny Posted March 1 Author Share Posted March 1 Has anyone used joist isolation strip like this stuff between plasterboard and ceiling joist ? Worth it ? https://soundstop.co.uk/products/joist-isolation-strip?gad_source=1&gclid=EAIaIQobChMIkuSHpb7ShAMVKYBQBh0CDA3uEAQYEiABEgL59_D_BwE Link to comment Share on other sites More sharing options...
Moonshine Posted March 1 Share Posted March 1 11 minutes ago, Dave Jones said: delink the roof from the new plasterboard. https://www.ikoustic.co.uk/products/isolation-clips/muteclip/ Expensive just use resilient bars 2 Link to comment Share on other sites More sharing options...
Moonshine Posted March 1 Share Posted March 1 11 minutes ago, Spinny said: Has anyone used joist isolation strip like this stuff between plasterboard and ceiling joist ? Worth it ? https://soundstop.co.uk/products/joist-isolation-strip?gad_source=1&gclid=EAIaIQobChMIkuSHpb7ShAMVKYBQBh0CDA3uEAQYEiABEgL59_D_BwE That's not what it's designed for, this stuff is to go on top of the joist, with a floating floor Link to comment Share on other sites More sharing options...
Spinny Posted March 1 Author Share Posted March 1 11 minutes ago, Moonshine said: You can create a temperature differential in that cavity under the vapour barrier which can cause condensation if the upper surface gets cold enough. With 150mm PIR in the south of England shouldn’t be a problem ? Was thinking to hold the rock wool up against or near the underside of the roof using some kind of support like chicken wire mesh ? Link to comment Share on other sites More sharing options...
Spinny Posted March 1 Author Share Posted March 1 5 minutes ago, Moonshine said: 17 minutes ago, Spinny said: That's not what it's designed for, this stuff is to go on top of the joist, with a floating floor It does say… ‘This product, used upside down, can also provide the resilient layer required for customers to make up their own resilient battens.’ But I suppose scores of penetrating plasterboard screws may render it useless. Link to comment Share on other sites More sharing options...
Moonshine Posted March 1 Share Posted March 1 16 minutes ago, Spinny said: But I suppose scores of penetrating plasterboard screws may render it useless. Yep, pretty much that. Link to comment Share on other sites More sharing options...
Iceverge Posted March 1 Share Posted March 1 11 hours ago, Dave Jones said: delink the roof from the new plasterboard. https://www.ikoustic.co.uk/products/isolation-clips/muteclip/ The cost might be prohibitively Vs resilient bars. 1 Link to comment Share on other sites More sharing options...
Iceverge Posted March 1 Share Posted March 1 11 hours ago, Spinny said: am not going to get rid of the recessed downlights and speakers because I want that aesthetic. This does mean the plasterboard will have some 25 apertures which compromises its use as an acoustic barrier. I can put 100mm rock wool between joists where there are no downlights. All the adding mass in the world makes little difference if the ceiling is full of holes. Think of a 1m wide solid stone dividing wall between two rooms with a door opening. You would hear more through it than the most crappy partition wall. You could always put in a couple of layers of plasterboard above a service cavity but you're loosing ceiling height then. These are the trade offs of building. 1 Link to comment Share on other sites More sharing options...
FuerteStu Posted March 1 Share Posted March 1 Just out of curiosity. You mentioned having speakers fitted, would it be possible to rig up a noise cancelling system? 🤔😂 1 Link to comment Share on other sites More sharing options...
Spinny Posted March 1 Author Share Posted March 1 4 hours ago, FuerteStu said: Just out of curiosity. You mentioned having speakers fitted, would it be possible to rig up a noise cancelling system? 🤔😂 Oh yeah sure, I could play white noise at just the right frequency to cancel the rain drop frequency. Or else Tina Turner with ‘I can’t stand the rain’ at 90db. 😜😂 Link to comment Share on other sites More sharing options...
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