albert Posted January 7, 2018 Share Posted January 7, 2018 Hi I have searched" rain noise" but wanted to discuss sound proofing on steel roof residential buildings. I am planning to use Tata or similar seamed product but my ceilings are vaulted and low at the eves so sound absorption is a very important factor. I have lived in NZ and the US under steel roofs with lofts and they were still noisy but you did get used to it but want to look at the best way to design the noise out. I wondered if anyone has experience in this field.? Link to comment Share on other sites More sharing options...
Russell griffiths Posted January 7, 2018 Share Posted January 7, 2018 I have also lived in oz with a steel roof and they are noisy, I think the difference will be you will probably be looking at having a roof build up with a thickness of at least 300mm maybe more, whereas I bet your roof in NZ was 100mm max with probably 25mm of insulation if you are lucky. Im having a steel roof with a vaulted ceiling and noise has not even crossed my mind. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted January 7, 2018 Share Posted January 7, 2018 (edited) I think your best bet might be to a roof build up like ours. Practically the whole of the South elevation of out roof has built-in solar panels, so potentially just as noisy a steel sheet, I suspect. From the inside out, our vaulted ceilings are structurally made up like this: - skimmed plasterboard - 50mm deep service void, supported on 50 x 50 battens aligned with the rafters - VCL taped and nailed behind 50 x 50 battens - Composite rafters, hung from a laminated timber ridge beam, that consist of 38 x 89 studs, nailplated with a 10mm thermal break to the lower chord of a 302mm deep I beam joist used as a ridge-hung rafter. - 22mm OSB3, nailed to the outside of the roof as both sarking and the airtight layer. - 50 x 25 counter battens nailed in line with the rafters on top of the sarking boards. - a layer of Aerotop vapour permeable, non-tenting membrane, laid to drape over the counter battens. - 50 x 25 roofing battens laid at the correct pitch for the in-roof solar panels and the surrounding slates. Finally, the key element, the insulation is 400mm of blown in cellulose insulation, that completely fills the void between the internal VCL and the external sarking board. This is not only a reasonably good insulator (the U value is around 0.1 W/m2.K) but is also has a nice long decrement delay, so is a great aid to comfort and heat control and, being fairly dense, it's an excellent sound insulator, too. Edited January 7, 2018 by JSHarris Link to comment Share on other sites More sharing options...
Cpd Posted January 7, 2018 Share Posted January 7, 2018 Well i can tell you what does not work, my room in roof has calotex in between the rafters 190mm fully foamed and sealed and you can still hear the rain beating down, i intend to put acoustic plasterboard up but this will be to little to late. Abstract thinking only tin roof attached to battens BUT with an acoustic dampener between the top batten and the cross batten cross batten breather membrane timber sheeting rafters 50mm breather gap dense acoustic rockwool batt 100mm timber fibre board to the inside face of the rafters calotex over the rafters vcl somewhere.... within one of the top layers service void if needed osb acoustic plasterboard You could take it all the way to the inside of the rafters and then wait for it to rain and make a decision on the final build up, adding in extra measures if required. Decoupling the plasterboard on professional acoustic hangers would be the final big step. As i said i am just thinking aloud but will be intrested to see what others come up with. Just read jsh post and that seems a lot easier but then i dont do things the easy way......... still learning. Link to comment Share on other sites More sharing options...
Ferdinand Posted January 7, 2018 Share Posted January 7, 2018 (edited) Then marzipan, icing and a chocolate Christmas Tree on top ! I have a Tenant with a buildup of inside to out cladding, membrane, 100mm rock wool, 4 ply polycarb (do not ask - conservatory conversion), ventilation, metal cladding ... on a sun lounge. She does get noise through the roof in the rain / hail but says it is acceptable. That suggests that you do need something more towards the type of thing @JSHarris is suggesting if you want to be much quieter. My only comment would be that acoustic plasterboard may be a possible shortcut should you need to simplify; It can be effective. F Edited January 7, 2018 by Ferdinand Link to comment Share on other sites More sharing options...
IanR Posted January 7, 2018 Share Posted January 7, 2018 I have and aluminium sheet roof (standing seam), over a 350mm I-Joist warm roof, filled with blown cellulose. I had similar concerns as you and was assured by everyone I spoke to that rain noise would be no worse than on a conventional tiled roof. I'm happy to say the assurances were correct and noise levels are no worse and probably better than a tiled roof. Link to comment Share on other sites More sharing options...
albert Posted January 7, 2018 Author Share Posted January 7, 2018 Interesting.... I had ruled out celotex as acoustically I don't think it has much to offer I also plan to keep to as low a build up as possible due to it being a conversion with restricted head height. I also have a weight restriction on the loading of the existing structure as well. so it may be a compromise. I haven't ruled out a lightweight recycle slate type product that i think will be less noisy. My research shows a flat profile on 18-20 mm sheathing to be less noisy than box profiles that can vibrate and resonate noise. Im looking at some industrial sites next week for ideas. Cpd I'm thinking similar set up but keeping the sheathing up tight under the tin ventilated below this. Not sure if I need ventilation directly under the tin to prevent rusting long term i would think its preferable. Thanks for the posts. JSH your roof sounds well designed but I am also on a tight budget and big meterage so a low cost solution will be needed. minimal cleotex for costs reasons now too!! Link to comment Share on other sites More sharing options...
Jeremy Harris Posted January 7, 2018 Share Posted January 7, 2018 10 minutes ago, albert said: Interesting.... I had ruled out celotex as acoustically I don't think it has much to offer I also plan to keep to as low a build up as possible due to it being a conversion with restricted head height. I also have a weight restriction on the loading of the existing structure as well. so it may be a compromise. I haven't ruled out a lightweight recycle slate type product that i think will be less noisy. My research shows a flat profile on 18-20 mm sheathing to be less noisy than box profiles that can vibrate and resonate noise. Im looking at some industrial sites next week for ideas. Cpd I'm thinking similar set up but keeping the sheathing up tight under the tin ventilated below this. Not sure if I need ventilation directly under the tin to prevent rusting long term i would think its preferable. Thanks for the posts. JSH your roof sounds well designed but I am also on a tight budget and big meterage so a low cost solution will be needed. minimal cleotex for costs reasons now too!! There's no Celotex or PUR foam anywhere in our build. The roof insulation is cellulose. effectively ground up old newspapers treated and blown in under pressure with a blower machine. Celoetex and all PIR/PUR foams are poor acoustically and have a low decrement delay, and I wouldn't use either in the walls and roof of a house, personally. 1 Link to comment Share on other sites More sharing options...
Cpd Posted January 7, 2018 Share Posted January 7, 2018 You dont need to ventilate directly below if you use the corect membrane, not sure which would be best for noise as no batten = direct noice tranfer into timber sheeting and battens create a break between sheeting and tin BUT create a space that could act like a drum ! And make the noice worse....... lots to think about and as i said i am very intrested as i have future projects that will have corrugated tin roofs and i want to make them more acoustic sealed than my calotex roof. Using diffrent density insulation will help as it absorbs diffrent noice wavelengths or some such technical term...... i think there is a lot of merit in using blown in cellulose as its so good on so many levels, due to location this just would not be possible for me but i would use it at the drop if a hat if i could. Link to comment Share on other sites More sharing options...
Nickfromwales Posted January 7, 2018 Share Posted January 7, 2018 I'd spray on a Shultz tote coating, the stone chip stuff that typically gets put onto car lower panels, sills prior to spray painting them, commonly referred to as stone chip. That's should help a lot, and be easy ( but messy ) to apply, but ideally would have to be applied after the roof is up. The dense rubber mats, available in 8'x4' x 1/4" - 1/2" thick as an underlay may also help out if you don't have the means to go for the much deeper cellulose filled cavity. Layering will need some thought to avoid it sweating. Link to comment Share on other sites More sharing options...
albert Posted January 7, 2018 Author Share Posted January 7, 2018 yes I'm with you in PU insulation we fill our houses with it and have you ever seen it burn it actually burns very well at any point where the foil is missing in high temps. if you have seen some site work i worry about it near fires and flues we always use a wool product in these locations. going off topic.. The boys in US like to put it on sheathing as they argue it lessens the vibration and resonance in rain. I see some logic in this but would want this floating over the structure ideally i think. Link to comment Share on other sites More sharing options...
albert Posted January 7, 2018 Author Share Posted January 7, 2018 What is the minimum depth I can use the blown cellulose at and how does it compare on cost? It sounds expensive. I have access for bulker blower trucks. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted January 7, 2018 Share Posted January 7, 2018 (edited) It's not blown in by a truck, just a small machine. This blog entry shows the cellulose being blown in to our walls: http://www.mayfly.eu/2013/11/part-twenty-one-putting-in-the-insulation/ The bare minimum in a roof is probably around 300mm, the thickness we have in our walls. 400mm would be better with a vaulted roof, though, as you need deep rafters anyway and you also need better insulation because of the increased insulated area compared with a cold roof and insulated ceiling. Edited January 7, 2018 by JSHarris Link to comment Share on other sites More sharing options...
albert Posted January 7, 2018 Author Share Posted January 7, 2018 Having looked at the cellulose I can not see how it would work in a low build up system as you have to pump it into small voids. This could leave cold spots if there is an obstruction. the R value is similar to a rockwool slab per 100mm I feel would be better off using a combination or acoustic slab and celotex in layers to achieve thermal and acoustic needs. Link to comment Share on other sites More sharing options...
albert Posted January 7, 2018 Author Share Posted January 7, 2018 Thanks Ill take a look. Link to comment Share on other sites More sharing options...
Jeremy Harris Posted January 7, 2018 Share Posted January 7, 2018 Just now, albert said: Having looked at the cellulose I can not see how it would work in a low build up system as you have to pump it into small voids. This could leave cold spots if there is an obstruction. the R value is similar to a rockwool slab per 100mm I feel would be better off using a combination or acoustic slab and celotex in layers to achieve thermal and acoustic needs. It can be blown into huge voids. Our walls are twinwall, so the insulation is blown into the hollow space between the whole wall width and height. Link to comment Share on other sites More sharing options...
albert Posted January 9, 2018 Author Share Posted January 9, 2018 Ok Thanks so I could use it and blow it in from the top of the roof structure. Nice tidy job by the way. Link to comment Share on other sites More sharing options...
passivhybrid Posted March 14, 2021 Share Posted March 14, 2021 On 07/01/2018 at 20:13, Jeremy Harris said: I think your best bet might be to a roof build up like ours. Practically the whole of the South elevation of out roof has built-in solar panels, so potentially just as noisy a steel sheet, I suspect. From the inside out, our vaulted ceilings are structurally made up like this: - skimmed plasterboard - 50mm deep service void, supported on 50 x 50 battens aligned with the rafters - VCL taped and nailed behind 50 x 50 battens - Composite rafters, hung from a laminated timber ridge beam, that consist of 38 x 89 studs, nailplated with a 10mm thermal break to the lower chord of a 302mm deep I beam joist used as a ridge-hung rafter. - 22mm OSB3, nailed to the outside of the roof as both sarking and the airtight layer. - 50 x 25 counter battens nailed in line with the rafters on top of the sarking boards. - a layer of Aerotop vapour permeable, non-tenting membrane, laid to drape over the counter battens. - 50 x 25 roofing battens laid at the correct pitch for the in-roof solar panels and the surrounding slates. Finally, the key element, the insulation is 400mm of blown in cellulose insulation, that completely fills the void between the internal VCL and the external sarking board. This is not only a reasonably good insulator (the U value is around 0.1 W/m2.K) but is also has a nice long decrement delay, so is a great aid to comfort and heat control and, being fairly dense, it's an excellent sound insulator, too. Can I ask what 10mm thermal break you used to the lower chord please any pictures of the build up? thankd Link to comment Share on other sites More sharing options...
Russell griffiths Posted March 14, 2021 Share Posted March 14, 2021 2 hours ago, passivhybrid said: Can I ask what 10mm thermal break you used to the lower chord please any pictures of the build up? thankd It’s just a gap, MBC timberframe set their roof joists apart with a gap between two timbers, look at some of their specs, Jeremy doesn’t come on here anymore. Link to comment Share on other sites More sharing options...
Crofter Posted March 23, 2021 Share Posted March 23, 2021 We have 100mm celotex and 150mm mineral wool in the warm roof. You can't really hear the rain on it, it's drowned out by the rain lashing the windows. (It doesn't always rain here... just when it does, you really know about it...) Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now