Green Building Forum

Home  5  Books  5  GBEzine Subscription  5  News  5  HelpDesk  5  Your Cart  5  Register
Sound reduction of king span vs warmcel - Green Building Forum


Welcome to the Green Building Forum. Reading any of the public conversations is free but if you want to join in the discussions then you need to register first to obtain a code for which there is a small charge. Please follow the link on the left. OR:

Get the next four copies of this fantastic magazine delivered directly to your door.
1 year Green Building magazine subscription
Price: £20.00
Discount books available with subscription:

Sound reduction of king span vs warmcel

ive an opportunity to form my timber frame walls as

140mm warmcel blown in between studs plus 80mm kingspan on the internal face of the wall over studs
140mm kingspan between studs plus 80 mm kingspan over studs

All other considerations aside, which one would make for the quieter house?


  • The Kingspan will keep you warm but offers little, if any, sound insulation.
  • Agreed, the Warmcel will give much better sound attenuation levels.
    PIR is rigid, good thermal insulation, but so rigid it transmits sound too well...:bigsmile:

    Good luck...:smile:
  • edited March 2015
    Airbourne sound transmission loss closely linked to density - though frequency also plays a part - which is why the flexible slabs are often advertised and used for sound insulation. The denser flexi products available being better (and much more expensive) Blown insulation somewhere in the middle density wise I imagine

    In reality though doubling the plasterboard is a smart cheap move....
  • The whole wall will be:

    140mm studs + (kingspan or warmcel or mineral wool batts)
    80mm kingspan
    AT membrane
    service void

    Warmcel pros: fast installation, no mess, sound deadening
    Warmcel cons: not as good thermally as kingspan

    Kingspan (in the 140) pros: thermal value
    Kingspan cons: messy, slow to install, little sound deadening

    Mineral wool pros: cheap, self fit, less messy than kingspany, acoustic insulating
    Mineral wool cons: itchy for a while after, more messy than warmcel

    Cost is about the same for KS and WC, and MW is about half the price, so I dare say it's probably the best thing to go for..
  • Mineral wool with high sound insulation value not cheap. The better ones are more dense and dearer RW 5 for example compared on the download here
  • Posted By: cjard

    Warmcel pros: no mess,

    Mineral wool cons: itchy for a while after, more messy than warmcel

    A few comments on these -

    We're building alongside a friend who's just had Warmcell pumped in. Our build is using SIPs, PUR boards and Rockwool in different places.

    Warmcel installation is extremely messy - the stuff seemed to end up everywhere. There's also a fair bit of mess created by cutting the holes to blow it in and work to repair them.

    Rockwool isn't anything like as itchy as traditional loft insulation. Using it wasn't nearly as unpleasant as I imagined it would be.
  • I thought the warmcel guys hoovered it up and put it back in the blower..

    Youtube lied to me!

    Anyhoos, it seemt he rockwool is half the price of warmcel and slightly better U in my application so I dare say we'll probably go for that. Already staring down the barrel of a twelve thousand pound bill for insulating, so any saving's a saving!
  • They do Hoover up and reuse but not so as to leave the place clean!
  • edited March 2015
    Chard - my wall build-up is very similar to yours, but my 80mm of Kingspan is going on the outside of the wall, so my build up is as follows, note the use of kingdoms and Warmcel within the frame.

    80mm Kingspan (located here it keeps the Timber Frame warm)
    140mm studs + (80mm of kingspan against the OSB and then a 60mm layer of warmcel) The idea is the Kingspan is great for u value and the Warmcel is great for gap sealing, air tightness, sound deading and adds decrement delay.
    AT membrane
    service void (am thinking of filling the majority of the unused void with insulation)
  • Triassic, is your AT membrane going to be vapour-open? I assume so because if the wall can't dry inwards I can't see why any failure in the membrane isn't going to eventually result in the outer OSB becoming saturated.

    With the vapour-closed Kingspan on the outside it'd seem sensible to me to put the airtightness layer there as well because then you could just use cheap polythene sheet and it would be well protected from electricians, mice and other vermin in the service void. E.g., between the studs and the outer OSB.

    I had similar ideas at one point but chickened out of putting the vapour-closed stuff on the outside - having PUR on the inside and mineral wool on the outside.
  • edited March 2015
    Sorry I should have deleted the air tight membrane from my build-up, I was going to simply use the internal OSB as the ATM. Good point about the vapour closed insulation, but as we all know OSB is vapour open so the wall should dry out.

    I wonder what WUFI would say about the proposed build-up?
  • edited March 2015
    I've talked to Warmcel about the idea of a composite kingspan/ Warmcel wall, something like 100mm of Kingspan and 90 mm of Warmcel, they said it's something they've done for clients in the past. They felt the Warmcell would add decrement delay, fill any small gaps, add sound deadening qualities and would do away with the need to foam the kingspan into place, as any gaps would be filled with warmcel. Their only observation about the wall build up, was that the kingspan would have to be on the inside and the warmcel on the outside, as in any wall build up the vapour open insulation should be on the outside to allow it to dry out. Trapping Warmcel between an internal vapour membrane and a vapour closed insulation board could spell disaster, as moisture could be trapped!
  • Posted By: Simon StillWarmcel installation is extremely messy - the stuff seemed to end up everywhere. There's also a fair bit of mess created by cutting the holes to blow it in and work to repair them.
    Hmm, ours wasn't extremely messy. Messy yes, but extremely no. And it's not difficult mess to sweep and vacuum up, just perfectly safe and pleasant dust (except when it's actually being injected, when it gets a bit much).

    We had some blown in through holes or just through missing pieces of board and some just blown in to open studwork with the contractors scrimming up as they went. Holes were easily patched with sticky patches designed for the purpose. Missing boards that the carpenters had pre-cut were nailed in place as we went. And boards went over the contractors' scrim after they finished. All pretty easy.

    We used rockwool in various places. It's not too bad to handle but definitely leaves you itchy for a day or two. Pushing it up into the ceiling was the worst part!

    I think that rather than a deep timber frame with foam on the outside, I'd be more tempted by a double timber frame.
Sign In or Register to comment.