Noise! Bubble Foil backed Acoustic Rockwool


16 Aug 2020
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United Kingdom

We live under a flight path and even with triple glazing I noticed a lot of the noise is coming down through our cold loft space which is a dual pitched roof, normal felt (non-penetrable) and continuous 25mm eave/soffit vents running the whole length.

I brought some packs of 50mm acoustic rockwool to fit between the rafters (the floor is already insulated with 300mm mineral wool) but to play it safe condensation wise I battened out 50mm onto the 70mm rafters so there is a good 50mm air gap between the acoustic wool and felt.

So the same amount of airflow also comes into the loft space itself, I installed 60mm rectangular funnel vents and entire length of the eaves (these come through the floor mineral wool at about 30 degree angle).

However, I also thought it might get VERY hot up there during the summer so cut out rectangular sections of two sided foil bubblewrap and using carpet adhesive spray stuck these to outside face towards the felt/tiles thinking it would reflect radiant heat away.

I now concerned though that if any warm rising air up into the loft (and though the non-airtight rockwool) might condense on the foil bubblewrap and run down to the wall plate/eaves/wet the rockwool itself? Thoughts?

I also installed felt lap vent on the overlaps so there is fresh air circulating in the air gap between the foil and the felt but would it be best to rip it all out and start again? (I'm over halfway now through..

Thanks for reading.
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