Loft conversion - Acoustic or thermal insulation (or both) between floors

[Cabbyfan]

Hi everyone,

Some of you will know I am part way through building a loft conversion on my bungalow. Looking at the insulation / soundproofing to go between by new ceiling/floor.

Last year I stripped out all the old fiberglass and replaced it with this:-

http://www.knaufinsulation.co.uk/pr.../loft-insulation-rolls/earthwool-loft-roll-44

However am I better fitting this "proper" acoustic stuff which is more denser.

http://www.knaufinsulation.co.uk/pr...l-rolls/acoustic-rolls/earthwool-acoustic-rol and then covering with my Rockwool ?

Bungalow is a semi and the joists and 200mm deep.

Thanks !

 

[Cabbyfan]

Update - according to Knauff's own helpline, the Acoustic Roll 100mm meets building control, the Earthwool Loft Roll doesnt for use between floors. I am hard pushed to see the difference in the 2 products to be honest. Their density per M/2 is very similar...

 

[Ian H]

I've got Knauf 100mm acoustic and someone on here said it looked more like loft roll.

Our loft design guy spec'd 100mm acoustic between the 200mm floor joists. Anything for thermal wants to be closer to the roof.

 

[Cabbyfan]

Thanks Ian, I have 200mm to play with so I am thinking 100mm acoustic and as I have it anyway I may as well top it up with the Earthwool loft roll. Thing I cant work out is what the actual difference is, loft roll is very soft and wont hold its own weight. I was expecting the acoustic stuff to be more dense.

 

[Ian H]

Only difference to me seems to be that the acoustic smells like candy floss !!

Anything is better than nothing. I'm having the loft room so don't want the kids hearing me walking round in my high heels

 

[Cabbyfan]

Interesting... cos its 5 times the price for the Acoustic - £53 ExVat at TPs.

 

[Ian H]

That's the stuff:

 

[Cabbyfan]

Spot on. How erm.. floppy is it ? And is it also split into 3 or just 2 (ie 400 or 600 )

 

[Ian H]

It's pretty floppy, usually a bit stiffer first thing in the morning

It splits into 2 or 3 and easily holds its own pushed between 4x2 in the stud walls which have 400mm centres.. Having said that, I used some loft roll between 2 of the kids rooms and that held its own too.

It's not much different at all. Next time I'm at the house I'll give it a tug and see if it's any stronger than the loft stuff.

 

[Cabbyfan]

Thanks Ian, I appreciate it. Looking at my current loft roll, it certainly cant be pushed between joists from below and stay put.