Rockwool vs fibreglass - opinions?

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apple1

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Hi, Just about to embark on TF build and need to make up my mind about insulation used. Would appreciate any advice on the question of rockwool vs fibreglass insulation. Thanks in advance, apple1.
 
Apple,

Starting a timberframed built in the next few week, I have gone for Rockwool insulation to internal walls and fibreglass to external walls. Rockwool would provide higher sound insulation properites over fibreglass, however it is slightly more expensive.
 
Folks ,

i read in one of the self build , magazines that both rockwool and fibreglass will sag after 10 + years unless you use rigid insulation .

Im cureently living in a TF semi d and i can already see the stuff sagging behind the exposed studs even though its held in place by battens and a plastic membrane. The house is only 12 years old !!!!!!..

The article aslo stated that some manafacturers will not gurrantee this not happening !!

Thats my 2-pence worth and It just could have been a misinformative article !! maybe some on AAM has more of an expert opinion on what I just quoted ?
 
This was one of the reasons I installed hemp insulation which will never sag. (I hope)

Lastbuilders
 
I am building a TF also and have come across Sheep Wool Insulation http://www.sheepwoolinsulation.ie
It is a natural insulator, can absorb moisture (good for TF structures), has good acoustic properties due to its bulky nature and requires no equipment or protective clothing to install. It all looks good on paper but I don't know anyone who has installed it.

Lastbuilders - I would be interested to hear why you chose hemp?
 
The reasons I choose it are as follows
  • Extremely high thermal resistance
  • No chemical protection required during growth
  • Hemp is a natural raw material
  • It has an ability to absorb & release moisture without effecting thermal performance
  • Thermo-Hemp does not sag
  • It is not affected by mould growth or insect attack as the fibre does not contain proteins
  • Thermo-Hemp creates a natural, healthy living climate
  • It has high acoustic properties
  • It does not cause irritation
  • No chemical additives
  • Lightweight - easy to handle, flexible & convenient to install
  • It is available in rolls & mats
  • It has a high thermal mass
  • It offers outstanding fire protection
Granted these are taken from a sales pitch I got but they are the main reasons.

The only negative point I would say is that it is quite a bit more expensive that fibreglass but I saw the long term benefits as more important.

It won an award a few weeks ago too at the grand designs award in England

[broken link removed]

I should add that I have a slight vested interest as a friend of mine works with a company that imports it.

Lastbuilders
 
You are meant to staple your insulation to the side of each timber frame panel, this stops it from sagging.

We went with rockwool in all external and internal walls, but fibre glass in the ceiling space between ground and first floor.
 
Thanks for that Lastbuilders, you should be getting commission!! I'm still undecided, will keep researching. tc
 
Thanks all. Are there any advantages from a thermal perspective for rockwool, or is it purely for acoustic reasons? In other words, should I use it only on internal walls & fibreglass on external? I've also been advised by someone in the trade that in a bungalow, there is no real requirement for insulation on internal walls at all - that there is no advantage from a thermal perspective? Interested in any comments on these questions. Thanks, apple1
 
none of the above. Well, ok, Rockwool over fibreglass.

But I'd do pumped Warmcell, instead.
 
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