Rockwoool as full fill for Cavity wall? Advice appreciated

Msmaloney26

Hi everyone!

Looking to start self build shortly, and have recieved a few quotes back from a number of Builders as I have decided on contract build.
Some of the builders are recommending a full fill slightly enlarged cavity (150mm) with pumped rockwool vs foil backed insulation method?
Now I have spent couple hours through the previous posts looking for info/experience on this method and trawled through the debates on full fill cavity vs traditional foil backed insulation, but have not got any solid direction.

Now, I'm still undecided on this method so I am looking to the technical expertise and experience on boards. Can any builders/archs give any advice? Is this a viable option for a 1.5 storey build?

Would there be dampness/water transmission issues---airflow problems?---can pockets of non-insulation occur?

Again any advice would be heartly welcomed, thanks in advance.

mickdw

The danger with any full fill insulation is the possibility of water transfer from outside to inside. The outer block has to be considered to be wet wall throughout so it is possible that water will be present all the way through the outer block. The damp proofing details are designed to allow for this.
With this being the case, the insulation is possibly going to act as a medium for transfer of water. Indeed full fill bead isnt recommended for use in areas of heavy driving rain for this reason.

gman2k

Use only registered contractors....



It can be done. Many previous threads here on boards about it.

My tuppence is not to use rockwool (based on advice from actual installers) for cavity walls.

frag4

Msmaloney26 wrote: »

Hi everyone!

Looking to start self build shortly, and have recieved a few quotes back from a number of Builders as I have decided on contract build.
Some of the builders are recommending a full fill slightly enlarged cavity (150mm) with pumped rockwool vs foil backed insulation method?
Now I have spent couple hours through the previous posts looking for info/experience on this method and trawled through the debates on full fill cavity vs traditional foil backed insulation, but have not got any solid direction.

Now, I'm still undecided on this method so I am looking to the technical expertise and experience on boards. Can any builders/archs give any advice? Is this a viable option for a 1.5 storey build?

Would there be dampness/water transmission issues---airflow problems?---can pockets of non-insulation occur?

Again any advice would be heartly welcomed, thanks in advance.

this might help http://www.insulation.kingspan.com/uk/issues01.htm

jasperok

Arent kingspan just trying to market their own product though?

either way , right or wrong i did indeed go with rockwool in a 150mm cavity and i am absolutely delighted - of course i have no trade xperience or indeed point of reference but its a big house and certainly very very warm and more importantly seems to be holding its heat well.

Its not a technical review i know but i am happy!

frag4

Well kingspan were never sued over the report.( although threatened)

sydthebeat

frag4 wrote: »

this might help http://www.insulation.kingspan.com/uk/issues01.htm

that 'report' is very funny....

the very issues they say 'can' compromise the mineral wool insulation are the exact issues that DOES compromise the board insulation.

Mortar snots are notorious for keeping boards from linking in with each other, and also from being held tight against the blockwork.... this alone can result in seriously reducing the board insulations performance..

pipeworks and other projections. Which do you think fits more snug around a pipe in a wall... blown in mineral wool or rigid board.... 'nuff said.

narrow or variable cavity widths. Again, once the cavity is over 50mm it can be pumped without issue. A variance on the width would actually cause more problems with board insulation as there would be more likelihood of moisture transference across ties or other media..

unsuitable injection hole patterns.... god knows what they are referring to here. a wall can always be re-rendered...

Msmaloney26

Thanks for the replies so far.
I am just weighing up info on this method, most builders give its a "great job altogether" response when I ask them on this but one or two are keen to stick with board insulation. I want to go with whats the best/suitable option.
Is it an easy option for a builder...hence the will to use it???

Msmaloney26

*Bump*

Hi all,

Just coming back to this question wondering if anyone could give me solid advice here, should i stay away from full fill rockwool and stick with the PU boards?

I am nervous in investing money in a system if its not proven or will prove a disaster in a few years.

thanks

muffler

Any product that carries an IAB Cert or the equivalent has been tried and tested and you will get a written guarantee with it. However workmanship isn't covered so if your wall ties are clean I see no reason why you shouldn't use the product.