Cavity pumped with bonded beads or rockwool

bogman

Looking for some advice please, 2000sq ft dormer house, got a price of 1700€ ex vat to pump in 50mm rockwool into a 100mm cavity with existing 50mm interlocking aeroboard on the inner leaf(18-20 years done)
Also includes 12" of rockwool, 4 ft wide 105ft long behind the dormers ( (540€ on its own ex vat)
which would provide better insulation, rockwool or bonded beads?
Is it a good idea to fill the cavity, may be problems with damp/condensation later
Thanks

Forgot to add that he is giving no guarantee with the filling of the cavity, says that cannot be done as 50mm aeroboard already exists and this may cause problems

gizmo555

bogman wrote: »

Looking for some advice please, 2000sq ft dormer house, got a price of 1700€ ex vat to pump in 50mm rockwool into a 100mm cavity with existing 50mm interlocking aeroboard on the inner leaf(18-20 years done)
Also includes 12" of rockwool, 4 ft wide 105ft long behind the dormers ( (540€ on its own ex vat)

Price sounds about right - I got 3 quotes for cavity fill only with bonded beads in my dormer bungalow, same floor area as yours, €1,100, €1,300 & €1,440.

bogman wrote: »

which would provide better insulation, rockwool or bonded beads?

Can't comment on whether bead or rockwool is better, although the BER assessor who advised me on this (and who is also a qualified engineer) recommended bead.

bogman wrote: »

Is it a good idea to fill the cavity, may be problems with damp/condensation later

The theory with bead is that it forms a mass of tightly packed spheres which still leaves small gaps for any moisture which pentrates the outer leaf of the wall to drain downwards.

A builder acquaintance advised checking whether I have galvanised steel wall ties - said pumped cavity insulation may accelerate corrosion of these, making expensive remedial work necessary. Apparently not a problem with plastic or stainless ties. I'm changing windows before getting the cavity pumped, so I'll have a good opportunity to check.

bogman wrote: »

Forgot to add that he is giving no guarantee with the filling of the cavity, says that cannot be done as 50mm aeroboard already exists and this may cause problems

That does ring a bell, I believe one advantage of bead is it is better able to flow around obstructions than rockwool, making gaps less likely. Can't swear to this though.

RKQ

Retro fit IMO Rockwool, as it gets into the crevaces better. I'd would recoment either if there is already 50mm aeroboard in the cavity!

Mice / rats love aeroboard! I've seen quite afew houses demolished or parts thereof for extensions etc - its not unusual to see tunnels dug in the insulation or parts totally eaten / dug away!

Bead might have a slightly better u-value. Bead is alot cheaper to buy, which IMO says something.

Shop around ensure your insulation method has a IAB cert.

bogman

Thanks for your help here

muffler

RKQ wrote: »

Retro fit IMO Rockwool, as it gets into the crevaces better. I'd would recoment either if there is already 50mm aeroboard in the cavity!

Mice / rats love aeroboard! I've seen quite afew houses demolished or parts thereof for extensions etc - its not unusual to see tunnels dug in the insulation or parts totally eaten / dug away!

Bead might have a slightly better u-value. Bead is alot cheaper to buy, which IMO says something.

Shop around ensure your insulation method has a IAB cert.

I thought you were opposed to this?

RKQ

muffler wrote: »

I thought you were opposed to this?

Thats correct. The reply quoted discusses RETRO-FIT. I further explain that I would not use either Rockwool or Bead in a cavity Partially filled with insulation board.
I think I've been quite clear and consistant.

Muffler you may be refering to another thread where Gizmo555 wants to use bead or rockwool in his partially filled cavity! Again I have been very consistant in my professional advice.

I offer my advice freely. It is up to the OP to accept or reject it.

muffler

bogman wrote: »

to pump in 50mm rockwool into a 100mm cavity with existing 50mm interlocking aeroboard on the inner ..............says that cannot be done as 50mm aeroboard already exists and this may cause problems

RKQ wrote: »

Thats correct. The reply quoted discusses RETRO-FIT. I further explain that I would not use either Rockwool or Bead in a cavity Partially filled with insulation board.

I think I've been quite clear and consistant.

Maybe Im missing something

RKQ

Muffler, I have bolded the relevant text above, to help you.

Feel free to PM me if you continue to have problems. I wouldn't like anyone to think you are deliberately trying to discredit me.

muffler

One more remark like that and you will be banned from this forum also. Seems as if you are running short of places to post.

I have had just about enough of you and your smart arsed comments. Posting in the conspiracy theories forum would be more appropriate to your line of thought.

muffler

And just for the record this is what you posted with the relevant piece in bold.

RKQ wrote: »

Retro fit IMO Rockwool, as it gets into the crevaces better. I'd would recoment either if there is already 50mm aeroboard in the cavity!

Mice / rats love aeroboard! I've seen quite afew houses demolished or parts thereof for extensions etc - its not unusual to see tunnels dug in the insulation or parts totally eaten / dug away!

Bead might have a slightly better u-value. Bead is alot cheaper to buy, which IMO says something.

Shop around ensure your insulation method has a IAB cert.

RKQ

I have raised this matter on the Help desk.

Muffler, I find your tone quite agressive. I answered your question and you jeer and threaten me?

What is your reference to the Conspiracy forum?

To clarify my post:-I'd would recoment either if there is already 50mm aeroboard in the cavity! is mis-spelling, it was meant to be "I wouldn'd recommend" not "I'd would recoment"

My post today, on the other thread, which you also posted on, is spelled correctly.

Over the last 24 hours, as you know, I have stated that I would not use either insulation in a partially insulated wall. I stated this opinion on numerous occassions today, so I do not understand your original query in post no. 5 above?