G
geraint
my colleague has listened to the bricklayers 50mm cellotex specified with a 100mm cavity they have full filled with 100mm rockwool. am i right or wrong saying no..
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G
geraint
i was after an answer of the properties.. not a discussion of the ins and outs...
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G
geraint
can you get any clearer....
First time you Mods have genuinely Fu**ed me off on here, removing my post! Why don't you ever steer OPs in the right direction? 
Its a standard alternative, but they should do as per the spec, and not change it without telling you. If they have used standard rockwool its a disaster, but batts are coated with water repellent and formed in layers so water should not track through, even through the joins.
The reason celotex has to have 50mm gap is because water will track through the joints if it gets there.
In some very exposed locations, the batts are not advised, but I would not worry. Just make sure the don't charge you for celotex when they have used batts !
Simon.
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OP
You asked for the properties.
Thermal insulation U values.
50 mm celotex 0.5
100 mm rockwool 0.4
So the Rockwool provides better insulation.
Rockwool roll ( you don't specify roll or batts) will hold water if it falls on it and this desroys the insulation completely. Ends up as a soggy mess.
Much chraper than Celotex, cheaper than batts.
Rockwool batts. same insulation, more expensive, remain vertical when positioned. I was unaware of what simonjay has written.
Celotex. Better insulation per cm of thickness, unaffected by water, about 5 times more expensive than Rockwool roll.
You asked for the properties.
Thermal insulation U values.
50 mm celotex 0.5
100 mm rockwool 0.4
So the Rockwool provides better insulation.
Rockwool roll ( you don't specify roll or batts) will hold water if it falls on it and this desroys the insulation completely. Ends up as a soggy mess.
Much chraper than Celotex, cheaper than batts.
Rockwool batts. same insulation, more expensive, remain vertical when positioned. I was unaware of what simonjay has written.
Celotex. Better insulation per cm of thickness, unaffected by water, about 5 times more expensive than Rockwool roll.
Mod11 wrote:
But hey ho, I will stand by your judgement!
That would have been one of mine then, I personally thought it was a valid response to and illogic post, by an ignorant member.
But hey ho, I will stand by your judgement!
I read both deleted posts and did not consider FMT post at all abusive
With regard to PBDerry post I considered that pure poetry.
oldun
With regard to PBDerry post I considered that pure poetry.
oldun
In my opinion Dritherm cavity batts (100mm full fill) is the simplest method by far.
They do not wick water.
...and you can set the brickwork (external leaf) out first.
I personally thing partial fill rigid foam is pants!
They do not wick water.
...and you can set the brickwork (external leaf) out first.
I personally thing partial fill rigid foam is pants!
G
geraint
an ignorant member... did you post a valid reply... no...
could you.... no...
and i thank the persons that have..
G
geraint
i agree.. but the designers... having seen it today.. it is a flank wall along side next doors wall.. so no chance of any ingress of rain. i was only asking originally whether good practice or where the bricklayers taking the ****.. we are never too old to learn... and i hope i am never too old...... thank you all...
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