Celotex type boards vs rock wool for cavity wall

[indus]

Hi

I've only ever seen rock wool type insulation put in external cavity walls. Having just come across another member's project on this forum I noticed his builder had used celotex boards instead.

I thought (obviously wrongly) that you couldn't use insulation boards as you needed air to be able to circulate in the cavity.

If insulation boards can be used surely they should always be used as rock wool will never achieve the same degree of insulation as insulation boards?

Thanks

 

[freddiemercurystwin]

indus are you being serious?

 

[indus]

indus are you being serious?

You're making me feel very worried now because I've obviously said something really stupid

Please remember I'm not a builder etc, I've just tried to take an interest in building type matters. So go easy but tell me, just how stupid have I been?

 

[stuart45]

You can use either, ones for full fill, the other part fill.

 

[RonnyRaygun]

As Stuart says, you can use either, but using Celotex type boards won't make your cavity wall any thinner, as you need the air gap. Sometimes the wall might even end up thicker, and it probably works out more expensive, and more difficult to install.

 

[tony1851]

You're making me feel very worried now because I've obviously said something really stupid

The fibreglass batts are used when full-fill cavity insulation is required. The rigid boards are partial-fill. They are just clipped to the cavity side of the inner skin, but they still leave a cavity against the outer skin.
The full-fill batts are better; rigid boards have to be carefully fitted, and sometimes the builders just don't have the skill.

(I once came across a Chinese saying; 'better to be a fool for 5 minutes, than a fool for the rest of your life')

 

[limerockconstruction]

As builders we use both - my preference is for Rockwool esque types of materials. As Tony says the Celotex has to be fitted very carefully. If is not, it doesn't work. It's not that people don't want to fix it properly, its just a bit tricky, and if they have apprentice's or junior bricklayers putting it in they may well have never been schooled in how to fit it properly. The Rockwool leaves less margin for error.

 

[indus]

Thank you all very much for the explanation

 

[noseall]

The full-fill batts are better; rigid boards have to be carefully fitted, and sometimes the builders just don't have the skill.

(I once came across a Chinese saying; 'better to be a fool for 5 minutes, than a fool for the rest of your life')

Ever had the choice of either feeding your family or spending valuable time faffing about cutting celotex to precision?

I suggest you do a bit of recession site bricklaying before making a ridiculous comment like that again.

 

[tony1851]

The full-fill batts are better; rigid boards have to be carefully fitted, and sometimes the builders just don't have the skill.

(I once came across a Chinese saying; 'better to be a fool for 5 minutes, than a fool for the rest of your life')

Ever had the choice of either feeding your family or spending valuable time faffing about cutting celotex to precision?

I suggest you do a bit of recession site bricklaying before making a ridiculous comment like that again.

What side of the bed did you get out of this morning?

 

[SimonH2]

Ever had the choice of either feeding your family or spending valuable time faffing about cutting celotex to precision?

I suggest you do a bit of recession site bricklaying before making a ridiculous comment like that again.

As a disinterested party, it would seem that if the job requires precision fitting rigid boards then the job should be priced accordingly. Your argument seems to be that the excuse for not doing the job properly is because you didn't price it right - ie you're bodging to cut costs.

 

[stuart45]

An advantage to cavity batt full fill is that you can stick the face work up first. There are also cavity boards for full fill which are normally used with stone outer skins in this area.

 

[noseall]

As a disinterested party, it would seem that if the job requires precision fitting rigid boards then the job should be priced accordingly. Your argument seems to be that the excuse for not doing the job properly is because you didn't price it right - ie you're bodging to cut costs.

Completely clueless.

 

[SimonH2]

Much the response I expected. I have you down as one of those bodgers that uses any excuse not to do the job right when they've quoted a low price to get the job from gullible idiots who don't understand the difference between price and quality. If you weren't, you wouldn't come out with the excuses like the one you gave earlier.
You assume that I'm a stranger to the concept of estimating a job and pricing it.

 

[limerockconstruction]

Much the response I expected. I have you down as one of those bodgers that uses any excuse not to do the job right when they've quoted a low price to get the job from gullible idiots who don't understand the difference between price and quality. If you weren't, you wouldn't come out with the excuses like the one you gave earlier.
You assume that I'm a stranger to the concept of estimating a job and pricing it.

....said the amateur plumber or electrician or whatever it is you do?!!!

The point is, you can you either product, its just that one is easier to use and install and provides less problems. Ironically this is the cheaper product as well, so its not a case of pricing low, and doing a ****e job, its that some people prefer one over the other. The fact is that given the backing block etc. 9 times out of 10 they both meet building regulations. So it doesn't mater.

No doubt all you plumbers still charge a fortune for running pipes even though you now use Hep2o and can pipe a house out in a faction of the time, also saving on the copper prices and then taking out all of the old copper and flogging that to your local scrap merchant.

The point noseall is making is to add that site bricklaying prices are dictated to you by the site foreman, sometimes its a case of taking it or being unemployed, so not every job can be priced accordingly especially with Mark ups like you lot put on boilers and consumer units.

And just out of interest if you are so disinterested you feel the need to tell us all, why not make no comment at all.