Kingspan 50mm v rockwool 100mm

crualaoidh

Hello everybody,
I'm building an extension soon and I'm wondering about insulation (among other things). My question is simply which is better kingspan or rockwool?

Take it gentle with me I'm a thread virgin

Thanks in advance

hopalong_ie

Hi,

50mm of Kingspan K7 (polyisocyurante) insulation is equal to 150mm of Rockwool and much better.

crualaoidh

Thanks hopalong
Based on this is it ok to batten a block wall with 2*2 battons and cut the 50mm kingspan to fit or do i need to use larger battons to allow air circulation?

crualaoidh

Also is fermacell worth the price or is it better/cheaper to use plasterboard and skim it?

Thanks again

Cherry Picker

Hi,
I presume you are taking about Cavity Wall Insulation? Have you considered pumping the cavity with Bonded Bead? A 100mm cavity with Bonded Bead will give you a u.value of 0.27. Have a look on www.warmfill.com there is a demo on this site.
If it's Roof Insulation, then in order to comply with current building regs you must use a product which will achieve 0.16. This can be achieved with 270mm of fibreglass - a much cleaner product than Rockwool - cheaper also.

crualaoidh

hi,
Thanks Cherry Picker. To clarify we are not quite ready to build just yet, I'm getting prices for both timber frame and block build. At the moment i'm trying to figure out what internal work I can do myself depending on which method we use. I don't particularly want to insulate the cavity as I feel having insulation on the inside would give better results (as i'm not heating the block first before reaching the insulation).
Obviously I'm open to correction on this point.

cubix

A bit of a curve ball but where you see people with older houses insulating the outside and giving it a light skim I presume they are doing it this way as its easier/cleaner than ripping the plaster board inside. How does this theroy work on new houses ie: insulate the outside and stop the cold getting in.
Or one step further insulation on the outside to stop cold getting in and another layer inside to stop heat getting out?

5.watt.halo

Is there any truth to rumour that pumping cavity walls is risky as it will provide a moisture bridge through any insulation weak spots. I was told NEVER to completely close the gaps in cavity walls / rafters as its your last line of defense (thermal aside)

Corkey123

crualaoidh wrote: »

Thanks hopalong
Based on this is it ok to batten a block wall with 2*2 battons and cut the 50mm kingspan to fit or do i need to use larger battons to allow air circulation?

Forget the idea of putting up battens. Use mushroom fittings to pin the kingspan (with or without plasterboard) to the block. Though I'd recommend foil backed plaster board with at least 60mill kingspan attached. You will have a wall done in no time

Delta Kilo

5.watt.halo wrote: »

Is there any truth to rumour that pumping cavity walls is risky as it will provide a moisture bridge through any insulation weak spots. I was told NEVER to completely close the gaps in cavity walls / rafters as its your last line of defense (thermal aside)

I always wondered this myself actually. Will the insulation create a bridge for moisture to be transferred from the outer to inner leaf of blockwork? I was with a civil engineer for a while and we went out to a new house where there was a big damp spot on the wall and it turned out to be a dirty wall tie. The block layer, in his haste, never cleaned the mortar off of it!

OP, if you can still here this, put cavity wall insulation in. It comes in sheets, is inexpensive and the block layer will put it in as he goes. 100mm cavity with 50mm insulation and 50mm air gap will be more than enough to keep your room warm. That stuff you are suggesting is more for older houses, not new builds and is very expensive. Very little is lost through the walls anyway, most goes out windows and a lot out the roof too.

BERmad

If you are building a block house you should get your house pumped and the internal walls drylined If the wall ties are clean there should be no problem with dampness. Allso by this time next year there will be insulation companys pumping walls for very keen prices as there has been a rise in insulation companys setting up to do the work for the SEI insulation grant but by the looks of things that grant scheme may be axed to save money. Which will leave very little work for these companys.

Cherry Picker

I have been a Cavity Wall Insulation Installer for over 20 years, and I would like to give you all a few pointers when choosing pumped cavity wall insulation. Firstly, yes it is used in existing buildings, but it is also widely used in new build situations. In the majority of new builds now, the cavity width is 150mm and empty - filled with Warmfill Silver Bonded Bead (giving a u.value of 0.19) Yes, the block layer should always ensure that the wall ties are clean - this also applies to any board insulation. It's not the insulation that will bring the water through to the inner leaf but the mortar on the wall tie. Secondly, yes I agree with the fact that because of the SEI Grant scheme, there is cavity wall insulation installers popping up all over the place. As I mentioned previously, I'm in this business 20+ years, and there is some terrible work being carried out at present mostly by people who have just set up in business and who will probably be gone again when the grant scheme runs out. Let me just give anyone out there some advice. Ask loads of questions - ask for references and speak to your neighbours who have had work done by the company, ask your friends at work. Both installer and manufacturer is supposed to be assessed and approved by the Irish Agrement Board (IAB). Ask to see the Installers Certification, ask them if they have the necessary insurances for work on your property. The Installer should be able to tell you of houses done in your area. In my company, we do not give out peoples names or telephone numbers, but we would give an address, that way, one can see the work from outside without having to bother the home owner. One last piece of advice, there are only a few manufacturers here in Ireland, and if you stick to the product & installer names that have been around for a long time - well that company has stood the test of time.
Our reputation 'has stood the test of time' and most of our business is word of mouth. Price does not come into quality.
One last thing - in older properties, if there is electrical cables in the cavity, then you must not use bonded Bead - in this case you must use a Knauf Supafil Mineral Wool. In houses built prior to 1975 ish, the wiring was ran through the cavity without the use of conduit. The casing on these cables was poor and over the years has broken down. There is a chemical reaction between the cables and the adhesive used for bonding the bead and so therefore, it is recommended one use a pumped mineral wool. (Knauf Supafil has this fire rating)
Feel free to ask - I'll be happy to help with any queries.

CJhaughey

hopalong_ie wrote: »

Hi,

50mm of Kingspan K7 (polyisocyurante) insulation is equal to 150mm of Rockwool and much better.

Thats correct but only if the kingspan is installed 100% correctly with no gaps, holes for wall ties or mortar snots between the T+G.
IME it is a lot easier to install Mineral fibre better than a rigid board simply because it is flexible.
Thats not to say properly installed Polyiso is not good when installed but the margin for error is lower than that of a flexible insulation material.

Cherry Picker

I completely agree with CJhaughey. A flexible material is much less likely to have gaps in the installation - therefore reducing the amount of heat lost.

BERmad

Yes but it is hardly rocket science to fit the hard back insulation as long as the installer takes there time and does it right.

Cherry Picker

BERmad wrote: »

Yes but it is hardly rocket science to fit the hard back insulation as long as the installer takes there time and does it right.

Actually BERman, it is 'rocket science' to some people who don't understand the purpose of insulation in the first place. Not everyone understands the whole energy efficient ways of today. I have seen new houses where the homeowner has had no other choice but to take the Kingspan Board out, because it has been so badly fitted - usually done by themselves trying to save on costs. Once is enough to have to pay for it, and you expect to have it right. So, my advice stands, if you feel you are unable to do it right yourself, get a carpenter or a reliable insulation company to do it for you. It's too expensive to mess around with.

CJhaughey

BERmad wrote: »

Yes but it is hardly rocket science to fit the hard back insulation as long as the installer takes there time and does it right.

Very true. Have you looked down many cavity walls? I woud say that easily 80% of the ones I have looked at have exactly the problems I outlined above and worse.

BERmad

Cherry Picker wrote: »

Actually BERman, it is 'rocket science' to some people who don't understand the purpose of insulation in the first place. Not everyone understands the whole energy efficient ways of today. I have seen new houses where the homeowner has had no other choice but to take the Kingspan Board out, because it has been so badly fitted - usually done by themselves trying to save on costs. Once is enough to have to pay for it, and you expect to have it right. So, my advice stands, if you feel you are unable to do it right yourself, get a carpenter or a reliable insulation company to do it for you. It's too expensive to mess around with.

It might be 'rocket science' if the person cant cut in a straight line and use a measuring tape. Other than that its not to tricky.

BERmad

CJhaughey wrote: »

Very true. Have you looked down many cavity walls? I woud say that easily 80% of the ones I have looked at have exactly the problems I outlined above and worse.

Yes I actually have and the block layers are good at there job they do it nice and tidy. With none of the problems you outlined above. As for the cavity walls you have looked at thats just down to bad workmanship.

supersimon

Hi guys

It's also worth noting that there are alot more factors that should influence your decision when choosing insulation.

Firstly, what is the material's resistance to fire? ie. how combustable is the product?

Also, what is the insulation in question's acoustic value? ie. How well does it keep out sound?

How sustainable is the insulation? Is it made from a renewable source and is it being recycled?

just something to think about....

5.watt.halo

I'm at the stage where I have dormer roof on and am pricing windows insulation etc...
I DO NOT KNOW what to put in rafter spaces. board or wool or where to source it. DIY or spend. Can you over insulate?
I'm getting my eyes opened big time. naively thought insulation wouldn't be that expensive, but if I want it do the job right... (still have the floors to insulate too!)

5.watt.halo

I'm at the stage where I have dormer roof on and am pricing windows insulation etc...
I DO NOT KNOW what to put in rafter spaces. board or wool or where to source it. DIY or spend. Can you over insulate?
I'm getting my eyes opened big time. naively thought insulation wouldn't be that expensive, but if I want it do the job right... (still have the floors to insulate too!)

Corkey123

5.watt.halo wrote: »

I'm at the stage where I have dormer roof on and am pricing windows insulation etc...
I DO NOT KNOW what to put in rafter spaces. board or wool or where to source it. DIY or spend. Can you over insulate?
I'm getting my eyes opened big time. naively thought insulation wouldn't be that expensive, but if I want it do the job right... (still have the floors to insulate too!)

You will require 300mm of rockwool. That is normaly done via 150mm between the joists and a further 150mm at right angles to the joist. If you think you'll need the attic for flooring you can get 50mm kingspan/extraterm attached to chipboard attic boards. Again these are installed at right angles to the joists. This will make up the balance of the 300 mm rockwool, etc.

good architect

I am a qualified and registered RIAI architect and have been in the construction business for over 20 years and have seen a lot of insulation products come and go....
In all this time, I have yet to see a block layer fit insulation boards properly, EVER!!!!
Blocklayers lay blocks.... simple... they don't want to do anything else, without first making a fuss, or worse, costing you more money.
They charge by the block and anything else is just a nuisance to them...

Unless the insulation is fitted within 1.5mm (yes... 1.5mm) of the inner block wall, then a thermal loop occurs in this air cavity which takes all the good out of the expensive insulation you have just paid for..... Does that make any real sense?

Believe me.... I am a registered BER energy assessor and can do all the U-value calculations first hand and in my sleep.... Theory and reality are definitely removed from each other when it comes to cavity insulation...

Katz83

good architect wrote: »

I am a qualified and registered RIAI architect and have been in the construction business for over 20 years and have seen a lot of insulation products come and go....
In all this time, I have yet to see a block layer fit insulation boards properly, EVER!!!!
Blocklayers lay blocks.... simple... they don't want to do anything else, without first making a fuss, or worse, costing you more money.
They charge by the block and anything else is just a nuisance to them...

Unless the insulation is fitted within 1.5mm (yes... 1.5mm) of the inner block wall, then a thermal loop occurs in this air cavity which takes all the good out of the expensive insulation you have just paid for..... Does that make any real sense?

Believe me.... I am a registered BER energy assessor and can do all the U-value calculations first hand and in my sleep.... Theory and reality are definitely removed from each other when it comes to cavity insulation...

Hi we are pumping the cavity with 150mm warmfill silver bonded bead do you think this is a good idea