Bio based foam insulation

danyosan

Anyone any experience with this product?

Basically I'm looking into different methods of retro insulating a dormer bungalow, and I have been led to believe that pumped foam would be the way to go, and I came across this stuff.

Any help, tips, ideas welcome.

danyosan

Surely someone has some opinion on this. All I seem to be able to find on boards is talk of the bead insulation.

sydthebeat

as far as i know theres no certified system over here..

therfore no cert = dont use.

Chimpster

sydthebeat wrote: »

as far as i know theres no certified system over here..

therfore no cert = dont use.

I've been told they will have certification in Sept but until I see it I would hold off.

The risks are the 'breathability' of the material. There is a risk of your timbers rotting if this material doesnt breath sufficently.

danyosan

So would the bead insulation be the way to go? Its for a retro fit to an existing building.

sydthebeat

bead or fibre... my preference would be fibre..

see rockwool energy saver

danyosan

sydthebeat wrote: »

bead or fibre... my preference would be fibre..

see rockwool energy saver

cheers

spadder

Foam has been used in the states for the last twenty years with no major problems.



Like any insulation if you put it in the wrong place it will cause problems.

sydthebeat

spadder wrote: »

Foam has been used in the states for the last twenty years with no major problems.



Like any insulation if you put it in the wrong place it will cause problems.

Ireland is not the states, we have different climatic features and regulations.

spadder

sydthebeat wrote: »

Ireland is not the states, we have different climatic features and regulations.

agreed, Norhtern US has much harsher winters and temp variations.

I have seen foam in place in the US, it is much better than fibreglass or beaded insulations Imho.

RKQ

Retro fit is fine as your choices are limited.
No certificate no use, don't risk an untested product!

Understand it has been used in US but do they have our wind driven rain?

Lots of products that work fine in USA are totally unsuitable here!
I'd rather use a tested material, with an Irish certificate, that has been sucessfully used in Ireland or even Wales / Scotland etc.
Something thats been used 10 or 20 years, without a problem.

Its easy to put it in the cavity but impossible to remove!

spadder

RKQ wrote: »

Understand it has been used in US but do they have our wind driven rain?

They might have seen a small bit:)

http://www.youtube.com/watch?v=fhUST6b6qNg&feature=related

RKQ

Long damp winter with consistent wind driven rain is hardly the same as a tornado!

They have tornados in the Caribbean also and use corrugated metal roof. Would you suggest uninsulated corrugated metal roof in Ireland would be ok!

They use igloo in the North pole would you suggest that construction too?



They build beautiful mud huts in Africa with straw roof.


Homebond are very careful to test all foreign construction methods in Ireland, in Irish conditions, to ensure they work in Ireland.


The fact remains it is untested and uncertified for use in Ireland.

spadder

The construction methods you mentioned are because of economic and local resource factors. We had many a house with corrugated metal roofs before the celtic tiger. Do you remember the Bull Mccabe promoting the virtues of a metal roof in " The field"?



I know from seeing the foam in action (in the US) it is a better solution. Fibreglass has to be one of the nastiest materials to bring into your house and work with.

http://www.asbestos-institute.ca/newsletters/nl-95-2/nl-95-2(part1).html


I understand this is a relatively new technology in Ireland, but I would have no problems using it in my house once ventilation issues are observed.

sydthebeat

spadder wrote: »

The construction methods you mentioned are because of economic and local resource factors. We had many a house with corrugated metal roofs before the celtic tiger.



I know from seeing the foam in action (in the US) it is a better solution. Fibreglass has to be one of the nastiest materials to bring into your house and work with.

http://www.asbestos-institute.ca/newsletters/nl-95-2/nl-95-2(part1).html


I understand this is a relatively new technology in Ireland, but I would have no problems using it in my house once ventilation issues are observed.

that article in the link is highly biased.

if you want to use it go ahead, but the OP came on asking for advise. The best advise is no certification equals no use.. .simple as.

Take for example if this was a new build and a BER assessment was done on it..... that insulation would have to be ignored completely.... no certification means it cant be included in calculations.

spadder

I understand it does not have homebond approval etc. As you metioned the OP was looking for advice,
I have seen it in use and I think it is an excellent system regardless of what Homebond think.

If it was my house i would'nt care about the BER rating, it's the Gas bill I am trying to reduce.

with regards to the fibreglass article, Google it yourself. I know from working with fibreglass it is a horrible material.

cheers
S

sydthebeat

spadder wrote: »

I understand it does not have homebond approval etc. As you metioned the OP was looking for advice,
I have seen it in use and I think it is an excellent system regardless of what Homebond think.

If it was my house i would'nt care about the BER rating, it's the Gas bill I am trying to reduce.

with regards to the fibreglass article, Google it yourself. I know from working with fibreglass it is a horrible material.

cheers
S

I always specify rockwool myself, because of its fire performance.

Im not talking about Homebond approval, im talking about IAB, BBA or relevant european standards that need to be met.

Having seen it in use does not determine its suitablility of performance over a 50 year lifespan. Testing under lab conditions does.

Spadder, im not questioning this product, i personally like the theory behind it, however as a professional i must act accordingly and couldnt advise someone as to the suitability of a product that hasnt been certified for the use its supposed to do. They claim a thermal conductivity valu eof 0.036 which is cloe enough to rockwool... as rockwool is certified, given a choice, i could only specify that ahead of teh soy based insulation.

spadder

Syd, What do you think of Hemp?

(not as a narcotic, but insulation)

sydthebeat

spadder wrote: »

Syd, What do you think of Hemp?

(not as a narcotic, but insulation)

lol... couldve got in trouble there!

Hemp is an excellent product. not only for its insulative properties, but also its ecological properties... it can actual absorb a lot of co2 over its lifetime.
the only negative points about it is you need greather thicknesses to match the insulation levels of say, PU or PIR..... also th eprice is a bit restrictive at the moment.

But if your serious about the green route, then definitely.

John mac

I always specify rockwool myself, because of its fire performance.

just had a look and there is no mention of Rockwool here! (on the latest list)

http://www.nsai.ie/index.cfm/area/page/information/CertProdInstal

plenty of yellow and white wool though. is it the same product just by a different manufacturer?

It seems to have been replaced, as it is mentioned on a few previous lists.

sydthebeat

http://www.greenspec.co.uk/html/product-pages/rockwoolenergy.php

John mac

yea i know its approved in England
but i was just pointing out that there are no approved Irish installers at the moment.
(I would like to get a quote from one) based on a few recommendations i have seen here.

there was on previous directories from the iab site.

danyosan

John mac wrote: »

just had a look and there is no mention of Rockwool here! (on the latest list)

http://www.nsai.ie/index.cfm/area/page/information/CertProdInstal

plenty of yellow and white wool though. is it the same product just by a different manufacturer?

It seems to have been replaced, as it is mentioned on a few previous lists.

Just did a cross reference there for installers. First one I checked from the rockwool website, also appears on the nsai list, although on the list it states instafibre white and yellow wool.

EyeOnTheBall

My brother got the roof rafters of his 150 year old cottage insulated with Biobased foam. They're relatively new here. If it's the same one you're thinking about it's soya based also. His was a retro fit (obviously). I know he was very, very impressed with it. He had asked about the condensation worries of an airtight house and was told that a good heat recovery ventilation system solves that. It does make sense, if your house is airtight, then you need some sort of ventilation to stop condensation (!!). He did say it was dearer than other insulations he had been looking at, but apparently when a house is airtight, it saves money on heating etc. He's a shrewd sod, so if he went with it then I suspect it's got to be okay. I'll be building a house next year and I'll be looking at putting it in.

gman2k

I've installed the soya based insulation in my new build timber frame house, and the job is spot on.
I've yet to be made happy regarding certification, but I've been promised that it's on it's way in the very near future.
PS the certification process is nothing less than a money racket, and anyone who tells you different doesn't know better. I know a good few manufacturers who've had hell over this. If you pays your money, you gets your cert (if the product is ok of course)
I'm not knocking the poster above re certification - far from it.
The other benefit of the soy based insulation is that it forms an airtight envelope (you still have to seal up elsewhere). I've done an airtight package, and installed a mech heat recovery ventilation system also.
If anybody wants to, they can come look at my build in the SE (at the weekends) just pm me.
I'll post again regarding certs...

sydthebeat

gman2k wrote: »

I've installed the soya based insulation in my new build timber frame house, and the job is spot on.
I've yet to be made happy regarding certification, but I've been promised that it's on it's way in the very near future.
PS the certification process is nothing less than a money racket, and anyone who tells you different doesn't know better. I know a good few manufacturers who've had hell over this. If you pays your money, you gets your cert (if the product is ok of course)
I'm not knocking the poster above re certification - far from it.
The other benefit of the soy based insulation is that it forms an airtight envelope (you still have to seal up elsewhere). I've done an airtight package, and installed a mech heat recovery ventilation system also.
If anybody wants to, they can come look at my build in the SE (at the weekends) just pm me.
I'll post again regarding certs...

certification matters a lot!

Firstly, if a new build TF uses a non-accredited product (ie if it doesn't have a certification that complies with TGD D) then that product HAS TO BE IGNORED from the calculations when assessing the Building Energy Rating of the dwelling. Imagine someone paying 10K to insulate their new build and then an assessor telling them that they only get a G rating because they have to ignore the product...!!!

Secondly, the same situation applies to 'certification in compliance with building regs'. If the product isn't certified with a cert recognised as part of TGD D, then the building cannot be certified To be in compliance with building regs.... and if any professional does certify it, then more fool them.

thirdly, certification is the consumers way of getting a guarantee that the product 'does what it says on the tin'. Without proper certification theres no proof that a product does what it claims... ie multifoils first came out saying they equated to 200mm of quilted insulation... that was quickly show to be balderdash when they applied for certification!!

Fourthly, if a company want to sell their product on the Irish market, then they should have no problem putting it to scrutiny to prove it works in the Irish climate and conditions. Yes, of course you have to pay for this. But if you don't, then do not expect an easy ride from professionals who have to deal with these products as part of their work.

gman2k

Thanks sydthebeat,

I spoke to my BER assessor, and he felt it was not as clear cut as you made out, but he is going to contact the SEI helpdesk regarding lack of certification.

Speaking to the insulation supplier, they are working hard at the moment sorting out accreditation with the BRE. He stated that the certification is expected in Oct 08.

sydthebeat

gman2k wrote: »

Thanks sydthebeat,

I spoke to my BER assessor, and he felt it was not as clear cut as you made out, but he is going to contact the SEI helpdesk regarding lack of certification.

Speaking to the insulation supplier, they are working hard at the moment sorting out accreditation with the BRE. He stated that the certification is expected in Oct 08.

Thats my understanding of the process anyway, im open for clarification... perhaps other here can shed some light??

sinnerboy

Page 3 Item B3 of this document below defines what "proper materials" are .

http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,1643,en.pdf

For how to calculate U Values - and what EN tests are relevant look here

http://www.bre.co.uk/filelibrary/rpts/uvalue/BR_443_(2006_Edition).pdf

How products are to be tested - specifically insulation products - see pages 37 + 38

I have looked some info published on a "naturally derived spray foam" - (forum rules forbid me to name names)

The product has "been in use" since 2003 - not long enough to establish a track record to show that by covering structural timbers with the foam - that the timbers do not subsequently rot . The OP query - "Anyone any experience with this product?" - the answer is not many people have - anywhere . It is a new product .

Statement that a lambda value of 0.036 "may be used" ( about the same as fibreglass ) - but no mention of how - in EN testing terms - this value is determined

Statement that surface Spread of flame class C1 was acheived "when tested" - but the EN test is not mentioned

Vapour resistance - values are stated - again with out reference to EN testing

To be fair - There is a statement that in March 07 European certification was applied for - results pending . The product may be fine ...... BUT as of TODAY , without

- a long track record of demonstrated success - IN IRELAND
- EN Certification / CE label
- IAB or BBA certification

I would not use it .

sinnerboy

gman2k wrote: »

I spoke to my BER assessor, and he felt it was not as clear cut as you made out, but he is going to contact the SEI helpdesk regarding lack of certification.

Please keep us up to speed with SEI response

gman2k wrote: »

Speaking to the insulation supplier, they are working hard at the moment sorting out accreditation with the BRE. He stated that the certification is expected in Oct 08.

And keep us up to date with this too please


Don't want to unfairly knock what may be a great product .
Just , as Syd said , multi foils "took a lot of people in" - only to disappoint

.

EyeOnTheBall

sinnerboy wrote: »

Page 3 Item B3 of this document below defines what "proper materials" are .

http://www.environ.ie/en/Publications/DevelopmentandHousing/BuildingStandards/FileDownLoad,1643,en.pdf

For how to calculate U Values - and what EN tests are relevant look here

http://www.bre.co.uk/filelibrary/rpts/uvalue/BR_443_(2006_Edition).pdf

How products are to be tested - specifically insulation products - see pages 37 + 38

I have looked some info published on a "naturally derived spray foam" - (forum rules forbid me to name names)

The product has "been in use" since 2003 - not long enough to establish a track record to show that by covering structural timbers with the foam - that the timbers do not subsequently rot . The OP query - "Anyone any experience with this product?" - the answer is not many people have - anywhere . It is a new product .

Statement that a lambda value of 0.036 "may be used" ( about the same as fibreglass ) - but no mention of how - in EN testing terms - this value is determined

Statement that surface Spread of flame class C1 was acheived "when tested" - but the EN test is not mentioned

Vapour resistance - values are stated - again with out reference to EN testing

To be fair - There is a statement that in March 07 European certification was applied for - results pending . The product may be fine ...... BUT as of TODAY , without

- a long track record of demonstrated success - IN IRELAND
- EN Certification / CE label
- IAB or BBA certification

I would not use it .

To Sinnerboy:
The old tale that's going around about spray foam 'rotting' attics comes from applicators in the UK who put on a closed cell insulation without allowing for breathability. That was just plain product ignorance and lack of adequate training.
It seems they didn't read the instructions on the barrel and ruined it......just like they did with their pints of Guinness!

sydthebeat

EyeOnTheBall wrote: »

To Sinnerboy:
The old tale that's going around about spray foam 'rotting' attics comes from applicators in the UK who put on a closed cell insulation without allowing for breathability. That was just plain product ignorance and lack of adequate training.
It seems they didn't read the instructions on the barrel and ruined it......just like they did with their pints of Guinness!

eyeontheball

perhaps you can give us the breathability (Sd) figures of open-cell foam insulation, and the accrediated test methods they were derived from?

iamlegend2008

Hi

I had a salesman in or a spray foam company today and got what I thought was a reasonable quote for 6 inches of foam (filling inbetween rafters with open cell breathable foam).

The Uvalue of the foam would be 0.19 (so within regs) but I would add insulated slabs on the dormer ceiling.

The pros (actually cons) of using a bio foam have been documented in another thread so its caveat emptor (let the buyer beware) as to whether anyone uses it and Im currently discussing with by BER assessor.

One of the points raised was that the salesman maintains that the dormer roof could be made airtight using this method and there would be no need for a breathable airtight membrane (such a siga or intello) etc

The sofit vents are not covered themselves but the purloin is sealed at the wallplate level with foam.

The walls would be made airtight by means of a scratch coat.

Does anyone have any comments about using the foam as a means to achieve airtightness in the dormer ?

Thanks.

sydthebeat

do not use a product that does not have proper certification...

as far as i know, these open cell, soy based spray on foam do not have iab,bba or european norm certification yet... so dont use it.

sales persons will tell you exactly what you need to hear...
"this is a great product..."
"used in the US for over 40 years..."
"creates an air tight barrier..."

etc etc

NONE of these claims mean anything without proper proof.

PS, your ber assessor should be telling you that any product that doesnt have the necessary certification HAS TO BE IGNORED from the point of view of an energy assessment.... if he/she doesnt know this then id be worried.....

sinnerboy

http://www.boards.ie/vbulletin/showthread.php?t=2055316775&highlight=foam

muffler

I think we can merge this with the other thread.

rowan

Just spoke to someone at http://www.biobasedinsulation.ie and he said they're getting BER certification for the foam insulation product next week, but not IAB/BBA.

So is a BER cert as good as an IAB/BBA cert, i.e., would you guys trust it enough to begin using it?

sydthebeat

rowan wrote: »

Just spoke to someone at http://www.biobasedinsulation.ie and he said they're getting BER certification for the foam insulation product next week, but not IAB/BBA.

So is a BER cert as good as an IAB/BBA cert, i.e., would you guys trust it enough to begin using it?

There is no such thing as BER certification on a market product...

a BER certificate is a certificate that explains the energy rating of a building....

if thats what they actually said to you, id run a thousand miles in the opposite direction.... they are either trying to bluff you or they do not have an understanding of what they are talking about....

and anyway, this product has will achieve similar u values to using plain old fibreglass insulation.. .
without certification all that they claim to do can be taken with a grain of salt...

its interesting to note that in icynenes situation (they have a bba cert).. there is no reference to the increase achieved in air tightness by using this product..... which is part of the sales pitch...

sas

sydthebeat wrote: »

There is no such thing as BER certification on a market product...

a BER certificate is a certificate that explains the energy rating of a building....

I wonder if he meant BRE? They do issue certifications AFAIK.

Just a thought...

PirateShampoo

Icynene Foam insulation is full certified to use in Ireland

sinnerboy

sydthebeat wrote: »

its interesting to note that in icynenes situation (they have a bba cert).. there is no reference to the increase achieved in air tightness by using this product..... which is part of the sales pitch...

They sort of claim it at 4.3 here Syd

http://www.nsai.ie/modules/certificates/uploads/pdf/IAB090333.pdf

2 Comments

1. OSB used as speciied in Table 1 will act as a vapour barrier - in the wrong location - see attachment below
2. U value calc - BR 443 2006 convention for repeat thermal bridging is 15% not 9%

I note the product has an excellent μ value - 3.3 . That compares to fibreglass - μ value -1

.

sinnerboy

iamlegend2008 wrote: »

Hi

I had a salesman in or a spray foam company today and got what I thought was a reasonable quote for 6 inches of foam (filling inbetween rafters with open cell breathable foam).

The Uvalue of the foam would be 0.19 (so within regs) but I would add insulated slabs on the dormer ceiling.

The pros (actually cons) of using a bio foam have been documented in another thread so its caveat emptor (let the buyer beware) as to whether anyone uses it and Im currently discussing with by BER assessor.

One of the points raised was that the salesman maintains that the dormer roof could be made airtight using this method and there would be no need for a breathable airtight membrane (such a siga or intello) etc

The sofit vents are not covered themselves but the purloin is sealed at the wallplate level with foam.

The walls would be made airtight by means of a scratch coat.

Does anyone have any comments about using the foam as a means to achieve airtightness in the dormer ?

Thanks.

Don't usually like gravedigging - but in the light of the recent appearance of

http://www.nsai.ie/modules/certifica.../IAB090333.pdf

It is worth noting at

1. Table 1 that 6 inches of foam results in U Value of 0.28 - not 0.19
2. 4.2 that a vapour control layer is required .

sydthebeat

sinnerboy wrote: »

2. U value calc - BR 443 2006 convention for repeat thermal bridging is 15% not 9%

section 4.6.1 shows ceiling joists at 600 c/c can have repeat thermal bridging at a default fraction of 0.09.... (48/600 + 0.01)

however, in most cases of 400 c/c rafters / joists.. the fraction will be...

48/400 + 0.01 = 0.13....

so typically the IAB cert has given every variable factor in favour of the material looking to be certified.....

lots of persons considering this material do not realise that it simply gives teh same u value as fibreglass....

in order to achieve a 0.16 ceiling u value youre looking at needing close to 300mm..... this is easy to achieve with 'rolled out' insulation... but to achieve it with spray foam you need to build a 300 deep structure.....

to achieve 0.2 on a sloping ceiling youre talking about using close to 220mm......

every single person who has come to me over the last 2 years about this product has been told incorrect facts from the sales reps..... each of these persons has decided not to use it when these lies were exposed.... "shooting yourself in the foot" comes to mind....

ardara1

Interesting article

On Icynene
Icynene has arrived in the UK. What is it and why should it raise you from your slumber? It’s a spray-in foam insulation system, hailing from Canada and its makers claim you can get PassivHaus style performance from it without having to build walls and roofs which are 500mm thick. In fact, it gets used in the high Artic where the temperature falls to minus 60°C at only 90mm thickness.

I interviewed Jeff Hood, one of Icynene’s owners and the man responsible for bringing the product into Europe. Since the company’s formation in 1986 in Toronto, it’s achieved spectacular growth in North America and now accounts for around 5% of installations in US new housing. It works equally well in hot climates as in cold. Unlike the more common polyurethane foams, Icynene is blown with water: this was originally done to avoid formaldehyde off gassing but they have stuck with it to produce a unique sponge-like product that remains flexible. This flexibility is one of the keys to its success because it produces a truly airtight barrier and one that will stay airtight indefinitely. Hood tells me that this factor alone makes Icynene much more effective than almost any other insulation system. “We don’t believe boards are really effective because the caulking around them is never going to be done perfectly and in any event it will crack over time.”

So far all well and good. However, Icynene faces one or two problems before it can become widely adopted in Europe. “Europe is U value obsessed,” says Hood. “We believe we can get excellent performance from this product at fairly minimal thicknesses and that, whilst we could apply it at 300mm depth, there is no point because the performance improvement is absolutely minimal. Why waste footprint needlessly?”

Europe however is still feeling the effects of a nasty little tiff with the multifoil industry which, in truth, is still not satisfactorily resolved. The multifoil manufacturers make very similar claims and thus far have not been able to establish them via traditional testing methods. Icynene is a very different product to multifoil but the claims made by Hood and his colleagues have many similarities. Thus far Icynene has won BBA approval for use in walls and roofs, but only as a substitute (in performance terms) with glass fibre and/or polystyrene, which makes it rather poorer than the polyurethane family. But Hood’s contention is that it’s actually much better than all the other available mainstream insulation products and to prove it he has hired the building scientists at Napier University in Edinburgh to run some tests on Icynene in their laboratory in Glenrothes, a facility I visited last year with the UK Timber Frame Association. Results should be available soon. If they confirm Hood’s contentions, it could re-ignite the debate over the effectiveness of the established testing method, the guarded hotbox test.

Many people will think that we’ve been here before. The multifoil debate raged for many years and it was all based around the validity or otherwise of the guarded hot box as being the best (or only) method for measuring the effectiveness of insulation materials. The difference this time is that, in Icynene, we have a manufacturer who can quite happily supply insulation at any thickness. As Hood explained to me: “We can spray at whatever thickness the client wants, we just don’t want to waste their money, or use more material or footprint than is necessary. We think that’s green. And we think the move in Europe towards PassivHaus-style massive insulation is a costly mistake.” With Icynene installed in over 200,000 buildings including several LEED platinum standards, it could be that our future insulation standards could once again be up for debate.

sydthebeat

can anyone point to independent analysis that shows

1. air tightness result before installation
2. air tightness result after installation....??

I agree that were are u value obsessed, but i dont believe that we should row back on current u value standards... i think we need to bring the other building physic issues such as thermal bridging, hygroscopicy, breathability etc to the fore so we can properly determine what a 'sustainable' house is...

if we only focused on u value we'd all live in caravans.....

ardara1

sydthebeat wrote: »

can anyone point to independent analysis that shows

1. air tightness result before installation
2. air tightness result after installation....??

I agree that were are u value obsessed, but i dont believe that we should row back on current u value standards... i think we need to bring the other building physic issues such as thermal bridging, hygroscopicy, breathability etc to the fore so we can properly determine what a 'sustainable' house is...

if we only focused on u value we'd all live in caravans.....

HI Syd -

I don't think the 'air tightness' of the material is a factor at all. We know where air leakage in a house comes from - services and junctions. The Acceditted/Accedptable details show us how to seal these.

And your right about measurment standards- they're there and thats what we should stick to (See my separate post o multifoils)

Foil manufacturers pushed for 'new' was to measure their performance - UK Gov't has dug their heels in and told them to play on the pitch where the game was being played.

sinnerboy

Great posts A1 - ( not for the 1st time ) . Thanks

chingching

Hi,Im building a timber frame dormer house(2800sqft) and im planning on putting a HRV system in and im looking for advice on the best ways to make the house air tight..Spray Foam maybe v fiber glass insulation?
Thanks.

gman2k

chingching wrote: »

Hi,Im building a timber frame dormer house(2800sqft) and im planning on putting a HRV system in and im looking for advice on the best ways to make the house air tight..Spray Foam maybe v fiber glass insulation?
Thanks.

Well glass fibre insulation will not do anything for air tightness.
Bio based spray foam insulation for domestic is imo only worth doing if you are building a timber frame. And at that, the biobased spray foam on it's own won't give you full airtightness - you still need to go around and caulk joints of studs, rails to floor etc. Also, window and door opes need special treatments with airtight tapes.

chingching

Thanks gman..:)

riccol1966

I'm no expert, but I know one thing - fibreglass/mineral wool/variants are all poor substitutes in any open vented attic. When wind moves across these products, their insulation properties reduce vastly. Wind goes through them and removes the trapped air and then replaces it with cold air.

I'm fed up with being told to "just put another layer of fibreglass at right angles to your existing fibreglass and you've got your u-value and have avoided thermal bridging" Yeah, right. And no proper tests of these products are done with wind movement which replicates the true conditions of any non-habited attic space. I'd love to see those calculations guys..

This is where foam insulation (with a nod to cellulose) comes in, open cell will close off x inches, so the actual u-value of those x inches will be close to the manufactures stated values, as regardless of conditions the insulation will perform the same. I'm not saying this will get you a lower U-value than fibre/mineral wool per inch of insulation, but at least it will be a consistent u-value regardless of outside conditions.