Some important building questions!!!!!!!!

ollie30

Hi,

We are about to start building a 2600 sq ft 2 storey house and have been searching the internet and threads for information but I'm totally confused. What I would like to know is: since we don't timer frame (currently live in timber frame and find wall fixing etc very troublesome for shelves etc). We also want concrete slabs on first floor,
what is best method: 1) Standard block and kingspan insulation. 2) Poroton block 3) AAC block by ytong or any similar 4) roadstone safewarm block. If option 1 is the best solution, is there any way of upgrading above standard regualtions. I have spoken to rep from ytong block and he thinks poroton are brittle to chase????? Also which is most cost effective????

I hope this makes sense and someone can help ease my confusion....

Thanks,

Ollie

ardara1

Thermally the difference between a 100mm normal concrete block and using the best available aerated insulating block is worth about 17mm of either Kingspan or Xtratherm PIR insulation - you need to decide if the aerated block has the strength to carry your loadings and whether the extra cost is worth going for the aerated. A lot of plasterers don't like plastering onto aerated because they'suck' the moisture out of the internal finish and is difficult to work with. 100mm cavity, well fitted partial fill PIR, heavy bloack - then dryline the inside with another 25mm - then seal before plasterboarding, tieing the seal in with floor barrier and roof vcl - you'll get about 0.22 U-value.

ollie30

Thanks ardara1,sorry for late reply,work dictates.Yes the ytong block can carry the load needed , u value comes at .26 just above building regs i think was worring about thermal bridge at cills,door jambs,cavity etc also as these other systems are suppose to eliminate these problems same for thermal looping.i was wondering if there was any higher standard cavity insulation than the mentioned even if ment using wider cavity and ties to try and not dry line so as the the block wall wont cool as quick (sort of thermal store)as what happens in timber frame

AJL

I am building a Kingpan TEK (SIP panel) house. It is quick like a timber frame but all the external, walls and some internal are alot more solid to fix items to. U value is 0.2

Mellor

If you are prepared to go the whole way a conc block wall get get a U-Value down to 0.1 W/m2K.
Just pointing that out.

As for standard cavity wall, using better insulation, insulation in other areas outside the cavity, internal for example. And a good level of detailing will give you above reg standard.

sas

Mellor wrote:

If you are prepared to go the whole way a conc block wall get get a U-Value down to 0.1 W/m2K.
Just pointing that out.
QUOTE]

Mellor, you have me a little confused with this statement. What specifically or in what context are you talking about a conc. block wall?

Mellor

I was refering to the OP question in his second post

i was wondering if there was any higher standard cavity insulation than the mentioned even if ment using wider cavity and ties to try and not dry line so as the the block wall wont cool as quick (sort of thermal store)

And i said that if he was willing to go this route and do it to a high standard, that he could get a U-Value of 0.1 W/m2K

sas

Mellor wrote:

I was refering to the OP question in his second post



And i said that if he was willing to go this route and do it to a high standard, that he could get a U-Value of 0.1 W/m2K

Great, thanks for that. So how wide a cavity would you be talking about and what would you put in there as insulation in order to achieve 0.1 W/m2k?

Viking House

I spoke to some Polish builders last week and the most common building system there is the Poroton block with external insulation. It was minus 30 degrees in Poland for 2 weeks last year in Poland.
When they use the Poroton block alone your heating cost can be about €100 per month for a standard family house.
When they insulate the Poroton block on the outside with 100mm polysterene they get their heating costs down to €50 per month.
When they insulate on the outside with 100mm Paroc granitewool the heating costs drop to €30 per month because of the higher density and specific heat capacity of Paroc.

Ytong is also available there but they prefer Poroton because of the healthier living conditions. Ytong is also brittle by the way.

I would personally try to steer clear of petrochemical insulations as they only give good results in the laboratory and give much poorer results in reality when you check your heating bill. Petrochemical insulation materials are seen as the poor mans insulation in Poland.

Insulating the cavity has been scrapped in every other country in Europe as a failed system because of Thermal Looping and cold bridging etc

We tried a block from Finland similar to the Safewarm block made from Lightweight aggregate instead of stone but we stopped using it because we wanted to use less polluting materials. Cement and petrochemical insulations like Kingspan and Aeroboard are very bad for the envoirnment.

We checked a number of Irish houses with a Thermal Imaging camera for heatloss and the major loss areas are where the wall meets the roof, where the wall meets the floor and around windowcills and lintels.
To address these problems we insulate externally (Paroc) which works well for the wall roof joints and around the windows, it also improves the loss between wall and floor because when we externally insulate we drop the insulation 8 inches below finished floor level on the outside helping th eliminate this problem.
We try to persuade customers not to use concrete/granite windowcills, chimneys and Velux windows as all are major heat loosers in a house.
We are importing a Sweedish foundation system that eliminates the cold bridge between the wall and the floor.

Mellor

sas wrote:

Great, thanks for that. So how wide a cavity would you be talking about and what would you put in there as insulation in order to achieve 0.1 W/m2k?

About 300 full-fill rockwool. it doesn't have thermal looping or brigding.
The inner leaf is thicker. And the insulation is a kind of cavity/external hybrid. With a outer leaf of brick/block/cladding.
I was giving this as an example of the best possible. This method was the lowest u-value from a wall I have seen. It will cost more, but heating will be at passive levels.

ardara1

Increasing your cavity above the standard 110, will neccestate more and bigger wall ties - these are thermal bridges and SIGNIFCANTLY brings down the performance of the over all wall U-value. Eg using strap ties in a cavity instead of wire will add 0.02 of a U-value to the contruction.

Viking - you seem to have chip on your shoulder about 'petro chemical' insulants - have you evidence of mis-selling the properties of solid boards? Or is it the practice of fitting them on site causes the problem?

Also insulating the cavity - another consequence of Global Warming is the fact that our nice Irish Mist of constant rain has developed into deluges of raindrops that have increased in sized and velocity - there might be a point in maintaing a cavity of some sort - especially of you're considering brick - See Brendan McWilliams acticle in the Irish Times. 28/10/2004

ircoha

Interesting post this.

Does the thermal looping problem make solid constructions such as CIF/SIP etc more "attractive".
I not being provocative here.

Is there is a consensus that the existing standards in Ireland are less than what they should be?

If there is we need to highlight it.

ardara1

ircoha wrote:

Interesting post this.

Does the thermal looping problem make solid constructions such as CIF/SIP etc more "attractive".
I not being provocative here.

Is there is a consensus that the existing standards in Ireland are less than what they should be?

If there is we need to highlight it.

Off course Irish standards are not not as expected - there's no inspection of site practice by any form of building control - nor are architects employed to keep an eye on what is happening on site - and most of the BS on energy efficiency come from as person with an agenda/ or somethinf to sell! - yet projects are signed off as being in compliance with Building regs, by people who haven't read or ubderstand the regs - people don't know what they're buying when they buy a house - bring on Eddie Hobbs!

Thermal looping would not be a problem if insulation was fitted properly - it happens with ALL types of materials, fibre or perto chemical.

UK have now standards to inpect Robust Detailing - SAME AS WE HAVE IN IRELAND - difference is in UK it has to be signed off by someone on site.

Viking House

ardara1 wrote:

Viking - you seem to have chip on your shoulder about 'petro chemical' insulants - have you evidence of mis-selling the properties of solid boards? Or is it the practice of fitting them on site causes the problem?

Petrochemical insulation materials are over rated because they let the heat through too quick, every other country in Europe knows this, we're just swamped by the Roadstone and Kingspan propaganda here.
Insulation and heatloss are a lot more complicated than just U-value.
My ideal wall has a Decrement delay of 12 hours where the midday heat reaches the inside of the house at midnight.

Four years ago I was in a pub with Finnish and German Engineers. I asked them how much it costs to heat an average 250m2 house in Finland and Germany per year? In Germany it was about €800 and in Finland it was about €900. I had just been in Tipperary discussing the same issues with some friends who were paying on average about €2500 per year to heat their 250m2 houses.
I was a builder building standard insulation in the cavity houses at the time and I set out on a four year education changing the way I build.
I now build passive timber frame and block built houses with the minimum use of concrete and plastic insulation.

Viking House

ardara1 wrote:

Thermal looping would not be a problem if insulation was fitted properly - it happens with ALL types of materials, fibre or perto chemical.

You don't get Thermal Looping when you use Rockwool in the cavity because you don't have a void between the wall and the insulation.
Thermal Looping is impossible to avoid when you use Kingspan in the cavity no matter how much attention to detail you take. Any gap greater than 1mm between the insulation and the wall will result in a drop in the U-value by 35%.
By the way Roadstone make cement blocks with a tolerence of +- 1mm so there can be a difference of 2mm thickness between two blocks side by side in every wall.

Mellor

ardara1 wrote:

Increasing your cavity above the standard 110, will neccestate more and bigger wall ties - these are thermal bridges and SIGNIFCANTLY brings down the performance of the over all wall U-value. Eg using strap ties in a cavity instead of wire will add 0.02 of a U-value to the contruction.

The u-value would only be brought down if you increased the cavity and didnt increase insulation. I don't think that anybody sugested that. So your point makes little sense.

ardara1

Mellor wrote:

The u-value would only be brought down if you increased the cavity and didnt increase insulation. I don't think that anybody sugested that. So your point makes little sense.

It's not 'increasing the cavity' and not increasing the insulation I'm on about. It's the increased proportion of WALL TIES GOING THRU' theinsulation that must be accounted for when calculating the U-value - more wall ties - more thermal bridging - lowering the U-value what ever the thickness of insulation.
This is probably an even biggre factor when fixing exterior insulation systems - simply a lot more foxings penetrating the insulation layer.
Plastic ties would perform best.

Personally I believe that the effect of heat loss via insulation fixings is exagerated.

I am building an ICF house and the polystyrene panels are held together by 4mm diameter steel rods at 200mm centres, both horizontally and vertically.
the rod extends out by 150mm (the thickness of the polystyrene on the outside face of the wall. this rod is then capped by a polythene "nut/disc.

Doing the calculations: with out the steel rods, the wall U value came in at approx 0.018 and factoring in the rods (and air space around the rod) 0.019
What I have not factored in is the fact that the long this rod will radiate heat along its length sideways into the insulation, thus reducing the amount radiated at the end.

Thermal bridging is an issue, but probably needs the cross section to be significant to have an adverse effect on the insulation quality of the wall.

ollie30

thanks for all opinions and help folks so is the general thinking standard partial fill cavity and dry line the cheaper form of upgrading(even though it leaves the need for extra long screws to fasten anything to wall)the 300 rockwool probably more expensive??viking hse is your block method the poroton with paroc, no fireplace and timber first floor as my intention is to have 2 fireplaces(1 sealable grate fire and 1 log burner)and concrete first floor even more against your thinking some natural donegal sandstone at a couple of places on the front.is there any way in your or anybody else opinion that this construcion can be made into a comfy well insulated house that wont cost a fortune to break from the norm.does the poroton,paroc system cost much more to construct than normal methods,one good contractor quoted 60euro per sq ft for normal method but still hoping break down of individual trades will cost even less.

Viking House

A good option is to build with 9 inch cavity blocks and insulate on the outside with 6 inches of Paroc.
We do 50mm/100mm Paroc external insulation for €75/€80 per m2.
A 250m2 house could have an external wall area of 200m2 so this job could cost €15k but you would have less blocks to lay, no outside plastering by your builder and a better build in my opinion.
This would reduce the three major cold bridge areas; where the wall meets the floor (because the insulation drops down 6 inches below finished floor level), where the wall meets the roof and around the windows.

Mellor

ardara1 wrote:

It's not 'increasing the cavity' and not increasing the insulation I'm on about. It's the increased proportion of WALL TIES GOING THRU' theinsulation that must be accounted for when calculating the U-value - more wall ties - more thermal bridging - lowering the U-value what ever the thickness of insulation.
This is probably an even biggre factor when fixing exterior insulation systems - simply a lot more foxings penetrating the insulation layer.
Plastic ties would perform best.

No, any drop in u value due to the increased size of the ties is outweighted by the increased u value.

which of the following, in your opinion, gives the better u value

110 cavity, filled with 70mm insulation.

215 cavity, filled with 175mm insulation. The ties on this wall be be stronger/thicker.

ardara1

Mellor wrote:

No, any drop in u value due to the increased size of the ties is outweighted by the increased u value.

which of the following, in your opinion, gives the better u value

110 cavity, filled with 70mm insulation.

215 cavity, filled with 175mm insulation. The ties on this wall be be stronger/thicker.

HI Mellor - you didn't mention type of insulation - lets take it as aerobord

70mm using ordinary wall ties - U-value 0.40
175mm using strtap ties @ 5/m2 - U-value 0.23
175mm and ignoring the ties - U-value 0.19

I take a hell of a difference - you'd have to put 220mm with the wall ties to make up the difference - your founds at 3 time the width would be min 4 foot wide! - then heads & cills - why would you do it?

Thermal bridging of fixings is generally ignored.

Viking House

ollie30 wrote:

thanks for all opinions and help folks so is the general thinking standard partial fill cavity and dry line the cheaper form of upgrading

When you dryline you are only insulating 90% of the wall because the walls and middle floors touching the outside are not insulated. You are moving the "Dew Point" of the wall to the inside when you should be moving it outwards. This brings the cold towards the inside causing mould/fungus where the wall meets the insulation.
Polyeurethene insulation is not allowed on the inside of buildings in Scandinavia because of offgassing etc.

All of these factors contribute to what is commonly known as "sick building syndrome".

ardara1

Viking House wrote:

When you dryline you are only insulating 90% of the wall because the walls and middle floors touching the outside are not insulated. You are moving the "Dew Point" of the wall to the inside when you should be moving it outwards. This brings the cold towards the inside causing mould/fungus where the wall meets the insulation.
Polyeurethene insulation is not allowed on the inside of buildings in Scandinavia because of offgassing etc.

All of these factors contribute to what is commonly known as "sick building syndrome".

Viking - there are a number of very emminent CEN scientific committees that have spent years formulating the procedures for thermal measurement, condensation risk assessment and product testing - they've settled on a few, pretty easy to digest CEN standards that most of us generally think are 'OK' - if you want to step out side the testing procedures to make some contrary claims, - back them up wth something conclusive.

Don't quotre 'Sick Building Syndrome' or 'Caravan Effect', without some scientific backing - I'm open to ALL methods of reducing CO2 in our buildings - but lets agree on standard measurement methodologies - we're fiddling as the earth burns Viking.

ardara1

Vik - whats - OFF GASSING?

Do-more

ardara1 wrote:

Vik - whats - OFF GASSING?

These links may help ardara1

http://www.modernsolutionsinc.com/newhome.htm
http://www.natureneutral.com/learnOff.php

For anyone wanting to spec "green" products for their build www.greenspec.co.uk is an excellent resource.

You will see from their list of insulation materials, whilst some polystyrene products are listed, no PUR products are...

http://www.greenspec.co.uk/html/products/list681.html

Do-more

VH I do find it rather contradictory that you come down so heavy against PUR insulation for off-gassing, whilst in another thread you said that you line the interior walls of your TF houses with OSB, which is one of the worst products for the emission of formaldehyde!?

Viking House

Hi Do-more

You are right about the OSB. This same issue has been going through my head for quite some time now but we need racking strength for the timber frame to stop them moving about.
We have found another more eco option which involves using the Fermacell for racking strength with a few diagonal T section lengths of steel in the frames. So we will use up our stock of OSB and move on to the new system.

Thank you for your observations!

Viking House

ardara1 wrote:

Viking - there are a number of very emminent CEN scientific committees that have spent years formulating the procedures for thermal measurement, condensation risk assessment and product testing - they've settled on a few, pretty easy to digest CEN standards that most of us generally think are 'OK' - if you want to step out side the testing procedures to make some contrary claims, - back them up wth something conclusive.

Don't quotre 'Sick Building Syndrome' or 'Caravan Effect', without some scientific backing - I'm open to ALL methods of reducing CO2 in our buildings - but lets agree on standard measurement methodologies - we're fiddling as the earth burns Viking.

There is a famous scientific test that was done in a housing estate of similar houses in Holland where they insulated all the houses to the same U-value.
Some were insulated with fibreglass and others were insulated with dense wood fibre.
Outside the daily temperature fluctuated by +- 30 degrees, there was no heating on in the houses. The houses insulated with fibreglass had a daily temperature fluctuation of +- 7 degrees and the houses insulated with wood fibre had a temperature fluctuation of +-3 degrees. Fibreglass has a higher mass than Kingspan.

How do you explain this Adara?
Maud put you onto the building theory page of the Paroc website which explains why denser insulation is better, if you would take time to read it.
I posted this website link for you in another thread explaining summer overheating and density of insulation materials http://naturalbuildingproductscouk.ntitemp.com/pdfs/Isolair_manual.pdf
Do more posted some good links on Offgassing.
Mellor has some good ideas on how to get higher U-values from cavity walling.

We are all trying to help (teach) you here and you continue to slag us off. Take a bit of time out and do a search for Sick building syndrome and its causes. I can give you plenty of examples of insulated plasterboard that I have taken off walls with big black fungus marks at the wall.

Here is an extract from an article by Patrick Daly who lectures in DIT on Envoirnamental Design

Thermal Results:
Some of most relevant aspects of the findings of the report relate to the thermal performance of the two test houses, which indicate that the lime hemp walls exceeded their notional design U Value.

On the basis of notional design the walls of the lime hemp houses had a poorer (higher) U Value (below UK Regulations) and the lime hemp houses had a resulting SAP rating of 77 compared to the Block Brick cavity house with a rating of 87, which met part L. This should have meant that the lime hemp house had lower temperatures and higher energy in use, but in fact the opposite turned out to be the case.

The implication of this is that the thermal performance of the Lime hemp construction was superior to its neighbouring brick block house, and that this was not reflected in the actual U Value or SAP calculations. This may have been due in part to the monolithic nature of the construction and the infill method, which should equate to reduced thermal bridging and lower air leakage rates. Likewise it may also have meant that the actual U value was greater than the notional one. The latter is supported by evidence that steady state U value assumptions do not reflect actual heat transfer, (which is multi directional) nor do they adequately take due account of thermal mass. There is debate in the industry regarding U value calculation methodologies, and questions regarding how effective the current methodology is, particularly in relation to thermal mass and the cyclical heat flows in walls.

Mellor

ardara1 wrote:

Increasing your cavity above the standard 110, will neccestate more and bigger wall ties - these are thermal bridges and SIGNIFCANTLY brings down the performance of the over all wall U-value. Eg using strap ties in a cavity instead of wire will add 0.02 of a U-value to the contruction.

I said it would reduce the u-value due to the the increased insulation. You went on again to say it wouldn't.

ardara1 wrote:

HI Mellor - you didn't mention type of insulation - lets take it as aerobord

70mm using ordinary wall ties - U-value 0.40
175mm using strtap ties @ 5/m2 - U-value 0.23
175mm and ignoring the ties - U-value 0.19

I take a hell of a difference - you'd have to put 220mm with the wall ties to make up the difference - your founds at 3 time the width would be min 4 foot wide! - then heads & cills - why would you do it?

Thermal bridging of fixings is generally ignored.

In your post your proved I was right. The more insulation, better u-value. Straps or not. I never said straps dont make a difference, i said the overall u value is better.

And you failed to show a u-value for the standard insulation without ties.
Probably around 0.38. So the values are not in full context.
As for making up difference due to ties, that point is a little out of place, as you could argue that you would have to do that anyway in a standard wall to compensatevstraps/ties.

The foundation is only a foot wider.

The reason you would do it is obvious, the OP asked how to improve a cavity wall by increasing it.Better proformance in a house is always better in the long run.

You still failed to answer by question, which has better U-value? Which would you prefere.

Navilluso

Sorry to butt in....I was recommended today to use a 150mm cavity with a pump filled platimum eps - giving a U of 0.2 ? Didn't know to ask about wall ties...
Any comments?

Do-more

Viking House wrote:

We are importing a Swedish foundation system that eliminates the cold bridge between the wall and the floor.

This product may be of interest also:

http://www.foamglas.co.uk/perinsul.htm

Designed to eliminate cold bridging at foundation/floor/roof to wall joints.

Viking House

Do-more wrote:

This product may be of interest also:

http://www.foamglas.co.uk/perinsul.htm

Designed to eliminate cold bridging at foundation/floor/roof to wall joints.

Thanks Do more, very interesting!

Viking House

Navilluso wrote:

Sorry to butt in....I was recommended today to use a 150mm cavity with a pump filled platimum eps - giving a U of 0.2 ? Didn't know to ask about wall ties...
Any comments?

Hi Navilluso

That system is a lot better than Kingspan/Xtratherm sheets in the cavity becuase it cuts out the Thermal looping. But eps has low density and looses heat quickly so you will need to keep your rads on all day to keep heat in the house.
By using denser insulations that hold onto heat longer, in Scandinavia, they can put the heat on for an hour in the morning and work in the room for the rest of the day even when its minus 20 outside.
I would not use cement plaster on the outside of the wall because you need higher quality plasters when you go for single leaf.

Wouldn't it be easier to build with a 9 inch cavity block and fix the 150mm insulation onto the cavity block and plaster directly onto the insulation.
Why do you need the block on the outside it only keeps the wall damp/cold?

Navilluso

Then which is the lesser of the two evils...thermal bridging or quicker heat loss? I can't imagine the point of installing insulation if you have to have heat on constantly to maintain the temps you want.

However, I'm not sure they have damp problems in Scandinavia....sometimes I think we are not comparing like with like...although they have very cold temperatures they don't have the same damp conditions as we do here. We don't need to be able to insulate against minus 30 temps, but dampness is probably a bigger issue here.

Wouldn't it be easier to build with a 9 inch cavity block and fix the 150mm insulation onto the cavity block and plaster directly onto the insulation.

If I told my father I was going building with a 9 inch cavity block...he'd lose the plot! LOL Considering his 70's house was built with exactly that....with NO insulation! Plasterboard just stuck on with some sort of glue at spots along the inside....(he didn't built it btw) Currently I'm living in a 70s house with a cavity and no insulation so to a certain extent anything would be better. I'd need to be convinced about the external insulation Viking but if you have personal experience......

Viking House

Then which is the lesser of the two evils...thermal bridging or quicker heat loss? I can't imagine the point of installing insulation if you have to have heat on constantly to maintain the temps you want.

I think full fill insulation is a big improvment on partial fill cavity insulation because you have no thermal looping but if I was given a choice I would like to use a denser insulation material that holds onto heat longer.
However, I'm not sure they have damp problems in Scandinavia....sometimes I think we are not comparing like with like...although they have very cold temperatures they don't have the same damp conditions as we do here. We don't need to be able to insulate against minus 30 temps, but dampness is probably a bigger issue here.

We are able to make hay and dry clothes on a line here in Ireland, we can even dry clothes in an outside shed while it is raining. The damp Irish climate is used as an excuse for a lot of bad building practices. Most of the problems in our buildings come from moisture from the inside. By allowing our buildings to breathe we are letting them dry out. If you wash your floor when it is raining outside, by leaving a window open your floor still dries.


If I told my father I was going building with a 9 inch cavity block...he'd lose the plot! LOL Considering his 70's house was built with exactly that....with NO insulation! Plasterboard just stuck on with some sort of glue at spots along the inside....(he didn't built it btw) Currently I'm living in a 70s house with a cavity and no insulation so to a certain extent anything would be better. I'd need to be convinced about the external insulation Viking but if you have personal experience......[/QUOTE]

Every system can be improved on just like Mellors wide cavity, we built two cavity block houses with external insulation last year, I think they are the two warmest concrete block built houses built in Ireland last year. One had 150mm of polysterene on the outside and the other had 150mm Paroc.

Mellor

Do-more wrote:

This product may be of interest also:

http://www.foamglas.co.uk/perinsul.htm

Designed to eliminate cold bridging at foundation/floor/roof to wall joints.

Thats very similar to a product I refered to in a previous thread on the issue. The one I seen was a german system.
But it eliminates the coldbridge at that area also. Basically it links up the vertical insulation upstand n the floor with the cavity or external insulation.

I still haven't decided how i'd like to build a house for myself.
i know alot about a wide range of technologys and the information is all understandable.

But the problem is in relation to performance. Calculations on paper and "ideas" only go so far. It will be interesting when the BER certs start getting issued, won't take long before timber or concrete or some other system is publishing a list that show they give the best ratings.

But if anyone has seen the sample rationg scale then they will know it is a joke.

ollie30

has any body else any thoughts on viking hse method of cavity block and outside paroc?is there any reason why we shouldnt use that method.i liked the sound of inside quinn lite leaf but is it mad building 2 expensive partil fill (1 quinn lite)walls when maybe vh method the easiest and maybe cheapest.not long before we start and still confussed quite a few methods but there doesnt seem to be a generaly agreed cost effective method of upgrading insulation (except dry lining and that doesnt seem to be too good ,dew point etc.)amongst the building trade. please help dont wana throw in the towel and just settle for standard practice because i cant decide in time

rooferPete

Hi Ollie,

I would have no problem using a 9" cavity block with a high performance insulation system, I would want the supplier to supply both the insulation and the fixings.

Offgassing was a problem when using some insulation on usually large industrial / commercial flat roofs, I am not taking about today or yesterday but as far back as the 1980's.

If the waterproofing systems were bonded direct to the insulation as little as one year later the membrane could have large blisters caused by gasses in the insulation.

The answer was to use a partial bond and vented system when fitting the finished roof.

Therefore based on past experience I have to agree with Viking regarding the sick building theory, because we knew about the problem over twenty years ago as did the manufacturers !

.

Viking House

ardara1 wrote:

It's the increased proportion of WALL TIES GOING THRU' theinsulation that must be accounted for when calculating the U-value - more wall ties - more thermal bridging - lowering the U-value what ever the thickness of insulation.
This is probably an even biggre factor when fixing exterior insulation systems - simply a lot more foxings penetrating the insulation layer.

With most external insulation systems you don't have any fixings through the insulation.

ollie30

thanks for your help guys,as i think i mentioned earlier i'm using stone on the face of the sun room and around a high window (both face north) if i used cavity block and paroc what would i do at the stone area??really want to keep the heat sapping stone as its a nice example which took a lot of effort to find

newbuild06

Viking House wrote:

Hi Viking

That system is a lot better than Kingspan/Xtratherm sheets in the cavity becuase it cuts out the Thermal looping. But eps has low density and looses heat quickly so you will need to keep your rads on all day to keep heat in the house.
By using denser insulations that hold onto heat longer, in Scandinavia, they can put the heat on for an hour in the morning and work in the room for the rest of the day even when its minus 20 outside.


Viking How would a pumped mineral wool bonded bead compare to eps or are they the same? The cavity area that would be pumped would be 130mm Would this hold heat longer than the eps???

Wouldn't it be easier to build with a 9 inch cavity block and fix the 150mm insulation onto the cavity block and plaster directly onto the insulation.
Why do you need the block on the outside it only keeps the wall damp/cold?

When you externally insulate do you also plaster the insulation as well?? and if so how does this hold up with cracks or gaps forming in the insulation ?? and please forgive my ignorance but would it take a house that has external insulation longer to heat up than having the insulation in the cavity??

Thanks

Viking House

That system is a lot better than Kingspan/Xtratherm sheets in the cavity becuase it cuts out the Thermal looping. But eps has low density and looses heat quickly so you will need to keep your rads on all day to keep heat in the house.
By using denser insulations that hold onto heat longer, in Scandinavia, they can put the heat on for an hour in the morning and work in the room for the rest of the day even when its minus 20 outside.


Viking How would a pumped mineral wool bonded bead compare to eps or are they the same? The cavity area that would be pumped would be 130mm Would this hold heat longer than the eps???

Rockwool is a lot denser than EPS so it should perform a lot better, can you send me info on the product you are considering.

Wouldn't it be easier to build with a 9 inch cavity block and fix the 150mm insulation onto the cavity block and plaster directly onto the insulation.
Why do you need the block on the outside it only keeps the wall damp/cold?

When you externally insulate do you also plaster the insulation as well?? and if so how does this hold up with cracks or gaps forming in the insulation ?? and please forgive my ignorance but would it take a house that has external insulation longer to heat up than having the insulation in the cavity??

You plaster directly onto the external granitewool sheets which are glued to the wall.
The plaster is a special fibreglass mesh supported breathable mineral plaster which is flexible and resistant to cracking in temperature fluctuations of +-30 degrees. If you were building a house with external insulation then there would be no cavity, and yes it would take a bit longer to heat up the house because concrete is always a cold product.
Bring a concrete block into your living room for a few days and sit on it for 15 mins on the third day, your bum still gets cold. This is why they like to use warm building materials in Scandinavia because, what is nearly as important as being cold is the feeling of cold that you get from standing beside cold objects like a concrete wall or a window, the temperature may not be lower in that part of the room but it has the feeling of cold.
In this instance you should consider building your house with warm Taracotta blocks, when you put your hand on a Poroton Taracotta block it will start to give you back heat in 10 seconds, with a concrete block your hand would turn white.

newbuild06

hi Viking

Viking How would a pumped mineral wool bonded bead compare to eps or are they the same? The cavity area that would be pumped would be 130mm Would this hold heat longer than the eps???

Rockwool is a lot denser than EPS so it should perform a lot better, can you send me info on the product you are considering.

THe email address is www.aandainsulation.com

the product is instafibre