Cold Bridging and Insulation : the issues and solutions

ircoha

There has been some commentary in a recent thread [http://www.boards.ie/vbulletin/showthread.php?t=2055158990 ] on CB and I think it worthwhile to assemble some succinct points on the topic in a standalone thread.
What follows is not presented as being definitive, but a starting point.

This link will serve to introduce the topic:http://www.bsria.co.uk/press/?press=232

we will focus on the problem in a domestic situation: eg a wall.

There are 3 basic methods of insulating:
A: internal dry lining
B: insulation fitted in cavity in cavity wall.
C: Externally Applied Insulation

They can be combined like in some of the ICF stuff. [A + C]

AFAIK, C is not that common here yet.

The 3 main areas where CB is a problem is
1: the wall itself
2: around doors and windows
3: from the foundation.

Internal Dry Lining

From what has been posted earlier, it seems that internal drylining can cause damp issues if not ventilated, and VH has posted that if the detailing provides for an air gap, the insulation in the cavity is rendered useless.

from Viking House in the post above: The Cold Bridge areas in 4 inch block partial filled cavity walls are where the inside block sits on the foundations and around the windows and doors and where the walls meet the roof. These are the areas where condensation/fungus/mould occur when you dryline. The correct way to dryline is to leave a ventilated air gap between the drylining and the wall which eliminates the effect of the insulation between the blocks.

The best place for insulation is on the outside of your walls or foundations.
2 inches on the outside has the same effect as four inches on the inside.

This poses the question as to what is the point of insulating the cavity.

The detailing for this around windows and doors can be tricky as generally the opes are the same dimensions on outside and inside so the insulation on the reveals will be much less because of the frames.

In an ideal world with a cavity wall the inner ope should be say 4 " bigger all round.

In addition it will be necessary to dryline all walls touching an external wall because of CB

Insulation fitted in cavity in cavity wall.

This is usually done with sheets of rigid polyXX and can be difficult to do properly with wall ties etc so quality of workmanship difficult to establish.

Is getting the cavity filled with some 'blown' insulation a better option, particularly in relation to airtightness?


Externally Applied Insulation

This is not that common here in Ireland and there seem to be issues with suitable renders.

However the concept seems good: the ope size issues are reversed.

However I am interested in what VH had to say

The best place for insulation is on the outside of your walls or foundations.
2 inches on the outside has the same effect as four inches on the inside.

as I dont see how external insulation solves the CB from foundations.


In terms of addressing the sources of CB as listed above

1: the wall itself
2: around doors and windows
3: from the foundation

it seems to me that Drylining is the only one that addresses the CB in all cases, including from the foundations, and to address the damp issue will need to be ventilated as per VH in .


I would welcome any observations/input.

Mellor

I commented on this in another thread and I had the same train of thought as you here. http://www.boards.ie/vbulletin/showpost.php?p=54156105&postcount=12

Each method of insulation has its downside, and each downside can be eliminated through good detailing.

Regarding the foundation coldbridging, It is true that the inner leaf sites on a cold rising wall and it is a source of heat loss. In an externally insulated wall, the contact area of the wall sitting on the cold rising wall is greater, therefore, imo, not only is external insulation exposed to the same flaw, it is greater here.
This flaw can be solved in both methods, by the same detailing.


The reveal problem also puzzles me, in drylining it is sovlable, granted you end up intruding on the frame, but it solves the cold bridge.

What is done externally? how is the external reveal formed? I'd like to see details as I am concerned about its strength.

kadman

Perfect answer to cold bridging, what do you think



kadman

ardara1

Thermal bridging at junctions becomes more of a problem in better insulated/sealed/performance building fabrics. The better the performance the more vunerable the junction. Our Part L recognizes the fact but doesn't quite tell you how to avoid problems.
We're supposed to build to basic guideline laid down in a Homebond Document 18 - 'Right on site' - we're then referred to Robust Detail for Construction printed in the UK - a document by DEFRA.

Bottom line is all junctions are measured as to their thermal performance AND the threat of condensation and moisture build up (Mould develops before moisture) by a single methodology - IP1/06.

If a junction is suspected to be prone to moisture/mould - bloody measure it - if there's a risk - fix it.

the amount of scare mongering that goes on from certain posters would scare you - lets get a realistic handle on things, most methods of measurement for moisture transfer/heat transfer or what ever has an agreed CEN methodology.

Mellor

kadman wrote:

Perfect answer to cold bridging, what do you think



kadman

Still a small cold bridge through the internal spray on structural concrete.
Not to mention the 3mm galvanised steel bridging the insulation, 84 per metre squared I believe.
There are still ways to improve all systems.

The foundation detail cold bridge in a cavity wall can be eliminated by using a foam glass block as the first course,

sas

Mellor wrote:

What is done externally? how is the external reveal formed? I'd like to see details as I am concerned about its strength.

In the case of the mosart passive house they built with 4 inch blocks on the flat with external insulation.

The windows are fitted prior to the external insulation and they are positioned so that the front of the windows are flush with the outer face of the wall i.e. no visible reveal.

Then the external insulation is fitted and they simply run the insulation across the frame of each window, thereby creating the reveal.

The IAB cert for the weber therm system (06/0260) has diagrams of this detailing which will explain it better than I probably did.

sas

Mellor wrote:

The foundation detail cold bridge in a cavity wall can be eliminated by using a foam glass block as the first course,

The latest issue of construct ireland has an article on a development in Kildare where they used Perinsul foam glass blocks to break the bridge.

They built a standard cavity wall (albeit with a 200mm cavity) and fully filled with ecobead platinum. They used 100mm perinsul blocks at the same level as the floor insulation on the inner leaf to break the bridge.

As a related aside, www.atil.ie supply these blocks in ireland if anyone is interested.

Mellor

sas wrote:

The latest issue of construct ireland has an article on a development in Kildare where they used Perinsul foam glass blocks to break the bridge.

They built a standard cavity wall (albeit with a 200mm cavity) and fully filled with ecobead platinum. They used 100mm perinsul blocks at the same level as the floor insulation on the inner leaf to break the bridge.

As a related aside, www.atil.ie supply these blocks in ireland if anyone is interested.

Thats similar to a detail I developed to great a domestic structure that had no significant cold bridges, all insulation was 100% continous. The only bridge was wall ties and these could be change to a less conductyive material than steel.


I get what you mean with the external insulation, I've never seen one in practice and often wonder on the strength of the revel corner, could it take a knock

sas

Mellor wrote:

The only bridge was wall ties and these could be change to a less conductyive material than steel.

The engineer in the article said that if he was going again he would consider using basalt wall ties. I looked these up out of interest and didn't find anything on them!

Mellor

Basalt is a rock similar to granite, its the rock found in the giants causeway,
it can be made into fibres that are similar to fibreglass or carbon fibre, it is used in fibre reinforced concrete
try looking for basalt fibre ties

Viking House

sas wrote:

The latest issue of construct ireland has an article on a development in Kildare where they used Perinsul foam glass blocks to break the bridge.
They built a standard cavity wall (albeit with a 200mm cavity) and fully filled with ecobead platinum. They used 100mm perinsul blocks at the same level as the floor insulation on the inner leaf to break the bridge.
As a related aside, www.atil.ie supply these blocks in ireland if anyone is interested.

The glass foam block has a lambda value of 0.3 so a 4 inch glass foam block has the same insulation effect as 10mm of Polysterene which is not so much.
Trying to modify a partial cavity wall to build an energy efficient house is like putting a new engine into a Ford Escort.

This is the system we are presently using giving a Swedish U-value of 0.11.
(1.1 U-value Swedish windows are 0.8 here.)



The house sits on a 300mm bed of structural Polysterene with no part of the house or foundations touching the soil. The external walls sit on the insulated ring beam designed to take the loads.
It completly eliminates all cold bridging between the floor and the wall when used with Poroton + external insulation or timber frame. The external wall insulation connects with the insulation around the ring beam and stops all cold bridging.
It offers the highest U-value in the world for a similar amount of insulation because all the thermographic lines are concentrated to the Polysterene upstand between the ring beam and the floor slab as you can see in the two images below.




This is the Thermograph (above) for the older L-element with 300mm Polysterene under slab.



This is the Thermograph (above) for the latest Swedish U-min foundation system with 300mm Polysterene under slab.

The U-value improves by 0.08 with no increase in material.
Scan Homes are keen to use this foundation system on all their new houses as they see the value.
The ring beam can take loads of up to 35 tonnes/linear metre.

Viking House

kadman wrote:

Perfect answer to cold bridging, what do you think
kadman

A colleague of mine worked as an Architect in London and one of his jobs was to oversee the fitting of Combi boilers in an apartment block. In the first apartment they were coring the wall to install the flew. The walls were mass concrete with Polysterene in the middle. When the core contents fell on the ground my colleague picked up the Polysterene. He squeezed it and it was like squeezing a wet sponge.

Poured vibrated concrete is quite dense and not very breathable and Condensation moisture was trapped between the two layers of dense concrete.

Your image shows similar detail Kadman, with insulation trapped between two materials with similar breathability. Better to put 300mm of Polysterene on 150mm compacted Hardcord (18mm-35mm) and pour the concrete only once, on top of the insulation and in the ring beam at the same time.

Viking House

sas wrote:

In the case of the mosart passive house they built with 4 inch blocks on the flat with external insulation.

It looks like the only Certified Passive House in Ireland has a 9 inch "Cold Bridge" all around the house, where the walls sit on the strip foundations.

I built using ICF in the rising wall as well as the main external walls, with a minimum of 50mm EPS between the internal floor concrete & the concrete in the wall, completely eliminating the CB at that junction.
The concrete within the ICF is still in direct contact with the strip foundation, therefore worst case U value is 0.25 (approx) at the junction between the floor & the strip foundation.

Viking House

Deleted User wrote:

I built using ICF in the rising wall as well as the main external walls, with a minimum of 50mm EPS between the internal floor concrete & the concrete in the wall, completely eliminating the CB at that junction.
The concrete within the ICF is still in direct contact with the strip foundation, therefore worst case U value is 0.25 (approx) at the junction between the floor & the strip foundation.

Hi DB

100mm EPS gives a U-value of 0.32 so 50mm would give a U-value of 0.45 at a guess.
You still have the issue of EPS between two layers of concrete though, creating a moisture trap.

VH

Mellor

Viking House wrote:

The glass foam block has a lambda value of 0.3 so a 4 inch glass foam block has the same insulation effect as 10mm of Polysterene which is not so much.


This is the system we are presently using giving a Swedish U-value of 0.11.
(1.1 U-value Swedish windows are 0.8 here.)


The house sits on a 300mm bed of structural Polysterene with no part of the house or foundations touching the soil.
It completly eliminates all cold bridging between the floor and the wall when used with Poroton + external insulation or timber frame. The outside insulation connects with the insulation around the ring beam and stops all cold bridging.


Scan Homes are keen to use this foundation system on all their new houses.
The ring beam can take loads of up to 35 tonnes/linear metre.

I have seen this insulated ring beam (or a similar one) when I met you at the RDS. It looks good, but I don't agree with the way you portray it when talking about other insulation methods.


Firstly, Foamed glass can have a conductivity in the range of .07-.10, so its alot better than you suggest. Some of the stuff I seen was at the low end of the scale. Also, if a concrete block was replaced with this material, the effective distance isn't 100 (4") you suggested, its 215 as the heat is travelling vertically towards the foundations at this area. That looks to be more than the thickness of the insulation under the ring beam, as the insulation in the ring beam is made to take higher loads I imagine it has a less effective conductivity. The more dense polystyrene is the less effective it is as an insulator.


The windows are also suitable for use with all other construction types, so thats universal too. They have a great U-Value, I'd be interested to get more info on them if possilble, maybe not this thread as its a little off topic.


You said the ring beam insulation is suitable for use with external insulation and timber frame, why not cavity block walls? I would imagine thats its perfectly acceptable to use it in conjunction with all construction, your comments are a little misleading



As for the strength per liner meter, 35 tonnes is very high. I'm impresssed, I would of thought it could handle domestic loads but not much more. The glass block can take 4 stories. Is the ring beam only supported by insulation, its not held at any point by piles is it?

Viking House

Viking House wrote:

Hi DB

100mm EPS gives a U-value of 0.32 so 50mm would give a U-value of 0.45 at a guess.
You still have the issue of EPS between two layers of concrete though, creating a moisture trap.

VH

I was taking into account 600mm of concrete section of rising wall as well. The EPS is not trapped as such, only a small section the thickness of the floor (100mm) is between two layers of concrete, below that the EPS is between concrete & hardcore (vented for radon) above that Internal fermacell.

Viking House

Mellor wrote:

Foamed glass can have a conductivity in the range of .07-.10, so its alot better than you suggest. Some of the stuff I seen was at the low end of the scale. Also, if a concrete block was replaced with this material, the effective distance isn't 100 (4") you suggested, its 215 as the heat is travelling vertically towards the foundations at this area. That looks to be more than the thickness of the insulation under the ring beam, as the insulation in the ring beam is made to take higher loads I imagine it has a less effective conductivity. The more dense polystyrene is the less effective it is as an insulator.

Aerobord told me that EPS 300 (The dense one) has a 17% better U-value than EPS 100. Something to do with more trapped air bubbles per m3.
I take your points on the Foam Glass block that it should be measured vertically but the heat is also travelling vertically on the EPS upstand to a depth of 400mm. Sorry for ranting on!

Mellor wrote:

You said the ring beam insulation is suitable for use with external insulation and timber frame, why not cavity block walls? I would imagine thats its perfectly acceptable to use it in conjunction with all construction, your comments are a little misleading.

You are right it is also suitable for cavity block walls. I am a bit biased on my comments on cavity block walls, I think it is a terrible system so my comments are not always fair on this point.

Mellor wrote:

As for the strength per liner meter, 35 tonnes is very high. I'm impresssed, I would of thought it could handle domestic loads but not much more. The glass block can take 4 stories. Is the ring beam only supported by insulation, its not held at any point by piles is it?

If you used piles you can increase the loads even further. When you use the system for high loads you need a Ringbeam shaped like an upside-down T.
I've seen 20 storey apartment blocks built on Polysterene-Waffle foundations in Sweden.

There's a Railway line in Ballisadare Co Sligo that sank into the Bog 10 years ago, they dug away all the aggregate and put 2 metres of EPS 300 under the tracks. A 500 tonne train has been passing over this line @100kph twice a day for the last 10 years with no problems or restrictions.

Viking House

Deleted User wrote:

I was taking into account 600mm of concrete section of rising wall as well. The EPS is not trapped as such, only a small section the thickness of the floor (100mm) is between two layers of concrete, below that the EPS is between concrete & hardcore (vented for radon) above that Internal fermacell.

I would have put down 300mm EPS on the compacted Hardcore and poured the concrete only once on top of the Polysterene.

In your case the heat in the screed will leak quickly through the 100mm EPS and into the slab below which probably has a direct Cold Bridge contact with the rising wall in the foundations. Forgive me if I am wrong!!

Keep it simple "Pour once" and wrap your rising wall/ring beam with EPS

Oops forgot to mention the 200mm EPS under the concrete floor.

Viking House

Mellor wrote:

Regarding the foundation coldbridging, It is true that the inner leaf sits on a cold rising wall and it is a source of heat loss. In an externally insulated wall, the contact area of the wall sitting on the cold rising wall is greater, therefore, imo, not only is external insulation exposed to the same flaw, it is greater here.

The cold comes further into your house when you Dryline. The "Dew Point" is pushed nearer the outside when you Externally Insulate. We only use Poroton blocks so the problem you mention would be reduced. When we Externally Insulate existing houses we try to insulate externally down to the footings which can sometimes be 30-50 cms below finish floor level.

Mellor wrote:

The reveal problem also puzzles me, in drylining it is solvable, granted you end up intruding on the frame, but it solves the cold bridge.
What is done externally? how is the external reveal formed? I'd like to see details as I am concerned about its strength.

The windows are installed flush with the outside of the wall and the external insulation covers 50-60% of the frames improving the U-value of the windows.

Mellor

Thanks for the replies VH, you clear a bit up for me, the reveal detail sound alot better than the ideas in my head,

sas

Viking House wrote:

It looks like the only Certified Passive House in Ireland has a 9 inch "Cold Bridge" all around the house, where the walls sit on the strip foundations.

This should not be dismissed lightly. This is a "certified" passive house which is an incredibly high standard to meet.

Does this not suggest that the cold bridge at the foundations may not be the big issue its being made out here to be? In performance terms I mean. Obviously I'm talking about the difference between using traditional detailing to reduce the bridge and one of the specialist systems.

You can use a specialist raft foundation system to achieve a specific u-value which in practise may make little or no difference to the cost of heating the house. Ultimately the aim is to reduce the energy requirement of the house, not to achieve a specific u-value. They may go hand in hand but given the mosart house, they may not.

I think it was ardara that pointed out on an older thread that the difference in heating bills between a b3 and a b1 house here for example could be as little as €50 per year. Is it worth the extra cost to achieve the b1?

Viking House

sas wrote:

Does this not suggest that the cold bridge at the foundations may not be the big issue its being made out here to be? In performance terms I mean. Obviously I'm talking about the difference between using traditional detailing to reduce the bridge and one of the specialist systems.

I just spoke to Tomas O'Leary and he used a row of Quinn Lite blocks where the 300mm EPS in the floor meets the rising walls.
It is not recommended to use Poroton or AAC (Quinnlite) blocks below the DPC level so thats a bit risky unless you have a very dry site which I think he has.

sas

Viking House wrote:

I just spoke to Tomas O'Leary and he used a layer of Quinn Lite blocks where the insulation in the floor meets the rising walls.

The B3 quinnlite block has the best thermal conductivity of the blocks featured in the IAB cert and that is 0.12W/mK

So what u-value could they have achieved for that junction?

If its a good enough detail then it would be a considerably cheaper solution than supergrund I have to imagine and alot easier to get certified too.

Mellor

Quinnlite blocks do have the best conductivity, but they shouldn't be used below dpc in a traditional sense as they are quite porous.

BUT that does not mean it can not be detailed correctly so that they are suitable for below DPC, This involves creating a dry area by using extra DPM

sas

Mellor wrote:

Quinnlite blocks do have the best conductivity, but they shouldn't be used below dpc in a traditional sense as they are quite porous.

BUT that does not mean it can not be detailed correctly so that they are suitable for below DPC, This involves creating a dry area by using extra DPM

Fair enough but the IAB cert makes no reference that I can recall to specific detailing when they are used for rising walls.

kadman

Viking House wrote: »

A colleague of mine worked as an Architect in London and one of his jobs was to oversee the fitting of Combi boilers in an apartment block. In the first apartment they were coring the wall to install the flew. The walls were mass concrete with Polysterene in the middle. When the core contents fell on the ground my colleague picked up the Polysterene. He squeezed it and it was like squeezing a wet sponge.

Poured vibrated concrete is quite dense and not very breathable and Condensation moisture was trapped between the two layers of dense concrete.

Your image shows similar detail Kadman, with insulation trapped between two materials with similar breathability. Better to put 300mm of Polysterene on 150mm compacted Hardcord (18mm-35mm) and pour the concrete only once, on top of the insulation and in the ring beam at the same time.

Hi VH,

As you know EPS has varying densities, the polystyrene in the pics has a manufacturing density of between 15-30 kg. There is no possibility of water soaking into this material, and then ringing it out. Test results have proved that the water absorption rate after a 24 hour full immersion test of virtually zero. I can organise a copy of the results for you. There is no evidence of water being trapped in the polystyrene panel due to its zero water absorption rates, conducted by independent testing facilities for the Irish Agrement Board.

This system of construction has been in use for over 30 years worldwide. In both domestic house construction , and commercial office blocks.

It is not a poured concrete construction. The wall and floor and roof panels are erected in a similar manner to traditional timberframe, and then sprayed in one or two coats of structural concrete, using a small portable concrete pump.I have been reliably informed recently, that this system is in use in Artic regions very successfully, as soon as I get more info I will post it.

Before you ask, Yes I do work for M2 Ireland, no I,m not touting for work, as we are run off our feet with our current projects, and yes I will send technical info , and test results ect for any one that wants some,


kadman

muffler

Im just going to make a couple of short and simple observations here lads.

Are we really going overboard with all the regs in relation to cold bridging etc? (Im playing devils advocate here btw).

in the absence of full Builing Control inspection how are we ever going to achieve what is discussed here and in other threads.

@Viking House. I havent had the time to go through all the posts in details but are you saying the methods you quoted above are in use in this country?

Finally - damn good thread and thanks to everyone for their input so far. keep up the good work.

ardara1

muffler wrote: »

Im just going to make a couple of short and simple observations here lads.

Are we really going overboard with all the regs in relation to cold bridging etc? (Im playing devils advocate here btw).

in the absence of full Builing Control inspection how are we ever going to achieve what is discussed here and in other threads.

@Viking House. I havent had the time to go through all the posts in details but are you saying the methods you quoted above are in use in this country?

Finally - damn good thread and thanks to everyone for their input so far. keep up the good work.

You're right Muffler - it's doing over board.

Under IP1/06 standards Psi values are set for thermal bridging at all junctions in a building. Passive levels (Averaging U-values in all elements of approx 0.15) are easily satisfied with thermal bridging at junctions achieving a Y value of around 0.03 - 0.04 (Current Part L regs 0.11 - draft version wanting 0.08 - UK proposing 0.04) These Y values are guite easily achieved with good standard detail - but will require drylining (Which are also tested under IP1/06 for f values that inicates the possibility for condensation forming in that junction). Floor/wall junctions are the weak areas and solutions are heading for a system of suppporting any suspended floors off an internal sleeper wall with insulation placed infront of it. Any system where the wall rests on the floor slab are having difficulty achieving th Psi value target and will necessitate separating the supporting perimeter from the main floor slab.

Viking House

kadman wrote: »

As you know EPS has varying densities, the polystyrene in the pics has a manufacturing density of between 15-30 kg. There is no possibility of water soaking into this material, and then ringing it out. Test results have proved that the water absorption rate after a 24 hour full immersion test of virtually zero.

Hi Kadman

The 15kg EPS would be EPS 70 is that right? We were on site during the summer and there was a downpour. We built a shelter from EPS 100 (20kgs) sheets. The rain came through the sheet of EPS. The air bubbles in the EPS were not affected by the rain but the rain came through the gaps between the air bubbles. With denser EPS 300 there are less gaps between the air bubbles so that would be more moisture resistant.

If you have a 2 degree difference between the ground and the slab you will get a capillary pull of moisture into the EPS from outside. 200mm of EPS eliminates the temperature difference and eliminates the capillary pull.
This means in theory that with 300mm under the slab you don't need a DPC.

Viking House

muffler wrote: »

@Viking House. I havent had the time to go through all the posts in details but are you saying the methods you quoted above are in use in this country?

There's about 10 U-min foundations built now Muffler.
Scan homes has used about 200 L-element foundations.

Mellor

Viking House wrote: »

Hi Kadman

The 15kg EPS would be EPS 70 is that right? We were on site during the summer and there was a downpour. We built a shelter from EPS 100 (20kgs) sheets. The rain came through the sheet of EPS. The air bubbles in the EPS were not affected by the rain but the rain came through the gaps between the air bubbles. With denser EPS 300 there are less gaps between the air bubbles so that would be more moisture resistant.

If you have a 2 degree difference between the ground and the slab you will get a capillary pull of moisture into the EPS from outside. 200mm of EPS eliminates the temperature difference and eliminates the capillary pull.
This means in theory that with 300mm under the slab you don't need a DPC.

Gaps between air bubbles??? What are talking about? The board is made up of pockets of air formed by polystyrene, not air bubbles stuck together.
You also said that the denser one has a better U-value are there is more air, this is wrong, yes more air equals less greater resistance BUT if there is more air its less dense.

I fail to see how 200mm eliminates a temp difference, if anything it increases it. Capillary action is based on gaps, water will enter a 2mm gap.
A dpc goes in the block work, not under the slab. A DPM goes under the slab, it would be harder for water to rise 300mm up gaps between boards, but suggesting that a DPM is not required in theory is totally wrong. In theory, a flood could cause the water table to rise above the height of the insulation, where due to columnation pressure it would rise through the insultion with detail. Temp isn't an issue here.
Not to mention the need for a DPM to act as a radon barrier (strictly speaking the randon barrier is acting as a DPM)

kadman

Viking House wrote: »

Hi Kadman

The 15kg EPS would be EPS 70 is that right? We were on site during the summer and there was a downpour. We built a shelter from EPS 100 (20kgs) sheets. The rain came through the sheet of EPS. The air bubbles in the EPS were not affected by the rain but the rain came through the gaps between the air bubbles. With denser EPS 300 there are less gaps between the air bubbles so that would be more moisture resistant.

If you have a 2 degree difference between the ground and the slab you will get a capillary pull of moisture into the EPS from outside. 200mm of EPS eliminates the temperature difference and eliminates the capillary pull.
This means in theory that with 300mm under the slab you don't need a DPC.

Hi VH,

I,m not too sure what roof material you used for your shelter, but you obviously should have used our polystyrene.
I think its wise to stick to the facts, so I,ve listed some of the tests that are available.

M2 material is manufactured to current European standards . All the raw materials are tested every 12 months by outside independant bodies.
Our tests are carried out in accordance with the following statutes and subsections.

1. Long term water absorption tests by partial immersion to EN 12087
2. Long term water absorption tests by total immersion to EN 12088.
Subsections of EN 13163:2001

In both the tests above the material passed with ease. I would be interested to know what material you were using, but it definitely was not manufactured to the rigorous guidelines used in the M2 system. As mentioned in my previous post, M2 are IAB certified. And I may be open to correction on this, but I believe M2 is the only full heght single wall panel system in Ireland that is certified.

If you would like to see any test results , or any indepth technical info VH, I can send them to you, or post some if they are not too big.

kadman

Viking House

Mellor wrote: »

Gaps between air bubbles??? What are talking about? The board is made up of pockets of air formed by polystyrene, not air bubbles stuck together. You also said that the denser one has a better U-value as there is more air, this is wrong, yes more air equals less greater resistance BUT if there is more air its less dense.

Polysterene (EPS) sheets are as you know made from lots of Polysterene balls (bubbles) with trapped air inside. The balls (bubbles) are heated with hot steam at 110 degrees and they stick together. This material is then compacted to give different densities of EPS. The Polysterene balls are spherical so there are gaps between them, they only melt together where they touch so there is a pathway (Free Air) through an EPS sheet where water and water vapour can get through.
Dense EPS has less Free Air but more trapped air.
EPS 70 is 15kgs/m3, EPS 100 is 20kgs/m3 and EPS 300 is 30kgs/m3.
The U-value is determined by the amount of trapped air within a sheet of EPS and not the free air between the ESP balls (bubbles). So there is more trapped air in dense EPS, hence the 17% better U-value.

Mellor wrote: »

I fail to see how 200mm eliminates a temp difference, if anything it increases it. Capillary action is based on gaps, water will enter a 2mm gap.

If you put a 2mm straw into a glass of water, the water will hardly rise at all. So you can put a sheet of EPS on saturated soil and you will get no capillary action so the EPS acts like a DPM, but it has the advantage of being able to let water vapour and water drops that could have condensed at the Dew Point drain through. But your slab needs to be designed properly to let this happen.

Mellor wrote: »

A dpc goes in the block work, not under the slab. A DPM goes under the slab, it would be harder for water to rise 300mm up gaps between boards, but suggesting that a DPM is not required in theory is totally wrong. In theory, a flood could cause the water table to rise above the height of the insulation, where due to columnation pressure it would rise through the insultion with detail. Temp isn't an issue here.
Not to mention the need for a DPM to act as a radon barrier (strictly speaking the randon barrier is acting as a DPM)

If your foundations/slab are designed/built right they work better without a DPM because the DPM prevents your slab from giving (sweating) off water vapour to the ground. Vapour moves from warm to cold and when the Water Vapour reached the Dew Point it would changes to water and drain to the ground.
You can use Radon proof concrete to eliminate the Radon barrier for example.
If your flood came it could also rise higher than the DPC.
The apsence of a Radon Barrier would allow the slab to dry out a lot quicker after the flood.

This is just my opinion after discussing this with a few people so don't lynch me yet.

Viking House

kadman wrote: »

Hi VH,
I,m not too sure what roof material you used for your shelter, but you obviously should have used our polystyrene.
I think its wise to stick to the facts, so I,ve listed some of the tests that are available.

Hi Kadman

If your EPS doesn't let water or vapour through then I don't want it. We buy from Aerobord who probably have similar tests. I am not knocking EPS because I know what you can of can't do with it. I just don't agree with putting it between 2 layers of non breathable concrete and trapping moisture in the slab. That's all!

galwaytt

Viking House wrote: »

Hi DB

100mm EPS gives a U-value of 0.32 so 50mm would give a U-value of 0.45 at a guess.
You still have the issue of EPS between two layers of concrete though, creating a moisture trap.

VH

Viking, you need to identify EPS better - you are referring to Expanded Polystyrene. There is also Extruded, and the 100mm extruded we use has a declared value of .29, not .32. On different sides of the Atlantic EPS gets you different things, so better to use the full description. Extruded is better, structurally, as well...........and more expensive, I might add.....

As for leaving internal reveals back to build up a non-CB detail, this is all well and good in theory, but recent requirements in the UK have been pointed out to us that this causes a problem with window replacement, and ongoing repair and renewal is now part of the accreditation process, at the behest of the insurance companies. Therefore detail like this is non-preferred, if you like..........so it's o.k. in a one-off house scenario, but you won't get schemes jumping on board to adopt it.......

Finally, and I haven't confirmed this yet personally, but an architect I work with occassionally had to re-design a house because Homebond would not accept the 6" cavity. I will check this out further and post back here.

Mellor

Viking House wrote: »

The apsence of a Radon Barrier would allow the slab to dry out a lot quicker after the flood.

This is just my opinion after discussing this with a few people so don't lynch me yet.

Thats probably true, but the radon barrier will prevent it being flooded in the first place. And if it rises above the DPC the damage will only be to the external leaf, as long as the standard correct detail is used. If water breaches over the DPC it will enter the cavity and fall below on to the DPM where is exits.
And the issue of water passing through the sheet of EPS could be possible, between the bubbles of free air as you said, but this shouldn't happen in quailty EPS, it should be quite tight at the surface.
Also radon proof concrete wouldn't let water vapour through, and wouldn't drain very well.

Viking House wrote: »

Hi Kadman

If your EPS doesn't let water or vapour through then I don't want it. We buy from Aerobord who probably have similar tests. I am not knocking EPS because I know what you can of can't do with it. I just don't agree with putting it between 2 layers of non breathable concrete and trapping moisture in the slab. That's all!

Aeroboard isn't exactly know for being of great quaility.

galwaytt wrote: »

Viking, you need to identify EPS better - you are referring to Expanded Polystyrene. There is also Extruded, and the 100mm extruded we use has a declared value of .29, not .32.

EPS is expanded, XPS is Extruded.
XPS is better is most aspects. And some XPS products can be alot lower than .29

kadman

Viking House wrote: »

Polysterene (EPS) sheets are as you know made from lots of Polysterene balls (bubbles) with trapped air inside. The balls (bubbles) are heated with hot steam at 110 degrees and they stick together. This material is then compacted to give different densities of EPS. The Polysterene balls are spherical so there are gaps between them, they only melt together where they touch so there is a pathway (Free Air) through an EPS sheet where water and water vapour can get through.
Dense EPS has less Free Air but more trapped air.
EPS 70 is 15kgs/m3, EPS 100 is 20kgs/m3 and EPS 300 is 30kgs/m3.
The U-value is determined by the amount of trapped air within a sheet of EPS and not the free air between the ESP balls (bubbles). So there is more trapped air in dense EPS, hence the 17% better U-value.
.

Hi VH,

Just to clarify one or two aspects of the M2 manufacturing process, which are totally different to the process you describe. I would be interested to know what ICF manufacturer uses your described method.

M2 manufacture all their panels from beads supplied by BASF , based in Germany. The process used block molding machines for the production of full size blocks of varying densities. the blocks are then passed through hot wire pantograph machines , which cut the various thickness,s , and profiles required for each house. At no time during the manufacture are any panels compressed to give a larger density material. this would only result in the panel regaining its shape after a few days, rather like squeezing a sponge, and then letting it go.

The densitiy of each panel is controlled by the amount of expansion of the virgin bead , throughout the block molding process. basically its relative to the amount of bead allowed into the molder, and the rate of its allowed expansion. In short , less bead and fully expanded = lower density block. More bead less expanded = higher density block. Our current density blocks range from 15-35kg.m3. But we have quoted for larger density blocks for swimming pools ect.

The link below, will explain the process. And if anyone would like a full factory tour and see the manufacture of the raw materials into single and double wall panels, as well as roof and floor panels, I can arrange it for you, as well as an M2 training session. Its tricky to describe the full process online.

http://iwww.plasticsportal.com/products/PDF/Styropor_BFL_Series.pdf

BTW , lynching is a long way off...;)

kadman

kadman

Viking House wrote: »

Hi Kadman

If your EPS doesn't let water or vapour through then I don't want it. We buy from Aerobord who probably have similar tests. I am not knocking EPS because I know what you can of can't do with it. I just don't agree with putting it between 2 layers of non breathable concrete and trapping moisture in the slab. That's all!

Hi VH,

Water cant get into the polystyrene wall panel, as its test results show its water absorption rate is virtually zero. So if it cant enter the wall panel between the 2 coats of 35 mm structural results, it cant get trapped there.

If you are still in doubt , call in , I,ll give you samples of the material , and you can make your own mind up on it. Its passed every test required for the IAB cert here, and certification worlwide. 2,000,000 structures worlwide I think is probably testament to its quality. Call in whenever you are passing by.


kadman

Viking House

galwaytt wrote: »

Viking, you need to identify EPS better - you are referring to Expanded Polystyrene. There is also Extruded, and the 100mm extruded we use has a declared value of .29, not .32. On different sides of the Atlantic EPS gets you different things, so better to use the full description. Extruded is better, structurally, as well...........and more expensive, I might add.....

Hi galwaytt

EPS (which is the stuff used for the foundations) is Extruded Polysterene.
XPS is Expanded Polysterene and not suitable for foundations.

Viking House

kadman wrote: »

Just to clarify one or two aspects of the M2 manufacturing process, which are totally different to the process you describe. I would be interested to know what ICF manufacturer uses your described method.

M2 manufacture all their panels from beads supplied by BASF , based in Germany. The process used block molding machines for the production of full size blocks of varying densities. the blocks are then passed through hot wire pantograph machines , which cut the various thickness,s , and profiles required for each house. At no time during the manufacture are any panels compressed to give a larger density material. this would only result in the panel regaining its shape after a few days, rather like squeezing a sponge, and then letting it go.

The densitiy of each panel is controlled by the amount of expansion of the virgin bead , throughout the block molding process. basically its relative to the amount of bead allowed into the molder, and the rate of its allowed expansion. In short , less bead and fully expanded = lower density block. More bead less expanded = higher density block. Our current density blocks range from 15-35kg.m3. But we have quoted for larger density blocks for swimming pools ect.

Thats the same stuff we use Kadman and Aerobord get their beads also from BASF as well. The mistake I made in my discription was that I said it was expanded first and then compacted. You said that they just put more beads into the expander and expand more beads in the same area seems more logical. Thanks for the info.

Viking House

kadman wrote: »

Water can't get into the polystyrene wall panel, as its test results show its water absorption rate is virtually zero. So if it can't enter the wall panel between the 2 coats of 35 mm structural results, it can't get trapped there.

Ok I'll double check this one again tomorrow to see if I have it right.
I'll call Eric Thalberg the Swede who has been at the forefront of most of the Polysterene advancements over the last 40 years and is on the European Polysterene comittee.
If its absorption rate of water is as you say "Virtually Zero" then it should be able to absorb water vapour to a greater degree. What happens when the Dew Point is in the middle of the EPS layer and the water vapour condenses? I believe the guy who said the EPS was wet in the concrete wall because he had no reason to lie. I said it to the Swedish and they thought it was normal that it should happen because the Polysterene should be to the outside.

On the other hand I have a piece of EPS 100 here in the office and I can't blow into it. I may hold a piece on a pot of boiling water to see if the steam comes through it.

Mellor

Viking House wrote: »

Ok I'll double check this one again tomorrow to see if I have it right.
I'll call Eric Thalberg the Swede who has been at the forefront of most of the Polysterene advancements over the last 40 years and is on the European Polysterene comittee.
If its absorption rate of water is as you say "Virtually Zero" then it should be able to absorb water vapour to a greater degree. What happens when the Dew Point is in the middle of the EPS layer and the water vapour condenses? I believe the guy who said the EPS was wet in the concrete wall because he had no reason to lie. I said it to the Swedish and they thought it was normal that it should happen because the Polysterene should be to the outside.

On the other hand I have a piece of EPS 100 here in the office and I can't blow into it. I may hold a piece on a pot of boiling water to see if the steam comes through it.

I imagine it would melt.

Water absorption should be virtually zero. Vapour permability will also very low.
The point about the Dew point is a good one VH, for the record the further the insulation is to the external side the more likely the dew point is of occuring there.
Its worth pointing out that the dew point occurs sooner the higher the humidity is (at the dewpoint). So if the insulation acts as a vapour check and controlls the passing of vapour, which is possible, the air entering the insulation will have a reduced RH and therefore the dewpoint would be further, it some board types its quite possible that the dew point could never occur in the insulation.

kadman

From the current technical documents I have at hand at the moment , the following figures are quoted in relation to water absorption , and water moisture.

Water absorption due to capilliarity , nil.
Absorption of moist air using a 20kg density panel in contact with air with relative humidity measuring 95% for 90 days , shows absorption of 0.7% in weight.

Impermeability tests in storms.

Panels have been classed as class E , after having been exposed to 140mm/h
rain with wind at 106km/h for 24 hrs.

I will try to locate the specific test criteria in more detail for the storm test if I can.

The technical manuals explain the manufactured panels more comprehensively, but are too large to scan and post. But I can by mail on request


kadman

kadman

Viking House

kadman wrote: »

From the current technical documents I have at hand at the moment , the following figures are quoted in relation to water absorption , and water moisture.

Water absorption due to capilliarity , nil.
Absorption of moist air using a 20kg density panel in contact with air with relative humidity measuring 95% for 90 days , shows absorption of 0.7% in weight.
Impermeability tests in storms.
Panels have been classed as class E , after having been exposed to 140mm/h
rain with wind at 106km/h for 24 hrs.

Hi Kadman

Those figures are for plastered panels. We are more concerned about are the moist air absorption figures of Polysterene of different densities.

The panels that were exposed to 140mm/hr rain are cement plastered panels with EPS inside which you would expect to have a very high resistance to rain.
For non breathable structures it is important to know what happens inside the wall, or not?

kadman

Viking House wrote: »

Hi Kadman

Those figures are for plastered panels. We are more concerned about are the moist air absorption figures of Polysterene of different densities.

The panels that were exposed to 140mm/hr rain are cement plastered panels with EPS inside which you would expect to have a very high resistance to rain.
For non breathable structures it is important to know what happens inside the wall, or not?

Hi VH,

As far as I am aware the figures quoted are for polystyrene panels , not plastered panels. I do know for definite that our water absorption tests, for full immersion and partial immersion, are definitely polystyrene only. As well as all our tests for thermal conductivity, panel densities ect.


I,ll check for other results and tests which will clarify things further.

kadman

sinnerboy

ardara1 wrote: »

Thermal bridging at junctions becomes more of a problem in better insulated/sealed/performance building fabrics. The better the performance the more vunerable the junction. Our Part L recognizes the fact but doesn't quite tell you how to avoid problems.
We're supposed to build to basic guideline laid down in a Homebond Document 18 - 'Right on site' - we're then referred to Robust Detail for Construction printed in the UK - a document by DEFRA.

Bottom line is all junctions are measured as to their thermal performance AND the threat of condensation and moisture build up (Mould develops before moisture) by a single methodology - IP1/06.

If a junction is suspected to be prone to moisture/mould - bloody measure it - if there's a risk - fix it.

the amount of scare mongering that goes on from certain posters would scare you - lets get a realistic handle on things, most methods of measurement for moisture transfer/heat transfer or what ever has an agreed CEN methodology.

Draft Part L 2007

http://www.environ.ie/en/DevelopmentandHousing/BuildingStandards/PublicConsultations/

refers to the UK Accredited details

http://www.planningportal.gov.uk/england/professionals/en/1115314255826.html

Theres is a usefull overview document together with sets of Standard Details
which inclcude "tick" boxes for the contractor to issue to the LA to show compliance ( though here I beleve he will return to certifying architect )

All views welcome !

ardara1

They're they documents - some much b-**** about DEAP experts knowing what the answer is - the answer is in the regulations - read them

VH - if you don't agree with them - give us a reasonable argument (or evidence) against their principals - not a 'theory'

metalscrubber

Excuse the simplistic nature of this question but just how big an issue is coldbridging in measurable terms ?

So I build the imposible house where each element, walls, windows, floor slab, roof, doors etc each have a Uvalue of 0.2

Using standard building techniques I end up with less than ideal, but not crummy thermal joints between these elements.

What does it do to th total Uvalue of the house ?

Or is this a how long is a piece of string ?

Metal

I can't give you an honest answer except to say reduce as many thermal bridges as you can (within budget and practical limitations).

Today for example, despite doing all I could to build a "low energy" house.

She leaves the door open!!!!

Live in the real world You can build the "zero energy house" and the simplest thing will screw it up!