Cold Bridging and Insulation : the issues and solutions

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!

metalscrubber

But you do make sense - I dont want to build a zero energy house but rather an economic as low energy as practical house.

Metal

ardara1

metalscrubber wrote: »

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

Hi MS -

If you go for the standard you're looking for and take a typical 3 bed semi, the HEATLOSS from the NON REPEATING thermal bridges at junctions will TYPICALLY be around 30 W/K for craappy detailing (min standards allowed under Part L) 16 W/K for better than those asked for in Part L - and approx 6 W/K for the standards being worked on for currently (Big change in details - but nothing over the top - basicallt lining of all junctions - no floor protrusion into inner skin of build)

In a well insulated house - such as that you're suggesting - can lose 1/3 of its faric heatloss thru bad detailing. This in its self is reason enough to improve things - but because we're building tighter - and the U-values are getting better the junctions are becomming more prone to moisture & mould. I've seen it happen even from the last revision in 2006 (Harwood floors going black at edges)

The draft Part L asks for big improvements - with an INSPECTION REGIME on site - but won't point you at any specific details - still working in them I suppose!

Your thermal bridging can be AND should be measured to make sure they can cope with the improvements else where in your design.

sinnerboy

"The draft Part L asks for big improvements - with an INSPECTION REGIME on site - but won't point you at any specific details - still working in them I suppose!"

Look here

http://www.planningportal.gov.uk/eng...314255826.html

Mellor

Cold bridges will have an effect of energy, and it brought up alot, especially in reference to new products.

Nobody mentions that building a one-off/detached house is loses alot of energy. I am talking about building form not construction energy or embodied energy btw

ardara1

sinnerboy wrote: »

"The draft Part L asks for big improvements - with an INSPECTION REGIME on site - but won't point you at any specific details - still working in them I suppose!"

Look here

http://www.planningportal.gov.uk/eng...314255826.html

The accreditted details you point to refer to the 2006 reveison of Part L Eng & Walers - they're being updated - we shoud have been following them from 2006! - now we've jumped further - the details need changed again!

Viking House

kadman wrote: »

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

Hi Kadman/Mellor

An update here on Polysterene.

The EPS we used on our roof shelter did not have the Polysterene air pockets bonded well enough together and let the rain through, normally this would not happen so I stand corrected!

Aerobord said one other interesting thing in that they have moved away from the market that is looking to use EPS on a flat roof as an inverted roof on top of a layer of Bitumen. There was water getting in between the sheets of EPS onto the bitumen roof. The heat from the bitumen evaporated the water and caused the EPS to get damp. The evaporating water-vapour got into the air pockets reducing the U-value of the EPS.

Mellor

I could well imagine that happening to sub standard EPS (water getting through where not 100% bonded). As for bitumen and EPS in conjunction, I have never been fond of using the two together, heat and EPS don't go well together. Its is more of an issue in warm roofs as at least an inverted can be let to cool (although it may not always happen, as in the case above). When I have been in a situation where I was detailing with EPS or similar and a hot applied finishing layer I insisted on a sheet of WBP ply inbetween to act as a heat sink.

ircoha

Some serious knowledge being imparted in this thread since I was here last:)


For completness am posting here a link to http://www.boards.ie/vbulletin/showthread.php?t=2055166109
as it will benefit others since it contains some of the same material

sydthebeat

Ben, come back to us when you have your BBA cert...

sinnerboy

As syd says - BBA cert please . On the face of it - good innovation

Do you have plans to develop stone wall cladding anchors and brackets ?