Mentioned it in the past , heard of it not used it , presumed it was graphite eps with vapour open finish , not sure what the board have special about them ? I've some product marketing info , but its not very detailed.
http://www.baumit.co.uk/upload/Bilder/2790_Baumit_EWI_Brochure.pdf

VH , what made you change your views, anything in particular or just general lack of science on subject

What a turn-around for all of us!

At root, it's because the enormous quantities of water that's in any building structure, hopefully harmless in vapour form, originates at least as much from outside, not so much from inside as everyone's been thinking - in fact overwhelmingly from outside. It enters mainly by penetration, both acceptable and uncontrolled, and leaves by drying, both outward and inward - a seasonal ebb and flow, mainly by diffusion.

If you add to that background, quantities of bulk air movement due to non-airtightness, that's a continuous supply of more water, which so far simulators like WUFI can only roughly estimate, but can overwhelm the predictable diffusion based ebb and flow.

So it's ironic that just when Fraunhofer/WUFI turns our understanding upside down, in the same breath they say that WUFI isn't (so far) designed to accurately handle what turns out to be the main threat - air infiltration/air tightness!

It's a powerful new argument for airtightness. The prev argument, that once you've super insulated, airchange is the biggest remaining heat loss, wasn't so compelling because it was still a pretty small loss, compared with hitherto.

Now the argument is that once you've super insulated, it'll condense and rot unless you also make it airtight.

Plus the one about MHRV isn't effective unless airtight.

I have recently put wood fibre EWI (NBT Diffutherm system) on my Victorian terraced house. The old brick wall was very wet mainly from rain penetration through external cement render defects. It had been water proofed internally some years ago and the damp was beginning to pop out around the edges of the internal waterproofing. I drilled into the wall and installed some i-buttons and the RH I measured was close to 100% ie the wall was saturated.
With the EWI it's been breathing for nearly a year now and seems to be much dryer. I'm about to do some more tests (will post). In this instance the breathability was a very important feature as we would have had to leave the brickwork exposed for quite a while to allow the wall to dry out.
I also think that breathability provides long term security against water ingress through defects that may arise in future.
More info on my house on http://www.piers-sadler.co.uk/news/2013/3/8/update-on-pierss-house.html

Not convinced about the idea of EPS with holes in it. Hygroscopicity is an important feature of natural fibres as it can hold and 'manage' the water.

Piers makes a good point. In homes where it's unrealistic to expect high levels of airtightness , doesn't a vapour open fabric give this moisture a route out ?

Having just EWIed the main house I am just contemplating doing similar to the another house on the farm. This house is a stone / rubble / stone wall 50cm thick, without any sort of DPC. The plan is (was?) to put in a french drain with EPS below ground level, continued up to 50cm above ground level then continue with (v. expensive) vapour open mineral wool.

The walls are of impermeable stone (actually basalt rocks) pointed with a variety of mixes form lime/sand through to cement/sand with most variations between. one side is rendered with sand/lime (putty)/cement at about 6:3:2. (the inside is rendered with similar)

I have wondered about the need for the expensive vapour open mineral wool as it can not be used down to ground level or below GL (hence the plan to use EPS in the french drain and for the first 50cm) so is there much point above that. Whilst the conventional wisdom is that stone walls should have breathable insulation if the rocks are impermeable this only leaves the pointing area to release any vapour so is there any need for an open insulation.

The content of this thread has opened the whole question again in my mind about the need for vapour open insulation on this type of wall. Air tightness is variable as the occupants are currently a family with 3 small boys and doors and windows are continually being opened and closed.

Given this description and the above thread - does the team think that the vapour open insulation is needed or can the much cheaper and more readily available EPS be used.

Who says EPS isn't (fairly) vapour open? And the pointing will let plenty plenty of vapour through. Never mind the lack of DPC - driving rain is the overwhelming source of water entering the wall (transforms to vapour just below the surface) and EWI will stop most of that. Thereafter, plenty of drying potential both inward and outward. Impervious EWI will halve that drying ability. Simple EPS EWI as thick as you like, sounds ideal, bomb proof. If in doubt, get a WUFI check.

The rockwool type EWI insulation here is about 2.5 times the price of EPS.You can get a complete EPS EWI package (adhesive at 5kg/M2, EPS, glass mesh, plastic nails and white finishing render) at a price / sq M that is less than the price of the rockwool type insulation alone!

Posted By: SteamyTeaCare to put some prices on it so we can compare to what we pay?

100mm insulation is the standard retrofit EWI here to the extent that if you want a house's worth of something else its ordered for you, otherwise 100mm is in stock.

100mm EPS is generally 4.32 gbp /m2, but I did find one place down to 3.9 gbp / m2
100mm package deals are about 9 gbp /m2, (5kg adhesive/m2 and white finish)

Rockwool for EWI is listed as 11.2 gbp / m2 and the best sale price I found is 8.65 gbp / m2

I've just done the family house, 100mm EPS, and the 250 m2 came out as materials 9.22 gbp / m2 (8kg adhesive / m2 and colour finish) plus 6.35 gbp / m2 labour

But to add some context the average wage in the UK is 2.6 times that of Hungary and the minimium wage in the UK is about 4 times that of Hungary. Domestic energy prices are higher here than the UK and the FIT is about 1/4 of the UK (which explains the lack of much PV here) (comparison data from tinternet so must be correct!)

Posted By: Viking HouseI've used Rockwool, Wood fiber-board and EPS external insulation on different wall types, if I was back again I would probably stick with EPS on all wall types.

What about cork Seamus, ever used that? If we hadn't had such a tight budget we would have used cork.

Wood should not be in any environment where it is likely to get wet unless it can just as readily dry out. If you think of a scaffold plank. It will take a very long time to rot while it is sat on scaffold. If you place the same plank on muddy ground how long will it take for the underside to rot?

So sealing any wood behind external render is not a smart idea . I would expect the render on top of the wood to expand and contract deferentially to that directly on the EPS. This possibly resulting in surface cracks; water ingress; and subsequent rot.

The risk of dry rot developing increases with increased levels of humidity which can occur following the installation of solid wall insulation. An increase in wet rot can be caused by high levels of moisture or humidity in timbers due to poor detailing.
Insect attack to timber structures is increased if the timbers are not kept dry. In older solid wall dwellings (where timbers are more prevalent) any increase in the relative humidity can lead to an increased risk of insect attack on timbers.

A number of household pests including dust mites, bed bugs and clothes moths are more active and prevalent in increased humidity which can follow the installation of solid wall insulation.

The risk of dry rot developing increases with increased levels of humidity which can occur following the installation of solid wall insulation. An increase in wet rot can be caused by high levels of moisture or humidity in timbers due to poor detailing.
Insect attack to timber structures is increased if the timbers are not kept dry. In older solid wall dwellings (where timbers are more prevalent) any increase in the relative humidity can lead to an increased risk of insect attack on timbers.

A number of household pests including dust mites, bed bugs and clothes moths are more active and prevalent in increased humidity which can follow the installation of solid wall insulation.

Hello DJH, sorry about the copy post not sure why ?? You mention the word "enough" what do you call enough ?

Thanks