# Forum Home Renovation Structural Renovation  EPS foam cladding

## sundancewfs

Many of you may have been following the ICF thread.... this is a side to that. We are renovating and will be building an ICF extension, on to our existing, no sarking ,un-insulated walls, brick veneer house. We will render the brick to the same finish as the ICF. Then I got to thinking.... Why don't I clad the BV with 100mm m-grade (same grade used by Masterwall) EPS foam sheets? By my reckoning I would have minimal, if any prep to the brickwork it would give a much smoother surface to work with, the increase in insulation value would be excellent and I'd get nice deep reveals on the windows. It would be effectively the same surface to render as the ICF so the same product and technique could be used on the entire structure. price wise the foam comes out at around $35.00 a sheet (1.2m x 2.4m) for 50 or more sheets. Can anyone see any flaws with this idea?Has anyone used EPS foam sheeting before and rendered it? (Expanded PolyStyrene)

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## myla

hi, 
this is the "traditional" usage of EPS in Europe where EPS is glued to solid masonry, and subsequently rendered 
they mostly use large like 600mm x 800mm EPS "blocks" and bond like brick 
it does everything you mention, it will create a few issues with downpipes, eaves, plumbing etc etc 
use the flexy bag renders throughout the entire process (ie. $30-$40 bags) 
thanks

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## sundancewfs

interesting myla. Thanks for that. We won't have problems with eaves or downpipes. Our eaves are 1966 fibreboard (asbestos) and will be pulled down and replaced, along with all the fascia boards, gutters and the roof for that matter... The down pipes are non-exsitent as the property was an old ex-rental and has had no maintainence for years, plumbing is all contained under the house and what isn't has to be relocated as it is in the way of the extension.

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## zacnelson

It certainly sounds like it would work.  However, I just don't see the point of all the extra time, work, and expense.  Since you are going to be rendering it all anyway, what difference does it make whether you stick the foam to the bricks first?  Are you planning on doing the rendering yourself?  Obviously you'll have a flatter surface to render over using the foam, but if you're paying a renderer it wouldn't bother them whether they were rendering over brick or foam.  And if you choose to learn to render yourself, then I would suggest that the learning curve will be so steep that the slight extra difficulty of rendering over bricks will be minor in the scheme of things.  (I taught myself how to render and my first project was over recycled bricks with raked joints and I survived!!) 
My other concern with the foam, is how do you intend to handle the junction between the earth and the foam?  With the brick veneer walls the bricks begin below ground level (assuming you are on footings and stumps), but do you intend for the bottom edge of the foam to just sit on the dirt?  I imagine over time this will get damaged, and also it may possibly expose you to rising damp?   
Anyway, for my own education I would be interested to know how you plan to handle the wall/ground junction, because I think foam cladding is a very exciting product and I'd like to know how people deal with it.  Mostly foam cladding seems to be used only on the top stories of double storey houses, with brick on the ground floor. 
Cheers, 
Zac

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## autogenous

All these acronyms 
ICF =  
EPS = 
How much is the stuff to buy?

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## sundancewfs

EPS= Expanded polystyrene foam
ICF= Insulated concrete form (made from EPS (see above))
The reasons why and price are in the initial post.
As far as the ground/foam junction this has given me some thinking to do... I dont have too big a problem there... nearly 3 sides of the house are concrete right up to the walls so the faom will not be sitting on the ground. On the side where the ground is against the wall I intend to remove soil that has, over the years, been heaped against the walls as garden soil to expose the lower courses of bricks and allow me to grade the ground away from the footings. this will provide better drainage and stop water building up under the house. At one point of the wall, I had to remove 400mm of garden bed soil from against the wall. I think then I will sit the base of the EPS panel on some sort of damp course or maybe the foam stripping used as expansion joints in concrete. I intend to do the base render coat with the mesh imbedded in it before installing the panels. They will be rendered horizontally on saw horses and the bottom and top edges with have the mesh and base coat extended around the edges (much the same as lapping a rail when you glass a surfboard, and with suprisingly similar materials.....) Please don't ask me to explain how to lap a rail.....
As for rising damp, EPS is closed cell and there is no capillary action with it. so no rising damp.

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## GraemeCook

> It certainly sounds like it would work.  However, I just don't see the point of all the extra time, work, and expense.  Since you are going to be rendering it all anyway, what difference does it make whether you stick the foam to the bricks first?  .... 
> Cheers, 
> Zac

  This amount of foam around the house would be good insulation, Zac.   Most houses lose 20-25% of the heat through the walls and this insulation might halve that loss, thus reducing the heating/cooling bills by about 10%, and also making the house feel much more snug. 
Good point about the earth/foam boundary.   I think I would be concerned about the accidental damage risk - nudged by a car, attacked by an overenthusiastic gardening tool, rubbed by an errant tree branch - with bagged foam too low down.   Maybe Sundance has considered this further? 
Cheers 
Graeme

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## autogenous

> Most houses lose 20-25% of the heat through the walls

  I thought the majority of loss would have been through the glass? 
Depending on where you live, bricks should retain some of the daytime heat from the sun? 
I would put much greater emphasis on ceiling insulation and glass 
In the UK the sun barely comes up and skims through the trees in the winter which gives little time for solar heating. Hence the bitter ice and snow. 
In the UK there is 100mm of EPS under the slab. 
The reason I reference the UK is because their regulations are more demanding.

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## myla

hi, 
seriously look at rendering the boards on the wall,  
full mesh system, you will get ups and downs at the joints and this way it allows you to "even" them out in situ with render 
you will need to mesh junction b/w styrene and brick on window reveals 
i would: 
apply render to polystyrene (it takes a while to dry as styrene has no suction) 
press mesh into wet render (bed in, applying a little render if needed) 
do another render coat and float 
then texture coat or paint if happy with previous coat finish 
thanks

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## sundancewfs

> I thought the majority of loss would have been through the glass? 
> Depending on where you live, bricks should retain some of the daytime heat from the sun? 
> I would put much greater emphasis on ceiling insulation and glass

  The windows have already been done. They are all now double-glazed UPVC framed (no thermal bridge) Weathershield Visions 3000 windows from Wisconsin USA. If you have ever been to Wisconsin in the winter you would know it gets a bit chilly there....
The current ceiling insulation is R5 Insulco batts. This will be upgraded when the roof is replaced, with another layer of R3.5 batts laid perpendicular to the R5's and Aircell Insulbreak sarking/insulation under the new roof.This will give a total of ~R10 for the roof.
The bricks do heat up duing the day...... Unfortunately not so much in winter... In the summer though on the days when it was above 40deg the inside wall that was in the sun was radiating with a surface temp of 36deg! When you have a 8mx4m radiator set to 36deg (effectivly what the whole wall was), I dont care what sort of airconditioner you have, it is going to have to deal with all that radiant heat, before it can think of cooling the ambient, inside air temperature down.
The foam will provide excellent insulation value but in the wall senario, more importantly a thermal break. 
As to its robustity..... In its self the foam is quite fragile. but with a full acrylic render system in place, not just a bagged finish, it will be coated in a 10mm thick rock-hard shell. Very tough indeed.
There will be no garden beds against the walls of the house, as there won't be any place to put them against the house once the renos are complete. This will also aid with termite inspections.

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## woodbe

This is an excellent idea. It is a common energy efficiency renovation upgrade in europe, and has the added benefit of placing the thermal mass of the brick walls within the structure.  
I would be checking out the fire rating of the panels (are you in a bushfire area) and wondering if a gap would be required between the brickwork and the panels. This relates to moisture, specifically how good is the existing dampcourse? 
You can get sealed panels such as those used in coolrooms 'Bondor' which may or may not be easier to fit, finish and render. More expensive, of course. 
Good on you for fitting decent glazing, it makes a big difference. 
woodbe.

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## myla

hi, 
sundance, 10mm render is extremely thick on the polystyrene unless you using coco-pop render or one of the Unitex systems, 
most coating over styrene is around 3-5mm total (including texture) 
"acrylic" is very difficult when put on even in 3mm passes because it will take ages to dry   
thanks

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## sundancewfs

> 10mm render is extremely thick on the polystyrene  
>  thanks

  I was probably being a bit over zealous with the 10mm thick  :Smilie: 
As you say myla, the EPS render is quite thin, but very tough. 
We don't have any bushfire overlays here, so i think that we should be ok there. I will be asking the building surveyor before I go and do it though.....

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## Gaza

i like your idea's our local builing indusrty is 20yrs behind EU & US with insulation and glazing. 
we just did a job an the spec was for R1.5 in the walls, in the USA they have R10 as min code.

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## sundancewfs

> we just did a job an the spec was for R1.5 in the walls, in the USA they have R10 as min code.

  
Bear in mind that we use SI units for our R-values and the USA uses its own unit of measurement. To convert from USA to Australian multiply the USA by .176. This gives R1.76 by our units from their R10. Also because their climate differs so much by region, their standards differ from place to place. But I agree they are way ahead as far as insulation. By my experience to achieve a 5 star rating for a building in Australia is a matter of juggling figures in one of the ratings software programs until you acheive the desired rating with the least outlay, ie if you shade the windows externally you get so many points, if you have more ceiling insulation, you get so many points but if you have larger windows, or the living areas are in the wrong part of the house you loose points. So you can make up points by adding more insulation in the roof as an offset for single glazed windows, etc etc etc... In the colder parts of the USA ( I lived in Chicago for 5 years) its not a trade off..... when its -25deg outside, if you have been playing silly-buggers with a computer to come up with what is necessary, you will freeze your but off! Insulating your house has to be a complete system and it has to work in the real world.

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## Gaza

> Bear in mind that we use SI units for our R-values and the USA uses its own unit of measurement. To convert from USA to Australian multiply the USA by .176. This gives R1.76 by our units from their R10. Also because their climate differs so much by region, their standards differ from place to place. But I agree they are way ahead as far as insulation. By my experience to achieve a 5 star rating for a building in Australia is a matter of juggling figures in one of the ratings software programs until you acheive the desired rating with the least outlay, ie if you shade the windows externally you get so many points, if you have more ceiling insulation, you get so many points but if you have larger windows, or the living areas are in the wrong part of the house you loose points. So you can make up points by adding more insulation in the roof as an offset for single glazed windows, etc etc etc... In the colder parts of the USA ( I lived in Chicago for 5 years) its not a trade off..... when its -25deg outside, if you have been playing silly-buggers with a computer to come up with what is necessary, you will freeze your but off! Insulating your house has to be a complete system and it has to work in the real world.

  the other thing which makes a lot of sense is the use of plywood on the outside of buildings before cladding and the use of an external sarking or tar paper and then a plastic vapour barrier on the inside,  in a couple of commerical projects we are doing have silmar details.  no one has a clue how to do the detailing right

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