EPS (expanded polystyrene) building cladding. Any advice welcome.
July 22, 2013 6:48 AM   Subscribe

Orange Board is a "fully compliant insulated cladding system". Basically, it's sheets of a foam-like plastic material that gets covered with mesh and stucco / render to serve as the external skin of buildings. I'd like to know how this or similar cladding systems compare to traditional building materials, particularly single-brick (brick veneer) and concrete. How does the longevity compare? Energy efficiency? How easy is it to restore the surface, and how often would it be necessary? I'd be happy for any information people can provide.
posted by Joe in Australia to Home & Garden (8 answers total) 1 user marked this as a favorite
I will be very interested to see what answers you get, because I myself am faced with taking down the concrete face of a 1931 home and replacing it with stucco.
posted by zagyzebra at 6:53 AM on July 22, 2013

It's an EIFS product, if that helps with your research. There are several manufacturers of EIFS systems here in North America. Dryvit is one that come to mind, if you would like to make a product comparison. These types of systems have different installation methods and I understand that the face-sealed systems are prone to water penetration problems. Check out this article at buildingscience.com for details.

It is a foam board under an acrylic-based coating and can suffer impact damage at ground level from car bumpers, rocks from lawnmowers, etc. But this can be easily repaired with patch kits. The energy efficiency depends on the thickness of the board and associated thermal resistance (R-value or maybe RSI in Australia?) A two inch thick board (about R8) will provide significantly better thermal resistance compared to traditional claddings like brick, concrete, or clapboards because they provide essentially a negligible thermal resistance.
posted by fundip at 7:35 AM on July 22, 2013

Also! The EIFS is not meant to replace interior wall insulation, but rather give the wall assembly an extra R-value boost. We often see it here used in exterior retrofits, especially when the existing cladding is in poor condition.
posted by fundip at 7:42 AM on July 22, 2013

Pursuant to fundips remark above, will this be the primary membrane, or is it going on top of an existing weathertight surface?
posted by aramaic at 9:20 AM on July 22, 2013

It also moves the condensation point usually outside of the building envelope, into the cladding itself. This keeps moisture out of the wall insulation and really cuts down on mold and mildew in the house.

On all buildings that are heated or cooled to a significantly different internal temperature from the outside ambient temperature the 'dew point' or temperature at which moisture will condense out of the air is usually between these two temperatures.
In a conventional wall insulation the physical point where this condensation is located is usually at the outside of the insulation, just under whatever material the house is sheathed in. This is why there is a 'vapor' barrier at this location in most houses to keep the dew point on the outside and prevent moisture from condensing inside the walls where it will feed mold and rot. However it causes condensation on the inside of the siding where it can lead to problems as well.
In older homes there is no barrier or the wall cladding isn't as tight and air can circulate and this will keep things manageable and the moisture from building up (except in wet climates like the Pacific northwest in the winter which have required special 'rain walls' construction techniques).
With new much tighter houses and much better insulation techniques this dew point and vapor barrier can now cause persistent moisture issues that never dry and REALLY feed mold and rot. With external eps wall cladding this condensation point is usually internal to the eps and no real moisture can build up there because there is NO air circulation (or very minimal) and even if it doesn, the eps isn't harmed by it and no rot or mildew can occur. So, like the old Mcdonalds packiging, It keeps the hot side hot and the cool side cool and performs as a much better vapor barrier than 6 mil plastic sheeting. (This is also why the tape you use to seal the eps joints is so important and must be applied correctly to keep it airtight).
posted by bartonlong at 9:56 AM on July 22, 2013 [1 favorite]

Response by poster: Pursuant to fundips remark above, will this be the primary membrane, or is it going on top of an existing weathertight surface?

It's being promoted as a replacement for, e.g., brick walls. So you put up a timber or light steel frame, put an exterior waterproof membrane on the frame, attach these panels to it (through the membrane), then render or stucco the outside of the panels. Inside the frame you would attach drywall or plywood or whatever.
posted by Joe in Australia at 5:56 PM on July 22, 2013

Response by poster: Those are great links. What I'm getting from my reading is that modern construction techniques are dramatically better at insulation, water resistance, avoiding condensation and so forth, but only if they're done properly. For example, putting insulation behind wall cladding can cause more harm then good, because it can change the point at which condensation occurs. So it's really important to have your design and construction done by someone who knows what they're doing.

The other thing is, Table 5 at this link says that EIFS panels (which "Orange Board" counts as, I think?) have an expected lifespan of 25 years, versus 100+ years for brick. This makes them seem like a bad idea despite the thermal efficiency, unless the cost differences are huge. Am I right on this?
posted by Joe in Australia at 10:20 PM on July 22, 2013

have an expected lifespan of 25 years,

This is mostly due to new materials with an unknown service life, where brick is well...as old as civilization. The warranty on most of it is 25 years, or whatever the expected lifespan is but it may or may not be the actual service life of the material at all. My guess would be the quality of the installation is key (true with just about anything-improperly built brick walls fail rapidly as well) with the big weak point being the tape joints. I know some systems use an adhesive as well as tape and that this would last considerably longer. And the big fail point would be a loss in R value, not the house falling apart.

For a great overview of a new material with bad service life read up on orangeburg pipe, which was replaced with PVC pipe and we are all better off for it (and PVC usually has a short life span and a 'service' life of 25-50 years, but I suspect this stuff to last better than concrete and ductile iron pipe (at least for sanitary sewer service), some which i work with has been in the ground and in good shape for 75-100 years (long enough we aren't really sure how old it is).

EFS panels can be combined with any facade btw, brick, stucco, wood lap, T1-11, whatever. This stuff is essentially styrofoam which lasts pretty much forever as long as it is protected from sunlight or mechanical damage.
posted by bartonlong at 9:06 AM on July 23, 2013

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