Hi all, I'm currently evaluating ICF as a construction method for my new house.

I recently read about the concerns of using PVC sheathed electrical wiring embedded in the polystyrene because of plasticizer migration which melts the polystyrene and causes the wire sheath to become brittle over time. (The accepted solutions seem to be conduit or LSZH wire sheathing)

I'm wondering if there are any concerns with hard PVC used for stormwater piping and even those electrical conduits mentioned above? I assume hard PVC piping don't contain those plasticizers which make the electrical cables pliable, so they are not as much of a concern?

What about the polyethylene tubing that are popularly used for plumbing applications nowadays? I can't seem to find any information about the reactivity between polyethylene and polystyrene. Might it be best to stick with copper piping? Obviously these are concerns best addressed when building the house, it will be a nightmare to have to replace all the piping in 10 years' time...

Looking forward to hearing from knowledgeable people out there.

This is the first time I ever heard of such a thing. Where did you read about this? Any links to studies?

http://www.generalcable.co.nz/getattachment/0ebda90b-b4f8-43ae-b622-c9280295116b/PVC-Cables-in-Contact-with-Polystyrene-or-Bitumen.aspx

http://www.branz.co.nz/cms_show_download.php?id=fb29a2046d5239aa476f66d111dff072bb3f2153

The specs for PVC sheathed cable also specifically state not to use it in contact with polystyrene. LSZH (Low smoke zero halogen) sheathing is recommended.

Posted By acediac on 24 May 2013 03:32 AM
http://www.generalcable.co.nz/getattachment/0ebda90b-b4f8-43ae-b622-c9280295116b/PVC-Cables-in-Contact-with-Polystyrene-or-Bitumen.aspx

http://www.branz.co.nz/cms_show_download.php?id=fb29a2046d5239aa476f66d111dff072bb3f2153

The specs for PVC sheathed cable also specifically state not to use it in contact with polystyrene. LSZH (Low smoke zero halogen) sheathing is recommended.

Thanks. Interesting and very informative. It was/is pretty much standard practice to put Romex into the EPS and foam it over.

I was never a fan of not putting electrical lines into conduit. With this new information I now would put the electrical line into conduit. I would use a steel or plastic conduit. I am pretty sure that the hard PVC does not have plasticizers in it.

I do not believe that hard PVC such as sewer and plumbing lines would cause problems with the EPS in ICF.

For wiring, you can use a nylon jacketed romex type house wiring that prevents contact between the exterior PVC jacket and the polystyrene. Your better quality wire has this. An example that is readily available is Southwire Romex SIMpull. This thin outer nylon jacket is "slick" which makes pulling the wire easier.

Note that most if not all romex type home wiring has a thin nylon jacket over the individual conductor insulation to prevent this plasticizer migration from the critical component of the wire insulation assembly. The outer jacket is primarily there for protection of the conductors during installation. Once installed, it can completely go away and the conductors are still insulated from each other and from ground.

I just found a discussion on this a few years ago:
http://www.greenbuildingtalk.com/Forums/tabid/53/aff/4/aft/77405/afv/topic/Default.aspx




But what I really want to know is if anyone knows anything about problems between Polyethylene and polystyrene?
If I were to use PEX tubing for potable water plumbing or gas piping (eg. http://www.cashacme.com/prod_sharkbite_pex.php) might that need shielding if installed in polystyrene too? I assume there are plasticizers in the polyethylene to make it flexible too...

I assume there are plasticizers in the polyethylene to make it flexible too...

I don't think so. Plasticizers are primarily for brittle PVC.