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#21773 - 02/10/03 10:23 AM Foam Block houses
cubby964 Offline

Registered: 10/18/02
Posts: 69
Loc: USA
Was just wondering if any of you guys have wired houses made with these fabricated blocks of styrofoam that are stacked up and filled with concrete. I have been asked to wire one for a client and have not done one like it before.
The walls are all up so no chance of getting anything in the concrete, but, the foam is a couple inches thick. Floors are TJs, with exposed timber framing for the upper ceiling, with plenty of access from below. Will be using metal boxes and romex where I can.
Questions are: whether any AHJs ask for additional protection for the romex between the "studs" in the foam, and if any body has any tips.

Thanks in advance,

Work Gear for Electricians and the Trades

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#21774 - 02/10/03 10:33 AM Re: Foam Block houses
Joe Tedesco Offline

Registered: 10/07/00
Posts: 3325
Loc: Boston, Massachusetts USA
See the 2002 NEC, Section 300.4(E) Cables and Raceways Installed in Shallow Grooves.

Added to the code to cover protection for foamed in place insulation ....
Joe Tedesco, NEC Consultant

#21775 - 02/10/03 12:03 PM Re: Foam Block houses
ElectricAL Offline

Registered: 10/10/01
Posts: 615
Loc: Minneapolis, MN USA
One manufacturer of this type of construction is the RASTRA prefab method . Their site includes this detail of electrical installation.
Note that the face of this manufacturer's prefab panel can be notched deeply enough to get the 1┬╝" clear space for NM.
Al Hildenbrand

#21776 - 02/10/03 12:12 PM Re: Foam Block houses
sparky66wv Offline

Registered: 11/17/00
Posts: 2334
Loc: West Virginia
Hoo boy, just last week installed a Service to one of these. Finding enough "meat" and long enough Tap-cons proved to be a major challenge in hanging the meterbase and panel, etc.

Some places 3-3/4" tapcons weren't long enough!!!


Finally after seeing a cut cross-section of what I was working with, did I understand better of how to fasten things to the stuff!

Haven't got to the rough-in yet, but 1-1/2" 4x4s with 1/2" plaster rings is how I'm going to tackle it...

And a hot knife.

Hebel Block is another trendy building material around here for the birkenstock wearers... Aerated Concrete... Interesting stuff.

#21777 - 02/10/03 12:15 PM Re: Foam Block houses
cubby964 Offline

Registered: 10/18/02
Posts: 69
Loc: USA
Thanks guys.
I am aware of the requirements, I have a video explaining the procedures, and I have talked to the AHJ for the area and he agrees with you(us).
I was more interested in any tricks of the trade, so to speak. Like if there are any supports unique to this type of installation, routing secrets, etc.
Most of my training is industrial and large commercial, the last three years on my own has gotten me into more residential than I can stand. Again, Thanks

#21778 - 02/11/03 08:52 AM Re: Foam Block houses
Texas_Ranger Offline

Registered: 12/17/01
Posts: 2332
Loc: Vienna, Austria
Yep, these concrete blocks are quite common here. The stuff is called "Ytong" here. Much easier to put up than bricks (the blocks are much bigger and lighter than bricks, plus they're absolutely square, requiring only few mortar and a thin layer of spackling compound instead of plaster. They're building entire houses with these blocks, I just used it to put up a new interior wall. Much tougher than sheetrock, try kicking a hole into a 2 or 3" solid block wall. Though some people say these walls tend to set and crack after some time.


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