insulated concrete form

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casualty

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I have a builder that is using the concrete insulated form for wall construction. He says that once the concrete is poured cured, his electrician cuts a groove in the 2 inches of insulation and installs the nonmetalic sheath cable into the groove. The electrician, then, uses spray foam and closes the groove that was cut in the insulation. The wiring is held in place by foam insulation, no anchoring is needed. The wiring is, possibly against the concrete wall. He said that when they refoam around the wiring that it will be encapsulated. Not sure that I like this. No support or protection.
 
I believe it is supported by the spray foam. And if it is located 2" back from the face of the ICF it should also be protected from physical damage. My concern would be the long-term effect of the spray foam on the cable insulation. I assume manufacturers of the various materials have run tests (as it is commonly used in standard stud walls), has anyone seen any test reports?
 
That same expanding spray foam insulation is used in most every hole with NM cable in a top plate and bottom plate of a wall to draftstop the wall.

They use spray foam insulation for walls and attics now where the entire cavity is filled with the foam and it encapsulates the NM cable in the cavities.

As far as support I have seen a couple of ICF wall installations and the NM cable when foamed in place is very well supported, and if installed 2" from the surface of the foam it will be protected just as well as if it was routed through holes drilled in nominal 2x4 studs.

Chris
 
raider1 said:
As far as support I have seen a couple of ICF wall installations and the NM cable when foamed in place is very well supported, and if installed 2" from the surface of the foam it will be protected just as well as if it was routed through holes drilled in nominal 2x4 studs.

Chris
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Is it required to be 2" from the surface of the foam or is this just a good idea? The 1.25" setback requirement is from a framing member so I don't see that applying here.
 
They cut the ICF foam to the concrete wall. There is no stud in the Insulated Concrete Form to secure the wiring to. There is a hard plastic form that when installing the interior walls that they attach them to. My concern was that the non metallic sheathing would be coming in contact with the concrete itself.
 
infinity said:
Is it required to be 2" from the surface of the foam or is this just a good idea? The 1.25" setback requirement is from a framing member so I don't see that applying here.
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Not required to be 2", but the foam is 2" thick and if you use a hot knife to cut out a groove in the ICF form it most likely will cut out all of the foam and leave you 2" from the surface.

Chris
 
casualty said:
They cut the ICF foam to the concrete wall. There is no stud in the Insulated Concrete Form to secure the wiring to. There is a hard plastic form that when installing the interior walls that they attach them to. My concern was that the non metallic sheathing would be coming in contact with the concrete itself.
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I don't see any problem with the the sheath of NM cable comming into contact with the concrete in the ICF wall.

Chris
 
The thing that I don't understand is the industry is so concerned with overheating when you run 5 14-2 nm cables thru a let's say 1-1/4" drilled hole in a series of joist. Many inspectors would say thats bundling and require de-rating. There are some localities that say no more than one or two cables allowed in a drilled hole. But it seems to be ok to enclose the cables completely in plastic foam and no de rating required.
 
casualty said:
They cut the ICF foam to the concrete wall. There is no stud in the Insulated Concrete Form to secure the wiring to. There is a hard plastic form that when installing the interior walls that they attach them to. My concern was that the non metallic sheathing would be coming in contact with the concrete itself.
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Welcome to the 21st century. This is a very common way of wireing in a ICF wall. I started doing them in the early 90's. My knife was an electric charcol lighter. Cutting the foam all the way down to the concrete is not nessessary but would not make any differance. Rx tuches the concrete block all the time does it not??? RX can touch the concrete just can't be poured into it.
 
macmikeman said:
The thing that I don't understand is the industry is so concerned with overheating when you run 5 14-2 nm cables thru a let's say 1-1/4" drilled hole in a series of joist. Many inspectors would say thats bundling and require de-rating. There are some localities that say no more than one or two cables allowed in a drilled hole. But it seems to be ok to enclose the cables completely in plastic foam and no de rating required.
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I never full the complete cut. I treat it just as you would with wood and staples. Just a spot here and there to hold it in place untill the drywall goes on.
 
Cavie said:
I never full the complete cut. I treat it just as you would with wood and staples. Just a spot here and there to hold it in place untill the drywall goes on.
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That is typically what I see as well, just spots every so often to hold the NM cable in the wall.

Chris
 
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I use a chainsaw with a gauge block clamped to the bar. Obviously I don't go all the way to the concrete. The wire is snug enough in the groove that I have never used any spray foam or anything else. Never had an inspector question it. The ICF insulation I have witnessed are more than 2" think, maybe 2 1/4".

I use an old chain on the saw. I cut through the sill plate and right down to the outlet/switch or horizontally from outlet to outlet.
 
Steviechia2 said:
I think the inspector would have a problem if it were completely filled in for the rough inspection.
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I agree, I did 3 houses like this last year. The NM has to be strapped as normal, for rough in inspection. The foam cannot be applied until afteward. I usually trough out the polystyrene and shoot the NM to the concrete with Remington. After rough in, foam the entire groove
 
I've been working bit by bit on a mansion sized house made entirely of "autoclaved airated concrete blocks and prestress slabs. Same idea, wire channels are routed with a "wait for it..... wait.... router" Softest concrete you ever saw. Anyway, I stapled the nm into the bottom of 2" slots to secure the 4-1/2 foot between supports, and then they just glue another course of block over that with thin set. Really different way to build a house. Germans. I went T+M. On Superbowl Sunday it will be 4 years now.
 
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