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We are at the wiring stage in a new cottage construction. Although finishing the basement is not high on the list of priorities, some wiring will done for lighting etc. What suggestions do you have for running wire in the walls of the basement which are constructed of insulated concrete forms? This will be a do it yourself project, but I’d be willing to invest some money in specialized tool(I)to move the job along more quickly.
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Daniel:
Depending on the brand of ICF form you used, you will have some requirements on the size and type of box you use. Either way, go to Lowes or HD and buy the cheapest electric chainsaw you can. Don't put any oil in the chain oil reservoir. Use the chainsaw to cut chases (may need to avoid the ties depending on which brand you used) let the chain hit the concrete, it will wear the chain down, but not enough to worry about on your basement. You can also cut out the rectangles for the boxes with the chainsaw. Once you have the chases cut, you can friction fit 14/2 or 12/2 wire into the chases. Use a shim to insure the wire is back to the concrete, use some expanding foam or liquid nails to adhere the wire every two feet or so. If your inspector requires mechanical fastening, prior to setting the wire, use the chainsaw to make some wider areas so that you can set wire clamps. If you used an ICF that creates a waffle or post and beam concrete configuration, you will be shocked (no pun intended) at what it will cost to use wide shallow boxes, mud rings and tons of nail protection to wire the walls. If you used a form that creates a solid continuous thickness of concrete and the foam is at least 2" thick, you should be able to use regular plastic boxes etc. They will anchor directly to the concrete without the hassle of shimming them so that they stay perpendicular to the finished wall. Hope this helps. Ian
*Some guys just use a router with a 1/2" dia dado bit.
*Bolt a pair of cheap plastic wheels through the nose of the chain saw bar to regulate the depth of cut.Ron BTW, Ian, I've been talking to Amvic about their product. Looks good.
*If I were going to buy a tool to do this job, it would be heat knife. They do a great job of cutting through the foam. I have seen electricians use them and they work great. To look at them I would think they weren't very expensive.Another option I just thought of might be an electric knife, like the one you use to cut turkey on Thanksgiving day. I've used it to cut foan in other applications.Steven
*DanielI am building a complete house out of such forms and have just finished much over the wiring. I used the 'old cheap chainsaw trick' ($50 - canadian) and bolted a block of wood as a spacer so that I cut just shy of the concrete. It works great but is a bit messy. I would have probably got a heat knife if I knew where to find it. I just push the wire into the slot with a blunt piece of wood. My electrical inspector (who seems to be a great guy) didn't complain or ask me to support the wire beyond that.I am really proud of the fact that I found some cheapy plastic boxes which are exactly 2 1/2" deep behind the drywall. (They are grey and have a kind of vertical wing attached to them). It turns out that the foam is exactly 2 1/2" thick, so all I have to do is cut out a square with my chainsaw and make a vertical slot for the wing. I pry out the block with a wonderbar and the box fits in beautifully. I wasn't able to figure out how to install metal boxes because they are so bumpy and have screw sticking out all over the place. By the way the plastic boxes are perfect for metal studs as well.I figure if a box is lose, I'll just put a 1" tapcon into the back.
*Our experience with routers is not so good. Hot melted EPS gets slung around...it burns like hell. The router gets all clogged up as well. The hot knife takes forever and doesn't give a consistent groove. The groove should be back to the concrete for nail protection. The blade of the hotknife tends to over melt the surface foam. You can order a hotknife at http://www.hotknife.com as well as all other foam working supplies. The electric knife hasn't worked so well for us for cutting grooves. It is good for cutting board foam, but it binds when cutting into a wall. I would advocate fastening all boxes to the concrete...easier to do it now than after the wall is finished and ripped out of the wall by the vacuum cleaner etc.
*one thing our inspector has asked is that we use the remodel type box and try to place them near the webs that stick out, that way we can attach the tab to the web to help hold the box secure. We have been using "blue max" and "form tech" icf's. Chain saw works good. Router is only good for a few minutes.
*Be sure to give thought to protecting your wire from inadvertant punctures when hanging pictures etc. As a general rule I run simpson strapps, glued in with urethane foam adhesive on all chases over 42" from the floor. This is most essential when you are finishing the ICF asa the wall. In most instances you will have less than 1-1/2 of spacing until your wire.walk good david
*The Formtech rep told us that we could run conduit in the forms before we poured. Is that not a good idea?
*PDF, yes you can do that but check with engineer. When we did that the local inspectors requested that we run a thicker wall to make up for the missing concrete, but then we were running two inch conduit to make all the " home runs " get to the panel
*Josh, didn't you have any trouble with the electrical inspection for running more than 3 current-carrying conductors in a conduit and having to "derate"?fv
*I have been wondering if it would be a good idea to upgrade the wire for ICF installations to reduce the chance of heat build up. I know 14/3 is safe when buried in glass or cellulose but it doesn't seem to me to be the same as when it's buried in tight grooves in EPS and foamed in, too. Any ideas?Ron
*PDF: I would suggest that if you want to run conduit, run it in the foam after you have placed concrete. This doesn't take away from the concrete in any way (consolidation, space, etc.)Nor interfere with reinforcing details. When we run conduit, we try to run the shortest distances out of the foam. When we used to set conduit in the concrete cavity, many times the owner changed something by the time it was to be roughed in so we abandoned much of it...easier and faster to do later on. Nail protection of wires is not really necessary if the ICF is made with foam of at least 2" thick (we use 2-1/2"), and the wire is set against the concrete....this allows greater protection than in a 2x4 stud wall assuming the hole is drilled precisely in the center of the stud. Code says 1-1/2" from the surface of the finish material...1/2" drywall so the wire must be recessed at least 1" from the surface of the foam. Doesn't hurt to put nail protection in anyway if you want.Ron: We advocate 12 ga. wire. I have been told that if heat build-up is a problem, there are greater problems than the fact that the wire is closely insulated. Remember, there isn't any real air flow to encourage combustion, and the foam would not sustain a flame by itself...just burn itself out immediately. Presumably the breaker would trip at that point.
*Ian,Thanks for the info on the downfalls of heat knives. I have only watched people use them and had never used them myself. Is the difference with electric knives working well on foam board the surface coating??Steven
*Our electrician uses an old skil saw, with a plywood blade. He just bends the blade a bit so it makes a wider kerf. Sometimes he cant get quite to the top of the wall due to joists in the way, but within 4 to 6 inches.. hacking distance.calvin.
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We are at the wiring stage in a new cottage construction. Although finishing the basement is not high on the list of priorities, some wiring will done for lighting etc. What suggestions do you have for running wire in the walls of the basement which are constructed of insulated concrete forms? This will be a do it yourself project, but I'd be willing to invest some money in specialized tool(I)to move the job along more quickly.