[BFEdenizen]

What's the best way to cut channels in vertical concrete walls? Not large channels, just enough to fit 1/2-inch PVC conduit.

Bit of background: My husband and I are working on remodeling our home. It's an old home from the 40s. We're about to start rewiring the house. The wiring is very old, the layout is....let's say, creative.... and it badly needs to be redone.

The house has cinderblock walls that have also been filled with concrete. That includes the interior walls. The original wiring and boxes are embedded in the concrete. No conduit, just straight embedded wiring.

We're just going to completely ditch the old electrical. The old outlet boxes are too close to the floor anyway and need to be raised. Our plan is to cut channels in the wall and embed 1/2-inch PVC conduit to run the new electrical. Yeah, it's going to be a pain. We're thinking about cutting a series of grooves with a diamond masonry blade and chiseling them out. Thoughts?

 

[joecaption]

Ya, do not do it that way. That would weaken the whole wall.
What do you plan on doing to finish the walls?
Right now you have no insulation in the walls, anyplace there's a small crack air can get in, that walls acting like a heat or cold sink and will transfure outside tempatures to the inside of the home.

 

[oh'mike]

I see that done in Mexico a lot----I don't know about any collateral damage to the strength of the block---But a wet cutting circular saw and a Bosch Clipping hammer would make short work of it---

A standard circular saw can be used with a segmented diamond blade----but the dust will be overwhelming---

An angle grinder with a diamond blade will also work well.

 

[BFEdenizen]

I didn't think a channel that shallow would weaken the wall. The walls are basically 7-inch-thick concrete, and only single-story height. But granted, I don't know a thing about this kind of wall material. All our previous experience has been drywall.

We could run the new wiring on the surface if it's required to keep the house structurally sound. I just really don't like the aesthetics of it. Do we have any other options?

We're not worried about any additional insulation or finishing on the walls. Cinder block is a very common form of construction with the older homes in this part of the world. Also, the exterior walls are finished and sided, which is rare here. Most of the cinder block homes are simply painted and left as they are. Our heating and cooling bills are significantly cheaper in this 1400 sq. ft. home than they were in our 1100 sq. foot home with modern construction.

Mike: Never thought of an angle grinder. We might have to look into it, provided it won't weaken the walls.

 

[stadry]

i wouldn't worry too much about strength if, as you say, the cells are conc filled,,, dustmuzzle has a good shield for circle saws & joe due's got the best shields for grinders - you supply your own dust vac,,, we have mexicans right here in the usa who do it the same way :yes:

like joe posted, i would insulate the walls unless its free heat but even touching winter cold walls is a no-no in our house

 

[oh'mike]

One possibility----
Surface mount the conduit----(or Romex)

Inset the boxes into the block---

Glue on foam insulation over the entire wall (except for the conduit)

Then Glue on 1/2" sheet rock (drywall) using enough Tapcon screws to hold the board in place as the glue dries.

Adds a lot to the cost of the project--but gives you some insulation and a nice finished wall--

I've done this successfully more than once.

 

[joecaption]

Depends on what's exceptable to you.
Not fun but in some cases you can pull new wire as your your pulling out the old wires.
You could add 3/4 blue foam then 3/4" strapping and use a shallow wall box like this.
http://www.amazon.com/Single-Gang-B...r=1-17&keywords=shallow+electrical+outlet+box

You would also need to add jamb extentions to all windows and doors.
This would give you a much nicer looking smooth looking wall, and more insulation.

 

[BFEdenizen]

i wouldn't worry too much about strength if, as you say, the cells are conc filled,,, dustmuzzle has a good shield for circle saws & joe due's got the best shields for grinders - you supply your own dust vac,,, we have mexicans right here in the usa who do it the same way :yes:

Yeah, the walls are concrete. We refer to our house as "The Bunker". :biggrin: You can't even make a scratch on it with a regular electric drill, regardless of the bit you use. And yup, we learned that the hard way. :wink: Simply installing curtain rods requires a hammer drill. And let's not get into the joy that was baseboards. On the upside, we never have to worry about trying to find a wall stud.

 

[BFEdenizen]

Not fun but in some cases you can pull new wire as your your pulling out the old wires.

Alas, that's the crux of our issue. We'd absolutely love to be able to do it that way. But with the old wiring solidly embedded in concrete, it's not going anywhere.

 

[BFEdenizen]

I'm going to put up pictures of our house on the projects forum. I'm sure it'll help if you can get a visual of the house. The concrete walls are finished on the inside, as well as finished and sided on the outside, and were when we bought the house. We'll, we made a stupid mistake. When we bought the house, the home inspector said the electrical wiring needed to replaced "in the next couple of years." We knew the walls were concrete filled. We consulted a friend who is a contractor before we bought the house, and he suggested the same thing Joe did: we could use the existing wiring to pull the new wiring into place. Overall, not a major job. So we went ahead and finished most of our other projects first, which at the time seemed to be more "major" projects than pulling some wires. It wasn't until we did our kitchen remodel and attempted to relocate an existing electrical outlet than we realized that the wiring (which everyone involved assumed was run through drilled holes in the wall, which I guess is the usual thing) was actually embedded in concrete. We'd never even heard of such a thing before, so it never occurred to us to check for it.

So we're now trying to redo the electrical while ideally doing as little surface damage to the walls as possible. As it is, we're going to have to remove kitchen cabinets and some of the tile backsplash to do it.

 

[oh'mike]

Don't be to hard on yourself---There is no substitute for experience---You are dealing with an unusual situation that was not in your field of expertise----

How do you think some of the old timers here know so much?

They ran across odd ball situations like yours and had to find a solution----Experience----You are having one with this house---and will be wiser when you are done----

 

[joecaption]

The trick of a true craftsman is when you screw up you make it look like it was suppost to be that way.

 

[BFEdenizen]

The trick of a true craftsman is when you screw up you make it look like it was suppost to be that way.

:laughing: Well, glad to know that we're not the only ones who've been in a predicament like this.

 

[jomama45]

Maybe I'm not understanding, but wouldn't surface mounted conduit look better than conduit recessed in rough cut block? The cut's in the block will not look finished by any means, unless you plan to cover the conduit with something??

CHeck out a product like "Wiremold" as well, it's a little smaller and less conspicuous than conduit..........

 

[BFEdenizen]

We plan to repair the concrete over the pvc conduit, basically embedding it. Or would that not work? Like I said, this is our first-ever experience in dealing with concrete walls.

 

[jomama45]

It's still going to stick out like a sour thumb, and could certainly chip off, unless you intend to set it back an inch or so. To me it seems like a lot more unwarranted work than it needs to be, with little gain.........

 

[BFEdenizen]

Thanks for the feedback on the walls. We looked up the wiremold. That's probably what we'll go with if running electrical inside the walls isn't an option, which is starting to look like the case.

 

[BFEdenizen]

Had a good conversation with the husband, and we decided Mike's idea of the foam/drywall combo is our best bet. It'll give us insulation, hide the wiring and have the added bonus of covering up all the old embedded outlets. It'll probably take us no longer to do than cutting channels and trying to embed conduit and be a lot less of pain. We hate to cover up walls we just repainted a few years ago, but frankly, paint is dirt cheap in terms of home improvement. Live and learn. Thank you all so much for helping us figure out how to do this properly.

But of course that leads to further questions. We're definitely using foam on exterior walls for insulation, but it necessary to use it on interior walls? We're thinking about just securing 1x2s (or something like that) to the interior walls at the standard stud spacing, and attaching the drywall to that. Also, we're probably going to keep the original concrete uncovered in part of the kitchen. We just installed a a new tile backsplash on that concrete a few weeks ago. Fortunately, it's on interior walls. We're thinking about drilling a hole straight through the concrete to the existing imbedded electrical boxes and running the wires up the opposite side of the wall, which will be covered by drywall. Would that work?

ETA: One more question about the romex. If we surface mount the romex, do we have to make cuts or something in the foam sheeting to allow for it, or can we install directly over the romex without a problem?

 

[stuart45]

http://www.youtube.com/watch?v=_loOGNvVSAs
These work quite well.

 

[jomama45]

The trick of a true craftsman is when you screw up you make it look like it was suppost to be that way.

Actually, I'd say the sign of a true craftsman would to be humble enough to take it apart and build it the right way, like you should have done the first time, regardless of how much time & money it costs you................