[RE-wrenches] Strawbale wall penetration

Sat Nov 20 08:08:26 PST 2010

I'd just be worried about the rebar blowing the plaster out, when it comes out the other side.
We welded a drill bit to the end of the rebar. 
Once we're through with our rebar/ bit thing, we use diamond grit hole saws to make a clean hole in the plaster.
I've been eyeing the Lenox carbide hole saws, but I got a a big set of the diamond grit ones at Harbor freight for $29, cheap yes, but I consider my tools for this type of wall excavation to be relatively disposable.
Another tool to consider for this work is a 1/2" regular chuck adapter for the Bosch SDS hammer drill, that allows you to chuck rebar, regular bits, hole saws, drill extensions, etc, in the Hammer drill.
The Bosch is a beast of a drill in non hammer mode.

R. Walters
ray at solarray.com
Solar Engineer

On Nov 20, 2010, at 1:04 AM, Phil Undercuffler wrote:

> Good bit (sorry for the pun) about  the carbide hole saws. Like you, I've also got a box of bell hanger bits. However, straw bale walls start out at 14" thick and can go deeper - 36" and more.   I've tried extensions and even the 4' long Jesus bits (you know, those ultra long flexible electrician bits that you pray to Jesus wind up in the same zip code as the wall you're aiming for), but for bale and Adobe, there's nothing like KISS rebar.  Trust me.
> 
> Phil Undercuffler
> 
> On Nov 19, 2010 8:27 PM, "William Miller" <william at millersolar.com> wrote:
> > Friends:
> > 
> > I keep a set of "grit edge" hole 
> > saws.http://www.lenoxtools.com/Pages/Product.aspx?id=CarbidegritHoleSaws 
> > These cut Stucco and plaster without degradation.
> > 
> > If I want to pilot a deep hole, I remove the ~4" pilot bit and chuck in a 
> > bell hanger bit. Linked is an 1/4 by 18" bit that will replace the pilot 
> > bit. Use with care, this is a long skinny bit. http://tinyurl.com/2cnupu3
> > 
> > William Miller
> > 
> > 
> > At 01:36 PM 11/19/2010, you wrote:
> >>Having a fair bit of experience with bale, I ditto what Bill mentioned but 
> >>I'll add a simple way that I discovered to getting the inside and outside 
> >>holes to line up.
> >>
> >>Bale walls are seriously thick, so standard extension bits aren't long 
> >>enough. I found taking a 2 or foot length of 3/8" rebar chucked into a 
> >>half inch drill works nicely for boring a pilot hole all the way through 
> >>the wall. Once you have the pilot hole, it's a simple matter of drilling 
> >>out a hole large enough for your conduit on both sides of the 
> >>wall. Either use a small bit to drill a series of holes around the 
> >>perimeter and connect the dots with a cold chisel, or use a hole saw that 
> >>you don't mind sacrificing on the plaster. You don't actually have to 
> >>"drill" through the entire wall, as the straw can be pushed to the 
> >>side. I usually spin the rebar in the hole while chunking it back and 
> >>forth a few times to clear a path, then thread the conduit through the 
> >>hole using the rebar as a guide to be able to find the hole on the other 
> >>side. It really helps to have a second person on the other side, to help 
> >>guide it in the final inches.
> >>
> >>Rebar as a drill bit also works great with adobe walls.
> >>
> >>If you do a lot of this, take a minute to grind down a flat spot on the 
> >>end of the bar or it will tear up your drill chuck. Drill chucks can be 
> >>spendy. Ask me how I know...
> >>
> >>
> >>Phil Undercuffler
> >>
> >>
> >>
> >>On Fri, Nov 19, 2010 at 11:27 AM, Bill Hoffer 
> >><<mailto:sunengser at gmail.com>sunengser at gmail.com> wrote:
> >>Benn
> >>I used PVC in the my bale walls with a Junction Box on both sides of the 
> >>penetration to protect the penetration (Outside a must!). I used EMT for 
> >>all my other wiring, but PVC seems better for an interior to exterior 
> >>penetration where the heat conduction of the EMT may cause some damaging 
> >>condensation towards the exterior of the bales. I used a hammer drill and 
> >>concrete bits to get through my stucco, it is tough stuff. I used 2 " 
> >>conduit so I had to make several smaller holes and knock it out by 
> >>hand. I did not have rebar in my bales, but heavyduty 6x6 mesh to get 
> >>through, as would be expected I never was able to hit the middle of the 
> >>grid, I just had to cut and hack saw when I hit something, pays to have a 
> >>sacrificial bit to find the metal. I then fashioned a home made bit out 
> >>of the conduit and used that to get through the bales by hand. That went 
> >>pretty easy and will allow you to locate the rebar without damaging an 
> >>expensive bit . Hard part is lining up to get a good mark on the opposite 
> >>side. I used foam to fill any gaps, replastered around the pipe and 
> >>fitting and caulked really well to seal against water on the outside. I 
> >>also located the JB on the outside of the building in a very protected 
> >>area for additional security. Water and straw bales do not play well 
> >>together! If anything I would favor a slight slope downward on the 
> >>outside so if there is a leak it will not follow the pipe inward into the 
> >>bales.
> >>
> >>Hope that helps!
> >>Bill
> >>On Fri, Nov 19, 2010 at 11:05 AM, benn kilburn 
> >><<mailto:benn at daystarsolar.ca>benn at daystarsolar.ca> wrote:
> >>Wrenches,
> >>Short of contacting the builder, i'm looking for your experiences, 
> >>practices and "look-out's" for penetrating a strawbale exterior wall with 
> >>conduit.
> >>For the project in question there is currently a teck cable from a wind 
> >>gen entering the home by sharing a HRV vent opening that i want to fix 
> >>(not my original system by the way) and i will also be adding another 
> >>penetration for a PV array that i am relocating on the property. The 
> >>original penetration for the PV was done properly but its not in an ideal 
> >>location for the re-located array wiring.
> >>I'm wondering if it is as simple as using a hole saw extension to go thru 
> >>the ~16" wall and use an LB/box on either side. I'm sure there is some 
> >>framework and/or rebar supporting the bales, how do you locate/avoid these 
> >>when there are no corners to measure from? (it is a round home)
> >>Any knowledge if PVC or EMT will react in anyway with the bales? I'm 
> >>thinking that PVC would be best....?
> >>... i am trying to contact the builder to address this, and also to ask a 
> >>few choice questions regarding the wiring methods (he?) used in the 
> >>original PV system set-up.
> >>Cheers,
> >>benn
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