[RE-wrenches] Strawbale wall penetration

nickl at sierrasolar.com nickl at sierrasolar.com
Fri Nov 19 12:52:20 PST 2010


Ditto what Phil and Bill said. Also, I've found that you must add a  
few sizes larger on the diameter of the hole as the straw tends to  
fill the gap as it's drilled. On a recent job we had to utilize a 2"  
hole for 1.25" conduit and it still needed to be forced a bit.  
Downward slope is great advice too. Luckily my customer did that by  
mistake.

Have fun, Nick


On Nov 19, 2010, at 12:22 PM, Phil Undercuffler 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 <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  
> <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
>
> DayStar Renewable Energy Inc.
> benn at daystarsolar.ca
> 780-906-7807
> HAVE A SUNNY DAY
>
>
>
>
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> -- 
> Bill Hoffer PE
> Sunergy Engineering Services PLLC
> 2504 Columbia Ave NW
> East Wenatchee WA 98802-3941
> SunEngSer at gmail.com (509)470-7762
> Cell(509)679-6165
>
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