Replies

1. 
   arnemckinley | Jul 08, 2007 02:34pm | #1

   drill through the center of where the opening will be  and use that as your reference for marking out the holes.

   or are you asking what tool to use it wasn't clear. a router, jigsaw, sawzall, or holesaw can be used to cut  your holes.

2. 
   ponytl | Jul 08, 2007 05:03pm | #2

   chainsaw  & caulk to fit...  if you want to go high end...

   p

3. 
   jhausch | Jul 08, 2007 06:09pm | #3

   For the plumbing penetrations, I am assuming that the T&G pine is not an issue since they are probably passing into the roof SIP inside an interior wall?

   Get a long drill bit (like an electricians bit or a 12" long 3/8" spade bit) and drill from the top plate of the interior wall up and through the full SIP.  Do your best to drill this hole as perfectly vertical and plumb as possible.

   I'd then chop a length of PVC at the roof pitch using a miter saw.  Then, put that on the roof centered over the hole from the bit and hold it plumb.  Draw around it with a sharpie, but hold the sharpie body flat against the pipe, that will give you a line about 1/4" larger all-around. 

   Drill a pilot hole and make the cutout with a jigsaw with a pivoting foot plate.  Keep the plate loose so you can keep the saw roughly plumb while tracing the oval.  Once the hole is cut, pop out the outer skin oval and now use a drywall keyhole saw to saw the rest of the foam to depth. Now, dig that foam out.

   I would then use the keyhole saw to saw from above and saw from the original center hole in the inner skin outwards like spokes to the outer diameter of the hole. Then you can go at it from below with the jigsaw again to connect the spokes.

   Does your 10" stove pipe hole allow for spacing to combustibles?  Will there be a thimble helping to support the stove pipe?  WIll that take up any irregularities in the hole-to-pipe-clearance?

   There is some technique for making the oval cut layout using a framing square, but I don't know how to do it.

   http://jhausch.blogspot.com
   Adventures in Home Building
   An online journal covering the preparation and construction of our new home.
4. 
   IdahoDon | Jul 09, 2007 01:10am | #4

   I've had great luck with the long (10"? 12"?) Sawzall blades from milwaky that have the coarse teeth with a little modification.  The blades have a decent set to the teeth so if the blade is simply thinned down it cuts tight corners quite well.

   With a minigrinder and cutoff wheel I'll take the blade down to no thicker than 1/2" and you'll be able to impress your friends with how tight and deep a corner can be cut in a SIP.  Unfortunately the long thin blade will be fragile and 10 minutes of work will go down the tubes the first time you bind the blade up, so don't do that.

   Good cutting.

   On the larger opening there may be a requirement from the manufacturer to ring the inside of the cutout with solid wood well sealed to the skins to better support the edges of the SIP.  Of course this makes it a square hole, not that this matters much.

    

    

   Beer was created so carpenters wouldn't rule the world.

5. 
   IdahoDon | Jul 09, 2007 01:12am | #5

   For cutting in outlets and whatnot, bosch makes some coarse jigsaw blades that will go 4" deep.  I picked some up just for this and they are the cat's meow.

    

   Beer was created so carpenters wouldn't rule the world.

6. 
   frenchy | Jul 09, 2007 02:04am | #6

   woodcreek,

    To go thru my roof (SIP) I did it three ways. first if it was flat  and a bigger hole I went with a hole saw because all you are really cutting is thru the OSB If you replace the little stub drill bit in the center with a long one you can also make nice even holes thru roof panels up to about 10/12 pitch.

    slice off the cut when it bottoms out and as long as the center is still there you will retain the ability to recenter the holesaw.

     Up to 4 inches you can use Milwaukees self feeding  hole saw, again you''l need to replace the self feed bit with a longer one for really steep angles..

     steeper than that you need to buy those 18 inch long sawzall blades and then the hole doesn't wind up being so nice and round..  

     sorry but that what great stuff is used for..