installing sky lights in patio roof

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24
Location
San Diego, CA
I built a covered patio roof which is composed of 2x6x12' stringers 24" o.c. Perpendicular to the stringers is 3/4" tongue & groove (T&G) with 15/32" plywood. The felt and rolled roofing has not been installed yet.
The covered roof, as I expected, really reduces the amount of natural light in the adjacent living room and family room. I want to install two curb mounted 2'x4' skylights between the strinters to draw in more natural light.

The first thing to do is cut a 2'x4' opening thru the T&G and plywood. Here is my intended procedure....after determining where the skylights go I'm going to drill a hole thru the roof from the underside about 1/2" from the stringer in the four corners where the skylight goes. I'll draw a line connecting the four holes and cut out with a circular saw. I'll then use a router bit with bearing to flush up the cutout with the stringer on two sides.

Here is my question....What kind of router bit will flush up the cutout and cut through 1 1/4" of wood? I think I can buy a 1/2" shank top bearing mounted flush trim bit with a 2" long cutting capacity. Comments and/or suggestions about this procedure would be appreciated.

Secondly, since I need the bit in a couple of days, where would I find this bit? Home Depot? Lowes? or Rockler?
 
Robert, I may be all wet here, but it sure seems to me that you're going to a whole lot of unecessary work to make those skylight openings. If I were doing it, I would do the first part like you, drilling from the underside. Next, I would make a cardboard pattern of the exact hole you want to make and then lay it on top of the patio so it is located equidistant from the 4 holes you drilled and tape it down. Mark the roof using the pattern and then screw a straightedge (board/mdf/plywood) to the roof to use as a guide for the circular saw, offsetting it from the pattern line by the distance from the edge of your circular saw's base to the blade and then I would carefully plunge cut the circular saw into the roof and make the cut, stopping just short of the end. I would repeat this process for all 4 sides of the hole. Then, before finishing the cuts at the corners, lay the straightedge across the hole so it overlaps the cuts on the long sides and put two screws through it into the cutout piece, (to keep it from trying to fall through before you complete the corner cuts and then use a handsaw or jigsaw, to finish the cuts at the corners. This should give you a perfect hole a lot easier than trying to use a router up there and cutting through something that thick. (Cheaper too, Buuuuuut....no excuse to buy a new router bit though):D

Note: Do not get disoriented and step or lean on the cutout after the first cut is made.:eek::D

Note II: There should be no splintering of the plywood on the underside (showing in the patio) due to the cutting direction of the CS blade).
 
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yup, skillsaw or jigsaw.....unless you just want to fiddle around with a router on a roof, cutting nails with 2" of bit exposed:eek:
 
Good suggestion and I thought about cutting the opening with a CS or jig saw. But my concern was getting the blade to close to the stringer and cutting into it. That's why I thought of using a router to clean up the edges nice and flush to the stringer. How would I get a nice flush fit against the stringer with a CS or jig saw? However, the ceiling and stringers will be painted not stained and I could sand or fill up any blade marks.
 
I'll chime in with a vote for a recip saw as I think it would be easier to get a more straight cut than a jig saw especially though 1 1/2" of wood.

You could actually do your cuts along the joists from the underside. Cut those 2 sides and then attach 2x4's to form your opening (which you'll need to do anyways) You can then temporaily attache another pair of 2X's to the joists to hold the piece while you cut the other sides.
 
I have installed lots of those sky lights and just lay it out with chalk lines on the roof and cut it out with a circular saw. It is the best way to keep the cut straight and square. Reciprocating saws and jig saws wander too much.
 
Why not use a router with a pattern tracing bit. Let it ride to the joist, Slide down the distance and then across.
 
I am another person who recommends using a jig saw for this job. That's what I used to cut the holes for the two skylights that I installed in my cabin. I was cutting through 1.5 inch spruce tongue and grove roof boards.
 
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