|Norm Abram's Best Tricks Of The Trade II: Cutting a Hole in Drywall|
David: Question: I have a dryer exhaust vent pipe to install through an exterior wall. How do I make a hole in the drywall that will line up perfectly with the hole in the siding?
?Joe Reed, Williamsburg, KY
Norm's answer: Starting inside the house, make a small hole in the drywall and check for studs, wires, and pipes. Once you know you have a clear spot, cut the hole for the pipe in the drywall. Take out any insulation that's in the way. Dryer-vent pipe is usually 4 inches in diameter, so the hole should be about 4? inches across to provide some wiggle room for fitting. Vent kits typically have a collar that covers minor gaps between drywall and pipe.
Here's the trick: Use a combination square to locate where to drill the hole in the sheathing and siding. Measure 2⅛ inches?half the hole diameter?from the edge of the rule to the square's leg and make a mark on that leg, as shown. Align this mark with the edge of the drywall, slide the rule to the sheathing, and mark where the corner of the rule and the sheathing meet. Do this in several locations around the hole just to verify the center point.
Now drill a small hole at that point through the sheathing and siding. That hole will show you the center for the bigger hole you'll then cut from outside the house.