Bill Robinson: When preparing the rough opening, it’s important to look for damage, and moisture is the main culprit. To check for damage here, I’m going to use my chisel and stick it into the wood and pry on it. Look for the wood to splinter up like that. That means it is sound wood. If it crumbles, you have to replace it. The felt paper you can see here is sound–it’s actually solid behind. I didn’t cut it when I removed the siding, so I’m not going to worry too much about water getting behind there. The felt paper is in pretty good shape. The window opening is big enough to fit the window. And it’s plumb, level and square enough that I can make some adjustments when I install the window. So we’re good to go. Bill fills in missing gaps of sheathing around the rough opening. Then he vacuums all the dust and dirt so that he’ll have no trouble installing the rigid and self-adhesive flashings. Bill: This is vinyl coil stock. It’s real thin, and what’s nice about it is that it pretty much won’t react with moisture or anything. I cut this in narrow strips and slide it behind the siding. Any water that might get inside the window opening will be forced to the outside. I work the coil stock down behind the siding carefully and use a little pry bar to pull the siding away from the felt paper so that I can get the vinyl coil stock behind there. It’s kind of a tight fit, but I need to get it in there. So, I’ve done the bottom with the vinyl coil stock. I’m going to do both sides but leave the top open so that the flashing tape will actually stick…