Doors – Tips for measuring a front door opening

From you description, it sounds like you have a hair over 1 1/2 inches of extra space to make up. If this is correct consider this method. Place a full 1x4 (or whatever the depth of the wall may be) on both sides, as long as the new door frame will still fit comfortably in the new opening. When ever possible, I like to mount the hinge side to a solid petition without excessive shims. This makes it more solid without having to bridge a large gap with your finish nails, and makes it a lot easier to perfectly plumb the hinge jam. I often replace the center hinge screw on the jam side with a longer matching screw that will attach to the jam. This does a few things for you. One, you don't need as many nails, gives a much more solid feeling and sounding door, and gives you a tool to fine adjust the plumb if necessary.(especially on heavier solid wood doors. Just like with security screws on an entry door. After you are sure you are happy with the plumb on the hinge side, simply use visual to get an even gap on the top and latch side, in that order. You can then use shims on the latch side and shoot your finish nail just below your shims. this keeps the shims from dropping as you work down the jam. i don't usually shoot through the shims because they often split and I may want to slightly adjust them before the trim casings are installed.

My favorite primer for wood doors is Bins Bullseye, pigmented shellac. This primer bonds well, hides wood grain well and gives a very smooth surface for top coats. If you prefer to stay with a latex product, then Kilz premium is good too.

Remember prep is of the utmost importance for a good finish. Sand everything and clean it well before applying primer. On a new piece, I like to lightly sand the first coat of primer. You will feel the difference, trust me. I like to use two coats of primer, then sand it again very lightly to make it super smooth: 220 grit used lightly is fine. Clean it well with a tact cloth or very slightly water dampened rag.

Now for the top coat. Use a premium quality 100% acrylic exterior trim paint. Usually a gloss or semi gloss looks great, but that's a personal preference. Don't skimp on the brush: get a good Purdy Glide, poly/nylon 2½" angled, soft chisel tip. Apply nice smooth, thin coats, and expect to do three coats for a good solid fill. Start in the panels and work your way out to the rails and stiles. If you can take the time to remove the door after it is installed, (never remove door from frame before installation!!!!) lay it flat to paint. Laying it flat will really help avoid drips and runs. Pay special attention to the panel corners and details for drips and puddles a few minutes after you apply the paint. Use long smooth strokes to finish each panel, rail and stile.

BTW, a really good latex 100% acrylic is every bit as durable as an oil based product. Oil based paints are going away and have been compromised greatly in recent years due to VOC laws. I stopped using oil paint several years ago. The only oil based product I use now is urethane.