This is where I was last week. An insulation brochure lists four steps for this project; I have highlighted, in green, these four steps.
1. Lay a ten-foot square of 6-mil polyethylene sheeting to cover the ground.
2. Unscrew the cover from the light fixture, and then unscrew its box from the strapping (1″ x 3″ boards) and pull out one of the brackets holding its power cord. Pry off the rest of the strapping that had held plastic sheeting over the joists.
3. Pull off the plastic sheeting (stapled to the joists with an office stapler; worse, the plastic was in the wrong place: it should lie between insulation and the warm-in-winter side of the house).
4. Remove the dirty, damp fiberglass insulation.
5. Remove the debris from the crawlspace and pack into three oversized garbage bags.
6. Sweep up the mouse droppings, mouse corpses, and fly pupae; discard.
7. Hammer flat any protruding nail ends that might interfere with smooth installation of new fiberglass batts.
8. Seal air leaks around wires.
9. Measure spaces between joists. Cut pieces of polyethylene sheeting to cover bottom of floor plus two or three inches down each joist/header. Attach with (proper, heavy-duty) stapler.
10. Cut R-20 insulation to size, and tuck between the joists. Note that the insulation is 6″ thick, leaving 2″ between it and the bottom of the 8″-deep joists.
11. Cut pieces of leftover vinyl siding edging, 8″ x 2″ x 1″, and screw onto joists just below the insulation.
12. Lay builder’s shims across insulation batts, the shim ends resting on the vinyl ledges, to help keep insulation from sagging.
13. Notice old furnace fuel oil line (a narrow copper pipe) that had been sawn through (when system was changed to electric), but never removed. Use claw hammer to pull out its brackets.
14. Wipe up half-cupful of fuel oil spilled onto poly groundsheet. Using hacksaw, remove fuel oil line.
15. Cut, measure, and staple lengths of aluminum window screening over joists, letting it descend a few inches around the perimeter.
16. Return to building centre for another roll of screening. Finish stapling.
17. Study the dryer duct that the previous owner had kept aloft with a length of string looped over a piece of strapping. Remove the string, turn one of the duct lengths around so that the pieces fit properly, and tape.
18. Screw new strapping along screening seams and around perimeter. Stuff steel wool into corners and along larger gaps in seams in hopes of keeping mice out of insulation.
19. Nail bracket back in over light fixture power cord. Using electric screwdriver as light source, and manual screwdriver to do the work, begin to reattach light fixture box to strapping. Watch the Arc’n’Spark Show. Abandon project till next morning.
20. Shut off power for entire house. Reattach light fixture box to strapping. Locate source of metalic tinkling. Using utility knife, carefully strip off 1/2″ of the black wire, and wrap around its screw post; tighten screw. Replace cover on fixture box. Turn house power back on.
21. Measure, build, and nail in a permanent panel that reduces the crawlspace hatch size by half.
22. Measure, cut, and place two vent covers in far end of crawlspace.
23. Measure, construct, and place new hatch cover.
Start to finish: five days.