Having 100 SFRs vs 100 units in an apartment community both provide insulation from vacancy and major expenses in one or a handful of doors. 

Energy Efficiency ImprovementsInstalling energy-efficient windows, doors, insulation, and HVAC systems can appeal to modern buyers who want to reduce utility bills.

I was thinking that the very thin hard carpet could serve as a sound insulation layer, and just installing click together LVP right over the thin carpet and the thin hard stick on tiles. 

However to save money when she had the house built, she left the basement unfinished--it is just studs, insulation, and windows/doors, plus plumbing in the foundation.

You are correct that insulation is almost certainly a bigger bang for the buck in a heating climate.

Sounds like if you know and follow the rules you should not only be OK but pretty well insulated from competition (people swarming in and oversaturating)

The only real violation might be that a wall was constructed in the door area, and I have seen additions where the door was left in place with insulation inside and wall covering and siding outside!

Paint rags and paint plastic $386.66 Initial 70% deposit Cabinets $13,029.02 Backer board, Fiber rock, Shower drains, Zinc backer board screws $385.71 Junk Removal $600.00 red gard ($123.10) Initial 50% deposit Windows $10,493.20 2x4 studs $52.33 Junk Removal $400.00 Flooring sample $6.01 Flooring sample $68.48 Flooring sample $62.62 Flooring sample $132.09 Paint samples for accent wall $38.34 10% Draw for Master bathroom demo $580.00 Wall and shower Tile+Grout-Guest bath $528.62 LVP Flooring $7,165.27 Demo Work $1,275.00 LVP Flooring $7,198.07 Floor tile-Guest bath $889.05 50% down for moisture barrier and animal extraction $2,541.30 Returning flooring samples ($263.19) Paint-2 5gallon buckets SW $382.38 Unsure on what these are $19.54 Unsure on what these are $48.00 Master shower floor tile $331.42 Paint $3,100.00 Flooring underlayment $888.42 Primer $178.71 Paint-5 1gallon buckets SW $180.26 Paint $3,100.00 Appliances $6,820.59 Master bath tub $986.76 Paint-1 5gallon buckets SW $194.81 Primer $268.54 Framing repair for rotted wood $1,000.00 Junk Removal $500.00 Floor tile-Guest bath $771.07 Floor and Shower wall tile-Master $4,559.43 Stair noses $334.20 Master shower floor tile $612.76 Farmhouse sink $385.91 Master ceiling paint $254.29 Drywall repair in kitchen ceiling $500.00 Childrens wall tile and floor tile $3,477.40 Master shower floor tile-Return ($331.43) Drop in sinks for children's bathroom $103.75 Drop in sinks for upstairs bathroom $51.87 Master sinks $147.64 Master floor tile $270.05 Electricity $169.70 16x cement backer board return ($139.60) Tub and shower faucets $414.96 4 x Toilet seats $788.22 Tile install materials for all bathrooms $863.00 Air filters $10.90 Gas pipe and AC tune up+Duct repair $1,216.00 Tile install materials for all bathrooms $984.78 Roll of insulation X2 $38.48 Primer refund $125.33 Shower faucets X2 $480.71 Water $11.41 Master shower floor tile-Return the original white one ($261.55) Demo and materials he bought $1,005.14 Pickup charge for picking up flooring $223.96 Flooring 1st payment $4,000.00 Flooring return-guest bathroom tile ($889.05) Red guard refund $71.34 Backer board, wall tile and floor tile upstairs master return ($134.34) Keys X3 $10.93 Remaining balance for moisture barrier $2,046.30 Subfloor repair $100.00 Flooring $9,900.64 Master tub filler faucet $311.35 Tile labor in all bathrooms $9,202.22 Stair treads and risers $1,160.76 Bathroom painting $2,000.00 Junk Removal $150.00 Return for stair noses ($334.20) Return for flooring ($13,488.73) Flooring $1,900.00 Flooring underlayment $899.35 Trim $1,053.17 Toilet supply lines $13.46 Tile sealer, garage epoxy, garbage disposal $313.00 Return for remaining balance ($1,098.57) Floor reducer $49.99 Garage door opener $267.66 Door hardware (Hinges and door handles) $451.14 Counter tops $5,287.01 Tile return ($981.43) Tile return ($685.14) Tile return ($385.53) Tile return ($153.19) Tile return ($613.13) Flooring $1,900.00 Plumbing and electrical work (Light fix, toilets, drains) $975.00 Light fixtures and faucets $975.49 Junk Removal $125.00 Baseboards $241.45 Switches, outlets, faceplates $234.53 Cabinet balance $5,583.86 Sink return ($155.62) Dining room light and 4 ceiling fans $923.70 Anti skid additive for garage floor $11.38 Flooring $1,900.00 Glidden gel paint $24.01 Paint refund ($1,046.40) Counter tops $2,304.23 Extension rods for ceiling fans $40.64 3 Ceiling fans (one was returned) $573.93 Return grills $100.11 Kitchen and nook light fixtures $283.80 Rod for curtains and toilet paper holder $84.10 Curtain rods $54.60 Garage door deposit $1,185.00 Cleaning $400.00 Water heater $756.18 Thermostat $181.41 Stump Removal $300.00 Dryer cord $28.53 Plumbing and electrical work (Light fix, toilets, drains) $3,525.00 Junk Removal $125.00 Grass seed $71.40 Return of shipping cost ($297.45) Duct cleaning $970.00 Drains for master $46.54 Sold Fridge ($200.00) Bathroom fans $91.92 Samples for brick $29.98 Peg board hooks $20.83 Wall plate covers $21.28 Steel pegboards $140.72 Return stair tread and Riser ($198.14) Pressure washing $1,216.00 Wall plate covers $8.11 Shower door for upstairs $729.83 Powder room counter top $702.99 Light bulbs $59.24 Shower door deposit $1,000.00 Staple gun, staples, supply lines $157.04 Bathtowel hanging hardware $130.89 Light bulbs $29.62 GFCIs, underlayment, downrods ($233.54) Sanding pads $59.10 Yard hanging tools $21.94 Supply line return ($13.12) Stair clips and balusters $779.58 Returned some bathroom tile ($109.05) Peg board hooks $120.04 Front door $3,235.01 Brick sealer $50.81 Bathroom fan light and peg board hooks $71.27 Sanding pads, sanding sheets, etc $38.48 Mirrors $65.84 Mirrors $291.88 Spray bottle for marble sealer $4.34 Brick backsplash $695.54 Sanding pads $2.20 Shelves and shelf brackets for storage room $73.14 Shower door balance $1,000.00 Mirrors $104.26 Returned mirrors ($89.50) Gutters $2,043.15 Floors for finishing room $373.78 Wall plate covers $8.07 Floetrel and hood vent $31.49 Plumbing and electrical work $175.00 Backsplash and fireplace $2,450.00 Trim paint $50.21 Tile for master finish $15.17 Returned something.

Most likely all new mechanicals, windows, a fair amount of framing, insulation, etc., etc.

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