Case Study 4-1: Dave Kowalski's Farmhouse — Finding the Leaks Before Spending the Money

Background

Dave Kowalski closed on his rural property in mid-October, three weeks before the first hard frost. The 1963 farmhouse had been a rental for the past eleven years. The inspection report described the attic insulation as "approximately 4–6 inches of fiberglass, adequate for the region." The furnace had been replaced eight years ago and tested fine. The inspector noted "some air infiltration typical of homes of this age" but gave the building an overall pass.

Dave moved in November first with two dogs, a truck full of tools, and a genuine enthusiasm for the DIY projects ahead. The November utility bill was $210. December was $295. January arrived in full force, and the bill was $418.

He called the propane company to ask whether their tank gauge was accurate. It was. He checked whether the furnace was running excessively — it was. He checked the thermostat settings, the filter (dirty, replaced it), and whether any rooms were poorly served by the duct system. Then he called the county cooperative extension office and asked if they knew anyone who did energy audits.

The Energy Audit

A certified home energy auditor from a local weatherization program arrived on a Tuesday in early February. She brought a blower door, an infrared camera, and a smoke pencil. Dave had heard about blower door tests but never seen one in person.

The auditor mounted the fan in the front door frame, depressurized the house to 50 Pascals, and took a reading: 22.7 ACH50.

"Is that bad?" Dave asked.

"It's about three times what a home built today would test at," she said. "Think of it as having a 28-inch square hole cut in your wall, open to the outside all winter."

She then walked through the house with her infrared camera while the blower door maintained pressure. The camera showed temperature differentials — cold spots on walls and ceilings glowed blue and purple. Dave followed her, quietly surprised.

What the camera revealed:

The attic floor was the biggest problem. Three plumbing chases — open top-plate penetrations where drain stacks ran from first floor to basement — were essentially open holes into the attic. Each one was channeling warm air directly from the basement through the wall cavities and into the unconditioned attic. These weren't small gaps. One chase was 6 inches by 12 inches, unstopped and uninsulated. The auditor estimated these three penetrations alone accounted for more than 15% of total air leakage.

The pull-down attic stairs were catastrophic. No weatherstripping on the frame. The door panel itself was a single layer of thin plywood — R-0.5 at best. Cold air poured down through the gaps visible on the camera.

The rim joists were completely bare. The entire perimeter of the basement, where the floor framing met the top of the concrete foundation wall, was exposed wood and air gaps. Frost was visible on the inner face of the rim boards in some areas — an indication that outdoor temperatures were being felt directly on the interior wood surface.

Recessed lights in the kitchen ceiling. Dave had admired the eight recessed fixtures in the kitchen when he bought the house. On the camera, each one was a bright blue circle — cold air descending from the attic through the fixture housing. The fixtures were old-style, non-airtight models with open wiring compartments.

The front door bottom. The door threshold gasket was worn flat. The auditor put her smoke pencil at the bottom of the door and the smoke streamed horizontally inward.

What the attic floor showed. When they climbed into the attic, the R-value measurement was grim: 4.5 inches of original fiberglass, settled, and in places flattened to 3 inches where a previous owner had walked on it. Estimated R-value: R-9.5, declining to R-7 in compressed areas. Recommended for Climate Zone 5: R-49.

The Priority List

The auditor produced a written report with a ranked list of improvements. She also provided an estimate from the weatherization program and a list of DIY-eligible items.

Priority 1: Attic air sealing — $0 materials if DIY

Seal the plumbing chases with rigid foam and canned foam, spray foam around any electrical penetrations through the top plates, and seal the perimeter top plate line where the ceiling drywall meets the exterior wall framing. The auditor estimated this work would reduce ACH50 by 4–6 points on its own.

Priority 2: Attic stair cover — $80 materials

Build an insulated box from 2-inch rigid foam board to drop over the pull-down stair opening from the attic side, weatherstripped at the perimeter. Or purchase a commercial cover (Battic Door, Access Panel Depot, etc.) for $80–$140.

Priority 3: Blown-in attic insulation — $2,100 professional or $650 DIY

Once air sealing is complete, bring the attic to R-49 minimum. The auditor recommended blown cellulose for its superior air resistance and price point. Professional quote: $2,100. DIY option: rent a blower from the home improvement store, buy 40 bags of cellulose ($650 approximate), blow to depth markers.

Priority 4: Rim joist insulation — $280 materials

Cut-and-cobble 2-inch XPS rigid foam boards to fit each joist bay at the rim, seal perimeter with low-expansion foam. Approximate materials for the full perimeter: 10 sheets of XPS ($250–$300) plus 4 cans of foam ($40). Full DIY project — no special skills required, just patience.

Priority 5: Kitchen recessed lights — $480 materials

Replace all eight old can lights with IC/ICAT-rated LED retrofit fixtures. Average cost per fixture: $45–$65 (retrofit trim kit with LED and airtight gasket). Electrical work is within DIY capability for someone comfortable with wiring, or approximately $200–$300 for an electrician to do the labor.

Priority 6: Door and window weatherstripping — $150 materials

Front door threshold, rear door, and four ground-floor windows with worn weatherstripping.

Not recommended yet: Wall insulation. The auditor ran the numbers: with Priorities 1–6 complete, wall conduction would represent approximately 18% of remaining heat loss. Dense-packing the walls would cost $6,000–$9,000 for the whole house and save perhaps $80–$120 per year. Payback: 50–75 years. Not worth it until the house needs re-siding, at which point exterior foam adds only marginal cost to an already-budgeted project.

What Dave Actually Did

Dave is an accountant by training. He built the spreadsheet. The numbers were stark.

Weekend 1 — Attic air sealing. Dave bought a case of low-expansion spray foam, a roll of housewrap tape, two cans of acoustical sealant, and 2 sheets of rigid foam board. He suited up with an N95 respirator, safety glasses, and a long-sleeved shirt on a Saturday morning in February. The attic was cold — 22°F — which he hadn't anticipated. He sealed the three plumbing chases with rigid foam covers and foam at the perimeter. He foamed around every electrical penetration through the top plates he could find. He sealed the continuous gap where the ceiling drywall met the top of the exterior wall framing by running a bead of acoustical sealant along the interior edge. Total time: 6 hours over two days. Total materials cost: $115.

Weekend 1 continued — Attic stair cover. Dave bought a commercial insulated cover for $95. Installation: 20 minutes. He felt the temperature difference immediately when he pulled the stairs down the following morning — no cold draft descending.

Weekend 2 — Rim joists. Dave measured the basement perimeter: 156 linear feet. He calculated how many sheets of XPS to buy. Nine hours of cutting and fitting over a Saturday and Sunday. The foam is rigid enough that cut pieces hold themselves in the bays; he ran foam around each piece's perimeter and moved to the next. Total cost: $295 in foam plus foam cans.

Week 3 — Recessed lights. Dave decided to do four fixtures himself and hire an electrician for the other four (he was uncertain about a three-way switching circuit in the kitchen). His four: $180 in materials, 3 hours. Electrician's four: $310 including labor and materials. Total: $490.

Total spent so far: $995

Dave's February propane bill came in at $287 — a $131 drop from the prior February, despite a colder month by about 4 degrees average. He estimated his savings pace at roughly $850–$1,100 per year.

Spring — Blown-in attic insulation. Dave rented the blower machine from the home improvement store (free with purchase of minimum 20 bags; he needed 42 bags). Cost: $812 in materials. Two Saturday mornings with his neighbor's help. He installed depth markers before starting (marked sticks at 14 inches — the target depth for R-49 in cellulose). The job took 7 hours total.

Running total: $1,807 in materials

One Year Later

Dave ran the numbers at the end of his first full year. Annual propane cost before improvements (extrapolated from the November–January bills and typical seasonal patterns): approximately $4,200. Annual cost after: $2,780. Savings: approximately $1,420 per year. Simple payback on his $1,807 investment: 15 months.

His ACH50, re-tested by the auditor six months after completion: 11.3, down from 22.7. Still above the ideal, but dramatically improved and at a cost of under $2,000.

The dog, for the record, now sleeps in the upstairs bedroom above the garage every night. The floor is warm.

Lessons

Get the energy audit first. Dave's instinct was to start buying insulation. The auditor reoriented his entire approach — air sealing first, specific locations first, insulation second. Without the audit, Dave might have spent $3,000 on wall insulation that would have delivered a fraction of the value of what he actually did.

DIY is genuinely viable here. Unlike plumbing, electrical, or structural work, attic air sealing and blown-in insulation require no licensed trades, no permits in most jurisdictions, and no special equipment. The learning curve is measured in hours, not years.

The financial case is compelling. A payback of 15 months is exceptional. Most financial investments don't return 80% annually. Homeowners who delay weatherization because "it's not exciting" are leaving money on the table every month.

The sequence matters. Dave sealed before he insulated. If he had blown in the insulation first, it would have buried and covered all the penetrations he needed to seal, making the air sealing much harder and less complete.