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Green Homes

Deep Energy Makeover: One Step At A Time

**A kitchen addition where a screened porch used to be** Structural Insulated Panels used as walls, floor and roof meant a dried in addition in a single day -- a good choice when building in winter.
Image Credit: Daniel Morrison
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The ultimate fixer-upper—failing stucco, uninsulated and ungrouted concrete block, knob-and-tube wiring, one bathroom, and no laundry hook-up. But the sound structure, the intact slate roof, and the double lot in a quiet neighborhood helped us see past the cons.
Image Credit: Peter Yost
**New office from a front porch** The office space is superinsulated and unconditioned except for an electric radiant panel on the ceiling.
Image Credit: Daniel Morrison
**A little space can go a long way** The SIP addition extends the kitchen only about six feet, but results in a spacious room.
Image Credit: Daniel Morrison
**A multitasking island** The long central island has room for cooking and entertaining.
Image Credit: Daniel Morrison
Comfortable to handle. The cotton batts were a bit of an experiment—pretty much early generation insulation that never did deliver quite the full loft expected. But it was nice to deal with in terms of skin contact.
Image Credit: Peter Yost
The first thing you notice after the spray-foam insulation installation is...the quiet. Since the basement wall framing is nonstructural, ripped 2x3s more than did the trick, and some were even shorties spliced together. The foam stiffened all of them up and the 1/2-in. USG Fiberock made 16-in. on-center framing completely unnecessary. Just after installation (including the shaving back to front of studs), the odor in the basement from the insulation was very strong, but a thorough vacuuming of the basement completely resolved this issue. It was caused more by all the shaved dust everywhere than outgassing from the insulation.
Image Credit: Peter Yost
From foundation to weathertight in just one day with a SIPS on piers kitchen addition.
Image Credit: Peter Yost
Transferring the shear to interior plywood accomplished two things: It made the switch to rigid foam insulation on the exterior of the gable end walls easy; and the 3/8-in. plywood under 1/2-in. wallboard matched the original lath and plaster depth, making the window trim easy to replace. Note the window exhaust fan; it was run continually during each room's gut rehab to manage dust and dirt.
Image Credit: Peter Yost
Retrofitting continuous barriers is challenging. Rigid insulation with taped seams works as a good air barrier and first layer of the thermal barrier on all of our second-floor ceilings. But because the gable end switches to exterior rigid insulation, there are disconnects along the rakes of the gable end walls.
Image Credit: Peter Yost
Easy foam installation. Seams on the exterior rigid foam were not taped because continuous and taped housewrap will achieve the air barrier and weather-resistive barrier on all second floor gables. The lift was invaluable for us semiretired remodelers: Minimal weight in the tool belt, no "rung-fatigue" on feet and legs, and a golf umbrella clamped to the cage meant completely bearable rainy-day work.
Image Credit: Peter Yost
Only spray foam on a calm day and cover EVERYTHING. The mist during spraying carried quite a distance before falling back to the ground, and it was a nightmare to remove from almost every surface. We didn't have to fret too much about spray foam next to jamb extensions and the like—the expansion ratio for closed-cell foam is only about 20 to 30 times (open-cell is more like 120 times), and, because the foam wasn't confined during installation, there was room to expand outward.
Image Credit: Peter Yost
**Extension jambs shield windows** Keeping the windows in plane of the original wall and extending the jambs out to account for extra insulation thickness shields windows from rain and sun.
Image Credit: Daniel Morrison
Even though the air and thermal barriers flip from the inside to the outside of the exterior walls, every attempt was made to have respectable overlap at these transitions. The ungrouted concrete blocks have still proven to be a problem in getting the building really air tight.
Image Credit: Steve Baczek
A big improvement. 77MMBtu/year. Over the course of 8 years Peter and his family have given this house a complete energy overhaul. Recent blower door testing has helped identify a few problem spots where additional air sealing and insulation could boost the performance even further.

An eight-year remodel of a 100-year old house produces a healthy home that will last another century.

When my wife Chris and I bought this nearly 100-year-old home in 2000, we knew we had our work cut out for us: virtually no insulation; original single-pane windows; a failing main bathroom; just four circuits of knob-and-tube wiring; no laundry hook-up; and a dysfunctional 12×12 kitchen with three windows and four doorways. But the pristine original red birch flooring, the rock maple trim throughout, and the double lot on a quiet street seemed to make the whole thing more than worthwhile. And being a building scientist and former remodeler, I felt up to the challenge. Avoiding re-dos and safety issues We planned each phase of this virtual gut rehab to keep the place healthy (during and after the work), to be as efficient as possible, and to prepare for future steps. This meant managing a radon problem that worsened as the house was tightened up, monitoring drainage issues around the building perimeter, and adding spot and whole-house mechanical ventilation as phases of the project progressed. Integrating mechanical, electrical, and plumbing work was tricky because we tackled the basement, attic, and individual rooms one at a time. Phase 1: Storm windows, wiring, and bathrooms The existing windows were leaky, uncomfortable, and energy inefficient. New triple-track, low-e storm windows from Harvey Industries gave us nearly instant improvement on all three of those fronts and reduced traffic noise as well. Eight years later, the enameled-frame storms still operate as if they were brand-new. We rewired the whole house before insulating or air sealing and kept penetrations in exterior walls to a minimum. Because interior walls weren’t all affected at the same time, we had to consider how subsequent phases would line up and wire accordingly. Both bathrooms had exterior walls that needed attention. We wanted to use insulating sheathing on the outside, and we found that adding interior plywood sheathing gave us the access and shear strength we needed to do the job right. Phase 2: Attic, then basement Particularly in cold climates, stack effect can drive basement moisture and soil gases up into the living area. Air-sealing and insulating the attic before tackling the basement is almost always the best way to deal with this. With the wiring done and the new bath exhaust fan in, we had a relatively easy time sealing attic penetrations before criss-cross layers of cotton batt insulation went down. After a full year of moisture monitoring and simple observation, we found that the basement walls were just a bit damp after the hardest spring rains, but we never saw any liquid water. This gave us confidence that 2×3 studs and vapor-permeable open-cell spray-foam insulation should be a safe way to to air-seal the basement and bring the whole-wall R-value up to about R-12. Unfortunately, radon readings spiked from 6 pCi/L (already 2 over the EPA action limit of 4 pCi/L) to 12 pCi/L in this now tighter space. In response, we sealed off and insulated the vented crawl space under the front porch (paving the way for the front porch to become a home office), removed a concrete block to have the crawl communicate with the basement, and added a 24/7 high-efficiency exhaust fan. While this didn’t lower the radon readings in the basement, the continuous exhaust ensures that radon readings in the first-floor living space are consistently 2.5 pCi/L or less. Phase 3: SIPS kitchen addition and second-floor bedrooms A 6×20 addition where roof, walls, and floor are all structural insulated structural insulated panels (SIPs) on piers gave us two things: a weather-tight addition in one long day; and a ready-made, weatherproof mudroom just off the kitchen addition. Because the shed roof for the addition came right up against the west-facing second-floor bedroom, we moved to this space next. We gutted, resheathed, insulated, air-sealed, and re-sided the room. As we gutted each bedroom, we pulled the gambrel kneewall spaces into conditioned space for a continuous air and thermal barrier along the more steeply pitched gambrel roofline. This improved energy performance and added about 1/3 more floor space (albeit with sloped ceilings) to each bedroom. Phase 4: First-floor exterior walls Because the concrete-block walls were ungrouted, uninsulated and have many step-cracks, we needed to pull them completely inside or keep them completely outside of the air- and thermal-barrier lines. Chris and I weren’t thrilled with the look of the split-faced block, so it was an easy decision to go with the much easier approach of insulating, air-sealing, and re-siding the exterior. A custom system of 2x2s bolted to angle brackets screwed into mortar joints created a space for three inches of high-density spray-foam insulation plus an air space. The surface of the foam now serves as a drainage plane, and finger-jointed, preprimed cedar lap siding covers it all up. A 10-in. shed roof bridges the transition between the second-floor walls and the now-thicker first-floor walls. Along the way: sash weight pockets and HVAC As we renovated each room, we pulled out the old single-pane windows and installed double-pane replacement sashes. Before everything was closed up, we insulated and air-sealed the often-overlooked but very important sash weight pockets. We replaced the aging 75% AFUE forced-air furnace with an 88% AFUE boiler. This allowed us to add a 40-gallon superinsulated indirect water heater and hydronic heating in the kitchen and downstairs bath/laundry. Because we decided to stick with fuel oil, the new boiler had to be atmospherically vented (there are no sealed-combustion residential fuel-oil boilers). This means that the 24/7 exhaust ventilation/radon mitigation fan had to be dialed in to avoid back-drafting the boiler. Eight years later: improved comfort, IAQ, and utility bills Patience, planning and eight years of “working vacations” gave us a home that is markedly more comfortable and has better indoor air quality and lower utility bills than when we bought it. It looks better, works better, and has more living space to boot.

Lessons Learned

We feel pretty fortunate. The problems with the original house kept it on the market for a long time and meant a really good purchase price for us. And the money we put into performance upgrades brought the cost pretty close to market value of any old house in our area.

We confronted many challenges and learned quite a few lessons along the way. The replacement sashes didn't work well with our out-of-square jambs, so more than a few windows are still leaky where they don't make continuous contact along the sill. The SIPs kitchen floor is just as high performance as the roof, but in the middle of winter, walking from the uninsulated floor with basement below versus walking on the SIPs floor is quite a shock; more insulation is needed to offset the floor being on piers over outside air.

Perhaps the biggest disappointment is in the air-tightness of the home. Despite careful planning of the overlaps of insulation and air-sealing systems, there is still a lot of untraced air leakage. Continuous pathways in the ungrouted block walls and tricky details at the four gambrel valleys are the likely culprits - more-targeted blower door testing should give us a better idea. As with most old homes, this will always be a work in progress.

General Specs and Team

Location: Brattleboro, VT
Bedrooms: 3
Bathrooms: 1.5
Living Space: 1800
Additional Notes: Construction cost: approximately $85,000; roughly 75% of labor was free (homeowner and family)

Construction/wiring: Peter Yost, Christian Yost, Israel Yost, Nathan Yost (sort of a New England version of Brothers Strong)
Plumbing and heating: Temple Plumbing and Heating, Dummerston, Vt.

Architect: Steve Baczek, RA


Walls (first floor): concrete block; uninsulated
Walls (second floor): wood frame; uninsulated
Windows: single-pane double-hung wood
Roof: unvented slope (steeper pitch of gambrel), vented attic (lower-pitch gambrel); old, loose-fill fiberglass in very poor condition (approx. R-5)
Basement: Uninsulated cast-concrete, broken concrete floor (one section of bare dirt); vented front-porch crawl space with bare dirt; single-pane awning, divided-light windows
Garage: detached

Foundation: basement, 3-1/2-in. open-cell spray foam in stud wall (R-12); crawl space, unvented 1-1/2-in. polyisocyanurate insulation board on perimeter walls sealed with approximately 1-in.-thick spray foam, double 6-mil poly sealed to perimeter walls (R-10)
Walls (first floor): 3-in. high-density, closed-cell spray foam on exterior (R-20+)
Walls (second floor): 2x4 studs; 3-1/2-in. fiberglass batt and 1-in. XPS insulation board (R-17+)
Windows: ;ow-e, double-glazed, wood-framed (U=.33, SHGC=.32)

Roof: sloped ceiling, R-19 fiberglass batts with interior 1-in. XPS (total R-24); flat ceiling, interior 1-in. XPS, criss-crossed triple-layer batt insulation, one fiberglass, two cotton batt (total R-value: 44+); cathedral ceiling in kitchen addition, R-38 polyisocyanurate 5.5-inch SIPs
Garage: detached (no change)


  • 88% AFUE fuel-oil boiler
  • Superinsulated stainless-steel jacketed indirect-tank water heater
  • Under-counter LED kitchen lighting
  • CFL or hard-wired throughout home (except three cluster fixtures in living/dining room and kitchen
  • Energy Star ceiling fan in master bedroom
  • No central air conditioning

Energy Specs

Pre-remodel K-factor
(number of heating degree days covered by one gallon of fuel oil): 7.5
Post-remodel K-factor: 15.85
Pre-remodel blower door: > 4,000 cfm @ 50 Pascals
Post-remodel blower door: 1,240 cfm @ 50 Pascals (still working on air-sealing issues)
Annual energy use: 77 MMBtus/yr (pre-remodel not known)

Water Efficiency

  • Energy Star dishwasher
  • Front-loading clothes washer
  • Low-flow toilet: 1.0 gpf pressure-assist
  • Hands-free electronic kitchen faucet

Indoor Air Quality

  • High-efficiency spot exhaust fans in kitchen and baths
  • High-efficiency 24/7 whole-house exhaust
  • Carbon monoxide detector in basement next to boiler

Green Materials and Resource Efficiency

  • Non-paper-faced gypsum board on all walls
  • Driveway redone with free-draining, locally quarried bluestone
  • All structural wood removed from home during renovation salvaged
  • 2x3s (basement) and 2x2s (reclad system first floor) ripped from ReNew salvaged lumber
  • All interior trim reused
  • Bedroom and kitchen shelving made from salvaged school furniture

Alternate Energy Utilization

One Comment

  1. charlie_sullivan | | #1

    Peter, I would be interested to hear whether open cell spray spay foam below grade is still something you would recommend, and whether you have have looked at whether it and the studs embedded in it have stayed dry, particularly near the bottom.

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