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Case Study

A Fast Kitchen Addition Made With SIPs

Location: Brattleboro, VT

Converting a back portch to living space makes a cramped kitchen roomy — and adds a mudroom to boot

Old houses didn't need big kitchens because they weren't the central gathering spot that today's kitchens are. The 12-ft. by 12-ft. kitchen in the house my wife, Chris, and I bought ten years ago was just such a space: small and dark. It was pretty typical for a 100-year-old New England home, but it was challenging for how a kitchen works in the 21st century.

We needed more space, more natural light, and better placement of the workstations, but the four doors and three windows limited our options. The most logical approach to designing a more functional kitchen was to expand out the back side of the house, but what would the configuration be? It was really helpful to work with architect Steve Baczek, who provided us with about six different options for the locations of major stations: sink, stove, refrigerator, dining, food prep. Interestingly, the layout that looked best involved the least reworking of major systems: space heating, electrical, and plumbing.

Choosing a building system

I have to admit something here: I am a member in good standing of both the Recovering Remodelers Association and the Wannabe Building Scientist Society. I want our home to be cost-effective, safe, and energy-efficient, but if I get to use new techniques, new tools, or new materials, I probably can't resist "experimenting." And I need projects that I can do largely on my own and that are staged according to lots of weekend and vacation work.

I had never built with structural insulated panels (SIP) before, and the kitchen/mudroom addition seemed like a perfect fit with a pier foundation I could do on my own. I knew that the toughest part of SIP construction is air sealing the panel joints, so I went with our local Winter Panel system because I like the panel joint detail the best and because the company manufactures polyiso foam panels, the highest R-per-inch on the market.

Resource efficient by design

Perhaps the trickiest part of this project was working out the dimensions to fit the existing west wall configuration and to minimize SIP cutoff waste. We pushed the addition just as far as we could to the south, right up against the downstairs bathroom window. This meant a pretty tight mudroom (6x6 outside dimensions), but it made the overall length exactly 18 ft., a 2-ft. module. In terms of the width, we had to honor the distance to the detached garage and make sure that the shed roof of the addition could still tuck under the existing rake of the west gable on the north end. It turns out that a 6-ft. width gave us the 2-ft. module on the floor, walls, and roof panels with a 4-in-12 pitch. It would be really tight at the north corner of the addition at the existing rake, but we double-checked this several times and even did a rough mock-up to ensure we had the room. We also ended up with less gypsum board cutoff waste on the interior.

The new home center

Our family has gone from avoiding the kitchen to living in it. The new space is great not only for cooking and dining, but also for homework and family game night. The large island draws the new and old spaces together, and the mudroom is a great weatherlock all year round. Although the kitchen addition and other work on our home have expanded the conditioned space by about 20%, our energy bills continue to decline each time we tackle yet another high-performance renovation.

Lessons Learned

An R-38 floor is still cold
The heat loss from the R-38 SIP floor in the addition is no greater than the heat loss from the R-38 walls and roof. The only problem is that we don't walk on the walls and roof. When we step from the kitchen floor over the basement to the kitchen floor of the addition in the middle of winter, the 5+ degree surface temperature drop is more than a bit uncomfortable in a home with a no-shoes-inside policy. Just as soon as I can get the lumber stock off the racks I built under the kitchen addition, I will be adding another layer of polyiso rigid insulation to the underside of the kitchen addition floor.

Too many windowsIn the kitchen (and the front home office, for that matter), we went with large double-hung windows (2.5 by 5) in the addition, with a pattern that matches the existing kitchen window layout. That adds up to 25% of the total exterior wall area of the kitchen, and it is simply too much. We love the way the banks of windows make the kitchen feel, but the heat loss in winter and solar gain (especially to the west) in summer is a feel we like a lot less.

If we had it to do over again, we would take out at least one if not both of the west wall kitchen addition windows. On the other hand, maybe really high-performance window treatments for both heat loss and solar gain will be available soon and give us the best of both worlds.

General Specs and Team

Location: Brattleboro, VT
Living Space: 250 sqf
Cost: $70/sqf
The original kitchen was 144 sq. ft.; the addition is 72 sq. ft. of kitchen space and 36 sq. ft. of mudroom. The approximately $18,000 cost of the kitchen addition/renovation does not include the author's labor or the appliances (stovetop, oven, refrigerator).
Construction crew: Christian Yost, Tom Henze, Ron Benson, Dave Gauthier (Winter Panel), Peter Yost
Roofing: Walker & Sons, Hinsdale, N.H.

  • Construction
  • Foundation: Concrete piers, Parallam beams
  • Floor, walls, roof: 6.5-in. SIPs
  • Wall cladding: Back-vented, factory-primed, finger-jointed cedar lap siding
  • Roof cladding: Galvalume standing seam metal roofing
  • Windows: Marvin Integrity double-hung metal-clad wood
  • Energy
  • Windows: U-factor = 0.32; SHGC = 0.28; VT = 0.48
  • Floor, walls, roof: R-38 polyisocyanurate foam
  • Refrigerator: Energy Star Amana (bottom freezer)
  • Water Efficiency
  • Kitchen faucet:Brizo SmartTouch electronic touch/motion sensor activation
  • Dishwasher: Energy Star Frigidaire
  • Indoor Air Quality
  • 150-cfm high-performance Fantech exhaust fan
  • Green Materials and Resource Efficiency
  • Pier foundation
  • Salvaged maple trim
  • Kitchen cabinets reused in garage and basement
  • Kitchen sink donated to ReNew Salvage for resale
  • Existing stove reused in family apartment complex
  • Locally quarried and finished granite countertop

Image Credits: Daniel Morrison, Peter Yost, Steve Baczek

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