Goal: To design and build personal housing that is financially sustainable, energy efficient, beautiful and durable

• Financially sustainable home residence. Rental income on main home will cover mortgage. ADU would generate a $1K/month in rental income (if I were not living in it); the $100K investment roughly translates to an 8.3 year investment payback period.

• Northwest Energy Star certified through Earth Advantage Institute with a projected EPS score of 40 (Oregon EPS avg is 89). This model assumes 6. 5 ACH @ 50 pascals; aiming for 1.5 ACH @ 50 pascals.

• Notable home design features: • staggered stud wall construction, slab-on-grade, concrete floors, • natural gas powered tankless water heater (92% efficient) for hydronic

heating and potable water • heat recovery ventilator (Fantech 1405R)• passive solar orientation (U 0.30 windows)• reused finished materials (doors, tub, sinks, etc)• space efficient design, lofts, exposed beams, and accent lighting.

Overview

799 sq ft. , 2.5 stories. 1 BR, 1 BA, office.

Sketchup Model

As Built (current status)

Selecting a House with an Appropriate ADU Site

• Neighborhood Livability: 71 Walkscore.com• Micro-Neighborhood: grouped yards, funky architectural zone, • Property/Site Selection: house cash flows, canopy to south

Current projected cost for the new construction is $115/sq ft.

Time

Design 2 monthsPermitting 1.5 months Building 4 months (projected)

Wall Assembly (from exterior to interior)• Cedar siding shingles- a naturally water repellant composition. • Rain screen from strips of dimple board,• Weather Protective Barrier- Siga Majvest weather protective wrap and Siga

Wigluv tape for the plywood sheathing joints. • Staggered stud framing. 8 ¾” insulation cavity ; little thermal bridging.• Loose fill blown in fiberglass in cavity- R33

Roof, Slab, and Glazing• The roof assembly will be R44 • Slab on grade floor will be R-15 (using 3” XPS foam) and is thermally

broken from the foundation walls (using 1” EPS foam)• The windows and French door are vinyl, with a U-value of 0.30

Building Envelope Features

Standard wall assembly detail and insulation and air sealing bid

RemRate analysis by Earth Advantage

Projected 39.6 MMBtu Translates to an EPS score of 40. Oregon EPS score average for

new homes is 89.

Materials

Materials

Surprised by the high cost of salvage materials. Often, it wasn’t any cheaper to use salvage. Will use salvage for finish materials:

• Cabinets• Flooring• Railings• Sink • Tub• Doors, etc.

Indoor Air Quality

• Only duct work is short runs for HRV. Pressure and moisture balancing• Open, lofted floor plan will leverage the stack effect and winds to

passively ventilate and cool the ADU - operable windows on East and West sides of the structure.

• All of the floor and wall surfaces in the house will be hard; concrete and hardwood.

• We’re using a high-quality weather resistant barrier in additional to cedar shingles; don’t anticipate moldy conditions in the walls.

Quality Control

• 3rd party certification- Since it’s my primary residence and it’s not for resale, I wasn’t as concerned about certifications for resale.

• Energy Star certification through Earth Advantage pays for itself and offers quality assurance.

• Technical drop-in visits from the Energy Trust subcontractor outreach specialist. Earth Advantage will be conducting a blower-door test to check the air pressure and to help identify any sealing gaps.

• Builder’s contract specifies using Energy Star’s ‘Thermal Bypass Checklist’

Learning Curve and Professional Application

• Document the design build process with a strong focus on ADUs • Observe and execute this first new construction project rather than try to

learn and execute the trades myself• Help other individuals and communities who are seeking to build ADUs.

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