Photo Credit – Sita Rupe
Builder – John McBride
Posted in Design Projects, tagged angles, art Studio, cedar, charred cedar, garden, LED, lighting design, Oakland, rainscreen, shou sugi ban, small buildings, tiny house, wood on January 30, 2017| Leave a Comment »
Photo Credit – Sita Rupe
Builder – John McBride
The garden is going in on this Oakland project. Time to go take some pictures. (Thanks to the owner for this preview)
John Mcbride photo. (He’s calling it Darth Vadar’s house.)
This 1972 budget modern house needed a tune-up. In the process of replacing the windows & siding, adding insulation, replacing the double level deck, and adding exterior window shades and a bright red-orange awning on the NW & SW sides, we also rearranged things and made the floor plan work better. That was the most satisfying part of the project, but it is hard to show it in photographs. Type “Navellier” in the search box to the right for photos of the process.
Here are some photos after construction:
I went on another tour of a couple of passive houses under construction in the San Jose area. The two were very different from each other. The first is a remodel, designed by Thamby Kumaran with energy modelling by the owner-builder, Scott Heeschen. It uses a lot of salvaged redwood for the rainscreen siding, a mixture of Marvin Integrity and Serious windows, and rainwater catchment. Clearly architecture was a priority, since attics and flat ceilings make it easier to maximize insulation. (Compared to this beautiful vaulted ceiling)
I am curious how the long strip of south-facing clerestory windows will perform in summer with such a minimal overhang.
Casement, awning, and fixed windows were chosen for their air tight seals.
The other house I had already visited in the fall of 2010.
This one is more of a standard high-end spec house, but it seems to be quite technically competent on many levels.
Total Cost: $24522.47 ($204/ SF)
Design: Free (by owner)
Permit Fees: $111.55 (Electrical only, 120 SF accessory building didn’t require a building permit.
Foundation materials: $1425.79 (incl sand, gravel, plastic, 30% Flyash concrete, forming materials, pumping labor, tool rental, rebar, etc)
Building Paper and Flashing: $397.00 (We had to buy the roofing felt twice because the roof installation was repeatedly delayed by rain.
3 Windows & 1 Door: $1720.02 $750 (half price) for the Loewen half glass aluminum clad fir door salvaged from another project. The windows are dbl glazed aluminum= inexpensive. I chose aluminum because It looks good with the redwood. This is a small outbuilding without heat and they work fine, but metal windows have lower U-value than wood, fiberglass and vinyl. It would be hard to justify metal windows in a larger project with a heating system. The glass in the south facing windows is Sungate 500. This is a special glass that is designed to have a high U-value and also a high solar heat gain coefficient. “In winter, Sungate 500 Low-E Glass transmits the sun’s visible light and directs solar shortwave infrared energy into the home. At the same time, it reflects longs wave infrared (heat) energy — like that which comes from a home’s heating system — back into the room”
Paints and Finishes: $544.90 (Penofin Verde, American Pride, Earth Paint, AFM Safecoat, Bioshield) These are not the cheapest finishes, but honestly way more pleasant to work with than the traditional smelly stuff. Ill have to report back on longevity and durability, but so far so good.
Insulation, Sheetrock install and finish (incl labor), Interior Trim (FSC certified): $1609.93
Roof: $2615.93 (galvanized standing seam painted red by Tri Sheet Metal, James Morgenroth) I hope this is a long lasting solution. It was chosen for the clean crisp lines and the cheerful color. I was considering a zinc roof for its infamous longevity advantages, but didn’t find a local installer familiar with the material.
Exterior Siding & Trim: $850.73 (All the redwood siding was milled from logs salvaged from a road widening project in Sonoma County and gifted to the building. (ie free, just involved a lot of labor and $200 worth of stainless steel screws)
The siding is installed as a rain screen with a space behind the siding for ventilation and drainage. The idea is to make everything last longer by preventing moisture from getting trapped and rotting the siding or the framing. I used Penofin Verde, an eco-friendly penetrating sealer on the redwood. I’m hoping that I wont have to reseal it more than every other year. I have used the more stinky petroleum product Marine Grade Penofin on my wood garage doors for several years. It seems to do a good job of protecting the wood, but since they are on the south side without much protection, I reapply every year.
I sealed the exposed fir rafter tails with penetrating epoxy before priming and painting. They should hold up well, but I need to keep an eye on the corner where the high-end rafters meet the wall. I can imagine water running down the underside and sitting in this corner.
Rain protection & Dump runs: $114.66
Tools and bits: $75.87
Landscaping: $1982.88 (brick path by Hornby Garden Design and Construction)
General Labor: $8,004.00 (carpentry, Built-in furniture, electrical, trenching, rough plumbing, etc. Some of this is discounted because it was done by my good friend John Mcbride. This does not include extensive work by owner/designer)
Cost analysis: The door, the roof and some of the lights are expensive. The built-ins were inexpensive, but involved a lot of labor that normally would have cost far more. The unusual shape involved more labor in framing, siding, and roofing. This building didn’t require a permit except for the electrical. Many components that were free would normally have cost a fair bit. The design labor and other extensive labor of the designer also would normally have cost money. For this reason, one should assume that a similar structure might cost at least $36,000, not including design. This would mean $300/ SF.
Things I would do differently or might change later: Insulate the concrete slab, use this sort of window trim detail
Performance: So far the thick and careful insulation (R19 in the 2×6 framed walls and R30 in the roof) and the passive solar features (mainly the south-facing windows with overhangs and a deciduous California Buckeye tree in front of them) perform wonderfully. The building is very comfortable without supplemental heat. On the occasional day that is too warm, opening the high windows works magic. When it is too cold I warm up the room by turning on a few lights and my computer. Sometimes I bring a large dog inside or do 10 jumping jacks to generate some heat. Because of the insulation, the heat sticks around.
Passive house is a fairly new word. This recent evolutionary step in building technology comes from Austria, but many of the concepts are ancient. The basic idea is to insulate really well and eliminate random air leakage and thereby require way less heating energy. Ideally all the heat needed will be generated by occupants, their computers and light bulbs, and the sun.
Pretty simple, right? The devil is in the details. Real Passive Houses also must pass a performance test to prove they actually work.
Nabih Tahan was an innovator on the west coast. The New York Times published an article about Passive Houses a houses in 2008 that mentions his Berkeley California renovation project.
Unfortunately, Nabih’s house failed the blower door test for leakiness, so doesn’t actually qualify as a passive house, but he has measured his energy use over the last two years and it performs extremely well. He had to install electric baseboard heaters to satisfy the building code. He rarely turns on these heaters, but since electric heat is inefficient, (a lot is wasted in transmission) his “source energy load” is slightly over the Passive House requirement. He thinks that he would have qualified if he had used gas heaters.
Here is a picture of Nabih’s Air to air heat exchanger (energy recovery ventilator) from Ultimate Air:
The guy in the picture designed and installed the system. His name is is George Nesbitt, and he has a company called Environmental Design-Build.
Nabih installed redwood rainscreen siding. I think it was made out of the old siding, milled into flat slats. His window details are pretty nice:
It is hard to get good pictures of the rainscreen assembly, but here are a few courtesy of Mr. Canivet.
The point of the rainscreen is to allow air to circulate behind the siding and dry out the backside. This way the moisture doesn’t instead get sucked inwards into the insulation and stud bays and the paper-backed sheet rock when you turn on your industrial kitchen hood. This can cause all sorts of problems. It also just keeps the moisture from lurking behind the siding.
The siding is 5/8″ thick fibercement lap siding. the furring is 1.5″x5/16″ cedar strips, and the drainage plane is good old-fashioned 2-ply building paper. In order to keep insects from building nests behind the siding Guillaume came up with a simple detail using wire mesh and filter fabric at the top and bottom and above and below each window.