Image Credit: All images: Hammer and Hand The wall assembly at the Courtland Place Passive House. The wall assembly at the Glasswood project. The wall assembly at Karuna House. The wall assembly at the Maple Leaf project. The wall assembly at the Puget project. The wall assembly at the Pumpkin Ridge Passive House.
Our construction company, Hammer & Hand, has built several wood-framed Passive House buildings in the Pacific Northwest. Over the years, our approach to building high-R walls has evolved.
Drawing on six projects from the pool of high-performance buildings constructed by Hammer & Hand, I will examine how each of five wall assemblies approached the issues of performance, cost, land use, and durability. These case studies will also chart Hammer & Hand’s move toward developing details that are more familiar to the building community and easier to assemble, as high-R walls transition from unusual oddities to common practice.
The five projects are:
- Courtland Place Passive House – a fun carpenter’s puzzle with a minimal budget
- Glasswood Commercial PH Retrofit – a Passive House retrofit of a commercial building
- Karuna House – a high-design, high-performance showcase
- Maple Leaf Passive House and Puget Passive House – projects that moved us closer toward standard practice
- Pumpkin Ridge Passive House – “Let’s do all cellulose!”
Courtland Place – a carpenter’s puzzle with a minimal budget
This personal project of Hammer & Hand’s Dan Whitmore focused on achieving the Passivhaus standard with a small budget, using readily available materials and the strengths of the building team to realize complex carpentry details.
The Courtland Place wall assembly is illustrated in Image #2, below.
Wall structure. This house sits atop an insulated slab on grade, with the wall cantilevered out to meet the exterior edge of the perimeter EPS and minimize thermal bridging at the foundation wall intersection. Dan used a wall truss whose interior chord bears the structural load and shear of the building. Like a Larsen truss, the exterior chord carries the faÃ§ade of the building and establishes the insulation cavity.
Air barrier. The shear panels (OSB) at the inside face of the wall truss form the air barrier, with panel junctions sealed with tape and sealants. (Note: placing the air barrier in this exposed location left it prone to damage from occupants. Though it saved on construction cost, Dan does not recommend the strategy to others.)
Moisture management. Bulk water is addressed at the cladding with a true ventilated rainscreen and a water-resistive barrier (WRB) over Homasote, a highly permeable exterior sheathing. The wall is vapor-open to the exterior. (Of course, diffusion can go in either direction.)
Insulation. 14-inch deep dense-packed blown-in fiberglass, completed in one pass.
Adaptability. This wall assembly is easily adapted to meet the specific performance requirements of any given project. Altering the dimension of the gusset spanning one chord to the next changes the depth of insulation.
Cost. As this project enjoyed very low costs for skilled labor (mostly Dan’s sweat equity, as this was his personal project), it was biased toward labor-intensive solutions over moderate- to high-cost materials in order to meet its budgetary targets. For our typical client, this would not have been an appropriate balance.
Land use. While this wall is fairly thick, choosing dense-packed fiberglass over cellulose helped reduce the wall thickness by 2 inches. In the end, the wall thickness has a moderate impact on the footprint of the building.
Glasswood – A Passive House retrofit of a commercial building
This retrofit of a 100-year-old commercial structure was an unusual project for us. Our goals were to reuse and reinforce the existing structure and achieve Passivhaus certification on a tight lot (and therefore with minimal added material outboard of the original wall face).
The Glasswood wall assembly is illustrated in Image #3, below.
Wall structure. We added shear panels to the exterior and a secondary interior framed wall for additional insulation. To meet fire code requirements, we installed DensGlass exterior gypsum sheathing over the layer of rigid exterior insulation.
Air barrier. The secondary sheathing layer on the interior face of the existing wall, taped at all panel edges, serves as the air barrier. It connects to the same material across the floor and across the ceiling to form a continuous center-of-the-wall air barrier. This air barrier layer is sandwiched between two 2×4 walls, both insulated with high-density cellulose. The interior 2×4 layer acts as a service cavity. The outboard 2×4 layer is the original wall and serves as the structure.
Moisture management. Exterior Hardie siding handles bulk water with a 3/4-inch ventilated rainscreen cavity. Per Building Science Corporation recommendations, we used Douglas fir furring strips in lieu of pressure-treated lumber in order to minimize environmental impact and construction costs. The WRB is a combination of the Prosoco R-Guard system at punched openings, integrated into a VaporShield membrane installed over the DensGlass. This wall will mostly dry to the interior, though it is open to the exterior through the thinner layer of EPS and ventilated rainscreen cavity. Interior moisture conditions are monitored through the ventilation system to ensure that vapor is not driven into the assembly from interior spaces.
Insulation. 2 inches of EPS exterior insulation, with 7 inches of dense-packed cellulose in the two wall cavities. This was a compromise. We originally planned for 2 inches of high-density mineral wool; however, the municipality was not comfortable with the information on this product’s fire rating.
Cost. Because this was part of a full building retrofit that involved bringing a historic building up to commercial code, the added expense of reaching the Passivhaus standard was nominal.
Land use. Due to the tight site, the 2 inches of EPS on the exterior of the existing wall and 7 inches of cellulose inside the wall made Passive House performance possible without increasing the building footprint appreciably.
Karuna House – a high-design, high-performance showcase
Our main project priority was to make this beautiful and complex design perform as a passive house.
The Karuna House wall assembly is illustrated in Image #4 at the bottom of the page.
Wall structure. A standard 2Ã—6 stick-framed wall is integrated into a larger steel structural skeleton. Due to the structural requirements of the exterior stucco cladding, the engineer required a Z-joist detail to transfer the load across the 6 inches of exterior polyisocyanurate insulation. This Z-joist assembly carries through to areas where the house is clad in cedar, as well. [Editor’s note: Sam Hagerman uses the term “Z-joist” to refer to a type of site-built stud (a variation on the Larsen truss) assembled from 5/8-inch plywood and strips of softwood lumber, as seen in the photo at left. To see how these Z-joists are used in the Karuna House wall assembly, consult Figure #4 at the bottom of the page.]
Air barrier. The exterior sheathing is coated with the Prosoco R-Guard system to create the home’s air barrier.
Moisture management. Bulk water is handled by a combination of cedar and stucco claddings with rainscreen cavities. The WRB is provided by the foil-faced exterior insulation, taped at all seams. The Prosoco system provides a secondary layer of bulk water protection of the structure. The wall dries to the interior.
Insulation. 6 inches of foil-faced polyisocyanurate wraps the building, and 5.5 inches of dense-packed cellulose forms the thermal layer inside the 2Ã—6 wall cavity.
Cost. This was not a budget-driven project, though the Passive House “intervention” had to be cost-effective. In the end, making the home perform as a Passive House cost less than 2% of the project budget.
Land use. The footprint of the house was not a concern. That said, the final wall thickness is just moderate.
Maple Leaf and Puget – projects that moved us closer toward standard practice
At these projects, we used standard materials and established trade practices to build cost-effective Passive House wall systems.
The Maple Leaf wall assembly is shown in Image #5, below. The Puget wall assembly is shown in Image #6.
Wall structure. For both projects, we used 2Ã—8 stud walls in order to establish a thicker wall cavity without the additional labor involved with a double-stud wall application.
Air barrier. Structural sheathing, sealed at panel edges, forms the air barrier. Due to field experience, we moved to Prosoco liquid-applied sealant in lieu of tape.
Moisture management. In both homes’ wall systems, we installed fiber-cement siding over a 3/4-inch ventilated rainscreen cavity. A membrane establishes the WRB over the rigid exterior insulation. At the exterior sheathing layer, a secondary WRB protects the structure. In the Puget house, we established this secondary WRB using Prosoco R-Guard. Due to lower exposure and budget constraints, we used Zip sheathing with its integrated WRB to establish the secondary WRB at the Maple Leaf house. The exterior rigid insulation (paper-faced polyisocyanurate) has a vapor-open covering, so vapor can move out to the ventilated rainscreen cavity or into the interior of the building.
Insulation. Paper-faced polyisocyanurate exterior insulation wraps each building (3 inches at Puget and 4 inches at Maple Leaf), and 7.25 inches of dense-packed fiberglass insulation forms an additional thermal layer inside the stud wall cavity.
Cost. The additional cost of exterior insulation, and the lengthy fasteners therefore needed for the siding assembly, was moderate. The time to build the assembly, and therefore the labor cost, closely tracks standard construction expectations.
Land use. With the higher performing R-value of the exterior polyiso, these assemblies have shaved a few valuable inches off the wall thickness and building footprint — an important “win” in their urban settings.
Pumpkin Ridge – “Let’s do all cellulose!”
For the wall at the Pumpkin Ridge Passive House we set out to do a low-embodied energy insulation package, partly to offset the global warming potential (GWP) of the EPS required in the foundation (necessary to handle sloped site conditions). We were also committed to keeping costs low enough that client utility bill savings could pay for any added mortgage service due to those high-performance building costs.
The Pumpkin Ridge wall assembly is illustrated in Image #7, below.
Wall structure. We used standard 2Ã—6 wall framing with a Larsen truss system using I-joists. The outer exterior sheathing layer uses Agepan fiberboard.
Air barrier. The air barrier was easily established at the sheathing layer with liquid-applied membrane at the seams.
Moisture management. Bulk water is managed with exterior cedar cladding over a 3/4-inch ventilated rainscreen cavity. The WRB is provided by the wax-impregnated Agepan sheathing. As a cellulose-based, diffusion-open wall, vapor can readily leave the assembly in either direction.
Insulation. With a total of 15 inches of blown-in cellulose in the 9.5-inch Larsen truss cavity and the 5.5-inch-thick interior stud bay, the building boasts a very robust, low-embodied-energy thermal envelope.
Cost. The ease of installing the I-joist and Agepan combination (and lower labor cost) mitigated the potential complexity of the Larsen truss application and the material costs of the I-joists and Agepan sheathing.
Land use. Land use was not an issue due to the large site, which allowed for a thick wall.
Client preferences, site constraints, and buildability
In reflecting on our approaches to these different wall assemblies, it is clear that the primary driver of design and construction decisions for Hammer & Hand continues to be client preference and site constraints. However, buildability — in terms of time, money, and resilience — will always be an important consideration, and may be the most important one for other builders.
If the client prefers a building with the lowest embodied energy possible, then stick-framed, exterior Larsen trusses with TJIs, Agepan sheathing, and blown-in cellulose insulation is a fantastic solution.
If, however, the project sits on a compact site and is bumping up against zoning restrictions, then the higher performing, and therefore thinner, exterior insulation options (like polyisocyanurate) become a better choice.
As the industry moves toward monolithic exterior rigid insulation in general, it’s a simple process to just thicken up that exterior layer a bit. Both Maple Leaf Passive House and Puget Passive House are good examples of this approach.
The buildability of each of these wall sections may differ from one practitioner to another. It is important to do a back-of-the-envelope parametric analysis of all the above factors, including climate considerations, to determine what the best wall assembly is for each project. The power of a performance-based building energy standard is that it allows the designer and builder freedom to optimize the assembly, taking into account all of these factors.
Sam Hagerman is president of Hammer & Hand, a construction company with offices in Seattle, Washington, and Portland, Oregon. He was also the inaugural president of the Passive House Alliance U.S., and continues to serve on the board.
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Best practices Manual
Very interesting blog - and thank you for making your Best practices Manual available on the Hammer and Hand site. A really invaluable resource.
Thanks for sharing this information with us Sam. You guys have accrued some good experience in the Passive House field and we apprecite you sharing your knowledge with us. I'm realy intrigued by the cost effective wall assemblies as that`s how we're going to make the greatest impact; bringing high performance buildings to the masses.
Keep it up
I wish more companies shared as much information as you guys. I subscribe to your YouTube channel and always enjoy the new videos. It's great learning material and I bet it's good marketing too.
I wish real dollar amounts were given instead of a broad & generic generalization.
These wall assemblies don't look inexpensive and I can see a builder/GC viewing these build-ups and dollar signs appearing everywhere. Out here it's 2x4 or 2x6 with R-13 or R-19 fiberglass batts, OSB in some places, 1.5" of EPS rigid foam and stucco. Anything outside of those parameters and you are in trouble both financially and structurally since nobody out here knows how to build such wall structures. If you gave these wall build-ups to a GC with no experience in doing such build-ups, they would charge you an arm and leg and learn on your dime.
I do remember seeing price per square foot on some of these projects and they were easily breaking the > $200 per square foot and that did not include the cost of the land, infrastructure or any extras.
These guys know what they are doing and are great carpenters, no doubt about that. It is a niche market though. Dropping close to a million dollars on some of these homes.
It would be nice to see real cost #'s to build these types of assemblies....
The more relevant cost number is ...
... the total financing + energy use costs for the place, not the construction cost per square foot.
For PassiveHouse homes the mechanical system costs go to near-zero, so there is some cost trade-off. But in most places it's now possible to build Net Zero Energy homes for less than what it costs to build a Passivehouse, and thus Net Zero usually a stronger financial rationale.
In California it has been sufficiently well vetted on a cost/benefit basis that Net Zero Energy will become code-min for new residential construction beginning in 2020. Someone building a house in California right now would be wise to build it "Net-Zero-Ready", even if they don't install the rooftop solar part until later (maybe after the installed cost hits the $2/watt range, or maybe sooner.) In locations a lot colder than CA (&/or with much cheaper energy) that may not make financial sense, but those places are becoming fewer every day.
The price trajectory of PV solar is still pretty steep- steeper in recent years than the 30 year or 40 year price curve (which has had a 22% "learning" rate, that is, every time the installed base of solar doubles, the cost has been reduced 22%. The learning rate since 2010 has been something like 40%, and it has crossed a threshold where the world installed base of PV is doubling in less than 2 years.) Soon the limiting factor for Net Zero Energy homes will be how efficient the building envelope has to be in order to fit enough PV necessary for Net Zero on the roof. This varies by climate & insolation, the efficiency of the PV, and the efficiecies of the mechanical systems. Commodity PV currently runs about 15% efficiency, but for a 25-50cent/watt premium 20% efficiency goods can be had, which reduces the amount of roof area needed, and thus the efficiency of the building that is needed. The efficiency of the mechanical systems also play a part, and heat pumps are continuing to see year-on-year improvements. The building envelope necessary for Net Zero today is quite a bit higher performance than what it will take in 2020 or 2030. The ideal balance point between building envelope cost & efficiency and systems costs & efficiencies is a moving target.
But few have ever complained about their home being TOO well insulated, eh?
Response to Dana Dorsett
You wrote, "For Passive House homes the mechanical system costs go to near-zero."
Many people wish that were true -- but it's not. Most of these homes have $8,000 Zehnder HRV systems -- and that's just the ventilation system, before we talk about heating, cooling, and domestic hot water.
Every analysis I've seen for actual Passivhaus buildings in North America show that the cost of the mechanical equipment is equal to, or more than, the cost of the mechanical equipment in a tract home. Passivhaus fans respond by saying that they get better comfort -- which is true.
What they don't get is cheap mechanical equipment.
Apples to Apples
To get any useful comparative data the cost of land and infrastructure needs to be left out. They are variables that are in no way influenced by the construction techniques used.
Zenhder, its complexity ( many house of labors ) and the markup from the installers
is what brings this air exchanger to ridiculous prices.
Way too complex for nothing unless you've got a very large house , which then defeats the hole purpose of PH building.
But you know how it is, PH here in NA is only half built for the right reasons,
the remaining half is " GREEN FLASH " and Zehnder stuff looks great in a machine room!!!!
As far as i know, the HRV only needs to be "balanced" by a pro with a report
and have efficiency of over 75% , its not like there are no other choices on the market now.
Dana: building NZ in California like climate is a joke.
So it should be mandatory.
partly to offset the global warming potential (GWP) of the EPS required in the foundation
Some of those assemblies would be a miss in cold climate.
It is always interesting to read about different wall systems.
I do wonder about the labor cost involved in the complex ones though.
Good blog, thanks for sharing knowledge!
Good point (response to Martin, #6)
Builders of PassiveHouses in the US tend toward the upscale, and arguably gold-plate the mechanical systems (some of the ventilation systems alone in some of these houses would exceed the budget for a tract home), but not all have taken it that far. It doesn't take an $8K Zender to properly ventilate a home, nor is it needed to hit the efficiency numbers.
"Near zero" is of course an overstatement, but compared to $40-75K of micro-zoned ground source heat pump that the very well-off might have paid for a code-min house the mechanical systems for even a gold-plated PassiveHouse are but a fraction of the cost.
Jin: "building NZ in California like climate is a joke."
Not so. California spans US climate zones 2 through 6- it's not all sunny beaches & orange groves.
That might be close to a joke in San Diego or Los Angeles, (coastally tempered US climate zone 3) but much less so in Truckee or South Lake Tahoe (US climate zone 6 east of the Sierra Nevada, where "warm" winter breezes coming over the mountains dump 3-6 feet of snow on them before it gets cold again.) These places have comparable heating degree-days to northern Vermont or southern Quebec locations, and a LOT more snowfall to complicate designing houses for resilience.
HRV & ERV - Alternatives
As mechanical ventilation becomes mandatory through the adoption of the 2012 IRC, more and more competition will flood the market. This will give Zehnder systems a run for their money. I can easily see systems drop into the $3k range instead of the current $8k range that was quoted here. There are other systems out there and they are lower priced than Zehnder. Some internet searching and it will turn up some options.
Reply to "Cost?" by Peter L
Thanks for your thoughts. Indeed all of these wall assemblies save one are in buildings that are more than $200 per square foot, although less than $250/ft in some cases.
But the wall assemblies have very little to do with the square foot cost.
Complex design/engineering, high dollar finishes and every-project-a-prototype are the real cost drivers. Dana is largely correct that the longer term operational costs make up any difference in the initial construction costs between code and Net Zero Ready, Passive House. It doesn't help that my firm ONLY builds projects that have an architect involved. That is my choice.
Driving costs down to a more affordable level is here. As Madge said "you're already soaking in it." As the valuation community is drug along by the nose ring to recognize the value of this type of building, we will see the question turned on it's head. Furthermore, we are only one or two significant spikes in energy costs away from the conversation turning to "I can't believe we ever thought we could build such crappy buildings. I hope.
If builders' complaints about things becoming to difficult and expensive to build governed our actions, we would be living in single wall wood houses with no plumbing, electrical heating (besides fire probably). And very few windows. And rocks for a foundation. Did mention the going #2 outside part?
These projects may be a little more expensive right now, but the perception of value is shifting and the building practices are becoming more commonplace.
In the meantime, criticizing projects like this for being unrealistically expensive is like criticizing a lighthouse for being too bright.
The reason why the 200$+ building only cost is criticized is because this kind of price point severly limits the quantity of families that can afford PH type buildings and nullifies the hole point of PH buildings.
We are supposed to try and reduce energy consumption all together, not on 0.001% of buildings.
It has to start somewhere, but using a 8000$+ HRV system and building a 300 000$+ house is not how it is going to work.
Tell us, of all your PH projects, was a single new homeowner/family financially relieved by the reduced energy consumption ? Or did they spend more on the additional building costs than what they will ever save?
Unfortunately, most will only be forced if economical reasons pushes them to do so.
Your clients and probably most of all current PH buildings in NA are probably environmentally conscious humans that were able to afford more efficient live style .
( did i really type that?? able to afford more efficient livestyle ... ouch ...i'll drink a few beers tonight i guess )
At the end, the only thing current PH buildings in NA will achieve is raise the consciousness and interest of everybody on high performance buildings, better than nothing for now.
That said, thanks again for sharing knowledge :)
Dana : most of CA is zone 3-5 ... that is what i was referring.
Don't bring micro climates just to push your discussion sifu :p
zone 3-5 = walk in the park = mandatory ASAP
Reply to Jin
I think the big benefit to PH, NZ and the like is the inevitable trickle down effect that we'll see. Not many years ago, the new guy on the crew stuffed the 2x4 cavity with fiberglass batts, because any fool could do it. Dense pack cellulose was unheard of. House all needed to breathe. IAQ was not a concern. When I built my first house in the 70's, insulating the foundation would have been laughed at. My new house, under construction now, won't be certified by anyone, but certainly includes many of the concepts developed by PH, et al.
Now, many builders realize the benefits of building a tight house, of IAQ, slab insulation, etc. The extremes of PH may never be incorporated into every house, but the general concepts probably will.
Thanks for posting the wall details
I can guess at the labor and material costs... would be nice to have that posted.
As to $200/sqft most of what I have done is more than that for much less wall.
Windows and doors over $100,000
Kitchens starting at $75,000 and up
Bathrooms that are over $25,000
2000sqft of tile
3500sqft of wide plank hardwood flooring
Solid panel doors 22 in a home
3 zones HVAC the zoning upcharge alone is 5-10K
Glad the CAPTCHA doesn't ask for the square root of i
How do any of you build for $100-200/sqft?
I've seen PH Certified entry doors selling for $7,000 - $20,000! I've seen quadruple pane windows being put on a 5,000 sqft home and homes with 36" of EPS foam under the slab in a Zone 5 climate. Who can afford this stuff?
It all goes back to the same mentality when rich celebrities fly around the world in private jets, live in 10,000 sqft mansions, own gas guzzling limos and SUVs, but then drive a hybrid when going to pick up their Starbucks coffee. This somehow absolves them of their "polluting sins", a sort of "indulgence" if you will, going back to the Roman Catholic days when kings/rulers would murder innocent people and then pay the pope for the remission of their sins.
One would think that a green building forum would embrace these high-R homes and these R-80 wall assemblies (another thread on GBA) but the reality is that most of the people here are not "buying it" because it's really not about being green but about THE GREEN $$. This stuff is out of reach for 95% of the population.
Congrats to the homeowners who can afford these builds and congrats to the builders who are making a good living building these homes but the reality is that most of this is financially out of reach for the majority of our population.
The last two houses I designed came in at $130 to $140 a sq ft. Nothing really high end. Ikea kitchens, basic hardware etc. The exteriors were a mixture of cedar and metal. Ceilings on the upstairs were fir as were all the doors and trim.
So a Zendher or German windows would be a significant addition to the budget. A full on Passive House build is out of the question. It isn't a matter of telling the client they have a choice between that and granite countertops or Miele appliances, they aren't getting them anyway. But as Stephen Sheehy said, incorporating a slimmed down version of one of the walls shown might well be one of the trickle down effects that my clients might go for. The question is whether these useful trickle downs are going to come from common sense construction innovation or through Passive House standards.
$130/sqft not possible here unless super super sharp pencil use.
Not possible today here... just the rain gardens "keeping all water on the lot" cut out affordability. And this water not leaving the property idea is nuts. Property water is not a pollution. Nuts. I am a tree hugger but the average tree hugger is nuts. They are follower fools, not independent thinkers and are driven by emotion not logic. Some trees produce some great nuts. Some people eat grape nuts... I just think nuts nuts nuts. Why? Just attended a massive expensive town meeting which has to do with the town future... engineers conducting it... good thoughts... the town folks input.. nuts.. all emotion... feel good nonsense. Nuts. Can you tell how I feel about this? Anyway, I am not being silent about this and am going to make way more noise than the fools. The loudest idiot gets his way, so I will be that idiot. Just be glad you don't work for my town so you don't have to put up with me.
Speaking of nuts... how are those bears doing and the nut trees and windmills in VT?
What do town governments do? They pass stupid zoning laws and have unelected boards review plans for building. Your nosy neighbor sits on these nosy boards. What color is the home going to be? Stupid stupid stuff.. Oh it's about lifestyle and community harmony and property values... NO.. it's about minding your neighbors business. Nosy and nosey both correct spellings... FYI
So building house boats next. No building permit!! I love the idea. And I they could be left on land I bet. Since it's a boat it's not a "structure" and we are allowed 3 boats on our land. Not allowed to set up a tent or live in a RV but that paragraph doesn't mention boats. As often as a law takes from us it leaves neat loopholes... gotta love the millions of laws on the books.
Way off on a tangent
great sharing of info
I'd like to thank Hammer and Hand for the effort they have put into sharing their know-how. The videos on YouTube are fantastic, for example. Many of the techniques that are detailed are can be incorporated into projects with relatively modest budgets.
Cool California zones
Jin: "most of CA is zone 3-5 ... that is what i was referring.
Don't bring micro climates just to push your discussion sifu :p
zone 3-5 = walk in the park = mandatory ASAP"
The zone 6 portion of California covers more than half the size of the state of Connecticut- it's not a micro-climate zone. There are higher altitude parts of CA such Mammoth Lakes (the town closest to the Mammoth ski resort) has a US climate zone 7 type climate. But since development in climate zone 7 parts CA tend to be smaller isolated areas, they are arguably considered a micro-climate zones. But not the zone-6 region- it a has a significant number of towns and overall development.
Net Zero energy in zone 5 would also not be aptly described as a "walk in the park", and the zone-5 fraction of CA is pretty large area- wise. (It might be lower in overall population than the zone 6 region though.) The new building code presents a real-enough challenge, and will affect where/how future development occurs, given that the cost of Net Zero will be much higher in zone 5/6 parts of the state than the rest.
Most of the current population of CA is zone 3, which will have a much lower financial impact for taking it to Net Zero. But to some extent a state-wide requirement feels a bit like "tyranny of the majority", since the cost of development in the warmer areas where most people live will be markedly less expensive than the cooler areas of lower population, at least in the near term. The state of CA has long had different requirements for local insulation levels based on 16 climate zones defined under their state code. CA climate zone 16 lumps the areas that are US climate zones 5-7 (and parts of US zone 4) together. Zone 16 is something like 30% of the land area, but has less than 10% of the population: http://www.pge.com/myhome/edusafety/workshopstraining/pec/toolbox/arch/climate/index.shtml
Still this is a compromise .
Still have to figure an economical way to move insulation completely to the exterior,
which in turns simplifies the air sealing labor and performance on the "framing enveloppe" .
I am working on a very simple idea to use any type of rigid foam economically
( maybe could even work with rockwool batts/boards ) and still retain structural strong enough
to install very thick insulation and heavy regular sidings, using homehardware store materials.
And this is why we all agree on a climate based variation of PH.
16 climate zones..ahhahaha
It is difficult here to have builders to move on high efficiency standard designs with only a single zone,
imagine with 16 !!
thanks for the enlightment on the CA climate status!
California zones are legitimate
Between the ocean tempered rain forests, high altitude zones, and below sea-level deserts the climate really does vary by quite a bit in CA. There are locations that see +50C outdoor temps every year, and others that see -30C every year..
Like Quebec, from north to south California spans more than 15 degrees of latitude too, but unlike Quebec there are significant population centers along the entire swath.
To manage the whole range from high cooling-dominated areas to the cool heating dominated areas they came up with a more refined map than the US Department of Energy zoning, enshrined in law under California Title 24, a body of energy-efficiency code that gets updated every few years, and is in a constant state of reformation, with drafts of proposed changes making the rounds every month or two. It is extremely detailed & specific compared to the IBC/IRC/IECC or NBC. See: http://www.energy.ca.gov/title24/
R-Guard vs Zip
Mr. Hagerman you used both R-Guard and the Zip system on similar wall assemblies, can you go into detail of what you would use in the future and do you feel one is superior to the other? I am adding a second floor to a cape cod in Connecticut and I am unsure whether I should sheath with Zip or use R-Guard over OSB
R-Guard vs. Zip, Kevin D.
In my opinion, Zip is the easiest, most cost-effective solution for your particular project.
The superior airtight and resilient qualities of the r-Guard system might not be justifiable/necessary given that your project is an addition.
If the whole skin is being replaced and you are in a heavy weather exposure, I would think the R-Guard might be the one to use.
But in reality, both systems are quite good when compared to the norm.
Hope that helps!
Simple, not spoken here.
What's with you Passive House Dudes, have you never heard about KISS principles? 9, 10, 11, layers, no wounder you find Passive House more expensive. Building Science needs to step-up their participation here and earn their $ here before we all lose faith in their science charts and chanting.
Thanks Sam -I'm with you!
Hammer n Hand is awesome I love your website and learned a lot from you guys!
I'm a contractor from Long Island NY(cz4), and I actually did grow up with a hammer in my hand. After three years of building nothing but passive house designs similar to the wall sections in the article i have 2 cents to throw in the pot. We've hosted multiple passivhaus open house events to the public and met with hundreds of interested peoples from all walks. We set up mini conference style booths with window and wall sections. The interest was great, and most were very excited to learn about passive design. But most can't afford it and those that can usually jump right to the question of cost and payback. Without having the patience and wisdom of longterm view most of the skeptics walk away without even hearing half the argument for super efficient design. I guess these are the same people who argued that seat belt requirements were an infringement on our freedom!
It is my personal opinion that just because one can afford to buy as much energy or water resources as they want -they have NO right to use an unlimited and ever increasing amount of OUR precious resources! There most certainly needs to be a sliding scale of building requirements similar to the progressive tax code. What is the sense of building a 20,000sf mansion for a billionaire that doesn't use the principles we discuss in these blogs. I look at hundreds of plans every year and I am appalled at the crap designs that comes across my desk! And these are the people that can afford these details in the first place. Mostly architects are to blame here.
On a more positive note passive/very efficient homes are being built every day, we've done it and even made it on the local TV news for our effort! So I'm still pretty psyched for the future. I'm seeing new product developments all over the place, things are improving every year. Its up to us to keep moving the needle forward.
Currently we are using 2x6 walls w/ dense cellulose, zip wall/tape, 3" continous (roxul comfort boards) exterior insulation, second wrb, 1x4 rain screen and fiber cement to great effect. We relaxed the total obsession with chasing air leaks and just go with the pretty darn good system and run with it. The liquid applied WRB systems are awesome if you can afford it. (By the way you can use it on ZIP seems if you can't stand the tape, its approved) Thats why we need to push these systems on those that can afford it so we get some economy of scale. We've gotten pretty efficient at this process already having completed 10 buildings with various versions of the system. While none of these projects are less then 200$/sf. Im confident I can get the cost down, even below 200$/' if given total autonomy of the project/budget decisions. One such project i hope to accomplish starting in the spring. Hey I'm delighted to at least be a part of the trickle down.
Hey Sam I would love to read your take on Hempcrete.
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