Ten years ago, Michael Maines wrote an article for GBA called “The Pretty Good House.” In the years since that article was published, GBA readers have followed along as a talented group of Maine builders and designers have refined the “pretty good house” philosophy, which advocates details that are more energy-efficient than usual, more cost-effective than those of label-based programs like Passive House, and environmentally responsible.
Now Taunton Press has published a handsome, well-illustrated hardback book, Pretty Good House, by four of the founders of the PGH movement: Dan Kolbert, Emily Mottram, Michael Maines, and Christopher Briley.
The authors are probably familiar to most GBA readers. Dan Kolbert is a builder and the author of a GBA article called “A Case for Double-Stud Walls.” Emily Mottram is an architect and one of the hosts of GBA’s “BS* + Beer Show.” Michael Maines is a designer and the author of countless GBA articles, including “Minimizing Concrete in a Slab-on-Grade Home” and “Windows in Thick Walls.” Christopher Briley is an architect and one of the hosts of GBA’s “Green Architects’ Lounge” podcast.
In short, these four authors have long been active members of the GBA community. Their new book is a practical introduction to basic principles of residential design and building science for homeowners, builders, and architects. The authors’ approach mirrors advice provided by Green Building Advisor—so if you’re a GBA fan, you should buy this book. If you’re planning to build a custom home, you should buy three copies: one to keep, one to give to your designer, and one to give to your builder.
Before I proceed with my book review, here’s a disclaimer: I’ve known these authors for years, and their book praises my work and the work of Green Building Advisor—facts that make me biased.
The book is one of the best available guides to residential construction. The authors are very familiar with the usual weaknesses of conventional construction practices, and provide a good introduction to how those who follow the Pretty Good House approach can affordably improve on these practices.
In addition to providing cogent explanations of building science principles, the authors publish excellent detail drawings. For example, the details on pages 100 to 102 do a great job of informing readers of a variety of wall-to-foundation transitions (including a wall with exterior rigid foam above a concrete frost wall with exterior rigid foam, a double-stud wall over a concrete frost wall without exterior rigid foam, a double-stud wall over a basement with exterior rigid foam, and a Larsen-truss wall over a frost-protected shallow foundation) and wall-to-roof transitions (including a cathedral ceiling with solid-sawn rafters and gusset-attached 2x3s below for added insulation depth, as well as a more conventional raised-heel truss for a vented attic, both shown over double-stud walls).
When it comes to residential design, most builders omit crucial basic steps, including optimizing the design with energy modeling software, accurately calculating the home’s heating and cooling loads, performing one or more blower-door tests, and commissioning the HVAC equipment. Pretty Good House covers all of these issues in depth.
The book recommends design simplicity and HVAC simplicity (page 61): “… Though … architectural frills add interest, they also add cost, often create wasted space, and are the hardest features to manage well in terms of water leakage, air sealing, and insulation. … And making a house more architecturally complex does not necessarily make it more interesting or attractive. The clean lines and utilitarian designs that follow the Shaker philosophy of simplicity, utility, and honesty are still considered fresh and beautiful.”
The book also quotes GBA contributor Carl Seville (page 26): “… So many buildings are overly complicated… If you just think simply, it’s really easy to build a high-performance house.”
The book includes ten case studies (all written by longtime GBA author Scott Gibson). Several of these case studies, including the Sugar Bush house on page 108 and the Low Chem house on page 178, are excellent examples of design simplicity.
Like most of us who write about building science, the authors of this book had to make assumptions about a big unknown: how many concepts does the typical reader understand, and how deep into the weeds is the typical reader willing to wade? The authors manage to strike a balance. Inevitably, some readers will occasionally be scratching their heads in confusion, while others will be left hungry for greater depth.
Fortunately, the authors direct readers who want more information to several web sites, including BuildingScience.com and Green Building Advisor.
Embodied carbon discussion
The book’s authors do their best to address an important hot-button issue in green construction: the need to reduce “embodied carbon” in building materials. To begin the discussion, they provide a clear definition (p. 155): “Embodied carbon is the amount of carbon that is released into the atmosphere to harvest, manufacture, and deliver that material to the jobsite.”
The basic tension in this discussion comes from the awkward fact that our planet cannot afford additional releases of carbon into our atmosphere at this time. On this point, Pretty Good House quotes Steve Konstantino, who said, “The most sustainable building is the one that is never built.” The authors continue, “It is a reminder that building things is not inherently good for the planet.”
So what’s a builder to do? Attempting to choose materials that are manufactured with relatively low levels of atmospheric carbon releases is probably the best bet (short of retiring). The authors admit that this is a tough issue, and simply advise readers to do their best (p. 157): “Every house should be as carbon-neutral as possible.” When it comes to materials, the advice is, “Use as little as possible.”
The authors make a bold claim when they write, “Pretty Good builders and designers are always brutally honest with themselves about the sustainability of their products.” I find this statement hard to believe, since so many aspects of the North American lifestyle are unsustainable.
The sentence can be read many ways; on its surface, it appears boastful. Naïve readers may assume that if they locate a builder who claims to follow the Pretty Good creed, the builder’s sustainability claims can always be trusted. But since I’m familiar with understated Yankee wit, I suspect that the authors are saying something else: “We all know that the work we do is unsustainable, and when we hang out drinking beer, we’re brutally honest about that fact.”
If you are a builder from Louisiana, Montana, or California, be forewarned: this book is deeply Maine-centric. That’s both a weakness and a strength. The authors have taken to heart the dictum to “think globally, act locally.” In response to their environmental concerns, they’ve created an intensely local movement. We need similar groups in every state and province.
Although the book includes one case study each from Massachusetts, Georgia, and California, the other seven case studies are all from Maine or Vermont.
The four authors, all friends and colleagues, have developed a consensus on the best way to build single-family homes in Maine. Readers from other states may nod their heads in agreement—or may roll their eyes at the prejudices of Maine builders. After all, everyone has an opinion.
Here are some examples of the Maine consensus:
Insulation (page 173): “Hands down, one of our favorite types of insulation is cellulose, both dense-packed and loose fill.”
Double stud walls (page 92): “Relatively affordable and simple to construct, the double stud wall is a hero of the PGH crowd.”
Basements (page 96): “We’re just going to go ahead and say it. Basements are not great spaces.”
Mineral wool insulation (page 175): “Mineral wool … is relatively high in embodied carbon and the binders that hold the fibers together are typically phenol and urea formaldehyde-based. … For these reasons, we typically relegate this product to exterior use only.”
Wood stoves (pave 185): “Save your fire lust for a winter solstice bonfire or a camping trip and enjoy your quietly humming heat pump the rest of the time.”
Solar hot water (page 201): “With the great advances in photovoltaic panels, we never do solar hot water systems anymore.”
These opinions were developed the old-fashioned way: by trial, error, and experimentation. The authors have reached conclusions about what works in Maine. In all cases, the authors explain their reasoning. Even when you disagree with some of their conclusions, you’ll probably admire their forthrightness.
On most pages of Pretty Good House, I found myself nodding in agreement. Here’s a sample of the book’s good advice.
The builder should insist on good envelope details (page 37): “An idea that emerged from one of our discussion group sessions was to make the building shell non-negotiable. The contractor, perhaps in conjunction with the designer, comes up with a wall section, roof section, air-sealing details, minimum window performance, rainscreen details, and so on. … They are based on the contractor’s experience, research, and expertise and are no up for negotiation when the budget gets tight.”
Complete the design before construction starts (page 39). “Simple things like thickening an interior wall for ductwork, making sure window and door trim or roof overhangs can accommodate a rainscreen, or designing a roof to maximize PV panels are very difficult to shoehorn in after construction has started.”
Do houses have to breathe? (page 67): “Do not put your health in jeopardy by eliminating the ventilation system and building a house that ‘breathes.’ Houses don’t need to breathe; people need to breathe, houses need to dry.”
Don’t say ‘U-value’ (page 86): “Note that it’s R-value and U-factor.”
Good advice on air sealing (page 103): Imagine “we’re building a boat. If it leaks, we sink and we die!”
Limit glazing area (page 135). “In most climate zones, the more glass you add, the worse the house performs from an energy standpoint.”
What about triple-glazed windows? (page 142): “In Passive House design, triple-glazed windows are required; in PGH-land we only recommend them, but they are often a sensible choice if you aren’t in a mild climate.”
Roof overhangs (page 145): “Doors should always have a protective overhang.”
Skylights (page 147): “While contemporary name-brand skylights rarely leak when installed properly, … they do tend to be condensation machines. It’s very rare to see one that doesn’t have water damage around the lower portions.”
Solar light tubes (page 148): “With the low cost and easy installation of LED fixtures, its usually better to burn a few watts of energy with artificial lighting than to install what amounts to a chimney through your roof.”
On ventilation rates (page 197): “There’s a catch: there is an energy penalty. … So the goal should be sufficient ventilation but not overventilation.”
On batteries for grid-connected PV systems (page 216): For power when the grid goes down, “… a fossil-fuel powered standby generator is usually more cost-effective than a battery system.”
One of the book’s strengths is its focus on “lessons learned.” For example, two of the book’s case studies include second thoughts over specifying ductless minsiplits. On page 25, the authors discuss the ductless minisplits that Carl Seville installed in his Georgia home: “There are two heads upstairs and one down, and while they have performed adequately, they have required more maintenance and repairs than Seville would have liked. In retrospect, he says he might have used ducted minisplits…”
Similarly, Jeffrey Adams regrets the installation of a single ductless minisplit on the second floor of his California house (p. 206): “Adams chose a ductless minisplit heat pump system consisting of two outdoor compressors and two indoor units, one upstairs and one downstairs. … In hindsight Adams would have looked into a ducted minisplit for better air circulation on the second floor, even if he had to sacrifice a little efficiency to do so.”
Two of the authors, Maines and Kolbert, collaborated on a renovation project that resulted in another “lesson learned” (page 221). They “decided to save as much of the existing one-story house as they could before adding a new second floor. … In hindsight, that was a mistake, Kolbert says. … ‘Now I tell clients that no matter how much we demo, in the end we’re going to wish we had done more. … We try to save what we reasonably can and usually end up wishing we had done a little more demolition.”
Green builders will note, of course, that this conclusion is somewhat at odds with the green impulse to favor renovation over new construction. It turns out that in green building, as in life, there is no black or white—only shades of gray.
A few quibbles
Pretty Good House is a monumental achievement, but there are inevitably a few flies in the ointment. One problem is the authors’ tendency to overstate the health risks of new homes, as when they write (page 2), “…Two decades into the new millennium … houses were being built by the millions, and far too many of them were being built badly. They are unhealthy for their occupants…” Really? There is scant evidence that new American homes cause health problems for occupants. In fact, the real health hazards—lead paint, friable asbestos, and extensive mold—are far more likely to be found in old homes than new homes.
A few statements are head-scratchers—for example, this discussion of “smart” vapor retarders (page 119): “…[Some] builders opt for vapor-variable membranes. These membranes are applied to the interior of the assembly (just behind the finish material). … The idea is that the [vapor-variable] membrane will block vapor from migrating into wall and roof cavities in the winter, when indoor humidity is low…” Whether indoor absolute humidity in winter is low or high depends entirely on the lifestyle of the occupants, but when compared to the outdoor absolute humidity, it is always high, not low. In fact, the reason you might want a vapor-variable membrane under your drywall is to address high indoor humidity in winter, not low indoor humidity in winter.
This discussion of continuous insulation on the exterior side of wall sheathing is also confusing (page 121): “… An ‘outsulation’ approach … [involves] installing layers of rigid insulation outside the sheathing, essentially wrapping the outside of the building in a continuous layer of insulation. … If that outsulation is a material such as mineral wool or rigid wood-fiber insulation, then it, too, is a vapor-open assembly and has a very low risk of mold or mildew.”
In fact, a properly installed outsulation layer of foil-faced polyisocyanurate (in other words, an exterior vapor barrier) also creates “a very low risk of mold or mildew.” It turns out that the vapor permeance of the outsulation layer is irrelevant to this discussion.
The authors imply that roof venting can keep roofs cool (page 123): “As with a rainscreen for a wall assembly, roofs can be vented. It is very common to install soffit vents at the eaves and ridge vents at the ridge to promote constant airflow at the exterior of the roof assembly just under the sheathing. This is often done to help keep the roof cool in the summertime…” In fact, roof venting barely affects roofing temperatures (especially in the upper sections of roof slopes). The most important factor affecting roofing temperatures is the color of the roofing.
The authors imply that houses need a continuous, uninterrupted vapor control layer (page 126): “Things to consider: … Have you defined the vapor control layer, and does it remain continuous around the whole building envelope?” This makes no sense. The authors are applying air-barrier principles to vapor control, and the lessons aren’t applicable. While an air barrier needs to be continuous, vapor control barriers do not. You need polyethylene under your basement slab, but you don’t need polyethylene in your straw-bale walls.
Weatherization contractors will be astounded to learn (on page 123) that “Spray foam should not be relied upon as an air control method.” Elsewhere (on page 177) this advice is repeated: “Some builders and architects erroneously believe that you can air-seal a project with spray foam.” Evidently, the authors are worried about homes with spray foam that has shrunk away from framing members, introducing air leaks. This type of shrinkage can occur, but such cases are relatively rare. Spray foam is such a useful tool for addressing air leakage in older homes that this issue deserves a much more nuanced discussion than the authors provide.
The book includes a few internal contradictions. Some of these contradictions, I suspect, may arise from the fact that the book has four authors. For example, whoever wrote the first part of Chapter 7 declared (on page 165), “Spray foam and other materials release isocyanates, which cause flu-like symptoms or worse.” That sounds alarming. A few pages later, whoever wrote the second part of Chapter 7 expressed this opinion (page 177): “A properly installed spray foam installation should be inert when complete. It will outgas VOCs as it cures but will cease once curing is complete.”
Whoever wrote Chapter 4 expressed (on page 104) an apparent preference for ERVs over HRVs: “With a tight house, you need to supply balanced ventilation through an energy-recovery ventilator (ERV).” Yet whoever wrote Chapter 8 declared (on page 198), “Much (virtual) ink has been spilled on whether and where to use an HRV or an ERV, but in the end the quality of the unit itself, along with the installation and the maintenance of the unit and ductwork, outweighs any advantage of one system over the other.”
Similarly, the author of Chapter 8 stated (correctly) on page 192, “Most air conditioners, including heat pumps, can handle dehumidification.” Yet whoever wrote Chapter 10 declared (incorrectly) on page 232, “Air conditioners rarely provide the necessary dehumidification, so a separate dehumidifier is usually needed.”
The wealthy-client problem
On page 47, the authors of this book describe one of the case study houses this way: “The house on Maquoit Bay is neither small nor inexpensive.” Like most designers and builders who focus on custom homes, the four authors of Pretty Good House work for a privileged elite—the small subset of Americans who can afford to build an architect-designed home. This fact doesn’t reflect poorly on the authors—it’s simply the way our economy works.
What do the homes described in this book have to do with helping house the world’s 8 billion people, or helping us transition to a future without a looming threat of climate disaster? I’m not sure. All I know is that each of us needs to look at our daily work, and find ways to reduce our environmental footprint.
I really love Dan Kolbert, Emily Mottram, Michael Maines, and Chris Briley. They are among the smartest, most conscientious designers and builders I know, and they care deeply for the future of our planet. Like all Americans, they are swimming in a sea of contradictions—designing and building fine homes for a small slice of the planet’s population as our world keeps getting warmer.
Pretty Good House is available for $34.99 from Taunton Press.
— Martin Holladay is a retired editor who lives in Vermont.
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"it’s simply the way our economy works." - An unfortunate problem, and a particularly american problem.
I like that Emily provides some pre-designed home plans. And I think if architects/designers really want to make a dent in green home building, more of this needs to become available. There are those that can custom design a home with a real architect, but as mentioned, those are privileged people. I thought I could do this, and we weren't even close to affording it. GBA provides lots of details that an educated home-owner can put together for an affordable design with an "ordinary" designer. But having some more premade designs available that use affordable and efficient techniques would be great. Way too often people over complicate things, there are simple ways to achieve great buildings. I also think Matt Rissinger's idea that if you advertise air sealing as bug sealing to help reel more people in is a good one as funny and simple as it is.
I bought the book last month, I thought it was very educational and provided a lot of useful info as I work on designing what I want in my own home. I'm still on the fence about a good sealed fireplace or listening to my heat pump...
That this great book, and Musings of an Energy Nerd, grew out of the GBA community is testament to how useful the site has been.
I have always wanted a text I could use as a catalyst for discussions on building science with clients. It's fantastic that this group of both well intentioned and skilled practitioners have distilled their knowledge into that for us.
Exactly, Malcolm. In fact, I just wrote Martin an email saying that PGH presumably would've just remained a clever joke in our discussion group if not for the boost it got from Martin and GBA.
Gee, I always thought that you four authors stole the PGH name from Martin, he talked about it on GBA so often! ;-)
Just started reading your book...
No, I'm not the originator. I'm the thief...
I prefer “midwife”
I stumbled upon GBA and the PGH concept around 2013 when we were thinking about a new house. We moved in in 2015 and it has been just as good as we had hoped. Easy to heat, low maintenance, low energy bills make it more than pretty good. Thanks to the four authors, Martin, GBA, our architects Jesse Thompson and Jamie Broadbent and our wonderful builder, Tom Greenleaf.
It's taken me a bit to realize smlaw47 is you Stephen!
Im a pony!
Martin, thank-you for your candid review. I received my copy a week ago and have made it through about a third of the book. I appreciate the non-preachy tone of the authors.
I agree that the Main-centric viewpoint makes it a bit harder to recommend here in the PNW but there are not many books of the same caliber. Martin's "Musings" book should sit on every bookshelf, though.
The only cringe-worthy thing I have seen so far in the PGH book is the HRV diagram on page 19 showing air supply and intake to the garage! I have serious concerns with how the HRV core would handle petrochemical fumes or exhaust.
The diagram in question does, indeed, show an HRV system that pulls exhaust air from bathrooms and the garage, while delivering fresh air to bedrooms and the garage (see attached image).
Is this dangerous? My first reaction is, "Probably not," and my second reaction is, "Maybe." My third reaction is, "In all my years of reviewing ventilation duct designs, I've never seen a design like this."
My fourth reaction is, "Readers should be very cautious about implementing such a ventilation system, which would certainly be unwise if the appliance were an ERV instead of an HRV."
In theory, HRV cores are designed to prevent the mixing of air streams in the core. That said, cross-contamination of air streams definitely occurs in ERV cores.
[Later edit: Some online research has revealed that at least one European manufacturer of HRVs recommends against locating an HRV's exhaust grilles or fresh air registers in a garage. The company is Alnor, a manufacturer in Poland. On the web page of the company's British distributor, this warning is posted: "Connecting a garage/boiler room to the system: A garage and boiler room should not be connected to the mechanical supply and exhaust ventilation system distributed in the rest of the house. In these rooms, gravitational ventilation will perform its function well. Additionally, it is a good idea to install tight doors there to prevent air from these rooms from entering the house (as it may contain flue gas or carbon monoxide)."]
I had asked a few mechanical engineers if they would share a diagram we could use to generally represent mechanical design. This type of diagram isn't common for homes but my friend Bob, a mechanical engineer for 40 years, came through with one he used on his own house, a duplex with a large garage space that is conditioned and that he uses as a workshop. I edited some of the labels such as "Super's Office" so it would look more typical but I didn't think about the garage supply and extract ports as being unusual, though of course they are not common and wouldn't be appropriate for most homes.
Sharing the image without the caption leaves out this important note: "Mechanical design... should be done by someone with training and experience..."
Thanks, Michael, for providing those details on the diagram. I apologize for posting the image without the caption (which I removed for the simple reason that I thought the font would be too small to be legible).
I have restored the original scan, with the caption included.
I appreciate that things get missed in the rush to get projects finished!
The HRV diagram stood out to me after seeing so much ink spilled about how important it is to air-seal your garage and diligently separate it from the living space. It was ironic to think that the diagram was then taking all the potentially contaminated air and streaming it through a delicate plastic membrane adjacent to all the fresh breathing air being brought into the house!
A small criticism, though. The book is excellent and I commend all the authors for their hard work.
Let’s call it a self-correcting problem.
It's not just the potential for harmful vapor transfer through the core: it's also the potential for an pressure imbalance to reverse flow in some of the ducts, and directly more air from the garage, through the ductwork into the house. For example, if you run a vented dryer, a range hood, or a bathroom exhaust fan, you could end up sucking air from the garage into the house, reversing the flow in an exhaust vent in the house, or reversing the flow in a supply vent in the garage. To avoid that, you'd need the CFM of ERV or HRV to exceed the CFM of the exhaust fan that needs makeup air. That could happen with even just one of the appliances on and is almost certain to happen with more than one on.
Good point. It really goes back to the fact that designers should be very clear on what is "inside" vs "outside" the air-control system of the house.
"Whether indoor relative humidity in winter is low or high depends entirely on the lifestyle of the occupants, but when compared to the outdoor relative humidity, it is always high, not low."
Not sure about this. In these parts, outdoor RH in winter is considerably higher than indoor RH unless one is running extremely moist conditions indoors. (See charts on average ambient RH in winter for Maine as example).
Good catch. I meant to write "absolute humidity," not "relative humidity." I appreciate your correction. (For a discussion of this issue, see "Cold Air is Dry Air.")
Martin, thank you for a thorough and fair review. Your compliments are appreciated and criticisms are justified; you're correct that for the most part they are the result of having four authors, all busy with our day jobs and reviewing each others' work on increasingly messy Word documents long after deadlines had passed, so some details were regrettably missed. We'll fix them on what we hope will be many future printings.
As Dan Kolbert has noted, PGH wouldn't have escaped our little discussion group and certainly wouldn't have retained popularity for ten years if not for your help, which does make you biased, but also uniquely qualified to critique what we wrote.
It's worth noting that Martin's book reviews are often scathing, including for books written by people he knows and likes. The fact that this one is highly praised with only minor quibbles means a lot more than someone reading just this review would realize. Congratulations on the most positive (first positive?) Holladay book review ever. (And congratulations on an excellent book!)
We've been buttering him up for decades for precisely this moment. And thanks.
WHAT A GREAT BOOK! You guys have managed to cover all or nearly all the
important points in a comprehensive and thought-provoking manner. And,
you managed to do it without lapsing into expressions of ideology and moral
indignation - been reading a chapter or two per day and enjoyed all of them.
With a little luck maybe this will become a Goto for builders and the DIY set
for years to come.
CLAP, CLAP, CLAP, Cheer, Whistle,Etc.
Thanks so much. We definitely were trying to make it approachable and useful for as wide an audience as possible.
I find it a little amusing that the house on the cover is a 1 1/2 story house.
Why do you find it amusing? It's slightly more challenging to build than a 1- or 2-story house but not much. It keeps the scale down, the proportions pleasing and doesn't compromise how the occupants use the spaces. It saves on materials, including windows that would be looking directly into neighbors' homes. I think it's a perfect example of the thoughtfulness that should go into PGH design. And it's really a 1 3/4 story, as it has balloon-framed kneewalls on the second floor.
Azgreg is probably thinking of the problems associated with the small attics in between the knee walls and exterior ones in some old houses. In new construction, as long as the insulation and air-sealing follow the roofline, they work well.
Don't get me wrong. I love the style of a 1 1/2 story Cape. I love the shape and look of those 1/2 story rooms. However, I always felt that one of the principles of a PGH is a solid, less expensive insulation plan and nothing is more solid and less expensive than an attic floor loaded with cellulose.
That is often a goal, but then you either have a full second floor that requires expensive windows and additional finishes inside and out, or you have a one-floor plan that requires a bigger footprint and more exterior surface area. A 1.5-story Cape or 1.75-story farmhouse makes insulation detailing a little trickier but that is easily saved in other ways.
It's really two stories with a scissor truss and 5' kneewalls. I was trying to keep the proportions good and not too tall. And Michael is correct that the height eliminates the need for side windows on the second floor that would allow the close neighbors to see in. This sketch doesn't show the scissor truss but does show how far down the eave trim comes in relation to the second floor.
For more photos of this beautiful house: https://www.bluetimecollaborative.com/greenfield
Predesigned house plans available as well.
I'm interested in the idea that it saves windows. One could of course build two stories and omit windows on the walls that wouldn't have had them, but presumably the idea is that that would look wrong. What I'm wondering about is whether the wrongness of it would primarily be the way it looks from the outside, or from the inside, or both equally?
"the proportions pleasing"
I've always thought high posted capes (1 and 3/4 story as you say) have some of the nicest looking proportions for common and reasonably sized footprints.
I agree. They help you follow Christopher Alexander's pattern of a "sheltering roof", rather than the roof feeling like a cap.
I read it as soon as it arrived, but I keep going back and dipping into it again most evenings. It's just a really good book!
“…Two decades into the new millennium … houses were being built by the millions, and far too many of them were being built badly. They are unhealthy for their occupants…” There is scant evidence that new American homes cause health problems for occupants.
Unfortunately I totally agree with the book on this. You may be more aware of older homes, but regardless of home age, millions of people live in homes with enough mold to make them sick, whether they know it or not. I know many mold sensitized people such as myself through online groups who have to look at hundreds of homes to find one they don't react to. Architect Cheryl Ciecko teaches classes in how to build or buy a house without mold, and drives around the country taking videos of poor construction which is likely to lead to mold, much of which are houses currently under construction. This is a much bigger problem that is generally known. Or ask one of the few good mold remediators in the country and see what they say. They pretty much say every tract house in America has mold by the time it is finished.
As to the comment: "In fact, a properly installed outsulation layer of foil-faced polyisocyanurate (in other words, an exterior vapor barrier) also creates 'a very low risk of mold or mildew.'"
1) As you know there is still much debate about the ability to dry in both directions, but in my mind more drying is always better.
2) The key phrase you mentioned is "properly installed". How many are being properly installed? In my CZ 6 town, new homes (even $5m+), are using 1" of foam insulation over 2x6 walls, when that doesn't even meet code for the ratio of internal to external insulation. They're putting it on because they were told they need external insulation, but they don't understand condensation and inspectors aren't requiring the appropriate amount to hit the ratio.
https://www.greenbuildingadvisor.com/article/the-exterior-rigid-foam-is-too-thin Interestingly, you made this comment in 2017.
"In other words, these walls work if there is interior polyethylene and if the interior walls are fairly airtight. Under other circumstances, these walls can fail. So builders of new homes should continue to follow the rules -- because we want our walls to be robust, even when errors occur."
And how many interior walls do you think are airtight? Because I may have a bridge to sell you.
For an in-depth look on research data on how home specifications relate to human health, see "Housing and Human Health." I have never seen data to support your claim. There is limited data suggesting that mold-infested older homes -- generally speaking, low-income homes in very poor condition -- aggravate childhood asthma. There is no convincing data showing human health problems related to newly built U.S. homes. When it comes to older homes with deteriorating lead-based paint, however, public health authorities have abundant data on how these homes injure the health of residents -- particularly children and pregnant women.
Lots of data support my reporting that properly specified exterior polyisocyanurate makes wall sheathing dryer, not more damp. Building Science Corp. of Westford, Mass., and John Straube of Waterloo, Ontario, have been involved with several studies definitively proving this fact, and I can provide links to the studies if you doubt my summary. (For a sampling of the data on this issue, see "Persistent Worries About Exterior Rigid Foam.")
Spreading accurate information about good building practices is one of the roles of web sites like GBA. You're right that many builders are failing to follow good practices. GBA does its best to address this problem. I'm not in favor of bad building practices. But I will continue to advise readers who want to keep their wall sheathing dry that an excellent way to do that is to install properly specified (thick enough) exterior polyiso. I will also continue to report, accurately, that there is almost no data to support the claim that newly built houses in the U.S. are causing widespread health problems.
I'm back from my summer travels and thrilled to see this book announcement. My 3 copies are on order.
Ok but you understand they’re all going to be the same, right?
Peter is probably planning to do what I have and ordered a couple of extra copies to lend to clients.
Thanks for this review. At some point we need a "Pretty Good Renovation". I live in an old predominantly pre 1940 community where we are having a lot of discussion about envelope improvements. Pretty Good fits in with my own own doctrine of non-ideology.
Can you shed some light on this and provide some context?
I had a recent discussion with a PH architect and they were kind of dismissive of anything short of PH, "Pretty Good" won't cut it. I like your criticism of PH, and I think it wholly reasonable (eg what are we really getting out of the last 12 inches of underslab CCSF?)
PH is fine, but for the time being focusing on the largest opportunities and "better" seem to be the best way forward for the planet.
Can you draw a continuum between PGH and PH? I seems PGH can inform the capture of a lot more carbon with regards to renovation vs tring to do this with PH.
Re - PG Renovation: in the intro to the book they talk about why they have focused on new builds even though renovation is usually greener (but perhaps not cheaper, my words). There are too many variables in renovation work, and the work requires experienced trades people that can adjust/fix/adapt to all the stuff that isn't square, level, to code, or rotten, or etc.
Thanks for saying it for me! Renovations involve a lot more judgement calls, which makes it harder to provide comprehensive recommendations. But if we write another book, the topic would likely be renovations, including detailed case studies from different climate zones so we can show house-by-house what was done and why, and why it's "Pretty Good." The quick version is that in most cases, I think it makes sense to at least bring renovations up to current building codes. But it depends on the situation. If you're renovating a single room your decisions will be different than if you're doing a full gut renovation.
All of the PGH authors are also Passive House fans, and the three of us architects/designers are PH consultants. The two programs don't have to be mutually exclusive; PGH is a more comprehensive approach while PH focuses more narrowly on energy performance and indoor air quality. PGH does not include training or oversight, two things that PH excels at. I would be thrilled if every home could meet Passive House criteria, as long as it was done with minimal embodied carbon. But after doing a fair amount of PHPP modeling on my projects, which are usually high-performance, I know just how hard it is to fully meet the PH threshold, and if all of the stars don't align it can be nearly impossible.
Edit to add: there actually is now a Pretty Good House training program: https://finehomebuilding.mykajabi.com/pgh-landing-page-1?preview_theme_id=2151571616.
Not a bad review! Nice job and kudos for pointing out the bias and some of the inconsistencies (that I'm sure will get cleaned up for the 2nd edition).
I'm looking forward to West coast sequel "Pretty Rad House"
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